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    Subject[PATCH 41/49] ext4: Add multi block allocator for ext4
    Date
    From: Alex Tomas <alex@clusterfs.com>

    Signed-off-by: Alex Tomas <alex@clusterfs.com>
    Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
    Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    Signed-off-by: Eric Sandeen <sandeen@redhat.com>
    Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
    ---
    fs/ext4/Makefile | 2 +-
    fs/ext4/balloc.c | 67 +-
    fs/ext4/extents.c | 45 +-
    fs/ext4/inode.c | 15 +-
    fs/ext4/mballoc.c | 4551 ++++++++++++++++++++++++++++++++++++++++++++
    fs/ext4/migrate.c | 10 +-
    fs/ext4/super.c | 61 +-
    fs/ext4/xattr.c | 4 +-
    include/linux/ext4_fs.h | 76 +-
    include/linux/ext4_fs_i.h | 4 +
    include/linux/ext4_fs_sb.h | 52 +
    11 files changed, 4850 insertions(+), 37 deletions(-)
    create mode 100644 fs/ext4/mballoc.c

    diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
    index d5fd80b..ac6fa8c 100644
    --- a/fs/ext4/Makefile
    +++ b/fs/ext4/Makefile
    @@ -6,7 +6,7 @@ obj-$(CONFIG_EXT4DEV_FS) += ext4dev.o

    ext4dev-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o \
    ioctl.o namei.o super.o symlink.o hash.o resize.o extents.o \
    - ext4_jbd2.o migrate.o
    + ext4_jbd2.o migrate.o mballoc.o

    ext4dev-$(CONFIG_EXT4DEV_FS_XATTR) += xattr.o xattr_user.o xattr_trusted.o
    ext4dev-$(CONFIG_EXT4DEV_FS_POSIX_ACL) += acl.o
    diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
    index 54d3da7..643046b 100644
    --- a/fs/ext4/balloc.c
    +++ b/fs/ext4/balloc.c
    @@ -577,6 +577,8 @@ void ext4_discard_reservation(struct inode *inode)
    struct ext4_reserve_window_node *rsv;
    spinlock_t *rsv_lock = &EXT4_SB(inode->i_sb)->s_rsv_window_lock;

    + ext4_mb_discard_inode_preallocations(inode);
    +
    if (!block_i)
    return;

    @@ -785,19 +787,29 @@ error_return:
    * @inode: inode
    * @block: start physical block to free
    * @count: number of blocks to count
    + * @metadata: Are these metadata blocks
    */
    void ext4_free_blocks(handle_t *handle, struct inode *inode,
    - ext4_fsblk_t block, unsigned long count)
    + ext4_fsblk_t block, unsigned long count,
    + int metadata)
    {
    struct super_block * sb;
    unsigned long dquot_freed_blocks;

    + /* this isn't the right place to decide whether block is metadata
    + * inode.c/extents.c knows better, but for safety ... */
    + if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode) ||
    + ext4_should_journal_data(inode))
    + metadata = 1;
    +
    sb = inode->i_sb;
    - if (!sb) {
    - printk ("ext4_free_blocks: nonexistent device");
    - return;
    - }
    - ext4_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
    +
    + if (!test_opt(sb, MBALLOC) || !EXT4_SB(sb)->s_group_info)
    + ext4_free_blocks_sb(handle, sb, block, count,
    + &dquot_freed_blocks);
    + else
    + ext4_mb_free_blocks(handle, inode, block, count,
    + metadata, &dquot_freed_blocks);
    if (dquot_freed_blocks)
    DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
    return;
    @@ -1576,7 +1588,7 @@ int ext4_should_retry_alloc(struct super_block *sb, int *retries)
    }

    /**
    - * ext4_new_blocks() -- core block(s) allocation function
    + * ext4_new_blocks_old() -- core block(s) allocation function
    * @handle: handle to this transaction
    * @inode: file inode
    * @goal: given target block(filesystem wide)
    @@ -1589,7 +1601,7 @@ int ext4_should_retry_alloc(struct super_block *sb, int *retries)
    * any specific goal block.
    *
    */
    -ext4_fsblk_t ext4_new_blocks(handle_t *handle, struct inode *inode,
    +ext4_fsblk_t ext4_new_blocks_old(handle_t *handle, struct inode *inode,
    ext4_fsblk_t goal, unsigned long *count, int *errp)
    {
    struct buffer_head *bitmap_bh = NULL;
    @@ -1849,13 +1861,46 @@ out:
    }

    ext4_fsblk_t ext4_new_block(handle_t *handle, struct inode *inode,
    - ext4_fsblk_t goal, int *errp)
    + ext4_fsblk_t goal, int *errp)
    +{
    + struct ext4_allocation_request ar;
    + ext4_fsblk_t ret;
    +
    + if (!test_opt(inode->i_sb, MBALLOC)) {
    + unsigned long count = 1;
    + ret = ext4_new_blocks_old(handle, inode, goal, &count, errp);
    + return ret;
    + }
    +
    + memset(&ar, 0, sizeof(ar));
    + ar.inode = inode;
    + ar.goal = goal;
    + ar.len = 1;
    + ret = ext4_mb_new_blocks(handle, &ar, errp);
    + return ret;
    +}
    +
    +ext4_fsblk_t ext4_new_blocks(handle_t *handle, struct inode *inode,
    + ext4_fsblk_t goal, unsigned long *count, int *errp)
    {
    - unsigned long count = 1;
    + struct ext4_allocation_request ar;
    + ext4_fsblk_t ret;

    - return ext4_new_blocks(handle, inode, goal, &count, errp);
    + if (!test_opt(inode->i_sb, MBALLOC)) {
    + ret = ext4_new_blocks_old(handle, inode, goal, count, errp);
    + return ret;
    + }
    +
    + memset(&ar, 0, sizeof(ar));
    + ar.inode = inode;
    + ar.goal = goal;
    + ar.len = *count;
    + ret = ext4_mb_new_blocks(handle, &ar, errp);
    + *count = ar.len;
    + return ret;
    }

    +
    /**
    * ext4_count_free_blocks() -- count filesystem free blocks
    * @sb: superblock
    diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
    index a60227c..8cf5545 100644
    --- a/fs/ext4/extents.c
    +++ b/fs/ext4/extents.c
    @@ -853,7 +853,7 @@ cleanup:
    for (i = 0; i < depth; i++) {
    if (!ablocks[i])
    continue;
    - ext4_free_blocks(handle, inode, ablocks[i], 1);
    + ext4_free_blocks(handle, inode, ablocks[i], 1, 1);
    }
    }
    kfree(ablocks);
    @@ -1698,7 +1698,7 @@ static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
    ext_debug("index is empty, remove it, free block %llu\n", leaf);
    bh = sb_find_get_block(inode->i_sb, leaf);
    ext4_forget(handle, 1, inode, bh, leaf);
    - ext4_free_blocks(handle, inode, leaf, 1);
    + ext4_free_blocks(handle, inode, leaf, 1, 1);
    return err;
    }

    @@ -1759,8 +1759,10 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
    {
    struct buffer_head *bh;
    unsigned short ee_len = ext4_ext_get_actual_len(ex);
    - int i;
    + int i, metadata = 0;

    + if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
    + metadata = 1;
    #ifdef EXTENTS_STATS
    {
    struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
    @@ -1789,7 +1791,7 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
    bh = sb_find_get_block(inode->i_sb, start + i);
    ext4_forget(handle, 0, inode, bh, start + i);
    }
    - ext4_free_blocks(handle, inode, start, num);
    + ext4_free_blocks(handle, inode, start, num, metadata);
    } else if (from == le32_to_cpu(ex->ee_block)
    && to <= le32_to_cpu(ex->ee_block) + ee_len - 1) {
    printk(KERN_INFO "strange request: removal %u-%u from %u:%u\n",
    @@ -2287,6 +2289,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
    ext4_fsblk_t goal, newblock;
    int err = 0, depth, ret;
    unsigned long allocated = 0;
    + struct ext4_allocation_request ar;

    __clear_bit(BH_New, &bh_result->b_state);
    ext_debug("blocks %u/%lu requested for inode %u\n",
    @@ -2397,8 +2400,15 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
    if (S_ISREG(inode->i_mode) && (!EXT4_I(inode)->i_block_alloc_info))
    ext4_init_block_alloc_info(inode);

    - /* allocate new block */
    - goal = ext4_ext_find_goal(inode, path, iblock);
    + /* find neighbour allocated blocks */
    + ar.lleft = iblock;
    + err = ext4_ext_search_left(inode, path, &ar.lleft, &ar.pleft);
    + if (err)
    + goto out2;
    + ar.lright = iblock;
    + err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright);
    + if (err)
    + goto out2;

    /*
    * See if request is beyond maximum number of blocks we can have in
    @@ -2421,7 +2431,18 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
    allocated = le16_to_cpu(newex.ee_len);
    else
    allocated = max_blocks;
    - newblock = ext4_new_blocks(handle, inode, goal, &allocated, &err);
    +
    + /* allocate new block */
    + ar.inode = inode;
    + ar.goal = ext4_ext_find_goal(inode, path, iblock);
    + ar.logical = iblock;
    + ar.len = allocated;
    + if (S_ISREG(inode->i_mode))
    + ar.flags = EXT4_MB_HINT_DATA;
    + else
    + /* disable in-core preallocation for non-regular files */
    + ar.flags = 0;
    + newblock = ext4_mb_new_blocks(handle, &ar, &err);
    if (!newblock)
    goto out2;
    ext_debug("allocate new block: goal %llu, found %llu/%lu\n",
    @@ -2429,14 +2450,17 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,

    /* try to insert new extent into found leaf and return */
    ext4_ext_store_pblock(&newex, newblock);
    - newex.ee_len = cpu_to_le16(allocated);
    + newex.ee_len = cpu_to_le16(ar.len);
    if (create == EXT4_CREATE_UNINITIALIZED_EXT) /* Mark uninitialized */
    ext4_ext_mark_uninitialized(&newex);
    err = ext4_ext_insert_extent(handle, inode, path, &newex);
    if (err) {
    /* free data blocks we just allocated */
    + /* not a good idea to call discard here directly,
    + * but otherwise we'd need to call it every free() */
    + ext4_mb_discard_inode_preallocations(inode);
    ext4_free_blocks(handle, inode, ext_pblock(&newex),
    - le16_to_cpu(newex.ee_len));
    + le16_to_cpu(newex.ee_len), 0);
    goto out2;
    }

    @@ -2445,6 +2469,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,

    /* previous routine could use block we allocated */
    newblock = ext_pblock(&newex);
    + allocated = le16_to_cpu(newex.ee_len);
    outnew:
    __set_bit(BH_New, &bh_result->b_state);

    @@ -2496,6 +2521,8 @@ void ext4_ext_truncate(struct inode * inode, struct page *page)
    down_write(&EXT4_I(inode)->i_data_sem);
    ext4_ext_invalidate_cache(inode);

    + ext4_mb_discard_inode_preallocations(inode);
    +
    /*
    * TODO: optimization is possible here.
    * Probably we need not scan at all,
    diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
    index 3c013e5..2947800 100644
    --- a/fs/ext4/inode.c
    +++ b/fs/ext4/inode.c
    @@ -551,7 +551,7 @@ static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
    return ret;
    failed_out:
    for (i = 0; i <index; i++)
    - ext4_free_blocks(handle, inode, new_blocks[i], 1);
    + ext4_free_blocks(handle, inode, new_blocks[i], 1, 0);
    return ret;
    }

    @@ -650,9 +650,9 @@ failed:
    ext4_journal_forget(handle, branch[i].bh);
    }
    for (i = 0; i <indirect_blks; i++)
    - ext4_free_blocks(handle, inode, new_blocks[i], 1);
    + ext4_free_blocks(handle, inode, new_blocks[i], 1, 0);

    - ext4_free_blocks(handle, inode, new_blocks[i], num);
    + ext4_free_blocks(handle, inode, new_blocks[i], num, 0);

    return err;
    }
    @@ -749,9 +749,10 @@ err_out:
    for (i = 1; i <= num; i++) {
    BUFFER_TRACE(where[i].bh, "call jbd2_journal_forget");
    ext4_journal_forget(handle, where[i].bh);
    - ext4_free_blocks(handle,inode,le32_to_cpu(where[i-1].key),1);
    + ext4_free_blocks(handle, inode,
    + le32_to_cpu(where[i-1].key), 1, 0);
    }
    - ext4_free_blocks(handle, inode, le32_to_cpu(where[num].key), blks);
    + ext4_free_blocks(handle, inode, le32_to_cpu(where[num].key), blks, 0);

    return err;
    }
    @@ -2051,7 +2052,7 @@ static void ext4_clear_blocks(handle_t *handle, struct inode *inode,
    }
    }

    - ext4_free_blocks(handle, inode, block_to_free, count);
    + ext4_free_blocks(handle, inode, block_to_free, count, 0);
    }

    /**
    @@ -2224,7 +2225,7 @@ static void ext4_free_branches(handle_t *handle, struct inode *inode,
    ext4_journal_test_restart(handle, inode);
    }

    - ext4_free_blocks(handle, inode, nr, 1);
    + ext4_free_blocks(handle, inode, nr, 1, 1);

    if (parent_bh) {
    /*
    diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
    new file mode 100644
    index 0000000..0398aa0
    --- /dev/null
    +++ b/fs/ext4/mballoc.c
    @@ -0,0 +1,4551 @@
    +/*
    + * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
    + * Written by Alex Tomas <alex@clusterfs.com>
    + *
    + * This program is free software; you can redistribute it and/or modify
    + * it under the terms of the GNU General Public License version 2 as
    + * published by the Free Software Foundation.
    + *
    + * This program is distributed in the hope that it will be useful,
    + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    + * GNU General Public License for more details.
    + *
    + * You should have received a copy of the GNU General Public Licens
    + * along with this program; if not, write to the Free Software
    + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
    + */
    +
    +
    +/*
    + * mballoc.c contains the multiblocks allocation routines
    + */
    +
    +#include <linux/time.h>
    +#include <linux/fs.h>
    +#include <linux/namei.h>
    +#include <linux/ext4_jbd2.h>
    +#include <linux/ext4_fs.h>
    +#include <linux/quotaops.h>
    +#include <linux/buffer_head.h>
    +#include <linux/module.h>
    +#include <linux/swap.h>
    +#include <linux/proc_fs.h>
    +#include <linux/pagemap.h>
    +#include <linux/seq_file.h>
    +#include <linux/version.h>
    +#include "group.h"
    +
    +/*
    + * MUSTDO:
    + * - test ext4_ext_search_left() and ext4_ext_search_right()
    + * - search for metadata in few groups
    + *
    + * TODO v4:
    + * - normalization should take into account whether file is still open
    + * - discard preallocations if no free space left (policy?)
    + * - don't normalize tails
    + * - quota
    + * - reservation for superuser
    + *
    + * TODO v3:
    + * - bitmap read-ahead (proposed by Oleg Drokin aka green)
    + * - track min/max extents in each group for better group selection
    + * - mb_mark_used() may allocate chunk right after splitting buddy
    + * - tree of groups sorted by number of free blocks
    + * - error handling
    + */
    +
    +/*
    + * The allocation request involve request for multiple number of blocks
    + * near to the goal(block) value specified.
    + *
    + * During initialization phase of the allocator we decide to use the group
    + * preallocation or inode preallocation depending on the size file. The
    + * size of the file could be the resulting file size we would have after
    + * allocation or the current file size which ever is larger. If the size is
    + * less that sbi->s_mb_stream_request we select the group
    + * preallocation. The default value of s_mb_stream_request is 16
    + * blocks. This can also be tuned via
    + * /proc/fs/ext4/<partition>/stream_req. The value is represented in terms
    + * of number of blocks.
    + *
    + * The main motivation for having small file use group preallocation is to
    + * ensure that we have small file closer in the disk.
    + *
    + * First stage the allocator looks at the inode prealloc list
    + * ext4_inode_info->i_prealloc_list contain list of prealloc spaces for
    + * this particular inode. The inode prealloc space is represented as:
    + *
    + * pa_lstart -> the logical start block for this prealloc space
    + * pa_pstart -> the physical start block for this prealloc space
    + * pa_len -> lenght for this prealloc space
    + * pa_free -> free space available in this prealloc space
    + *
    + * The inode preallocation space is used looking at the _logical_ start
    + * block. If only the logical file block falls within the range of prealloc
    + * space we will consume the particular prealloc space. This make sure that
    + * that the we have contiguous physical blocks representing the file blocks
    + *
    + * The important thing to be noted in case of inode prealloc space is that
    + * we don't modify the values associated to inode prealloc space except
    + * pa_free.
    + *
    + * If we are not able to find blocks in the inode prealloc space and if we
    + * have the group allocation flag set then we look at the locality group
    + * prealloc space. These are per CPU prealloc list repreasented as
    + *
    + * ext4_sb_info.s_locality_groups[smp_processor_id()]
    + *
    + * The reason for having a per cpu locality group is to reduce the contention
    + * between CPUs. It is possible to get scheduled at this point.
    + *
    + * The locality group prealloc space is used looking at whether we have
    + * enough free space (pa_free) withing the prealloc space.
    + *
    + * If we can't allocate blocks via inode prealloc or/and locality group
    + * prealloc then we look at the buddy cache. The buddy cache is represented
    + * by ext4_sb_info.s_buddy_cache (struct inode) whose file offset gets
    + * mapped to the buddy and bitmap information regarding different
    + * groups. The buddy information is attached to buddy cache inode so that
    + * we can access them through the page cache. The information regarding
    + * each group is loaded via ext4_mb_load_buddy. The information involve
    + * block bitmap and buddy information. The information are stored in the
    + * inode as:
    + *
    + * { page }
    + * [ group 0 buddy][ group 0 bitmap] [group 1][ group 1]...
    + *
    + *
    + * one block each for bitmap and buddy information. So for each group we
    + * take up 2 blocks. A page can contain blocks_per_page (PAGE_CACHE_SIZE /
    + * blocksize) blocks. So it can have information regarding groups_per_page
    + * which is blocks_per_page/2
    + *
    + * The buddy cache inode is not stored on disk. The inode is thrown
    + * away when the filesystem is unmounted.
    + *
    + * We look for count number of blocks in the buddy cache. If we were able
    + * to locate that many free blocks we return with additional information
    + * regarding rest of the contiguous physical block available
    + *
    + * Before allocating blocks via buddy cache we normalize the request
    + * blocks. This ensure we ask for more blocks that we needed. The extra
    + * blocks that we get after allocation is added to the respective prealloc
    + * list. In case of inode preallocation we follow a list of heuristics
    + * based on file size. This can be found in ext4_mb_normalize_request. If
    + * we are doing a group prealloc we try to normalize the request to
    + * sbi->s_mb_group_prealloc. Default value of s_mb_group_prealloc is set to
    + * 512 blocks. This can be tuned via
    + * /proc/fs/ext4/<partition/group_prealloc. The value is represented in
    + * terms of number of blocks. If we have mounted the file system with -O
    + * stripe=<value> option the group prealloc request is normalized to the
    + * stripe value (sbi->s_stripe)
    + *
    + * The regular allocator(using the buddy cache) support few tunables.
    + *
    + * /proc/fs/ext4/<partition>/min_to_scan
    + * /proc/fs/ext4/<partition>/max_to_scan
    + * /proc/fs/ext4/<partition>/order2_req
    + *
    + * The regular allocator use buddy scan only if the request len is power of
    + * 2 blocks and the order of allocation is >= sbi->s_mb_order2_reqs. The
    + * value of s_mb_order2_reqs can be tuned via
    + * /proc/fs/ext4/<partition>/order2_req. If the request len is equal to
    + * stripe size (sbi->s_stripe), we try to search for contigous block in
    + * stripe size. This should result in better allocation on RAID setup. If
    + * not we search in the specific group using bitmap for best extents. The
    + * tunable min_to_scan and max_to_scan controll the behaviour here.
    + * min_to_scan indicate how long the mballoc __must__ look for a best
    + * extent and max_to_scanindicate how long the mballoc __can__ look for a
    + * best extent in the found extents. Searching for the blocks starts with
    + * the group specified as the goal value in allocation context via
    + * ac_g_ex. Each group is first checked based on the criteria whether it
    + * can used for allocation. ext4_mb_good_group explains how the groups are
    + * checked.
    + *
    + * Both the prealloc space are getting populated as above. So for the first
    + * request we will hit the buddy cache which will result in this prealloc
    + * space getting filled. The prealloc space is then later used for the
    + * subsequent request.
    + */
    +
    +/*
    + * mballoc operates on the following data:
    + * - on-disk bitmap
    + * - in-core buddy (actually includes buddy and bitmap)
    + * - preallocation descriptors (PAs)
    + *
    + * there are two types of preallocations:
    + * - inode
    + * assiged to specific inode and can be used for this inode only.
    + * it describes part of inode's space preallocated to specific
    + * physical blocks. any block from that preallocated can be used
    + * independent. the descriptor just tracks number of blocks left
    + * unused. so, before taking some block from descriptor, one must
    + * make sure corresponded logical block isn't allocated yet. this
    + * also means that freeing any block within descriptor's range
    + * must discard all preallocated blocks.
    + * - locality group
    + * assigned to specific locality group which does not translate to
    + * permanent set of inodes: inode can join and leave group. space
    + * from this type of preallocation can be used for any inode. thus
    + * it's consumed from the beginning to the end.
    + *
    + * relation between them can be expressed as:
    + * in-core buddy = on-disk bitmap + preallocation descriptors
    + *
    + * this mean blocks mballoc considers used are:
    + * - allocated blocks (persistent)
    + * - preallocated blocks (non-persistent)
    + *
    + * consistency in mballoc world means that at any time a block is either
    + * free or used in ALL structures. notice: "any time" should not be read
    + * literally -- time is discrete and delimited by locks.
    + *
    + * to keep it simple, we don't use block numbers, instead we count number of
    + * blocks: how many blocks marked used/free in on-disk bitmap, buddy and PA.
    + *
    + * all operations can be expressed as:
    + * - init buddy: buddy = on-disk + PAs
    + * - new PA: buddy += N; PA = N
    + * - use inode PA: on-disk += N; PA -= N
    + * - discard inode PA buddy -= on-disk - PA; PA = 0
    + * - use locality group PA on-disk += N; PA -= N
    + * - discard locality group PA buddy -= PA; PA = 0
    + * note: 'buddy -= on-disk - PA' is used to show that on-disk bitmap
    + * is used in real operation because we can't know actual used
    + * bits from PA, only from on-disk bitmap
    + *
    + * if we follow this strict logic, then all operations above should be atomic.
    + * given some of them can block, we'd have to use something like semaphores
    + * killing performance on high-end SMP hardware. let's try to relax it using
    + * the following knowledge:
    + * 1) if buddy is referenced, it's already initialized
    + * 2) while block is used in buddy and the buddy is referenced,
    + * nobody can re-allocate that block
    + * 3) we work on bitmaps and '+' actually means 'set bits'. if on-disk has
    + * bit set and PA claims same block, it's OK. IOW, one can set bit in
    + * on-disk bitmap if buddy has same bit set or/and PA covers corresponded
    + * block
    + *
    + * so, now we're building a concurrency table:
    + * - init buddy vs.
    + * - new PA
    + * blocks for PA are allocated in the buddy, buddy must be referenced
    + * until PA is linked to allocation group to avoid concurrent buddy init
    + * - use inode PA
    + * we need to make sure that either on-disk bitmap or PA has uptodate data
    + * given (3) we care that PA-=N operation doesn't interfere with init
    + * - discard inode PA
    + * the simplest way would be to have buddy initialized by the discard
    + * - use locality group PA
    + * again PA-=N must be serialized with init
    + * - discard locality group PA
    + * the simplest way would be to have buddy initialized by the discard
    + * - new PA vs.
    + * - use inode PA
    + * i_data_sem serializes them
    + * - discard inode PA
    + * discard process must wait until PA isn't used by another process
    + * - use locality group PA
    + * some mutex should serialize them
    + * - discard locality group PA
    + * discard process must wait until PA isn't used by another process
    + * - use inode PA
    + * - use inode PA
    + * i_data_sem or another mutex should serializes them
    + * - discard inode PA
    + * discard process must wait until PA isn't used by another process
    + * - use locality group PA
    + * nothing wrong here -- they're different PAs covering different blocks
    + * - discard locality group PA
    + * discard process must wait until PA isn't used by another process
    + *
    + * now we're ready to make few consequences:
    + * - PA is referenced and while it is no discard is possible
    + * - PA is referenced until block isn't marked in on-disk bitmap
    + * - PA changes only after on-disk bitmap
    + * - discard must not compete with init. either init is done before
    + * any discard or they're serialized somehow
    + * - buddy init as sum of on-disk bitmap and PAs is done atomically
    + *
    + * a special case when we've used PA to emptiness. no need to modify buddy
    + * in this case, but we should care about concurrent init
    + *
    + */
    +
    + /*
    + * Logic in few words:
    + *
    + * - allocation:
    + * load group
    + * find blocks
    + * mark bits in on-disk bitmap
    + * release group
    + *
    + * - use preallocation:
    + * find proper PA (per-inode or group)
    + * load group
    + * mark bits in on-disk bitmap
    + * release group
    + * release PA
    + *
    + * - free:
    + * load group
    + * mark bits in on-disk bitmap
    + * release group
    + *
    + * - discard preallocations in group:
    + * mark PAs deleted
    + * move them onto local list
    + * load on-disk bitmap
    + * load group
    + * remove PA from object (inode or locality group)
    + * mark free blocks in-core
    + *
    + * - discard inode's preallocations:
    + */
    +
    +/*
    + * Locking rules
    + *
    + * Locks:
    + * - bitlock on a group (group)
    + * - object (inode/locality) (object)
    + * - per-pa lock (pa)
    + *
    + * Paths:
    + * - new pa
    + * object
    + * group
    + *
    + * - find and use pa:
    + * pa
    + *
    + * - release consumed pa:
    + * pa
    + * group
    + * object
    + *
    + * - generate in-core bitmap:
    + * group
    + * pa
    + *
    + * - discard all for given object (inode, locality group):
    + * object
    + * pa
    + * group
    + *
    + * - discard all for given group:
    + * group
    + * pa
    + * group
    + * object
    + *
    + */
    +
    +/*
    + * with AGGRESSIVE_CHECK allocator runs consistency checks over
    + * structures. these checks slow things down a lot
    + */
    +#define AGGRESSIVE_CHECK__
    +
    +/*
    + * with DOUBLE_CHECK defined mballoc creates persistent in-core
    + * bitmaps, maintains and uses them to check for double allocations
    + */
    +#define DOUBLE_CHECK__
    +
    +/*
    + */
    +#define MB_DEBUG__
    +#ifdef MB_DEBUG
    +#define mb_debug(fmt, a...) printk(fmt, ##a)
    +#else
    +#define mb_debug(fmt, a...)
    +#endif
    +
    +/*
    + * with EXT4_MB_HISTORY mballoc stores last N allocations in memory
    + * and you can monitor it in /proc/fs/ext4/<dev>/mb_history
    + */
    +#define EXT4_MB_HISTORY
    +#define EXT4_MB_HISTORY_ALLOC 1 /* allocation */
    +#define EXT4_MB_HISTORY_PREALLOC 2 /* preallocated blocks used */
    +#define EXT4_MB_HISTORY_DISCARD 4 /* preallocation discarded */
    +#define EXT4_MB_HISTORY_FREE 8 /* free */
    +
    +#define EXT4_MB_HISTORY_DEFAULT (EXT4_MB_HISTORY_ALLOC | \
    + EXT4_MB_HISTORY_PREALLOC)
    +
    +/*
    + * How long mballoc can look for a best extent (in found extents)
    + */
    +#define MB_DEFAULT_MAX_TO_SCAN 200
    +
    +/*
    + * How long mballoc must look for a best extent
    + */
    +#define MB_DEFAULT_MIN_TO_SCAN 10
    +
    +/*
    + * How many groups mballoc will scan looking for the best chunk
    + */
    +#define MB_DEFAULT_MAX_GROUPS_TO_SCAN 5
    +
    +/*
    + * with 'ext4_mb_stats' allocator will collect stats that will be
    + * shown at umount. The collecting costs though!
    + */
    +#define MB_DEFAULT_STATS 1
    +
    +/*
    + * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
    + * by the stream allocator, which purpose is to pack requests
    + * as close each to other as possible to produce smooth I/O traffic
    + * We use locality group prealloc space for stream request.
    + * We can tune the same via /proc/fs/ext4/<parition>/stream_req
    + */
    +#define MB_DEFAULT_STREAM_THRESHOLD 16 /* 64K */
    +
    +/*
    + * for which requests use 2^N search using buddies
    + */
    +#define MB_DEFAULT_ORDER2_REQS 2
    +
    +/*
    + * default group prealloc size 512 blocks
    + */
    +#define MB_DEFAULT_GROUP_PREALLOC 512
    +
    +static struct kmem_cache *ext4_pspace_cachep;
    +
    +#ifdef EXT4_BB_MAX_BLOCKS
    +#undef EXT4_BB_MAX_BLOCKS
    +#endif
    +#define EXT4_BB_MAX_BLOCKS 30
    +
    +struct ext4_free_metadata {
    + ext4_group_t group;
    + unsigned short num;
    + ext4_grpblk_t blocks[EXT4_BB_MAX_BLOCKS];
    + struct list_head list;
    +};
    +
    +struct ext4_group_info {
    + unsigned long bb_state;
    + unsigned long bb_tid;
    + struct ext4_free_metadata *bb_md_cur;
    + unsigned short bb_first_free;
    + unsigned short bb_free;
    + unsigned short bb_fragments;
    + struct list_head bb_prealloc_list;
    +#ifdef DOUBLE_CHECK
    + void *bb_bitmap;
    +#endif
    + unsigned short bb_counters[];
    +};
    +
    +#define EXT4_GROUP_INFO_NEED_INIT_BIT 0
    +#define EXT4_GROUP_INFO_LOCKED_BIT 1
    +
    +#define EXT4_MB_GRP_NEED_INIT(grp) \
    + (test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
    +
    +
    +struct ext4_prealloc_space {
    + struct list_head pa_inode_list;
    + struct list_head pa_group_list;
    + union {
    + struct list_head pa_tmp_list;
    + struct rcu_head pa_rcu;
    + } u;
    + spinlock_t pa_lock;
    + atomic_t pa_count;
    + unsigned pa_deleted;
    + ext4_fsblk_t pa_pstart; /* phys. block */
    + ext4_lblk_t pa_lstart; /* log. block */
    + unsigned short pa_len; /* len of preallocated chunk */
    + unsigned short pa_free; /* how many blocks are free */
    + unsigned short pa_linear; /* consumed in one direction
    + * strictly, for grp prealloc */
    + spinlock_t *pa_obj_lock;
    + struct inode *pa_inode; /* hack, for history only */
    +};
    +
    +
    +struct ext4_free_extent {
    + ext4_lblk_t fe_logical;
    + ext4_grpblk_t fe_start;
    + ext4_group_t fe_group;
    + int fe_len;
    +};
    +
    +/*
    + * Locality group:
    + * we try to group all related changes together
    + * so that writeback can flush/allocate them together as well
    + */
    +struct ext4_locality_group {
    + /* for allocator */
    + struct semaphore lg_sem; /* to serialize allocates */
    + struct list_head lg_prealloc_list;/* list of preallocations */
    + spinlock_t lg_prealloc_lock;
    +};
    +
    +struct ext4_allocation_context {
    + struct inode *ac_inode;
    + struct super_block *ac_sb;
    +
    + /* original request */
    + struct ext4_free_extent ac_o_ex;
    +
    + /* goal request (after normalization) */
    + struct ext4_free_extent ac_g_ex;
    +
    + /* the best found extent */
    + struct ext4_free_extent ac_b_ex;
    +
    + /* copy of the bext found extent taken before preallocation efforts */
    + struct ext4_free_extent ac_f_ex;
    +
    + /* number of iterations done. we have to track to limit searching */
    + unsigned long ac_ex_scanned;
    + __u16 ac_groups_scanned;
    + __u16 ac_found;
    + __u16 ac_tail;
    + __u16 ac_buddy;
    + __u16 ac_flags; /* allocation hints */
    + __u8 ac_status;
    + __u8 ac_criteria;
    + __u8 ac_repeats;
    + __u8 ac_2order; /* if request is to allocate 2^N blocks and
    + * N > 0, the field stores N, otherwise 0 */
    + __u8 ac_op; /* operation, for history only */
    + struct page *ac_bitmap_page;
    + struct page *ac_buddy_page;
    + struct ext4_prealloc_space *ac_pa;
    + struct ext4_locality_group *ac_lg;
    +};
    +
    +#define AC_STATUS_CONTINUE 1
    +#define AC_STATUS_FOUND 2
    +#define AC_STATUS_BREAK 3
    +
    +struct ext4_mb_history {
    + struct ext4_free_extent orig; /* orig allocation */
    + struct ext4_free_extent goal; /* goal allocation */
    + struct ext4_free_extent result; /* result allocation */
    + unsigned pid;
    + unsigned ino;
    + __u16 found; /* how many extents have been found */
    + __u16 groups; /* how many groups have been scanned */
    + __u16 tail; /* what tail broke some buddy */
    + __u16 buddy; /* buddy the tail ^^^ broke */
    + __u16 flags;
    + __u8 cr:3; /* which phase the result extent was found at */
    + __u8 op:4;
    + __u8 merged:1;
    +};
    +
    +struct ext4_buddy {
    + struct page *bd_buddy_page;
    + void *bd_buddy;
    + struct page *bd_bitmap_page;
    + void *bd_bitmap;
    + struct ext4_group_info *bd_info;
    + struct super_block *bd_sb;
    + __u16 bd_blkbits;
    + ext4_group_t bd_group;
    +};
    +#define EXT4_MB_BITMAP(e4b) ((e4b)->bd_bitmap)
    +#define EXT4_MB_BUDDY(e4b) ((e4b)->bd_buddy)
    +
    +#ifndef EXT4_MB_HISTORY
    +#define ext4_mb_store_history(ac)
    +#else
    +static void ext4_mb_store_history(struct ext4_allocation_context *ac);
    +#endif
    +
    +#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
    +
    +static struct proc_dir_entry *proc_root_ext4;
    +struct buffer_head *read_block_bitmap(struct super_block *, ext4_group_t);
    +ext4_fsblk_t ext4_new_blocks_old(handle_t *handle, struct inode *inode,
    + ext4_fsblk_t goal, unsigned long *count, int *errp);
    +
    +static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
    + ext4_group_t group);
    +static void ext4_mb_poll_new_transaction(struct super_block *, handle_t *);
    +static void ext4_mb_free_committed_blocks(struct super_block *);
    +static void ext4_mb_return_to_preallocation(struct inode *inode,
    + struct ext4_buddy *e4b, sector_t block,
    + int count);
    +static void ext4_mb_put_pa(struct ext4_allocation_context *,
    + struct super_block *, struct ext4_prealloc_space *pa);
    +static int ext4_mb_init_per_dev_proc(struct super_block *sb);
    +static int ext4_mb_destroy_per_dev_proc(struct super_block *sb);
    +
    +
    +static inline void ext4_lock_group(struct super_block *sb, ext4_group_t group)
    +{
    + struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
    +
    + bit_spin_lock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
    +}
    +
    +static inline void ext4_unlock_group(struct super_block *sb,
    + ext4_group_t group)
    +{
    + struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
    +
    + bit_spin_unlock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
    +}
    +
    +static inline int ext4_is_group_locked(struct super_block *sb,
    + ext4_group_t group)
    +{
    + struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
    +
    + return bit_spin_is_locked(EXT4_GROUP_INFO_LOCKED_BIT,
    + &(grinfo->bb_state));
    +}
    +
    +static ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
    + struct ext4_free_extent *fex)
    +{
    + ext4_fsblk_t block;
    +
    + block = (ext4_fsblk_t) fex->fe_group * EXT4_BLOCKS_PER_GROUP(sb)
    + + fex->fe_start
    + + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
    + return block;
    +}
    +
    +#if BITS_PER_LONG == 64
    +#define mb_correct_addr_and_bit(bit, addr) \
    +{ \
    + bit += ((unsigned long) addr & 7UL) << 3; \
    + addr = (void *) ((unsigned long) addr & ~7UL); \
    +}
    +#elif BITS_PER_LONG == 32
    +#define mb_correct_addr_and_bit(bit, addr) \
    +{ \
    + bit += ((unsigned long) addr & 3UL) << 3; \
    + addr = (void *) ((unsigned long) addr & ~3UL); \
    +}
    +#else
    +#error "how many bits you are?!"
    +#endif
    +
    +static inline int mb_test_bit(int bit, void *addr)
    +{
    + mb_correct_addr_and_bit(bit, addr);
    + return ext4_test_bit(bit, addr);
    +}
    +
    +static inline void mb_set_bit(int bit, void *addr)
    +{
    + mb_correct_addr_and_bit(bit, addr);
    + ext4_set_bit(bit, addr);
    +}
    +
    +static inline void mb_set_bit_atomic(spinlock_t *lock, int bit, void *addr)
    +{
    + mb_correct_addr_and_bit(bit, addr);
    + ext4_set_bit_atomic(lock, bit, addr);
    +}
    +
    +static inline void mb_clear_bit(int bit, void *addr)
    +{
    + mb_correct_addr_and_bit(bit, addr);
    + ext4_clear_bit(bit, addr);
    +}
    +
    +static inline void mb_clear_bit_atomic(spinlock_t *lock, int bit, void *addr)
    +{
    + mb_correct_addr_and_bit(bit, addr);
    + ext4_clear_bit_atomic(lock, bit, addr);
    +}
    +
    +static inline void *mb_find_buddy(struct ext4_buddy *e4b, int order, int *max)
    +{
    + char *bb;
    +
    + /* FIXME!! is this needed */
    + BUG_ON(EXT4_MB_BITMAP(e4b) == EXT4_MB_BUDDY(e4b));
    + BUG_ON(max == NULL);
    +
    + if (order > e4b->bd_blkbits + 1) {
    + *max = 0;
    + return NULL;
    + }
    +
    + /* at order 0 we see each particular block */
    + *max = 1 << (e4b->bd_blkbits + 3);
    + if (order == 0)
    + return EXT4_MB_BITMAP(e4b);
    +
    + bb = EXT4_MB_BUDDY(e4b) + EXT4_SB(e4b->bd_sb)->s_mb_offsets[order];
    + *max = EXT4_SB(e4b->bd_sb)->s_mb_maxs[order];
    +
    + return bb;
    +}
    +
    +#ifdef DOUBLE_CHECK
    +static void mb_free_blocks_double(struct inode *inode, struct ext4_buddy *e4b,
    + int first, int count)
    +{
    + int i;
    + struct super_block *sb = e4b->bd_sb;
    +
    + if (unlikely(e4b->bd_info->bb_bitmap == NULL))
    + return;
    + BUG_ON(!ext4_is_group_locked(sb, e4b->bd_group));
    + for (i = 0; i < count; i++) {
    + if (!mb_test_bit(first + i, e4b->bd_info->bb_bitmap)) {
    + ext4_fsblk_t blocknr;
    + blocknr = e4b->bd_group * EXT4_BLOCKS_PER_GROUP(sb);
    + blocknr += first + i;
    + blocknr +=
    + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
    +
    + ext4_error(sb, __FUNCTION__, "double-free of inode"
    + " %lu's block %llu(bit %u in group %lu)\n",
    + inode ? inode->i_ino : 0, blocknr,
    + first + i, e4b->bd_group);
    + }
    + mb_clear_bit(first + i, e4b->bd_info->bb_bitmap);
    + }
    +}
    +
    +static void mb_mark_used_double(struct ext4_buddy *e4b, int first, int count)
    +{
    + int i;
    +
    + if (unlikely(e4b->bd_info->bb_bitmap == NULL))
    + return;
    + BUG_ON(!ext4_is_group_locked(e4b->bd_sb, e4b->bd_group));
    + for (i = 0; i < count; i++) {
    + BUG_ON(mb_test_bit(first + i, e4b->bd_info->bb_bitmap));
    + mb_set_bit(first + i, e4b->bd_info->bb_bitmap);
    + }
    +}
    +
    +static void mb_cmp_bitmaps(struct ext4_buddy *e4b, void *bitmap)
    +{
    + if (memcmp(e4b->bd_info->bb_bitmap, bitmap, e4b->bd_sb->s_blocksize)) {
    + unsigned char *b1, *b2;
    + int i;
    + b1 = (unsigned char *) e4b->bd_info->bb_bitmap;
    + b2 = (unsigned char *) bitmap;
    + for (i = 0; i < e4b->bd_sb->s_blocksize; i++) {
    + if (b1[i] != b2[i]) {
    + printk("corruption in group %lu at byte %u(%u):"
    + " %x in copy != %x on disk/prealloc\n",
    + e4b->bd_group, i, i * 8, b1[i], b2[i]);
    + BUG();
    + }
    + }
    + }
    +}
    +
    +#else
    +#define mb_free_blocks_double(a, b, c, d)
    +#define mb_mark_used_double(a, b, c)
    +#define mb_cmp_bitmaps(a, b)
    +#endif
    +
    +#ifdef AGGRESSIVE_CHECK
    +
    +#define MB_CHECK_ASSERT(assert) \
    +do { \
    + if (!(assert)) { \
    + printk(KERN_EMERG \
    + "Assertion failure in %s() at %s:%d: \"%s\"\n", \
    + function, file, line, # assert); \
    + BUG(); \
    + } \
    +} while (0)
    +
    +static int __mb_check_buddy(struct ext4_buddy *e4b, char *file,
    + const char *function, int line)
    +{
    + struct super_block *sb = e4b->bd_sb;
    + int order = e4b->bd_blkbits + 1;
    + int max;
    + int max2;
    + int i;
    + int j;
    + int k;
    + int count;
    + struct ext4_group_info *grp;
    + int fragments = 0;
    + int fstart;
    + struct list_head *cur;
    + void *buddy;
    + void *buddy2;
    +
    + if (!test_opt(sb, MBALLOC))
    + return 0;
    +
    + {
    + static int mb_check_counter;
    + if (mb_check_counter++ % 100 != 0)
    + return 0;
    + }
    +
    + while (order > 1) {
    + buddy = mb_find_buddy(e4b, order, &max);
    + MB_CHECK_ASSERT(buddy);
    + buddy2 = mb_find_buddy(e4b, order - 1, &max2);
    + MB_CHECK_ASSERT(buddy2);
    + MB_CHECK_ASSERT(buddy != buddy2);
    + MB_CHECK_ASSERT(max * 2 == max2);
    +
    + count = 0;
    + for (i = 0; i < max; i++) {
    +
    + if (mb_test_bit(i, buddy)) {
    + /* only single bit in buddy2 may be 1 */
    + if (!mb_test_bit(i << 1, buddy2)) {
    + MB_CHECK_ASSERT(
    + mb_test_bit((i<<1)+1, buddy2));
    + } else if (!mb_test_bit((i << 1) + 1, buddy2)) {
    + MB_CHECK_ASSERT(
    + mb_test_bit(i << 1, buddy2));
    + }
    + continue;
    + }
    +
    + /* both bits in buddy2 must be 0 */
    + MB_CHECK_ASSERT(mb_test_bit(i << 1, buddy2));
    + MB_CHECK_ASSERT(mb_test_bit((i << 1) + 1, buddy2));
    +
    + for (j = 0; j < (1 << order); j++) {
    + k = (i * (1 << order)) + j;
    + MB_CHECK_ASSERT(
    + !mb_test_bit(k, EXT4_MB_BITMAP(e4b)));
    + }
    + count++;
    + }
    + MB_CHECK_ASSERT(e4b->bd_info->bb_counters[order] == count);
    + order--;
    + }
    +
    + fstart = -1;
    + buddy = mb_find_buddy(e4b, 0, &max);
    + for (i = 0; i < max; i++) {
    + if (!mb_test_bit(i, buddy)) {
    + MB_CHECK_ASSERT(i >= e4b->bd_info->bb_first_free);
    + if (fstart == -1) {
    + fragments++;
    + fstart = i;
    + }
    + continue;
    + }
    + fstart = -1;
    + /* check used bits only */
    + for (j = 0; j < e4b->bd_blkbits + 1; j++) {
    + buddy2 = mb_find_buddy(e4b, j, &max2);
    + k = i >> j;
    + MB_CHECK_ASSERT(k < max2);
    + MB_CHECK_ASSERT(mb_test_bit(k, buddy2));
    + }
    + }
    + MB_CHECK_ASSERT(!EXT4_MB_GRP_NEED_INIT(e4b->bd_info));
    + MB_CHECK_ASSERT(e4b->bd_info->bb_fragments == fragments);
    +
    + grp = ext4_get_group_info(sb, e4b->bd_group);
    + buddy = mb_find_buddy(e4b, 0, &max);
    + list_for_each(cur, &grp->bb_prealloc_list) {
    + ext4_group_t groupnr;
    + struct ext4_prealloc_space *pa;
    + pa = list_entry(cur, struct ext4_prealloc_space, group_list);
    + ext4_get_group_no_and_offset(sb, pa->pstart, &groupnr, &k);
    + MB_CHECK_ASSERT(groupnr == e4b->bd_group);
    + for (i = 0; i < pa->len; i++)
    + MB_CHECK_ASSERT(mb_test_bit(k + i, buddy));
    + }
    + return 0;
    +}
    +#undef MB_CHECK_ASSERT
    +#define mb_check_buddy(e4b) __mb_check_buddy(e4b, \
    + __FILE__, __FUNCTION__, __LINE__)
    +#else
    +#define mb_check_buddy(e4b)
    +#endif
    +
    +/* find most significant bit */
    +static int fmsb(unsigned short word)
    +{
    + int order;
    +
    + if (word > 255) {
    + order = 7;
    + word >>= 8;
    + } else {
    + order = -1;
    + }
    +
    + do {
    + order++;
    + word >>= 1;
    + } while (word != 0);
    +
    + return order;
    +}
    +
    +/* FIXME!! need more doc */
    +static void ext4_mb_mark_free_simple(struct super_block *sb,
    + void *buddy, unsigned first, int len,
    + struct ext4_group_info *grp)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + unsigned short min;
    + unsigned short max;
    + unsigned short chunk;
    + unsigned short border;
    +
    + BUG_ON(len >= EXT4_BLOCKS_PER_GROUP(sb));
    +
    + border = 2 << sb->s_blocksize_bits;
    +
    + while (len > 0) {
    + /* find how many blocks can be covered since this position */
    + max = ffs(first | border) - 1;
    +
    + /* find how many blocks of power 2 we need to mark */
    + min = fmsb(len);
    +
    + if (max < min)
    + min = max;
    + chunk = 1 << min;
    +
    + /* mark multiblock chunks only */
    + grp->bb_counters[min]++;
    + if (min > 0)
    + mb_clear_bit(first >> min,
    + buddy + sbi->s_mb_offsets[min]);
    +
    + len -= chunk;
    + first += chunk;
    + }
    +}
    +
    +static void ext4_mb_generate_buddy(struct super_block *sb,
    + void *buddy, void *bitmap, ext4_group_t group)
    +{
    + struct ext4_group_info *grp = ext4_get_group_info(sb, group);
    + unsigned short max = EXT4_BLOCKS_PER_GROUP(sb);
    + unsigned short i = 0;
    + unsigned short first;
    + unsigned short len;
    + unsigned free = 0;
    + unsigned fragments = 0;
    + unsigned long long period = get_cycles();
    +
    + /* initialize buddy from bitmap which is aggregation
    + * of on-disk bitmap and preallocations */
    + i = ext4_find_next_zero_bit(bitmap, max, 0);
    + grp->bb_first_free = i;
    + while (i < max) {
    + fragments++;
    + first = i;
    + i = ext4_find_next_bit(bitmap, max, i);
    + len = i - first;
    + free += len;
    + if (len > 1)
    + ext4_mb_mark_free_simple(sb, buddy, first, len, grp);
    + else
    + grp->bb_counters[0]++;
    + if (i < max)
    + i = ext4_find_next_zero_bit(bitmap, max, i);
    + }
    + grp->bb_fragments = fragments;
    +
    + if (free != grp->bb_free) {
    + printk(KERN_DEBUG
    + "EXT4-fs: group %lu: %u blocks in bitmap, %u in gd\n",
    + group, free, grp->bb_free);
    + grp->bb_free = free;
    + }
    +
    + clear_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
    +
    + period = get_cycles() - period;
    + spin_lock(&EXT4_SB(sb)->s_bal_lock);
    + EXT4_SB(sb)->s_mb_buddies_generated++;
    + EXT4_SB(sb)->s_mb_generation_time += period;
    + spin_unlock(&EXT4_SB(sb)->s_bal_lock);
    +}
    +
    +/* The buddy information is attached the buddy cache inode
    + * for convenience. The information regarding each group
    + * is loaded via ext4_mb_load_buddy. The information involve
    + * block bitmap and buddy information. The information are
    + * stored in the inode as
    + *
    + * { page }
    + * [ group 0 buddy][ group 0 bitmap] [group 1][ group 1]...
    + *
    + *
    + * one block each for bitmap and buddy information.
    + * So for each group we take up 2 blocks. A page can
    + * contain blocks_per_page (PAGE_CACHE_SIZE / blocksize) blocks.
    + * So it can have information regarding groups_per_page which
    + * is blocks_per_page/2
    + */
    +
    +static int ext4_mb_init_cache(struct page *page, char *incore)
    +{
    + int blocksize;
    + int blocks_per_page;
    + int groups_per_page;
    + int err = 0;
    + int i;
    + ext4_group_t first_group;
    + int first_block;
    + struct super_block *sb;
    + struct buffer_head *bhs;
    + struct buffer_head **bh;
    + struct inode *inode;
    + char *data;
    + char *bitmap;
    +
    + mb_debug("init page %lu\n", page->index);
    +
    + inode = page->mapping->host;
    + sb = inode->i_sb;
    + blocksize = 1 << inode->i_blkbits;
    + blocks_per_page = PAGE_CACHE_SIZE / blocksize;
    +
    + groups_per_page = blocks_per_page >> 1;
    + if (groups_per_page == 0)
    + groups_per_page = 1;
    +
    + /* allocate buffer_heads to read bitmaps */
    + if (groups_per_page > 1) {
    + err = -ENOMEM;
    + i = sizeof(struct buffer_head *) * groups_per_page;
    + bh = kmalloc(i, GFP_NOFS);
    + if (bh == NULL)
    + goto out;
    + memset(bh, 0, i);
    + } else
    + bh = &bhs;
    +
    + first_group = page->index * blocks_per_page / 2;
    +
    + /* read all groups the page covers into the cache */
    + for (i = 0; i < groups_per_page; i++) {
    + struct ext4_group_desc *desc;
    +
    + if (first_group + i >= EXT4_SB(sb)->s_groups_count)
    + break;
    +
    + err = -EIO;
    + desc = ext4_get_group_desc(sb, first_group + i, NULL);
    + if (desc == NULL)
    + goto out;
    +
    + err = -ENOMEM;
    + bh[i] = sb_getblk(sb, ext4_block_bitmap(sb, desc));
    + if (bh[i] == NULL)
    + goto out;
    +
    + if (buffer_uptodate(bh[i]))
    + continue;
    +
    + lock_buffer(bh[i]);
    + if (buffer_uptodate(bh[i])) {
    + unlock_buffer(bh[i]);
    + continue;
    + }
    +
    + if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
    + ext4_init_block_bitmap(sb, bh[i],
    + first_group + i, desc);
    + set_buffer_uptodate(bh[i]);
    + unlock_buffer(bh[i]);
    + continue;
    + }
    + get_bh(bh[i]);
    + bh[i]->b_end_io = end_buffer_read_sync;
    + submit_bh(READ, bh[i]);
    + mb_debug("read bitmap for group %lu\n", first_group + i);
    + }
    +
    + /* wait for I/O completion */
    + for (i = 0; i < groups_per_page && bh[i]; i++)
    + wait_on_buffer(bh[i]);
    +
    + err = -EIO;
    + for (i = 0; i < groups_per_page && bh[i]; i++)
    + if (!buffer_uptodate(bh[i]))
    + goto out;
    +
    + first_block = page->index * blocks_per_page;
    + for (i = 0; i < blocks_per_page; i++) {
    + int group;
    + struct ext4_group_info *grinfo;
    +
    + group = (first_block + i) >> 1;
    + if (group >= EXT4_SB(sb)->s_groups_count)
    + break;
    +
    + /*
    + * data carry information regarding this
    + * particular group in the format specified
    + * above
    + *
    + */
    + data = page_address(page) + (i * blocksize);
    + bitmap = bh[group - first_group]->b_data;
    +
    + /*
    + * We place the buddy block and bitmap block
    + * close together
    + */
    + if ((first_block + i) & 1) {
    + /* this is block of buddy */
    + BUG_ON(incore == NULL);
    + mb_debug("put buddy for group %u in page %lu/%x\n",
    + group, page->index, i * blocksize);
    + memset(data, 0xff, blocksize);
    + grinfo = ext4_get_group_info(sb, group);
    + grinfo->bb_fragments = 0;
    + memset(grinfo->bb_counters, 0,
    + sizeof(unsigned short)*(sb->s_blocksize_bits+2));
    + /*
    + * incore got set to the group block bitmap below
    + */
    + ext4_mb_generate_buddy(sb, data, incore, group);
    + incore = NULL;
    + } else {
    + /* this is block of bitmap */
    + BUG_ON(incore != NULL);
    + mb_debug("put bitmap for group %u in page %lu/%x\n",
    + group, page->index, i * blocksize);
    +
    + /* see comments in ext4_mb_put_pa() */
    + ext4_lock_group(sb, group);
    + memcpy(data, bitmap, blocksize);
    +
    + /* mark all preallocated blks used in in-core bitmap */
    + ext4_mb_generate_from_pa(sb, data, group);
    + ext4_unlock_group(sb, group);
    +
    + /* set incore so that the buddy information can be
    + * generated using this
    + */
    + incore = data;
    + }
    + }
    + SetPageUptodate(page);
    +
    +out:
    + if (bh) {
    + for (i = 0; i < groups_per_page && bh[i]; i++)
    + brelse(bh[i]);
    + if (bh != &bhs)
    + kfree(bh);
    + }
    + return err;
    +}
    +
    +static int ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
    + struct ext4_buddy *e4b)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + struct inode *inode = sbi->s_buddy_cache;
    + int blocks_per_page;
    + int block;
    + int pnum;
    + int poff;
    + struct page *page;
    +
    + mb_debug("load group %lu\n", group);
    +
    + blocks_per_page = PAGE_CACHE_SIZE / sb->s_blocksize;
    +
    + e4b->bd_blkbits = sb->s_blocksize_bits;
    + e4b->bd_info = ext4_get_group_info(sb, group);
    + e4b->bd_sb = sb;
    + e4b->bd_group = group;
    + e4b->bd_buddy_page = NULL;
    + e4b->bd_bitmap_page = NULL;
    +
    + /*
    + * the buddy cache inode stores the block bitmap
    + * and buddy information in consecutive blocks.
    + * So for each group we need two blocks.
    + */
    + block = group * 2;
    + pnum = block / blocks_per_page;
    + poff = block % blocks_per_page;
    +
    + /* we could use find_or_create_page(), but it locks page
    + * what we'd like to avoid in fast path ... */
    + page = find_get_page(inode->i_mapping, pnum);
    + if (page == NULL || !PageUptodate(page)) {
    + if (page)
    + page_cache_release(page);
    + page = find_or_create_page(inode->i_mapping, pnum, GFP_NOFS);
    + if (page) {
    + BUG_ON(page->mapping != inode->i_mapping);
    + if (!PageUptodate(page)) {
    + ext4_mb_init_cache(page, NULL);
    + mb_cmp_bitmaps(e4b, page_address(page) +
    + (poff * sb->s_blocksize));
    + }
    + unlock_page(page);
    + }
    + }
    + if (page == NULL || !PageUptodate(page))
    + goto err;
    + e4b->bd_bitmap_page = page;
    + e4b->bd_bitmap = page_address(page) + (poff * sb->s_blocksize);
    + mark_page_accessed(page);
    +
    + block++;
    + pnum = block / blocks_per_page;
    + poff = block % blocks_per_page;
    +
    + page = find_get_page(inode->i_mapping, pnum);
    + if (page == NULL || !PageUptodate(page)) {
    + if (page)
    + page_cache_release(page);
    + page = find_or_create_page(inode->i_mapping, pnum, GFP_NOFS);
    + if (page) {
    + BUG_ON(page->mapping != inode->i_mapping);
    + if (!PageUptodate(page))
    + ext4_mb_init_cache(page, e4b->bd_bitmap);
    +
    + unlock_page(page);
    + }
    + }
    + if (page == NULL || !PageUptodate(page))
    + goto err;
    + e4b->bd_buddy_page = page;
    + e4b->bd_buddy = page_address(page) + (poff * sb->s_blocksize);
    + mark_page_accessed(page);
    +
    + BUG_ON(e4b->bd_bitmap_page == NULL);
    + BUG_ON(e4b->bd_buddy_page == NULL);
    +
    + return 0;
    +
    +err:
    + if (e4b->bd_bitmap_page)
    + page_cache_release(e4b->bd_bitmap_page);
    + if (e4b->bd_buddy_page)
    + page_cache_release(e4b->bd_buddy_page);
    + e4b->bd_buddy = NULL;
    + e4b->bd_bitmap = NULL;
    + return -EIO;
    +}
    +
    +static void ext4_mb_release_desc(struct ext4_buddy *e4b)
    +{
    + if (e4b->bd_bitmap_page)
    + page_cache_release(e4b->bd_bitmap_page);
    + if (e4b->bd_buddy_page)
    + page_cache_release(e4b->bd_buddy_page);
    +}
    +
    +
    +static int mb_find_order_for_block(struct ext4_buddy *e4b, int block)
    +{
    + int order = 1;
    + void *bb;
    +
    + BUG_ON(EXT4_MB_BITMAP(e4b) == EXT4_MB_BUDDY(e4b));
    + BUG_ON(block >= (1 << (e4b->bd_blkbits + 3)));
    +
    + bb = EXT4_MB_BUDDY(e4b);
    + while (order <= e4b->bd_blkbits + 1) {
    + block = block >> 1;
    + if (!mb_test_bit(block, bb)) {
    + /* this block is part of buddy of order 'order' */
    + return order;
    + }
    + bb += 1 << (e4b->bd_blkbits - order);
    + order++;
    + }
    + return 0;
    +}
    +
    +static void mb_clear_bits(spinlock_t *lock, void *bm, int cur, int len)
    +{
    + __u32 *addr;
    +
    + len = cur + len;
    + while (cur < len) {
    + if ((cur & 31) == 0 && (len - cur) >= 32) {
    + /* fast path: clear whole word at once */
    + addr = bm + (cur >> 3);
    + *addr = 0;
    + cur += 32;
    + continue;
    + }
    + mb_clear_bit_atomic(lock, cur, bm);
    + cur++;
    + }
    +}
    +
    +static void mb_set_bits(spinlock_t *lock, void *bm, int cur, int len)
    +{
    + __u32 *addr;
    +
    + len = cur + len;
    + while (cur < len) {
    + if ((cur & 31) == 0 && (len - cur) >= 32) {
    + /* fast path: clear whole word at once */
    + addr = bm + (cur >> 3);
    + *addr = 0xffffffff;
    + cur += 32;
    + continue;
    + }
    + mb_set_bit_atomic(lock, cur, bm);
    + cur++;
    + }
    +}
    +
    +static int mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b,
    + int first, int count)
    +{
    + int block = 0;
    + int max = 0;
    + int order;
    + void *buddy;
    + void *buddy2;
    + struct super_block *sb = e4b->bd_sb;
    +
    + BUG_ON(first + count > (sb->s_blocksize << 3));
    + BUG_ON(!ext4_is_group_locked(sb, e4b->bd_group));
    + mb_check_buddy(e4b);
    + mb_free_blocks_double(inode, e4b, first, count);
    +
    + e4b->bd_info->bb_free += count;
    + if (first < e4b->bd_info->bb_first_free)
    + e4b->bd_info->bb_first_free = first;
    +
    + /* let's maintain fragments counter */
    + if (first != 0)
    + block = !mb_test_bit(first - 1, EXT4_MB_BITMAP(e4b));
    + if (first + count < EXT4_SB(sb)->s_mb_maxs[0])
    + max = !mb_test_bit(first + count, EXT4_MB_BITMAP(e4b));
    + if (block && max)
    + e4b->bd_info->bb_fragments--;
    + else if (!block && !max)
    + e4b->bd_info->bb_fragments++;
    +
    + /* let's maintain buddy itself */
    + while (count-- > 0) {
    + block = first++;
    + order = 0;
    +
    + if (!mb_test_bit(block, EXT4_MB_BITMAP(e4b))) {
    + ext4_fsblk_t blocknr;
    + blocknr = e4b->bd_group * EXT4_BLOCKS_PER_GROUP(sb);
    + blocknr += block;
    + blocknr +=
    + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
    +
    + ext4_error(sb, __FUNCTION__, "double-free of inode"
    + " %lu's block %llu(bit %u in group %lu)\n",
    + inode ? inode->i_ino : 0, blocknr, block,
    + e4b->bd_group);
    + }
    + mb_clear_bit(block, EXT4_MB_BITMAP(e4b));
    + e4b->bd_info->bb_counters[order]++;
    +
    + /* start of the buddy */
    + buddy = mb_find_buddy(e4b, order, &max);
    +
    + do {
    + block &= ~1UL;
    + if (mb_test_bit(block, buddy) ||
    + mb_test_bit(block + 1, buddy))
    + break;
    +
    + /* both the buddies are free, try to coalesce them */
    + buddy2 = mb_find_buddy(e4b, order + 1, &max);
    +
    + if (!buddy2)
    + break;
    +
    + if (order > 0) {
    + /* for special purposes, we don't set
    + * free bits in bitmap */
    + mb_set_bit(block, buddy);
    + mb_set_bit(block + 1, buddy);
    + }
    + e4b->bd_info->bb_counters[order]--;
    + e4b->bd_info->bb_counters[order]--;
    +
    + block = block >> 1;
    + order++;
    + e4b->bd_info->bb_counters[order]++;
    +
    + mb_clear_bit(block, buddy2);
    + buddy = buddy2;
    + } while (1);
    + }
    + mb_check_buddy(e4b);
    +
    + return 0;
    +}
    +
    +static int mb_find_extent(struct ext4_buddy *e4b, int order, int block,
    + int needed, struct ext4_free_extent *ex)
    +{
    + int next = block;
    + int max;
    + int ord;
    + void *buddy;
    +
    + BUG_ON(!ext4_is_group_locked(e4b->bd_sb, e4b->bd_group));
    + BUG_ON(ex == NULL);
    +
    + buddy = mb_find_buddy(e4b, order, &max);
    + BUG_ON(buddy == NULL);
    + BUG_ON(block >= max);
    + if (mb_test_bit(block, buddy)) {
    + ex->fe_len = 0;
    + ex->fe_start = 0;
    + ex->fe_group = 0;
    + return 0;
    + }
    +
    + /* FIXME dorp order completely ? */
    + if (likely(order == 0)) {
    + /* find actual order */
    + order = mb_find_order_for_block(e4b, block);
    + block = block >> order;
    + }
    +
    + ex->fe_len = 1 << order;
    + ex->fe_start = block << order;
    + ex->fe_group = e4b->bd_group;
    +
    + /* calc difference from given start */
    + next = next - ex->fe_start;
    + ex->fe_len -= next;
    + ex->fe_start += next;
    +
    + while (needed > ex->fe_len &&
    + (buddy = mb_find_buddy(e4b, order, &max))) {
    +
    + if (block + 1 >= max)
    + break;
    +
    + next = (block + 1) * (1 << order);
    + if (mb_test_bit(next, EXT4_MB_BITMAP(e4b)))
    + break;
    +
    + ord = mb_find_order_for_block(e4b, next);
    +
    + order = ord;
    + block = next >> order;
    + ex->fe_len += 1 << order;
    + }
    +
    + BUG_ON(ex->fe_start + ex->fe_len > (1 << (e4b->bd_blkbits + 3)));
    + return ex->fe_len;
    +}
    +
    +static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
    +{
    + int ord;
    + int mlen = 0;
    + int max = 0;
    + int cur;
    + int start = ex->fe_start;
    + int len = ex->fe_len;
    + unsigned ret = 0;
    + int len0 = len;
    + void *buddy;
    +
    + BUG_ON(start + len > (e4b->bd_sb->s_blocksize << 3));
    + BUG_ON(e4b->bd_group != ex->fe_group);
    + BUG_ON(!ext4_is_group_locked(e4b->bd_sb, e4b->bd_group));
    + mb_check_buddy(e4b);
    + mb_mark_used_double(e4b, start, len);
    +
    + e4b->bd_info->bb_free -= len;
    + if (e4b->bd_info->bb_first_free == start)
    + e4b->bd_info->bb_first_free += len;
    +
    + /* let's maintain fragments counter */
    + if (start != 0)
    + mlen = !mb_test_bit(start - 1, EXT4_MB_BITMAP(e4b));
    + if (start + len < EXT4_SB(e4b->bd_sb)->s_mb_maxs[0])
    + max = !mb_test_bit(start + len, EXT4_MB_BITMAP(e4b));
    + if (mlen && max)
    + e4b->bd_info->bb_fragments++;
    + else if (!mlen && !max)
    + e4b->bd_info->bb_fragments--;
    +
    + /* let's maintain buddy itself */
    + while (len) {
    + ord = mb_find_order_for_block(e4b, start);
    +
    + if (((start >> ord) << ord) == start && len >= (1 << ord)) {
    + /* the whole chunk may be allocated at once! */
    + mlen = 1 << ord;
    + buddy = mb_find_buddy(e4b, ord, &max);
    + BUG_ON((start >> ord) >= max);
    + mb_set_bit(start >> ord, buddy);
    + e4b->bd_info->bb_counters[ord]--;
    + start += mlen;
    + len -= mlen;
    + BUG_ON(len < 0);
    + continue;
    + }
    +
    + /* store for history */
    + if (ret == 0)
    + ret = len | (ord << 16);
    +
    + /* we have to split large buddy */
    + BUG_ON(ord <= 0);
    + buddy = mb_find_buddy(e4b, ord, &max);
    + mb_set_bit(start >> ord, buddy);
    + e4b->bd_info->bb_counters[ord]--;
    +
    + ord--;
    + cur = (start >> ord) & ~1U;
    + buddy = mb_find_buddy(e4b, ord, &max);
    + mb_clear_bit(cur, buddy);
    + mb_clear_bit(cur + 1, buddy);
    + e4b->bd_info->bb_counters[ord]++;
    + e4b->bd_info->bb_counters[ord]++;
    + }
    +
    + mb_set_bits(sb_bgl_lock(EXT4_SB(e4b->bd_sb), ex->fe_group),
    + EXT4_MB_BITMAP(e4b), ex->fe_start, len0);
    + mb_check_buddy(e4b);
    +
    + return ret;
    +}
    +
    +/*
    + * Must be called under group lock!
    + */
    +static void ext4_mb_use_best_found(struct ext4_allocation_context *ac,
    + struct ext4_buddy *e4b)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
    + int ret;
    +
    + BUG_ON(ac->ac_b_ex.fe_group != e4b->bd_group);
    + BUG_ON(ac->ac_status == AC_STATUS_FOUND);
    +
    + ac->ac_b_ex.fe_len = min(ac->ac_b_ex.fe_len, ac->ac_g_ex.fe_len);
    + ac->ac_b_ex.fe_logical = ac->ac_g_ex.fe_logical;
    + ret = mb_mark_used(e4b, &ac->ac_b_ex);
    +
    + /* preallocation can change ac_b_ex, thus we store actually
    + * allocated blocks for history */
    + ac->ac_f_ex = ac->ac_b_ex;
    +
    + ac->ac_status = AC_STATUS_FOUND;
    + ac->ac_tail = ret & 0xffff;
    + ac->ac_buddy = ret >> 16;
    +
    + /* XXXXXXX: SUCH A HORRIBLE **CK */
    + /*FIXME!! Why ? */
    + ac->ac_bitmap_page = e4b->bd_bitmap_page;
    + get_page(ac->ac_bitmap_page);
    + ac->ac_buddy_page = e4b->bd_buddy_page;
    + get_page(ac->ac_buddy_page);
    +
    + /* store last allocated for subsequent stream allocation */
    + if ((ac->ac_flags & EXT4_MB_HINT_DATA)) {
    + spin_lock(&sbi->s_md_lock);
    + sbi->s_mb_last_group = ac->ac_f_ex.fe_group;
    + sbi->s_mb_last_start = ac->ac_f_ex.fe_start;
    + spin_unlock(&sbi->s_md_lock);
    + }
    +}
    +
    +/*
    + * regular allocator, for general purposes allocation
    + */
    +
    +static void ext4_mb_check_limits(struct ext4_allocation_context *ac,
    + struct ext4_buddy *e4b,
    + int finish_group)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
    + struct ext4_free_extent *bex = &ac->ac_b_ex;
    + struct ext4_free_extent *gex = &ac->ac_g_ex;
    + struct ext4_free_extent ex;
    + int max;
    +
    + /*
    + * We don't want to scan for a whole year
    + */
    + if (ac->ac_found > sbi->s_mb_max_to_scan &&
    + !(ac->ac_flags & EXT4_MB_HINT_FIRST)) {
    + ac->ac_status = AC_STATUS_BREAK;
    + return;
    + }
    +
    + /*
    + * Haven't found good chunk so far, let's continue
    + */
    + if (bex->fe_len < gex->fe_len)
    + return;
    +
    + if ((finish_group || ac->ac_found > sbi->s_mb_min_to_scan)
    + && bex->fe_group == e4b->bd_group) {
    + /* recheck chunk's availability - we don't know
    + * when it was found (within this lock-unlock
    + * period or not) */
    + max = mb_find_extent(e4b, 0, bex->fe_start, gex->fe_len, &ex);
    + if (max >= gex->fe_len) {
    + ext4_mb_use_best_found(ac, e4b);
    + return;
    + }
    + }
    +}
    +
    +/*
    + * The routine checks whether found extent is good enough. If it is,
    + * then the extent gets marked used and flag is set to the context
    + * to stop scanning. Otherwise, the extent is compared with the
    + * previous found extent and if new one is better, then it's stored
    + * in the context. Later, the best found extent will be used, if
    + * mballoc can't find good enough extent.
    + *
    + * FIXME: real allocation policy is to be designed yet!
    + */
    +static void ext4_mb_measure_extent(struct ext4_allocation_context *ac,
    + struct ext4_free_extent *ex,
    + struct ext4_buddy *e4b)
    +{
    + struct ext4_free_extent *bex = &ac->ac_b_ex;
    + struct ext4_free_extent *gex = &ac->ac_g_ex;
    +
    + BUG_ON(ex->fe_len <= 0);
    + BUG_ON(ex->fe_len >= EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
    + BUG_ON(ex->fe_start >= EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
    + BUG_ON(ac->ac_status != AC_STATUS_CONTINUE);
    +
    + ac->ac_found++;
    +
    + /*
    + * The special case - take what you catch first
    + */
    + if (unlikely(ac->ac_flags & EXT4_MB_HINT_FIRST)) {
    + *bex = *ex;
    + ext4_mb_use_best_found(ac, e4b);
    + return;
    + }
    +
    + /*
    + * Let's check whether the chuck is good enough
    + */
    + if (ex->fe_len == gex->fe_len) {
    + *bex = *ex;
    + ext4_mb_use_best_found(ac, e4b);
    + return;
    + }
    +
    + /*
    + * If this is first found extent, just store it in the context
    + */
    + if (bex->fe_len == 0) {
    + *bex = *ex;
    + return;
    + }
    +
    + /*
    + * If new found extent is better, store it in the context
    + */
    + if (bex->fe_len < gex->fe_len) {
    + /* if the request isn't satisfied, any found extent
    + * larger than previous best one is better */
    + if (ex->fe_len > bex->fe_len)
    + *bex = *ex;
    + } else if (ex->fe_len > gex->fe_len) {
    + /* if the request is satisfied, then we try to find
    + * an extent that still satisfy the request, but is
    + * smaller than previous one */
    + if (ex->fe_len < bex->fe_len)
    + *bex = *ex;
    + }
    +
    + ext4_mb_check_limits(ac, e4b, 0);
    +}
    +
    +static int ext4_mb_try_best_found(struct ext4_allocation_context *ac,
    + struct ext4_buddy *e4b)
    +{
    + struct ext4_free_extent ex = ac->ac_b_ex;
    + ext4_group_t group = ex.fe_group;
    + int max;
    + int err;
    +
    + BUG_ON(ex.fe_len <= 0);
    + err = ext4_mb_load_buddy(ac->ac_sb, group, e4b);
    + if (err)
    + return err;
    +
    + ext4_lock_group(ac->ac_sb, group);
    + max = mb_find_extent(e4b, 0, ex.fe_start, ex.fe_len, &ex);
    +
    + if (max > 0) {
    + ac->ac_b_ex = ex;
    + ext4_mb_use_best_found(ac, e4b);
    + }
    +
    + ext4_unlock_group(ac->ac_sb, group);
    + ext4_mb_release_desc(e4b);
    +
    + return 0;
    +}
    +
    +static int ext4_mb_find_by_goal(struct ext4_allocation_context *ac,
    + struct ext4_buddy *e4b)
    +{
    + ext4_group_t group = ac->ac_g_ex.fe_group;
    + int max;
    + int err;
    + struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
    + struct ext4_super_block *es = sbi->s_es;
    + struct ext4_free_extent ex;
    +
    + if (!(ac->ac_flags & EXT4_MB_HINT_TRY_GOAL))
    + return 0;
    +
    + err = ext4_mb_load_buddy(ac->ac_sb, group, e4b);
    + if (err)
    + return err;
    +
    + ext4_lock_group(ac->ac_sb, group);
    + max = mb_find_extent(e4b, 0, ac->ac_g_ex.fe_start,
    + ac->ac_g_ex.fe_len, &ex);
    +
    + if (max >= ac->ac_g_ex.fe_len && ac->ac_g_ex.fe_len == sbi->s_stripe) {
    + ext4_fsblk_t start;
    +
    + start = (e4b->bd_group * EXT4_BLOCKS_PER_GROUP(ac->ac_sb)) +
    + ex.fe_start + le32_to_cpu(es->s_first_data_block);
    + /* use do_div to get remainder (would be 64-bit modulo) */
    + if (do_div(start, sbi->s_stripe) == 0) {
    + ac->ac_found++;
    + ac->ac_b_ex = ex;
    + ext4_mb_use_best_found(ac, e4b);
    + }
    + } else if (max >= ac->ac_g_ex.fe_len) {
    + BUG_ON(ex.fe_len <= 0);
    + BUG_ON(ex.fe_group != ac->ac_g_ex.fe_group);
    + BUG_ON(ex.fe_start != ac->ac_g_ex.fe_start);
    + ac->ac_found++;
    + ac->ac_b_ex = ex;
    + ext4_mb_use_best_found(ac, e4b);
    + } else if (max > 0 && (ac->ac_flags & EXT4_MB_HINT_MERGE)) {
    + /* Sometimes, caller may want to merge even small
    + * number of blocks to an existing extent */
    + BUG_ON(ex.fe_len <= 0);
    + BUG_ON(ex.fe_group != ac->ac_g_ex.fe_group);
    + BUG_ON(ex.fe_start != ac->ac_g_ex.fe_start);
    + ac->ac_found++;
    + ac->ac_b_ex = ex;
    + ext4_mb_use_best_found(ac, e4b);
    + }
    + ext4_unlock_group(ac->ac_sb, group);
    + ext4_mb_release_desc(e4b);
    +
    + return 0;
    +}
    +
    +/*
    + * The routine scans buddy structures (not bitmap!) from given order
    + * to max order and tries to find big enough chunk to satisfy the req
    + */
    +static void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
    + struct ext4_buddy *e4b)
    +{
    + struct super_block *sb = ac->ac_sb;
    + struct ext4_group_info *grp = e4b->bd_info;
    + void *buddy;
    + int i;
    + int k;
    + int max;
    +
    + BUG_ON(ac->ac_2order <= 0);
    + for (i = ac->ac_2order; i <= sb->s_blocksize_bits + 1; i++) {
    + if (grp->bb_counters[i] == 0)
    + continue;
    +
    + buddy = mb_find_buddy(e4b, i, &max);
    + BUG_ON(buddy == NULL);
    +
    + k = ext4_find_next_zero_bit(buddy, max, 0);
    + BUG_ON(k >= max);
    +
    + ac->ac_found++;
    +
    + ac->ac_b_ex.fe_len = 1 << i;
    + ac->ac_b_ex.fe_start = k << i;
    + ac->ac_b_ex.fe_group = e4b->bd_group;
    +
    + ext4_mb_use_best_found(ac, e4b);
    +
    + BUG_ON(ac->ac_b_ex.fe_len != ac->ac_g_ex.fe_len);
    +
    + if (EXT4_SB(sb)->s_mb_stats)
    + atomic_inc(&EXT4_SB(sb)->s_bal_2orders);
    +
    + break;
    + }
    +}
    +
    +/*
    + * The routine scans the group and measures all found extents.
    + * In order to optimize scanning, caller must pass number of
    + * free blocks in the group, so the routine can know upper limit.
    + */
    +static void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
    + struct ext4_buddy *e4b)
    +{
    + struct super_block *sb = ac->ac_sb;
    + void *bitmap = EXT4_MB_BITMAP(e4b);
    + struct ext4_free_extent ex;
    + int i;
    + int free;
    +
    + free = e4b->bd_info->bb_free;
    + BUG_ON(free <= 0);
    +
    + i = e4b->bd_info->bb_first_free;
    +
    + while (free && ac->ac_status == AC_STATUS_CONTINUE) {
    + i = ext4_find_next_zero_bit(bitmap,
    + EXT4_BLOCKS_PER_GROUP(sb), i);
    + if (i >= EXT4_BLOCKS_PER_GROUP(sb)) {
    + BUG_ON(free != 0);
    + break;
    + }
    +
    + mb_find_extent(e4b, 0, i, ac->ac_g_ex.fe_len, &ex);
    + BUG_ON(ex.fe_len <= 0);
    + BUG_ON(free < ex.fe_len);
    +
    + ext4_mb_measure_extent(ac, &ex, e4b);
    +
    + i += ex.fe_len;
    + free -= ex.fe_len;
    + }
    +
    + ext4_mb_check_limits(ac, e4b, 1);
    +}
    +
    +/*
    + * This is a special case for storages like raid5
    + * we try to find stripe-aligned chunks for stripe-size requests
    + * XXX should do so at least for multiples of stripe size as well
    + */
    +static void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
    + struct ext4_buddy *e4b)
    +{
    + struct super_block *sb = ac->ac_sb;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + void *bitmap = EXT4_MB_BITMAP(e4b);
    + struct ext4_free_extent ex;
    + ext4_fsblk_t first_group_block;
    + ext4_fsblk_t a;
    + ext4_grpblk_t i;
    + int max;
    +
    + BUG_ON(sbi->s_stripe == 0);
    +
    + /* find first stripe-aligned block in group */
    + first_group_block = e4b->bd_group * EXT4_BLOCKS_PER_GROUP(sb)
    + + le32_to_cpu(sbi->s_es->s_first_data_block);
    + a = first_group_block + sbi->s_stripe - 1;
    + do_div(a, sbi->s_stripe);
    + i = (a * sbi->s_stripe) - first_group_block;
    +
    + while (i < EXT4_BLOCKS_PER_GROUP(sb)) {
    + if (!mb_test_bit(i, bitmap)) {
    + max = mb_find_extent(e4b, 0, i, sbi->s_stripe, &ex);
    + if (max >= sbi->s_stripe) {
    + ac->ac_found++;
    + ac->ac_b_ex = ex;
    + ext4_mb_use_best_found(ac, e4b);
    + break;
    + }
    + }
    + i += sbi->s_stripe;
    + }
    +}
    +
    +static int ext4_mb_good_group(struct ext4_allocation_context *ac,
    + ext4_group_t group, int cr)
    +{
    + unsigned free, fragments;
    + unsigned i, bits;
    + struct ext4_group_desc *desc;
    + struct ext4_group_info *grp = ext4_get_group_info(ac->ac_sb, group);
    +
    + BUG_ON(cr < 0 || cr >= 4);
    + BUG_ON(EXT4_MB_GRP_NEED_INIT(grp));
    +
    + free = grp->bb_free;
    + fragments = grp->bb_fragments;
    + if (free == 0)
    + return 0;
    + if (fragments == 0)
    + return 0;
    +
    + switch (cr) {
    + case 0:
    + BUG_ON(ac->ac_2order == 0);
    + /* If this group is uninitialized, skip it initially */
    + desc = ext4_get_group_desc(ac->ac_sb, group, NULL);
    + if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))
    + return 0;
    +
    + bits = ac->ac_sb->s_blocksize_bits + 1;
    + for (i = ac->ac_2order; i <= bits; i++)
    + if (grp->bb_counters[i] > 0)
    + return 1;
    + break;
    + case 1:
    + if ((free / fragments) >= ac->ac_g_ex.fe_len)
    + return 1;
    + break;
    + case 2:
    + if (free >= ac->ac_g_ex.fe_len)
    + return 1;
    + break;
    + case 3:
    + return 1;
    + default:
    + BUG();
    + }
    +
    + return 0;
    +}
    +
    +static int ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
    +{
    + ext4_group_t group;
    + ext4_group_t i;
    + int cr;
    + int err = 0;
    + int bsbits;
    + struct ext4_sb_info *sbi;
    + struct super_block *sb;
    + struct ext4_buddy e4b;
    + loff_t size, isize;
    +
    + sb = ac->ac_sb;
    + sbi = EXT4_SB(sb);
    + BUG_ON(ac->ac_status == AC_STATUS_FOUND);
    +
    + /* first, try the goal */
    + err = ext4_mb_find_by_goal(ac, &e4b);
    + if (err || ac->ac_status == AC_STATUS_FOUND)
    + goto out;
    +
    + if (unlikely(ac->ac_flags & EXT4_MB_HINT_GOAL_ONLY))
    + goto out;
    +
    + /*
    + * ac->ac2_order is set only if the fe_len is a power of 2
    + * if ac2_order is set we also set criteria to 0 so that we
    + * try exact allocation using buddy.
    + */
    + i = fls(ac->ac_g_ex.fe_len);
    + ac->ac_2order = 0;
    + /*
    + * We search using buddy data only if the order of the request
    + * is greater than equal to the sbi_s_mb_order2_reqs
    + * You can tune it via /proc/fs/ext4/<partition>/order2_req
    + */
    + if (i >= sbi->s_mb_order2_reqs) {
    + /*
    + * This should tell if fe_len is exactly power of 2
    + */
    + if ((ac->ac_g_ex.fe_len & (~(1 << (i - 1)))) == 0)
    + ac->ac_2order = i - 1;
    + }
    +
    + bsbits = ac->ac_sb->s_blocksize_bits;
    + /* if stream allocation is enabled, use global goal */
    + size = ac->ac_o_ex.fe_logical + ac->ac_o_ex.fe_len;
    + isize = i_size_read(ac->ac_inode) >> bsbits;
    + if (size < isize)
    + size = isize;
    +
    + if (size < sbi->s_mb_stream_request &&
    + (ac->ac_flags & EXT4_MB_HINT_DATA)) {
    + /* TBD: may be hot point */
    + spin_lock(&sbi->s_md_lock);
    + ac->ac_g_ex.fe_group = sbi->s_mb_last_group;
    + ac->ac_g_ex.fe_start = sbi->s_mb_last_start;
    + spin_unlock(&sbi->s_md_lock);
    + }
    +
    + /* searching for the right group start from the goal value specified */
    + group = ac->ac_g_ex.fe_group;
    +
    + /* Let's just scan groups to find more-less suitable blocks */
    + cr = ac->ac_2order ? 0 : 1;
    + /*
    + * cr == 0 try to get exact allocation,
    + * cr == 3 try to get anything
    + */
    +repeat:
    + for (; cr < 4 && ac->ac_status == AC_STATUS_CONTINUE; cr++) {
    + ac->ac_criteria = cr;
    + for (i = 0; i < EXT4_SB(sb)->s_groups_count; group++, i++) {
    + struct ext4_group_info *grp;
    + struct ext4_group_desc *desc;
    +
    + if (group == EXT4_SB(sb)->s_groups_count)
    + group = 0;
    +
    + /* quick check to skip empty groups */
    + grp = ext4_get_group_info(ac->ac_sb, group);
    + if (grp->bb_free == 0)
    + continue;
    +
    + /*
    + * if the group is already init we check whether it is
    + * a good group and if not we don't load the buddy
    + */
    + if (EXT4_MB_GRP_NEED_INIT(grp)) {
    + /*
    + * we need full data about the group
    + * to make a good selection
    + */
    + err = ext4_mb_load_buddy(sb, group, &e4b);
    + if (err)
    + goto out;
    + ext4_mb_release_desc(&e4b);
    + }
    +
    + /*
    + * If the particular group doesn't satisfy our
    + * criteria we continue with the next group
    + */
    + if (!ext4_mb_good_group(ac, group, cr))
    + continue;
    +
    + err = ext4_mb_load_buddy(sb, group, &e4b);
    + if (err)
    + goto out;
    +
    + ext4_lock_group(sb, group);
    + if (!ext4_mb_good_group(ac, group, cr)) {
    + /* someone did allocation from this group */
    + ext4_unlock_group(sb, group);
    + ext4_mb_release_desc(&e4b);
    + continue;
    + }
    +
    + ac->ac_groups_scanned++;
    + desc = ext4_get_group_desc(sb, group, NULL);
    + if (cr == 0 || (desc->bg_flags &
    + cpu_to_le16(EXT4_BG_BLOCK_UNINIT) &&
    + ac->ac_2order != 0))
    + ext4_mb_simple_scan_group(ac, &e4b);
    + else if (cr == 1 &&
    + ac->ac_g_ex.fe_len == sbi->s_stripe)
    + ext4_mb_scan_aligned(ac, &e4b);
    + else
    + ext4_mb_complex_scan_group(ac, &e4b);
    +
    + ext4_unlock_group(sb, group);
    + ext4_mb_release_desc(&e4b);
    +
    + if (ac->ac_status != AC_STATUS_CONTINUE)
    + break;
    + }
    + }
    +
    + if (ac->ac_b_ex.fe_len > 0 && ac->ac_status != AC_STATUS_FOUND &&
    + !(ac->ac_flags & EXT4_MB_HINT_FIRST)) {
    + /*
    + * We've been searching too long. Let's try to allocate
    + * the best chunk we've found so far
    + */
    +
    + ext4_mb_try_best_found(ac, &e4b);
    + if (ac->ac_status != AC_STATUS_FOUND) {
    + /*
    + * Someone more lucky has already allocated it.
    + * The only thing we can do is just take first
    + * found block(s)
    + printk(KERN_DEBUG "EXT4-fs: someone won our chunk\n");
    + */
    + ac->ac_b_ex.fe_group = 0;
    + ac->ac_b_ex.fe_start = 0;
    + ac->ac_b_ex.fe_len = 0;
    + ac->ac_status = AC_STATUS_CONTINUE;
    + ac->ac_flags |= EXT4_MB_HINT_FIRST;
    + cr = 3;
    + atomic_inc(&sbi->s_mb_lost_chunks);
    + goto repeat;
    + }
    + }
    +out:
    + return err;
    +}
    +
    +#ifdef EXT4_MB_HISTORY
    +struct ext4_mb_proc_session {
    + struct ext4_mb_history *history;
    + struct super_block *sb;
    + int start;
    + int max;
    +};
    +
    +static void *ext4_mb_history_skip_empty(struct ext4_mb_proc_session *s,
    + struct ext4_mb_history *hs,
    + int first)
    +{
    + if (hs == s->history + s->max)
    + hs = s->history;
    + if (!first && hs == s->history + s->start)
    + return NULL;
    + while (hs->orig.fe_len == 0) {
    + hs++;
    + if (hs == s->history + s->max)
    + hs = s->history;
    + if (hs == s->history + s->start)
    + return NULL;
    + }
    + return hs;
    +}
    +
    +static void *ext4_mb_seq_history_start(struct seq_file *seq, loff_t *pos)
    +{
    + struct ext4_mb_proc_session *s = seq->private;
    + struct ext4_mb_history *hs;
    + int l = *pos;
    +
    + if (l == 0)
    + return SEQ_START_TOKEN;
    + hs = ext4_mb_history_skip_empty(s, s->history + s->start, 1);
    + if (!hs)
    + return NULL;
    + while (--l && (hs = ext4_mb_history_skip_empty(s, ++hs, 0)) != NULL);
    + return hs;
    +}
    +
    +static void *ext4_mb_seq_history_next(struct seq_file *seq, void *v,
    + loff_t *pos)
    +{
    + struct ext4_mb_proc_session *s = seq->private;
    + struct ext4_mb_history *hs = v;
    +
    + ++*pos;
    + if (v == SEQ_START_TOKEN)
    + return ext4_mb_history_skip_empty(s, s->history + s->start, 1);
    + else
    + return ext4_mb_history_skip_empty(s, ++hs, 0);
    +}
    +
    +static int ext4_mb_seq_history_show(struct seq_file *seq, void *v)
    +{
    + char buf[25], buf2[25], buf3[25], *fmt;
    + struct ext4_mb_history *hs = v;
    +
    + if (v == SEQ_START_TOKEN) {
    + seq_printf(seq, "%-5s %-8s %-23s %-23s %-23s %-5s "
    + "%-5s %-2s %-5s %-5s %-5s %-6s\n",
    + "pid", "inode", "original", "goal", "result", "found",
    + "grps", "cr", "flags", "merge", "tail", "broken");
    + return 0;
    + }
    +
    + if (hs->op == EXT4_MB_HISTORY_ALLOC) {
    + fmt = "%-5u %-8u %-23s %-23s %-23s %-5u %-5u %-2u "
    + "%-5u %-5s %-5u %-6u\n";
    + sprintf(buf2, "%lu/%d/%u@%u", hs->result.fe_group,
    + hs->result.fe_start, hs->result.fe_len,
    + hs->result.fe_logical);
    + sprintf(buf, "%lu/%d/%u@%u", hs->orig.fe_group,
    + hs->orig.fe_start, hs->orig.fe_len,
    + hs->orig.fe_logical);
    + sprintf(buf3, "%lu/%d/%u@%u", hs->goal.fe_group,
    + hs->goal.fe_start, hs->goal.fe_len,
    + hs->goal.fe_logical);
    + seq_printf(seq, fmt, hs->pid, hs->ino, buf, buf3, buf2,
    + hs->found, hs->groups, hs->cr, hs->flags,
    + hs->merged ? "M" : "", hs->tail,
    + hs->buddy ? 1 << hs->buddy : 0);
    + } else if (hs->op == EXT4_MB_HISTORY_PREALLOC) {
    + fmt = "%-5u %-8u %-23s %-23s %-23s\n";
    + sprintf(buf2, "%lu/%d/%u@%u", hs->result.fe_group,
    + hs->result.fe_start, hs->result.fe_len,
    + hs->result.fe_logical);
    + sprintf(buf, "%lu/%d/%u@%u", hs->orig.fe_group,
    + hs->orig.fe_start, hs->orig.fe_len,
    + hs->orig.fe_logical);
    + seq_printf(seq, fmt, hs->pid, hs->ino, buf, "", buf2);
    + } else if (hs->op == EXT4_MB_HISTORY_DISCARD) {
    + sprintf(buf2, "%lu/%d/%u", hs->result.fe_group,
    + hs->result.fe_start, hs->result.fe_len);
    + seq_printf(seq, "%-5u %-8u %-23s discard\n",
    + hs->pid, hs->ino, buf2);
    + } else if (hs->op == EXT4_MB_HISTORY_FREE) {
    + sprintf(buf2, "%lu/%d/%u", hs->result.fe_group,
    + hs->result.fe_start, hs->result.fe_len);
    + seq_printf(seq, "%-5u %-8u %-23s free\n",
    + hs->pid, hs->ino, buf2);
    + }
    + return 0;
    +}
    +
    +static void ext4_mb_seq_history_stop(struct seq_file *seq, void *v)
    +{
    +}
    +
    +static struct seq_operations ext4_mb_seq_history_ops = {
    + .start = ext4_mb_seq_history_start,
    + .next = ext4_mb_seq_history_next,
    + .stop = ext4_mb_seq_history_stop,
    + .show = ext4_mb_seq_history_show,
    +};
    +
    +static int ext4_mb_seq_history_open(struct inode *inode, struct file *file)
    +{
    + struct super_block *sb = PDE(inode)->data;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + struct ext4_mb_proc_session *s;
    + int rc;
    + int size;
    +
    + s = kmalloc(sizeof(*s), GFP_KERNEL);
    + if (s == NULL)
    + return -ENOMEM;
    + s->sb = sb;
    + size = sizeof(struct ext4_mb_history) * sbi->s_mb_history_max;
    + s->history = kmalloc(size, GFP_KERNEL);
    + if (s->history == NULL) {
    + kfree(s);
    + return -ENOMEM;
    + }
    +
    + spin_lock(&sbi->s_mb_history_lock);
    + memcpy(s->history, sbi->s_mb_history, size);
    + s->max = sbi->s_mb_history_max;
    + s->start = sbi->s_mb_history_cur % s->max;
    + spin_unlock(&sbi->s_mb_history_lock);
    +
    + rc = seq_open(file, &ext4_mb_seq_history_ops);
    + if (rc == 0) {
    + struct seq_file *m = (struct seq_file *)file->private_data;
    + m->private = s;
    + } else {
    + kfree(s->history);
    + kfree(s);
    + }
    + return rc;
    +
    +}
    +
    +static int ext4_mb_seq_history_release(struct inode *inode, struct file *file)
    +{
    + struct seq_file *seq = (struct seq_file *)file->private_data;
    + struct ext4_mb_proc_session *s = seq->private;
    + kfree(s->history);
    + kfree(s);
    + return seq_release(inode, file);
    +}
    +
    +static ssize_t ext4_mb_seq_history_write(struct file *file,
    + const char __user *buffer,
    + size_t count, loff_t *ppos)
    +{
    + struct seq_file *seq = (struct seq_file *)file->private_data;
    + struct ext4_mb_proc_session *s = seq->private;
    + struct super_block *sb = s->sb;
    + char str[32];
    + int value;
    +
    + if (count >= sizeof(str)) {
    + printk(KERN_ERR "EXT4-fs: %s string too long, max %u bytes\n",
    + "mb_history", (int)sizeof(str));
    + return -EOVERFLOW;
    + }
    +
    + if (copy_from_user(str, buffer, count))
    + return -EFAULT;
    +
    + value = simple_strtol(str, NULL, 0);
    + if (value < 0)
    + return -ERANGE;
    + EXT4_SB(sb)->s_mb_history_filter = value;
    +
    + return count;
    +}
    +
    +static struct file_operations ext4_mb_seq_history_fops = {
    + .owner = THIS_MODULE,
    + .open = ext4_mb_seq_history_open,
    + .read = seq_read,
    + .write = ext4_mb_seq_history_write,
    + .llseek = seq_lseek,
    + .release = ext4_mb_seq_history_release,
    +};
    +
    +static void *ext4_mb_seq_groups_start(struct seq_file *seq, loff_t *pos)
    +{
    + struct super_block *sb = seq->private;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + ext4_group_t group;
    +
    + if (*pos < 0 || *pos >= sbi->s_groups_count)
    + return NULL;
    +
    + group = *pos + 1;
    + return (void *) group;
    +}
    +
    +static void *ext4_mb_seq_groups_next(struct seq_file *seq, void *v, loff_t *pos)
    +{
    + struct super_block *sb = seq->private;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + ext4_group_t group;
    +
    + ++*pos;
    + if (*pos < 0 || *pos >= sbi->s_groups_count)
    + return NULL;
    + group = *pos + 1;
    + return (void *) group;;
    +}
    +
    +static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v)
    +{
    + struct super_block *sb = seq->private;
    + long group = (long) v;
    + int i;
    + int err;
    + struct ext4_buddy e4b;
    + struct sg {
    + struct ext4_group_info info;
    + unsigned short counters[16];
    + } sg;
    +
    + group--;
    + if (group == 0)
    + seq_printf(seq, "#%-5s: %-5s %-5s %-5s "
    + "[ %-5s %-5s %-5s %-5s %-5s %-5s %-5s "
    + "%-5s %-5s %-5s %-5s %-5s %-5s %-5s ]\n",
    + "group", "free", "frags", "first",
    + "2^0", "2^1", "2^2", "2^3", "2^4", "2^5", "2^6",
    + "2^7", "2^8", "2^9", "2^10", "2^11", "2^12", "2^13");
    +
    + i = (sb->s_blocksize_bits + 2) * sizeof(sg.info.bb_counters[0]) +
    + sizeof(struct ext4_group_info);
    + err = ext4_mb_load_buddy(sb, group, &e4b);
    + if (err) {
    + seq_printf(seq, "#%-5lu: I/O error\n", group);
    + return 0;
    + }
    + ext4_lock_group(sb, group);
    + memcpy(&sg, ext4_get_group_info(sb, group), i);
    + ext4_unlock_group(sb, group);
    + ext4_mb_release_desc(&e4b);
    +
    + seq_printf(seq, "#%-5lu: %-5u %-5u %-5u [", group, sg.info.bb_free,
    + sg.info.bb_fragments, sg.info.bb_first_free);
    + for (i = 0; i <= 13; i++)
    + seq_printf(seq, " %-5u", i <= sb->s_blocksize_bits + 1 ?
    + sg.info.bb_counters[i] : 0);
    + seq_printf(seq, " ]\n");
    +
    + return 0;
    +}
    +
    +static void ext4_mb_seq_groups_stop(struct seq_file *seq, void *v)
    +{
    +}
    +
    +static struct seq_operations ext4_mb_seq_groups_ops = {
    + .start = ext4_mb_seq_groups_start,
    + .next = ext4_mb_seq_groups_next,
    + .stop = ext4_mb_seq_groups_stop,
    + .show = ext4_mb_seq_groups_show,
    +};
    +
    +static int ext4_mb_seq_groups_open(struct inode *inode, struct file *file)
    +{
    + struct super_block *sb = PDE(inode)->data;
    + int rc;
    +
    + rc = seq_open(file, &ext4_mb_seq_groups_ops);
    + if (rc == 0) {
    + struct seq_file *m = (struct seq_file *)file->private_data;
    + m->private = sb;
    + }
    + return rc;
    +
    +}
    +
    +static struct file_operations ext4_mb_seq_groups_fops = {
    + .owner = THIS_MODULE,
    + .open = ext4_mb_seq_groups_open,
    + .read = seq_read,
    + .llseek = seq_lseek,
    + .release = seq_release,
    +};
    +
    +static void ext4_mb_history_release(struct super_block *sb)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    +
    + remove_proc_entry("mb_groups", sbi->s_mb_proc);
    + remove_proc_entry("mb_history", sbi->s_mb_proc);
    +
    + kfree(sbi->s_mb_history);
    +}
    +
    +static void ext4_mb_history_init(struct super_block *sb)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + int i;
    +
    + if (sbi->s_mb_proc != NULL) {
    + struct proc_dir_entry *p;
    + p = create_proc_entry("mb_history", S_IRUGO, sbi->s_mb_proc);
    + if (p) {
    + p->proc_fops = &ext4_mb_seq_history_fops;
    + p->data = sb;
    + }
    + p = create_proc_entry("mb_groups", S_IRUGO, sbi->s_mb_proc);
    + if (p) {
    + p->proc_fops = &ext4_mb_seq_groups_fops;
    + p->data = sb;
    + }
    + }
    +
    + sbi->s_mb_history_max = 1000;
    + sbi->s_mb_history_cur = 0;
    + spin_lock_init(&sbi->s_mb_history_lock);
    + i = sbi->s_mb_history_max * sizeof(struct ext4_mb_history);
    + sbi->s_mb_history = kmalloc(i, GFP_KERNEL);
    + if (likely(sbi->s_mb_history != NULL))
    + memset(sbi->s_mb_history, 0, i);
    + /* if we can't allocate history, then we simple won't use it */
    +}
    +
    +static void ext4_mb_store_history(struct ext4_allocation_context *ac)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
    + struct ext4_mb_history h;
    +
    + if (unlikely(sbi->s_mb_history == NULL))
    + return;
    +
    + if (!(ac->ac_op & sbi->s_mb_history_filter))
    + return;
    +
    + h.op = ac->ac_op;
    + h.pid = current->pid;
    + h.ino = ac->ac_inode ? ac->ac_inode->i_ino : 0;
    + h.orig = ac->ac_o_ex;
    + h.result = ac->ac_b_ex;
    + h.flags = ac->ac_flags;
    + h.found = ac->ac_found;
    + h.groups = ac->ac_groups_scanned;
    + h.cr = ac->ac_criteria;
    + h.tail = ac->ac_tail;
    + h.buddy = ac->ac_buddy;
    + h.merged = 0;
    + if (ac->ac_op == EXT4_MB_HISTORY_ALLOC) {
    + if (ac->ac_g_ex.fe_start == ac->ac_b_ex.fe_start &&
    + ac->ac_g_ex.fe_group == ac->ac_b_ex.fe_group)
    + h.merged = 1;
    + h.goal = ac->ac_g_ex;
    + h.result = ac->ac_f_ex;
    + }
    +
    + spin_lock(&sbi->s_mb_history_lock);
    + memcpy(sbi->s_mb_history + sbi->s_mb_history_cur, &h, sizeof(h));
    + if (++sbi->s_mb_history_cur >= sbi->s_mb_history_max)
    + sbi->s_mb_history_cur = 0;
    + spin_unlock(&sbi->s_mb_history_lock);
    +}
    +
    +#else
    +#define ext4_mb_history_release(sb)
    +#define ext4_mb_history_init(sb)
    +#endif
    +
    +static int ext4_mb_init_backend(struct super_block *sb)
    +{
    + ext4_group_t i;
    + int j, len, metalen;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + int num_meta_group_infos =
    + (sbi->s_groups_count + EXT4_DESC_PER_BLOCK(sb) - 1) >>
    + EXT4_DESC_PER_BLOCK_BITS(sb);
    + struct ext4_group_info **meta_group_info;
    +
    + /* An 8TB filesystem with 64-bit pointers requires a 4096 byte
    + * kmalloc. A 128kb malloc should suffice for a 256TB filesystem.
    + * So a two level scheme suffices for now. */
    + sbi->s_group_info = kmalloc(sizeof(*sbi->s_group_info) *
    + num_meta_group_infos, GFP_KERNEL);
    + if (sbi->s_group_info == NULL) {
    + printk(KERN_ERR "EXT4-fs: can't allocate buddy meta group\n");
    + return -ENOMEM;
    + }
    + sbi->s_buddy_cache = new_inode(sb);
    + if (sbi->s_buddy_cache == NULL) {
    + printk(KERN_ERR "EXT4-fs: can't get new inode\n");
    + goto err_freesgi;
    + }
    + EXT4_I(sbi->s_buddy_cache)->i_disksize = 0;
    +
    + metalen = sizeof(*meta_group_info) << EXT4_DESC_PER_BLOCK_BITS(sb);
    + for (i = 0; i < num_meta_group_infos; i++) {
    + if ((i + 1) == num_meta_group_infos)
    + metalen = sizeof(*meta_group_info) *
    + (sbi->s_groups_count -
    + (i << EXT4_DESC_PER_BLOCK_BITS(sb)));
    + meta_group_info = kmalloc(metalen, GFP_KERNEL);
    + if (meta_group_info == NULL) {
    + printk(KERN_ERR "EXT4-fs: can't allocate mem for a "
    + "buddy group\n");
    + goto err_freemeta;
    + }
    + sbi->s_group_info[i] = meta_group_info;
    + }
    +
    + /*
    + * calculate needed size. if change bb_counters size,
    + * don't forget about ext4_mb_generate_buddy()
    + */
    + len = sizeof(struct ext4_group_info);
    + len += sizeof(unsigned short) * (sb->s_blocksize_bits + 2);
    + for (i = 0; i < sbi->s_groups_count; i++) {
    + struct ext4_group_desc *desc;
    +
    + meta_group_info =
    + sbi->s_group_info[i >> EXT4_DESC_PER_BLOCK_BITS(sb)];
    + j = i & (EXT4_DESC_PER_BLOCK(sb) - 1);
    +
    + meta_group_info[j] = kzalloc(len, GFP_KERNEL);
    + if (meta_group_info[j] == NULL) {
    + printk(KERN_ERR "EXT4-fs: can't allocate buddy mem\n");
    + i--;
    + goto err_freebuddy;
    + }
    + desc = ext4_get_group_desc(sb, i, NULL);
    + if (desc == NULL) {
    + printk(KERN_ERR
    + "EXT4-fs: can't read descriptor %lu\n", i);
    + goto err_freebuddy;
    + }
    + memset(meta_group_info[j], 0, len);
    + set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT,
    + &(meta_group_info[j]->bb_state));
    +
    + /*
    + * initialize bb_free to be able to skip
    + * empty groups without initialization
    + */
    + if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
    + meta_group_info[j]->bb_free =
    + ext4_free_blocks_after_init(sb, i, desc);
    + } else {
    + meta_group_info[j]->bb_free =
    + le16_to_cpu(desc->bg_free_blocks_count);
    + }
    +
    + INIT_LIST_HEAD(&meta_group_info[j]->bb_prealloc_list);
    +
    +#ifdef DOUBLE_CHECK
    + {
    + struct buffer_head *bh;
    + meta_group_info[j]->bb_bitmap =
    + kmalloc(sb->s_blocksize, GFP_KERNEL);
    + BUG_ON(meta_group_info[j]->bb_bitmap == NULL);
    + bh = read_block_bitmap(sb, i);
    + BUG_ON(bh == NULL);
    + memcpy(meta_group_info[j]->bb_bitmap, bh->b_data,
    + sb->s_blocksize);
    + brelse(bh);
    + }
    +#endif
    +
    + }
    +
    + return 0;
    +
    +err_freebuddy:
    + while (i >= 0) {
    + kfree(ext4_get_group_info(sb, i));
    + i--;
    + }
    + i = num_meta_group_infos;
    +err_freemeta:
    + while (--i >= 0)
    + kfree(sbi->s_group_info[i]);
    + iput(sbi->s_buddy_cache);
    +err_freesgi:
    + kfree(sbi->s_group_info);
    + return -ENOMEM;
    +}
    +
    +int ext4_mb_init(struct super_block *sb, int needs_recovery)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + unsigned i;
    + unsigned offset;
    + unsigned max;
    +
    + if (!test_opt(sb, MBALLOC))
    + return 0;
    +
    + i = (sb->s_blocksize_bits + 2) * sizeof(unsigned short);
    +
    + sbi->s_mb_offsets = kmalloc(i, GFP_KERNEL);
    + if (sbi->s_mb_offsets == NULL) {
    + clear_opt(sbi->s_mount_opt, MBALLOC);
    + return -ENOMEM;
    + }
    + sbi->s_mb_maxs = kmalloc(i, GFP_KERNEL);
    + if (sbi->s_mb_maxs == NULL) {
    + clear_opt(sbi->s_mount_opt, MBALLOC);
    + kfree(sbi->s_mb_maxs);
    + return -ENOMEM;
    + }
    +
    + /* order 0 is regular bitmap */
    + sbi->s_mb_maxs[0] = sb->s_blocksize << 3;
    + sbi->s_mb_offsets[0] = 0;
    +
    + i = 1;
    + offset = 0;
    + max = sb->s_blocksize << 2;
    + do {
    + sbi->s_mb_offsets[i] = offset;
    + sbi->s_mb_maxs[i] = max;
    + offset += 1 << (sb->s_blocksize_bits - i);
    + max = max >> 1;
    + i++;
    + } while (i <= sb->s_blocksize_bits + 1);
    +
    + /* init file for buddy data */
    + i = ext4_mb_init_backend(sb);
    + if (i) {
    + clear_opt(sbi->s_mount_opt, MBALLOC);
    + kfree(sbi->s_mb_offsets);
    + kfree(sbi->s_mb_maxs);
    + return i;
    + }
    +
    + spin_lock_init(&sbi->s_md_lock);
    + INIT_LIST_HEAD(&sbi->s_active_transaction);
    + INIT_LIST_HEAD(&sbi->s_closed_transaction);
    + INIT_LIST_HEAD(&sbi->s_committed_transaction);
    + spin_lock_init(&sbi->s_bal_lock);
    +
    + sbi->s_mb_max_to_scan = MB_DEFAULT_MAX_TO_SCAN;
    + sbi->s_mb_min_to_scan = MB_DEFAULT_MIN_TO_SCAN;
    + sbi->s_mb_stats = MB_DEFAULT_STATS;
    + sbi->s_mb_stream_request = MB_DEFAULT_STREAM_THRESHOLD;
    + sbi->s_mb_order2_reqs = MB_DEFAULT_ORDER2_REQS;
    + sbi->s_mb_history_filter = EXT4_MB_HISTORY_DEFAULT;
    + sbi->s_mb_group_prealloc = MB_DEFAULT_GROUP_PREALLOC;
    +
    + i = sizeof(struct ext4_locality_group) * NR_CPUS;
    + sbi->s_locality_groups = kmalloc(i, GFP_NOFS);
    + if (sbi->s_locality_groups == NULL) {
    + clear_opt(sbi->s_mount_opt, MBALLOC);
    + kfree(sbi->s_mb_offsets);
    + kfree(sbi->s_mb_maxs);
    + return -ENOMEM;
    + }
    + for (i = 0; i < NR_CPUS; i++) {
    + struct ext4_locality_group *lg;
    + lg = &sbi->s_locality_groups[i];
    + sema_init(&lg->lg_sem, 1);
    + INIT_LIST_HEAD(&lg->lg_prealloc_list);
    + spin_lock_init(&lg->lg_prealloc_lock);
    + }
    +
    + ext4_mb_init_per_dev_proc(sb);
    + ext4_mb_history_init(sb);
    +
    + printk("EXT4-fs: mballoc enabled\n");
    + return 0;
    +}
    +
    +static void ext4_mb_cleanup_pa(struct ext4_group_info *grp)
    +{
    + struct ext4_prealloc_space *pa;
    + struct list_head *cur, *tmp;
    + int count = 0;
    +
    + list_for_each_safe(cur, tmp, &grp->bb_prealloc_list) {
    + pa = list_entry(cur, struct ext4_prealloc_space, pa_group_list);
    + list_del_rcu(&pa->pa_group_list);
    + count++;
    + kfree(pa);
    + }
    + if (count)
    + mb_debug("mballoc: %u PAs left\n", count);
    +
    +}
    +
    +int ext4_mb_release(struct super_block *sb)
    +{
    + ext4_group_t i;
    + int num_meta_group_infos;
    + struct ext4_group_info *grinfo;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    +
    + if (!test_opt(sb, MBALLOC))
    + return 0;
    +
    + /* release freed, non-committed blocks */
    + spin_lock(&sbi->s_md_lock);
    + list_splice_init(&sbi->s_closed_transaction,
    + &sbi->s_committed_transaction);
    + list_splice_init(&sbi->s_active_transaction,
    + &sbi->s_committed_transaction);
    + spin_unlock(&sbi->s_md_lock);
    + ext4_mb_free_committed_blocks(sb);
    +
    + if (sbi->s_group_info) {
    + for (i = 0; i < sbi->s_groups_count; i++) {
    + grinfo = ext4_get_group_info(sb, i);
    +#ifdef DOUBLE_CHECK
    + kfree(grinfo->bb_bitmap);
    +#endif
    + ext4_mb_cleanup_pa(grinfo);
    + kfree(grinfo);
    + }
    + num_meta_group_infos = (sbi->s_groups_count +
    + EXT4_DESC_PER_BLOCK(sb) - 1) >>
    + EXT4_DESC_PER_BLOCK_BITS(sb);
    + for (i = 0; i < num_meta_group_infos; i++)
    + kfree(sbi->s_group_info[i]);
    + kfree(sbi->s_group_info);
    + }
    + kfree(sbi->s_mb_offsets);
    + kfree(sbi->s_mb_maxs);
    + if (sbi->s_buddy_cache)
    + iput(sbi->s_buddy_cache);
    + if (sbi->s_mb_stats) {
    + printk(KERN_INFO
    + "EXT4-fs: mballoc: %u blocks %u reqs (%u success)\n",
    + atomic_read(&sbi->s_bal_allocated),
    + atomic_read(&sbi->s_bal_reqs),
    + atomic_read(&sbi->s_bal_success));
    + printk(KERN_INFO
    + "EXT4-fs: mballoc: %u extents scanned, %u goal hits, "
    + "%u 2^N hits, %u breaks, %u lost\n",
    + atomic_read(&sbi->s_bal_ex_scanned),
    + atomic_read(&sbi->s_bal_goals),
    + atomic_read(&sbi->s_bal_2orders),
    + atomic_read(&sbi->s_bal_breaks),
    + atomic_read(&sbi->s_mb_lost_chunks));
    + printk(KERN_INFO
    + "EXT4-fs: mballoc: %lu generated and it took %Lu\n",
    + sbi->s_mb_buddies_generated++,
    + sbi->s_mb_generation_time);
    + printk(KERN_INFO
    + "EXT4-fs: mballoc: %u preallocated, %u discarded\n",
    + atomic_read(&sbi->s_mb_preallocated),
    + atomic_read(&sbi->s_mb_discarded));
    + }
    +
    + kfree(sbi->s_locality_groups);
    +
    + ext4_mb_history_release(sb);
    + ext4_mb_destroy_per_dev_proc(sb);
    +
    + return 0;
    +}
    +
    +static void ext4_mb_free_committed_blocks(struct super_block *sb)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + int err;
    + int i;
    + int count = 0;
    + int count2 = 0;
    + struct ext4_free_metadata *md;
    + struct ext4_buddy e4b;
    +
    + if (list_empty(&sbi->s_committed_transaction))
    + return;
    +
    + /* there is committed blocks to be freed yet */
    + do {
    + /* get next array of blocks */
    + md = NULL;
    + spin_lock(&sbi->s_md_lock);
    + if (!list_empty(&sbi->s_committed_transaction)) {
    + md = list_entry(sbi->s_committed_transaction.next,
    + struct ext4_free_metadata, list);
    + list_del(&md->list);
    + }
    + spin_unlock(&sbi->s_md_lock);
    +
    + if (md == NULL)
    + break;
    +
    + mb_debug("gonna free %u blocks in group %lu (0x%p):",
    + md->num, md->group, md);
    +
    + err = ext4_mb_load_buddy(sb, md->group, &e4b);
    + /* we expect to find existing buddy because it's pinned */
    + BUG_ON(err != 0);
    +
    + /* there are blocks to put in buddy to make them really free */
    + count += md->num;
    + count2++;
    + ext4_lock_group(sb, md->group);
    + for (i = 0; i < md->num; i++) {
    + mb_debug(" %u", md->blocks[i]);
    + err = mb_free_blocks(NULL, &e4b, md->blocks[i], 1);
    + BUG_ON(err != 0);
    + }
    + mb_debug("\n");
    + ext4_unlock_group(sb, md->group);
    +
    + /* balance refcounts from ext4_mb_free_metadata() */
    + page_cache_release(e4b.bd_buddy_page);
    + page_cache_release(e4b.bd_bitmap_page);
    +
    + kfree(md);
    + ext4_mb_release_desc(&e4b);
    +
    + } while (md);
    +
    + mb_debug("freed %u blocks in %u structures\n", count, count2);
    +}
    +
    +#define EXT4_ROOT "ext4"
    +#define EXT4_MB_STATS_NAME "stats"
    +#define EXT4_MB_MAX_TO_SCAN_NAME "max_to_scan"
    +#define EXT4_MB_MIN_TO_SCAN_NAME "min_to_scan"
    +#define EXT4_MB_ORDER2_REQ "order2_req"
    +#define EXT4_MB_STREAM_REQ "stream_req"
    +#define EXT4_MB_GROUP_PREALLOC "group_prealloc"
    +
    +
    +
    +#define MB_PROC_VALUE_READ(name) \
    +static int ext4_mb_read_##name(char *page, char **start, \
    + off_t off, int count, int *eof, void *data) \
    +{ \
    + struct ext4_sb_info *sbi = data; \
    + int len; \
    + *eof = 1; \
    + if (off != 0) \
    + return 0; \
    + len = sprintf(page, "%ld\n", sbi->s_mb_##name); \
    + *start = page; \
    + return len; \
    +}
    +
    +#define MB_PROC_VALUE_WRITE(name) \
    +static int ext4_mb_write_##name(struct file *file, \
    + const char __user *buf, unsigned long cnt, void *data) \
    +{ \
    + struct ext4_sb_info *sbi = data; \
    + char str[32]; \
    + long value; \
    + if (cnt >= sizeof(str)) \
    + return -EINVAL; \
    + if (copy_from_user(str, buf, cnt)) \
    + return -EFAULT; \
    + value = simple_strtol(str, NULL, 0); \
    + if (value <= 0) \
    + return -ERANGE; \
    + sbi->s_mb_##name = value; \
    + return cnt; \
    +}
    +
    +MB_PROC_VALUE_READ(stats);
    +MB_PROC_VALUE_WRITE(stats);
    +MB_PROC_VALUE_READ(max_to_scan);
    +MB_PROC_VALUE_WRITE(max_to_scan);
    +MB_PROC_VALUE_READ(min_to_scan);
    +MB_PROC_VALUE_WRITE(min_to_scan);
    +MB_PROC_VALUE_READ(order2_reqs);
    +MB_PROC_VALUE_WRITE(order2_reqs);
    +MB_PROC_VALUE_READ(stream_request);
    +MB_PROC_VALUE_WRITE(stream_request);
    +MB_PROC_VALUE_READ(group_prealloc);
    +MB_PROC_VALUE_WRITE(group_prealloc);
    +
    +#define MB_PROC_HANDLER(name, var) \
    +do { \
    + proc = create_proc_entry(name, mode, sbi->s_mb_proc); \
    + if (proc == NULL) { \
    + printk(KERN_ERR "EXT4-fs: can't to create %s\n", name); \
    + goto err_out; \
    + } \
    + proc->data = sbi; \
    + proc->read_proc = ext4_mb_read_##var ; \
    + proc->write_proc = ext4_mb_write_##var; \
    +} while (0)
    +
    +static int ext4_mb_init_per_dev_proc(struct super_block *sb)
    +{
    + mode_t mode = S_IFREG | S_IRUGO | S_IWUSR;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + struct proc_dir_entry *proc;
    + char devname[64];
    +
    + snprintf(devname, sizeof(devname) - 1, "%s",
    + bdevname(sb->s_bdev, devname));
    + sbi->s_mb_proc = proc_mkdir(devname, proc_root_ext4);
    +
    + MB_PROC_HANDLER(EXT4_MB_STATS_NAME, stats);
    + MB_PROC_HANDLER(EXT4_MB_MAX_TO_SCAN_NAME, max_to_scan);
    + MB_PROC_HANDLER(EXT4_MB_MIN_TO_SCAN_NAME, min_to_scan);
    + MB_PROC_HANDLER(EXT4_MB_ORDER2_REQ, order2_reqs);
    + MB_PROC_HANDLER(EXT4_MB_STREAM_REQ, stream_request);
    + MB_PROC_HANDLER(EXT4_MB_GROUP_PREALLOC, group_prealloc);
    +
    + return 0;
    +
    +err_out:
    + printk(KERN_ERR "EXT4-fs: Unable to create %s\n", devname);
    + remove_proc_entry(EXT4_MB_GROUP_PREALLOC, sbi->s_mb_proc);
    + remove_proc_entry(EXT4_MB_STREAM_REQ, sbi->s_mb_proc);
    + remove_proc_entry(EXT4_MB_ORDER2_REQ, sbi->s_mb_proc);
    + remove_proc_entry(EXT4_MB_MIN_TO_SCAN_NAME, sbi->s_mb_proc);
    + remove_proc_entry(EXT4_MB_MAX_TO_SCAN_NAME, sbi->s_mb_proc);
    + remove_proc_entry(EXT4_MB_STATS_NAME, sbi->s_mb_proc);
    + remove_proc_entry(devname, proc_root_ext4);
    + sbi->s_mb_proc = NULL;
    +
    + return -ENOMEM;
    +}
    +
    +static int ext4_mb_destroy_per_dev_proc(struct super_block *sb)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + char devname[64];
    +
    + if (sbi->s_mb_proc == NULL)
    + return -EINVAL;
    +
    + snprintf(devname, sizeof(devname) - 1, "%s",
    + bdevname(sb->s_bdev, devname));
    + remove_proc_entry(EXT4_MB_GROUP_PREALLOC, sbi->s_mb_proc);
    + remove_proc_entry(EXT4_MB_STREAM_REQ, sbi->s_mb_proc);
    + remove_proc_entry(EXT4_MB_ORDER2_REQ, sbi->s_mb_proc);
    + remove_proc_entry(EXT4_MB_MIN_TO_SCAN_NAME, sbi->s_mb_proc);
    + remove_proc_entry(EXT4_MB_MAX_TO_SCAN_NAME, sbi->s_mb_proc);
    + remove_proc_entry(EXT4_MB_STATS_NAME, sbi->s_mb_proc);
    + remove_proc_entry(devname, proc_root_ext4);
    +
    + return 0;
    +}
    +
    +int __init init_ext4_mballoc(void)
    +{
    + ext4_pspace_cachep =
    + kmem_cache_create("ext4_prealloc_space",
    + sizeof(struct ext4_prealloc_space),
    + 0, SLAB_RECLAIM_ACCOUNT, NULL);
    + if (ext4_pspace_cachep == NULL)
    + return -ENOMEM;
    +
    +#ifdef CONFIG_PROC_FS
    + proc_root_ext4 = proc_mkdir(EXT4_ROOT, proc_root_fs);
    + if (proc_root_ext4 == NULL)
    + printk(KERN_ERR "EXT4-fs: Unable to create %s\n", EXT4_ROOT);
    +#endif
    +
    + return 0;
    +}
    +
    +void exit_ext4_mballoc(void)
    +{
    + /* XXX: synchronize_rcu(); */
    + kmem_cache_destroy(ext4_pspace_cachep);
    +#ifdef CONFIG_PROC_FS
    + remove_proc_entry(EXT4_ROOT, proc_root_fs);
    +#endif
    +}
    +
    +
    +/*
    + * Check quota and mark choosed space (ac->ac_b_ex) non-free in bitmaps
    + * Returns 0 if success or error code
    + */
    +static int ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
    + handle_t *handle)
    +{
    + struct buffer_head *bitmap_bh = NULL;
    + struct ext4_super_block *es;
    + struct ext4_group_desc *gdp;
    + struct buffer_head *gdp_bh;
    + struct ext4_sb_info *sbi;
    + struct super_block *sb;
    + ext4_fsblk_t block;
    + int err;
    +
    + BUG_ON(ac->ac_status != AC_STATUS_FOUND);
    + BUG_ON(ac->ac_b_ex.fe_len <= 0);
    +
    + sb = ac->ac_sb;
    + sbi = EXT4_SB(sb);
    + es = sbi->s_es;
    +
    + ext4_debug("using block group %lu(%d)\n", ac->ac_b_ex.fe_group,
    + gdp->bg_free_blocks_count);
    +
    + err = -EIO;
    + bitmap_bh = read_block_bitmap(sb, ac->ac_b_ex.fe_group);
    + if (!bitmap_bh)
    + goto out_err;
    +
    + err = ext4_journal_get_write_access(handle, bitmap_bh);
    + if (err)
    + goto out_err;
    +
    + err = -EIO;
    + gdp = ext4_get_group_desc(sb, ac->ac_b_ex.fe_group, &gdp_bh);
    + if (!gdp)
    + goto out_err;
    +
    + err = ext4_journal_get_write_access(handle, gdp_bh);
    + if (err)
    + goto out_err;
    +
    + block = ac->ac_b_ex.fe_group * EXT4_BLOCKS_PER_GROUP(sb)
    + + ac->ac_b_ex.fe_start
    + + le32_to_cpu(es->s_first_data_block);
    +
    + if (block == ext4_block_bitmap(sb, gdp) ||
    + block == ext4_inode_bitmap(sb, gdp) ||
    + in_range(block, ext4_inode_table(sb, gdp),
    + EXT4_SB(sb)->s_itb_per_group)) {
    +
    + ext4_error(sb, __FUNCTION__,
    + "Allocating block in system zone - block = %llu",
    + block);
    + }
    +#ifdef AGGRESSIVE_CHECK
    + {
    + int i;
    + for (i = 0; i < ac->ac_b_ex.fe_len; i++) {
    + BUG_ON(mb_test_bit(ac->ac_b_ex.fe_start + i,
    + bitmap_bh->b_data));
    + }
    + }
    +#endif
    + mb_set_bits(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group), bitmap_bh->b_data,
    + ac->ac_b_ex.fe_start, ac->ac_b_ex.fe_len);
    +
    + spin_lock(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group));
    + if (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
    + gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
    + gdp->bg_free_blocks_count =
    + cpu_to_le16(ext4_free_blocks_after_init(sb,
    + ac->ac_b_ex.fe_group,
    + gdp));
    + }
    + gdp->bg_free_blocks_count =
    + cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count)
    + - ac->ac_b_ex.fe_len);
    + gdp->bg_checksum = ext4_group_desc_csum(sbi, ac->ac_b_ex.fe_group, gdp);
    + spin_unlock(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group));
    + percpu_counter_sub(&sbi->s_freeblocks_counter, ac->ac_b_ex.fe_len);
    +
    + err = ext4_journal_dirty_metadata(handle, bitmap_bh);
    + if (err)
    + goto out_err;
    + err = ext4_journal_dirty_metadata(handle, gdp_bh);
    +
    +out_err:
    + sb->s_dirt = 1;
    + brelse(bitmap_bh);
    + return err;
    +}
    +
    +/*
    + * here we normalize request for locality group
    + * Group request are normalized to s_strip size if we set the same via mount
    + * option. If not we set it to s_mb_group_prealloc which can be configured via
    + * /proc/fs/ext4/<partition>/group_prealloc
    + *
    + * XXX: should we try to preallocate more than the group has now?
    + */
    +static void ext4_mb_normalize_group_request(struct ext4_allocation_context *ac)
    +{
    + struct super_block *sb = ac->ac_sb;
    + struct ext4_locality_group *lg = ac->ac_lg;
    +
    + BUG_ON(lg == NULL);
    + if (EXT4_SB(sb)->s_stripe)
    + ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_stripe;
    + else
    + ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc;
    + mb_debug("#%u: goal %lu blocks for locality group\n",
    + current->pid, ac->ac_g_ex.fe_len);
    +}
    +
    +/*
    + * Normalization means making request better in terms of
    + * size and alignment
    + */
    +static void ext4_mb_normalize_request(struct ext4_allocation_context *ac,
    + struct ext4_allocation_request *ar)
    +{
    + int bsbits, max;
    + ext4_lblk_t end;
    + struct list_head *cur;
    + loff_t size, orig_size, start_off;
    + ext4_lblk_t start, orig_start;
    + struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
    +
    + /* do normalize only data requests, metadata requests
    + do not need preallocation */
    + if (!(ac->ac_flags & EXT4_MB_HINT_DATA))
    + return;
    +
    + /* sometime caller may want exact blocks */
    + if (unlikely(ac->ac_flags & EXT4_MB_HINT_GOAL_ONLY))
    + return;
    +
    + /* caller may indicate that preallocation isn't
    + * required (it's a tail, for example) */
    + if (ac->ac_flags & EXT4_MB_HINT_NOPREALLOC)
    + return;
    +
    + if (ac->ac_flags & EXT4_MB_HINT_GROUP_ALLOC) {
    + ext4_mb_normalize_group_request(ac);
    + return ;
    + }
    +
    + bsbits = ac->ac_sb->s_blocksize_bits;
    +
    + /* first, let's learn actual file size
    + * given current request is allocated */
    + size = ac->ac_o_ex.fe_logical + ac->ac_o_ex.fe_len;
    + size = size << bsbits;
    + if (size < i_size_read(ac->ac_inode))
    + size = i_size_read(ac->ac_inode);
    +
    + /* max available blocks in a free group */
    + max = EXT4_BLOCKS_PER_GROUP(ac->ac_sb) - 1 - 1 -
    + EXT4_SB(ac->ac_sb)->s_itb_per_group;
    +
    +#define NRL_CHECK_SIZE(req, size, max,bits) \
    + (req <= (size) || max <= ((size) >> bits))
    +
    + /* first, try to predict filesize */
    + /* XXX: should this table be tunable? */
    + start_off = 0;
    + if (size <= 16 * 1024) {
    + size = 16 * 1024;
    + } else if (size <= 32 * 1024) {
    + size = 32 * 1024;
    + } else if (size <= 64 * 1024) {
    + size = 64 * 1024;
    + } else if (size <= 128 * 1024) {
    + size = 128 * 1024;
    + } else if (size <= 256 * 1024) {
    + size = 256 * 1024;
    + } else if (size <= 512 * 1024) {
    + size = 512 * 1024;
    + } else if (size <= 1024 * 1024) {
    + size = 1024 * 1024;
    + } else if (NRL_CHECK_SIZE(size, 4 * 1024 * 1024, max, bsbits)) {
    + start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
    + (20 - bsbits)) << 20;
    + size = 1024 * 1024;
    + } else if (NRL_CHECK_SIZE(size, 8 * 1024 * 1024, max, bsbits)) {
    + start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
    + (22 - bsbits)) << 22;
    + size = 4 * 1024 * 1024;
    + } else if (NRL_CHECK_SIZE(ac->ac_o_ex.fe_len,
    + (8<<20)>>bsbits, max, bsbits)) {
    + start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
    + (23 - bsbits)) << 23;
    + size = 8 * 1024 * 1024;
    + } else {
    + start_off = (loff_t)ac->ac_o_ex.fe_logical << bsbits;
    + size = ac->ac_o_ex.fe_len << bsbits;
    + }
    + orig_size = size = size >> bsbits;
    + orig_start = start = start_off >> bsbits;
    +
    + /* don't cover already allocated blocks in selected range */
    + if (ar->pleft && start <= ar->lleft) {
    + size -= ar->lleft + 1 - start;
    + start = ar->lleft + 1;
    + }
    + if (ar->pright && start + size - 1 >= ar->lright)
    + size -= start + size - ar->lright;
    +
    + end = start + size;
    +
    + /* check we don't cross already preallocated blocks */
    + rcu_read_lock();
    + list_for_each_rcu(cur, &ei->i_prealloc_list) {
    + struct ext4_prealloc_space *pa;
    + unsigned long pa_end;
    +
    + pa = list_entry(cur, struct ext4_prealloc_space, pa_inode_list);
    +
    + if (pa->pa_deleted)
    + continue;
    + spin_lock(&pa->pa_lock);
    + if (pa->pa_deleted) {
    + spin_unlock(&pa->pa_lock);
    + continue;
    + }
    +
    + pa_end = pa->pa_lstart + pa->pa_len;
    +
    + /* PA must not overlap original request */
    + BUG_ON(!(ac->ac_o_ex.fe_logical >= pa_end ||
    + ac->ac_o_ex.fe_logical < pa->pa_lstart));
    +
    + /* skip PA normalized request doesn't overlap with */
    + if (pa->pa_lstart >= end) {
    + spin_unlock(&pa->pa_lock);
    + continue;
    + }
    + if (pa_end <= start) {
    + spin_unlock(&pa->pa_lock);
    + continue;
    + }
    + BUG_ON(pa->pa_lstart <= start && pa_end >= end);
    +
    + if (pa_end <= ac->ac_o_ex.fe_logical) {
    + BUG_ON(pa_end < start);
    + start = pa_end;
    + }
    +
    + if (pa->pa_lstart > ac->ac_o_ex.fe_logical) {
    + BUG_ON(pa->pa_lstart > end);
    + end = pa->pa_lstart;
    + }
    + spin_unlock(&pa->pa_lock);
    + }
    + rcu_read_unlock();
    + size = end - start;
    +
    + /* XXX: extra loop to check we really don't overlap preallocations */
    + rcu_read_lock();
    + list_for_each_rcu(cur, &ei->i_prealloc_list) {
    + struct ext4_prealloc_space *pa;
    + unsigned long pa_end;
    + pa = list_entry(cur, struct ext4_prealloc_space, pa_inode_list);
    + spin_lock(&pa->pa_lock);
    + if (pa->pa_deleted == 0) {
    + pa_end = pa->pa_lstart + pa->pa_len;
    + BUG_ON(!(start >= pa_end || end <= pa->pa_lstart));
    + }
    + spin_unlock(&pa->pa_lock);
    + }
    + rcu_read_unlock();
    +
    + if (start + size <= ac->ac_o_ex.fe_logical &&
    + start > ac->ac_o_ex.fe_logical) {
    + printk(KERN_ERR "start %lu, size %lu, fe_logical %lu\n",
    + (unsigned long) start, (unsigned long) size,
    + (unsigned long) ac->ac_o_ex.fe_logical);
    + }
    + BUG_ON(start + size <= ac->ac_o_ex.fe_logical &&
    + start > ac->ac_o_ex.fe_logical);
    + BUG_ON(size <= 0 || size >= EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
    +
    + /* now prepare goal request */
    +
    + /* XXX: is it better to align blocks WRT to logical
    + * placement or satisfy big request as is */
    + ac->ac_g_ex.fe_logical = start;
    + ac->ac_g_ex.fe_len = size;
    +
    + /* define goal start in order to merge */
    + if (ar->pright && (ar->lright == (start + size))) {
    + /* merge to the right */
    + ext4_get_group_no_and_offset(ac->ac_sb, ar->pright - size,
    + &ac->ac_f_ex.fe_group,
    + &ac->ac_f_ex.fe_start);
    + ac->ac_flags |= EXT4_MB_HINT_TRY_GOAL;
    + }
    + if (ar->pleft && (ar->lleft + 1 == start)) {
    + /* merge to the left */
    + ext4_get_group_no_and_offset(ac->ac_sb, ar->pleft + 1,
    + &ac->ac_f_ex.fe_group,
    + &ac->ac_f_ex.fe_start);
    + ac->ac_flags |= EXT4_MB_HINT_TRY_GOAL;
    + }
    +
    + mb_debug("goal: %u(was %u) blocks at %u\n", (unsigned) size,
    + (unsigned) orig_size, (unsigned) start);
    +}
    +
    +static void ext4_mb_collect_stats(struct ext4_allocation_context *ac)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
    +
    + if (sbi->s_mb_stats && ac->ac_g_ex.fe_len > 1) {
    + atomic_inc(&sbi->s_bal_reqs);
    + atomic_add(ac->ac_b_ex.fe_len, &sbi->s_bal_allocated);
    + if (ac->ac_o_ex.fe_len >= ac->ac_g_ex.fe_len)
    + atomic_inc(&sbi->s_bal_success);
    + atomic_add(ac->ac_found, &sbi->s_bal_ex_scanned);
    + if (ac->ac_g_ex.fe_start == ac->ac_b_ex.fe_start &&
    + ac->ac_g_ex.fe_group == ac->ac_b_ex.fe_group)
    + atomic_inc(&sbi->s_bal_goals);
    + if (ac->ac_found > sbi->s_mb_max_to_scan)
    + atomic_inc(&sbi->s_bal_breaks);
    + }
    +
    + ext4_mb_store_history(ac);
    +}
    +
    +/*
    + * use blocks preallocated to inode
    + */
    +static void ext4_mb_use_inode_pa(struct ext4_allocation_context *ac,
    + struct ext4_prealloc_space *pa)
    +{
    + ext4_fsblk_t start;
    + ext4_fsblk_t end;
    + int len;
    +
    + /* found preallocated blocks, use them */
    + start = pa->pa_pstart + (ac->ac_o_ex.fe_logical - pa->pa_lstart);
    + end = min(pa->pa_pstart + pa->pa_len, start + ac->ac_o_ex.fe_len);
    + len = end - start;
    + ext4_get_group_no_and_offset(ac->ac_sb, start, &ac->ac_b_ex.fe_group,
    + &ac->ac_b_ex.fe_start);
    + ac->ac_b_ex.fe_len = len;
    + ac->ac_status = AC_STATUS_FOUND;
    + ac->ac_pa = pa;
    +
    + BUG_ON(start < pa->pa_pstart);
    + BUG_ON(start + len > pa->pa_pstart + pa->pa_len);
    + BUG_ON(pa->pa_free < len);
    + pa->pa_free -= len;
    +
    + mb_debug("use %llu/%lu from inode pa %p\n", start, len, pa);
    +}
    +
    +/*
    + * use blocks preallocated to locality group
    + */
    +static void ext4_mb_use_group_pa(struct ext4_allocation_context *ac,
    + struct ext4_prealloc_space *pa)
    +{
    + unsigned len = ac->ac_o_ex.fe_len;
    +
    + ext4_get_group_no_and_offset(ac->ac_sb, pa->pa_pstart,
    + &ac->ac_b_ex.fe_group,
    + &ac->ac_b_ex.fe_start);
    + ac->ac_b_ex.fe_len = len;
    + ac->ac_status = AC_STATUS_FOUND;
    + ac->ac_pa = pa;
    +
    + /* we don't correct pa_pstart or pa_plen here to avoid
    + * possible race when tte group is being loaded concurrently
    + * instead we correct pa later, after blocks are marked
    + * in on-disk bitmap -- see ext4_mb_release_context() */
    + /*
    + * FIXME!! but the other CPUs can look at this particular
    + * pa and think that it have enought free blocks if we
    + * don't update pa_free here right ?
    + */
    + mb_debug("use %u/%u from group pa %p\n", pa->pa_lstart-len, len, pa);
    +}
    +
    +/*
    + * search goal blocks in preallocated space
    + */
    +static int ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
    +{
    + struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
    + struct ext4_locality_group *lg;
    + struct ext4_prealloc_space *pa;
    + struct list_head *cur;
    +
    + /* only data can be preallocated */
    + if (!(ac->ac_flags & EXT4_MB_HINT_DATA))
    + return 0;
    +
    + /* first, try per-file preallocation */
    + rcu_read_lock();
    + list_for_each_rcu(cur, &ei->i_prealloc_list) {
    + pa = list_entry(cur, struct ext4_prealloc_space, pa_inode_list);
    +
    + /* all fields in this condition don't change,
    + * so we can skip locking for them */
    + if (ac->ac_o_ex.fe_logical < pa->pa_lstart ||
    + ac->ac_o_ex.fe_logical >= pa->pa_lstart + pa->pa_len)
    + continue;
    +
    + /* found preallocated blocks, use them */
    + spin_lock(&pa->pa_lock);
    + if (pa->pa_deleted == 0 && pa->pa_free) {
    + atomic_inc(&pa->pa_count);
    + ext4_mb_use_inode_pa(ac, pa);
    + spin_unlock(&pa->pa_lock);
    + ac->ac_criteria = 10;
    + rcu_read_unlock();
    + return 1;
    + }
    + spin_unlock(&pa->pa_lock);
    + }
    + rcu_read_unlock();
    +
    + /* can we use group allocation? */
    + if (!(ac->ac_flags & EXT4_MB_HINT_GROUP_ALLOC))
    + return 0;
    +
    + /* inode may have no locality group for some reason */
    + lg = ac->ac_lg;
    + if (lg == NULL)
    + return 0;
    +
    + rcu_read_lock();
    + list_for_each_rcu(cur, &lg->lg_prealloc_list) {
    + pa = list_entry(cur, struct ext4_prealloc_space, pa_inode_list);
    + spin_lock(&pa->pa_lock);
    + if (pa->pa_deleted == 0 && pa->pa_free >= ac->ac_o_ex.fe_len) {
    + atomic_inc(&pa->pa_count);
    + ext4_mb_use_group_pa(ac, pa);
    + spin_unlock(&pa->pa_lock);
    + ac->ac_criteria = 20;
    + rcu_read_unlock();
    + return 1;
    + }
    + spin_unlock(&pa->pa_lock);
    + }
    + rcu_read_unlock();
    +
    + return 0;
    +}
    +
    +/*
    + * the function goes through all preallocation in this group and marks them
    + * used in in-core bitmap. buddy must be generated from this bitmap
    + */
    +static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
    + ext4_group_t group)
    +{
    + struct ext4_group_info *grp = ext4_get_group_info(sb, group);
    + struct ext4_prealloc_space *pa;
    + struct list_head *cur;
    + ext4_group_t groupnr;
    + ext4_grpblk_t start;
    + int preallocated = 0;
    + int count = 0;
    + int len;
    +
    + /* all form of preallocation discards first load group,
    + * so the only competing code is preallocation use.
    + * we don't need any locking here
    + * notice we do NOT ignore preallocations with pa_deleted
    + * otherwise we could leave used blocks available for
    + * allocation in buddy when concurrent ext4_mb_put_pa()
    + * is dropping preallocation
    + */
    + list_for_each_rcu(cur, &grp->bb_prealloc_list) {
    + pa = list_entry(cur, struct ext4_prealloc_space, pa_group_list);
    + spin_lock(&pa->pa_lock);
    + ext4_get_group_no_and_offset(sb, pa->pa_pstart,
    + &groupnr, &start);
    + len = pa->pa_len;
    + spin_unlock(&pa->pa_lock);
    + if (unlikely(len == 0))
    + continue;
    + BUG_ON(groupnr != group);
    + mb_set_bits(sb_bgl_lock(EXT4_SB(sb), group),
    + bitmap, start, len);
    + preallocated += len;
    + count++;
    + }
    + mb_debug("prellocated %u for group %lu\n", preallocated, group);
    +}
    +
    +static void ext4_mb_pa_callback(struct rcu_head *head)
    +{
    + struct ext4_prealloc_space *pa;
    + pa = container_of(head, struct ext4_prealloc_space, u.pa_rcu);
    + kmem_cache_free(ext4_pspace_cachep, pa);
    +}
    +#define mb_call_rcu(__pa) call_rcu(&(__pa)->u.pa_rcu, ext4_mb_pa_callback)
    +
    +/*
    + * drops a reference to preallocated space descriptor
    + * if this was the last reference and the space is consumed
    + */
    +static void ext4_mb_put_pa(struct ext4_allocation_context *ac,
    + struct super_block *sb, struct ext4_prealloc_space *pa)
    +{
    + unsigned long grp;
    +
    + if (!atomic_dec_and_test(&pa->pa_count) || pa->pa_free != 0)
    + return;
    +
    + /* in this short window concurrent discard can set pa_deleted */
    + spin_lock(&pa->pa_lock);
    + if (pa->pa_deleted == 1) {
    + spin_unlock(&pa->pa_lock);
    + return;
    + }
    +
    + pa->pa_deleted = 1;
    + spin_unlock(&pa->pa_lock);
    +
    + /* -1 is to protect from crossing allocation group */
    + ext4_get_group_no_and_offset(sb, pa->pa_pstart - 1, &grp, NULL);
    +
    + /*
    + * possible race:
    + *
    + * P1 (buddy init) P2 (regular allocation)
    + * find block B in PA
    + * copy on-disk bitmap to buddy
    + * mark B in on-disk bitmap
    + * drop PA from group
    + * mark all PAs in buddy
    + *
    + * thus, P1 initializes buddy with B available. to prevent this
    + * we make "copy" and "mark all PAs" atomic and serialize "drop PA"
    + * against that pair
    + */
    + ext4_lock_group(sb, grp);
    + list_del_rcu(&pa->pa_group_list);
    + ext4_unlock_group(sb, grp);
    +
    + spin_lock(pa->pa_obj_lock);
    + list_del_rcu(&pa->pa_inode_list);
    + spin_unlock(pa->pa_obj_lock);
    +
    + mb_call_rcu(pa);
    +}
    +
    +/*
    + * creates new preallocated space for given inode
    + */
    +static int ext4_mb_new_inode_pa(struct ext4_allocation_context *ac)
    +{
    + struct super_block *sb = ac->ac_sb;
    + struct ext4_prealloc_space *pa;
    + struct ext4_group_info *grp;
    + struct ext4_inode_info *ei;
    +
    + /* preallocate only when found space is larger then requested */
    + BUG_ON(ac->ac_o_ex.fe_len >= ac->ac_b_ex.fe_len);
    + BUG_ON(ac->ac_status != AC_STATUS_FOUND);
    + BUG_ON(!S_ISREG(ac->ac_inode->i_mode));
    +
    + pa = kmem_cache_alloc(ext4_pspace_cachep, GFP_NOFS);
    + if (pa == NULL)
    + return -ENOMEM;
    +
    + if (ac->ac_b_ex.fe_len < ac->ac_g_ex.fe_len) {
    + int winl;
    + int wins;
    + int win;
    + int offs;
    +
    + /* we can't allocate as much as normalizer wants.
    + * so, found space must get proper lstart
    + * to cover original request */
    + BUG_ON(ac->ac_g_ex.fe_logical > ac->ac_o_ex.fe_logical);
    + BUG_ON(ac->ac_g_ex.fe_len < ac->ac_o_ex.fe_len);
    +
    + /* we're limited by original request in that
    + * logical block must be covered any way
    + * winl is window we can move our chunk within */
    + winl = ac->ac_o_ex.fe_logical - ac->ac_g_ex.fe_logical;
    +
    + /* also, we should cover whole original request */
    + wins = ac->ac_b_ex.fe_len - ac->ac_o_ex.fe_len;
    +
    + /* the smallest one defines real window */
    + win = min(winl, wins);
    +
    + offs = ac->ac_o_ex.fe_logical % ac->ac_b_ex.fe_len;
    + if (offs && offs < win)
    + win = offs;
    +
    + ac->ac_b_ex.fe_logical = ac->ac_o_ex.fe_logical - win;
    + BUG_ON(ac->ac_o_ex.fe_logical < ac->ac_b_ex.fe_logical);
    + BUG_ON(ac->ac_o_ex.fe_len > ac->ac_b_ex.fe_len);
    + }
    +
    + /* preallocation can change ac_b_ex, thus we store actually
    + * allocated blocks for history */
    + ac->ac_f_ex = ac->ac_b_ex;
    +
    + pa->pa_lstart = ac->ac_b_ex.fe_logical;
    + pa->pa_pstart = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
    + pa->pa_len = ac->ac_b_ex.fe_len;
    + pa->pa_free = pa->pa_len;
    + atomic_set(&pa->pa_count, 1);
    + spin_lock_init(&pa->pa_lock);
    + pa->pa_deleted = 0;
    + pa->pa_linear = 0;
    +
    + mb_debug("new inode pa %p: %llu/%u for %u\n", pa,
    + pa->pa_pstart, pa->pa_len, pa->pa_lstart);
    +
    + ext4_mb_use_inode_pa(ac, pa);
    + atomic_add(pa->pa_free, &EXT4_SB(sb)->s_mb_preallocated);
    +
    + ei = EXT4_I(ac->ac_inode);
    + grp = ext4_get_group_info(sb, ac->ac_b_ex.fe_group);
    +
    + pa->pa_obj_lock = &ei->i_prealloc_lock;
    + pa->pa_inode = ac->ac_inode;
    +
    + ext4_lock_group(sb, ac->ac_b_ex.fe_group);
    + list_add_rcu(&pa->pa_group_list, &grp->bb_prealloc_list);
    + ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
    +
    + spin_lock(pa->pa_obj_lock);
    + list_add_rcu(&pa->pa_inode_list, &ei->i_prealloc_list);
    + spin_unlock(pa->pa_obj_lock);
    +
    + return 0;
    +}
    +
    +/*
    + * creates new preallocated space for locality group inodes belongs to
    + */
    +static int ext4_mb_new_group_pa(struct ext4_allocation_context *ac)
    +{
    + struct super_block *sb = ac->ac_sb;
    + struct ext4_locality_group *lg;
    + struct ext4_prealloc_space *pa;
    + struct ext4_group_info *grp;
    +
    + /* preallocate only when found space is larger then requested */
    + BUG_ON(ac->ac_o_ex.fe_len >= ac->ac_b_ex.fe_len);
    + BUG_ON(ac->ac_status != AC_STATUS_FOUND);
    + BUG_ON(!S_ISREG(ac->ac_inode->i_mode));
    +
    + BUG_ON(ext4_pspace_cachep == NULL);
    + pa = kmem_cache_alloc(ext4_pspace_cachep, GFP_NOFS);
    + if (pa == NULL)
    + return -ENOMEM;
    +
    + /* preallocation can change ac_b_ex, thus we store actually
    + * allocated blocks for history */
    + ac->ac_f_ex = ac->ac_b_ex;
    +
    + pa->pa_pstart = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
    + pa->pa_lstart = pa->pa_pstart;
    + pa->pa_len = ac->ac_b_ex.fe_len;
    + pa->pa_free = pa->pa_len;
    + atomic_set(&pa->pa_count, 1);
    + spin_lock_init(&pa->pa_lock);
    + pa->pa_deleted = 0;
    + pa->pa_linear = 1;
    +
    + mb_debug("new group pa %p: %llu/%u for %u\n", pa,
    + pa->pa_pstart, pa->pa_len, pa->pa_lstart);
    +
    + ext4_mb_use_group_pa(ac, pa);
    + atomic_add(pa->pa_free, &EXT4_SB(sb)->s_mb_preallocated);
    +
    + grp = ext4_get_group_info(sb, ac->ac_b_ex.fe_group);
    + lg = ac->ac_lg;
    + BUG_ON(lg == NULL);
    +
    + pa->pa_obj_lock = &lg->lg_prealloc_lock;
    + pa->pa_inode = NULL;
    +
    + ext4_lock_group(sb, ac->ac_b_ex.fe_group);
    + list_add_rcu(&pa->pa_group_list, &grp->bb_prealloc_list);
    + ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
    +
    + spin_lock(pa->pa_obj_lock);
    + list_add_tail_rcu(&pa->pa_inode_list, &lg->lg_prealloc_list);
    + spin_unlock(pa->pa_obj_lock);
    +
    + return 0;
    +}
    +
    +static int ext4_mb_new_preallocation(struct ext4_allocation_context *ac)
    +{
    + int err;
    +
    + if (ac->ac_flags & EXT4_MB_HINT_GROUP_ALLOC)
    + err = ext4_mb_new_group_pa(ac);
    + else
    + err = ext4_mb_new_inode_pa(ac);
    + return err;
    +}
    +
    +/*
    + * finds all unused blocks in on-disk bitmap, frees them in
    + * in-core bitmap and buddy.
    + * @pa must be unlinked from inode and group lists, so that
    + * nobody else can find/use it.
    + * the caller MUST hold group/inode locks.
    + * TODO: optimize the case when there are no in-core structures yet
    + */
    +static int ext4_mb_release_inode_pa(struct ext4_buddy *e4b,
    + struct buffer_head *bitmap_bh,
    + struct ext4_prealloc_space *pa)
    +{
    + struct ext4_allocation_context ac;
    + struct super_block *sb = e4b->bd_sb;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + unsigned long end;
    + unsigned long next;
    + ext4_group_t group;
    + ext4_grpblk_t bit;
    + sector_t start;
    + int err = 0;
    + int free = 0;
    +
    + BUG_ON(pa->pa_deleted == 0);
    + ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, &bit);
    + BUG_ON(group != e4b->bd_group && pa->pa_len != 0);
    + end = bit + pa->pa_len;
    +
    + ac.ac_sb = sb;
    + ac.ac_inode = pa->pa_inode;
    + ac.ac_op = EXT4_MB_HISTORY_DISCARD;
    +
    + while (bit < end) {
    + bit = ext4_find_next_zero_bit(bitmap_bh->b_data, end, bit);
    + if (bit >= end)
    + break;
    + next = ext4_find_next_bit(bitmap_bh->b_data, end, bit);
    + if (next > end)
    + next = end;
    + start = group * EXT4_BLOCKS_PER_GROUP(sb) + bit +
    + le32_to_cpu(sbi->s_es->s_first_data_block);
    + mb_debug(" free preallocated %u/%u in group %u\n",
    + (unsigned) start, (unsigned) next - bit,
    + (unsigned) group);
    + free += next - bit;
    +
    + ac.ac_b_ex.fe_group = group;
    + ac.ac_b_ex.fe_start = bit;
    + ac.ac_b_ex.fe_len = next - bit;
    + ac.ac_b_ex.fe_logical = 0;
    + ext4_mb_store_history(&ac);
    +
    + mb_free_blocks(pa->pa_inode, e4b, bit, next - bit);
    + bit = next + 1;
    + }
    + if (free != pa->pa_free) {
    + printk(KERN_ERR "pa %p: logic %lu, phys. %lu, len %lu\n",
    + pa, (unsigned long) pa->pa_lstart,
    + (unsigned long) pa->pa_pstart,
    + (unsigned long) pa->pa_len);
    + printk(KERN_ERR "free %u, pa_free %u\n", free, pa->pa_free);
    + }
    + BUG_ON(free != pa->pa_free);
    + atomic_add(free, &sbi->s_mb_discarded);
    +
    + return err;
    +}
    +
    +static int ext4_mb_release_group_pa(struct ext4_buddy *e4b,
    + struct ext4_prealloc_space *pa)
    +{
    + struct ext4_allocation_context ac;
    + struct super_block *sb = e4b->bd_sb;
    + ext4_group_t group;
    + ext4_grpblk_t bit;
    +
    + ac.ac_op = EXT4_MB_HISTORY_DISCARD;
    +
    + BUG_ON(pa->pa_deleted == 0);
    + ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, &bit);
    + BUG_ON(group != e4b->bd_group && pa->pa_len != 0);
    + mb_free_blocks(pa->pa_inode, e4b, bit, pa->pa_len);
    + atomic_add(pa->pa_len, &EXT4_SB(sb)->s_mb_discarded);
    +
    + ac.ac_sb = sb;
    + ac.ac_inode = NULL;
    + ac.ac_b_ex.fe_group = group;
    + ac.ac_b_ex.fe_start = bit;
    + ac.ac_b_ex.fe_len = pa->pa_len;
    + ac.ac_b_ex.fe_logical = 0;
    + ext4_mb_store_history(&ac);
    +
    + return 0;
    +}
    +
    +/*
    + * releases all preallocations in given group
    + *
    + * first, we need to decide discard policy:
    + * - when do we discard
    + * 1) ENOSPC
    + * - how many do we discard
    + * 1) how many requested
    + */
    +static int ext4_mb_discard_group_preallocations(struct super_block *sb,
    + ext4_group_t group, int needed)
    +{
    + struct ext4_group_info *grp = ext4_get_group_info(sb, group);
    + struct buffer_head *bitmap_bh = NULL;
    + struct ext4_prealloc_space *pa, *tmp;
    + struct list_head list;
    + struct ext4_buddy e4b;
    + int err;
    + int busy = 0;
    + int free = 0;
    +
    + mb_debug("discard preallocation for group %lu\n", group);
    +
    + if (list_empty(&grp->bb_prealloc_list))
    + return 0;
    +
    + bitmap_bh = read_block_bitmap(sb, group);
    + if (bitmap_bh == NULL) {
    + /* error handling here */
    + ext4_mb_release_desc(&e4b);
    + BUG_ON(bitmap_bh == NULL);
    + }
    +
    + err = ext4_mb_load_buddy(sb, group, &e4b);
    + BUG_ON(err != 0); /* error handling here */
    +
    + if (needed == 0)
    + needed = EXT4_BLOCKS_PER_GROUP(sb) + 1;
    +
    + grp = ext4_get_group_info(sb, group);
    + INIT_LIST_HEAD(&list);
    +
    +repeat:
    + ext4_lock_group(sb, group);
    + list_for_each_entry_safe(pa, tmp,
    + &grp->bb_prealloc_list, pa_group_list) {
    + spin_lock(&pa->pa_lock);
    + if (atomic_read(&pa->pa_count)) {
    + spin_unlock(&pa->pa_lock);
    + busy = 1;
    + continue;
    + }
    + if (pa->pa_deleted) {
    + spin_unlock(&pa->pa_lock);
    + continue;
    + }
    +
    + /* seems this one can be freed ... */
    + pa->pa_deleted = 1;
    +
    + /* we can trust pa_free ... */
    + free += pa->pa_free;
    +
    + spin_unlock(&pa->pa_lock);
    +
    + list_del_rcu(&pa->pa_group_list);
    + list_add(&pa->u.pa_tmp_list, &list);
    + }
    +
    + /* if we still need more blocks and some PAs were used, try again */
    + if (free < needed && busy) {
    + busy = 0;
    + ext4_unlock_group(sb, group);
    + /*
    + * Yield the CPU here so that we don't get soft lockup
    + * in non preempt case.
    + */
    + yield();
    + goto repeat;
    + }
    +
    + /* found anything to free? */
    + if (list_empty(&list)) {
    + BUG_ON(free != 0);
    + goto out;
    + }
    +
    + /* now free all selected PAs */
    + list_for_each_entry_safe(pa, tmp, &list, u.pa_tmp_list) {
    +
    + /* remove from object (inode or locality group) */
    + spin_lock(pa->pa_obj_lock);
    + list_del_rcu(&pa->pa_inode_list);
    + spin_unlock(pa->pa_obj_lock);
    +
    + if (pa->pa_linear)
    + ext4_mb_release_group_pa(&e4b, pa);
    + else
    + ext4_mb_release_inode_pa(&e4b, bitmap_bh, pa);
    +
    + list_del(&pa->u.pa_tmp_list);
    + mb_call_rcu(pa);
    + }
    +
    +out:
    + ext4_unlock_group(sb, group);
    + ext4_mb_release_desc(&e4b);
    + brelse(bitmap_bh);
    + return free;
    +}
    +
    +/*
    + * releases all non-used preallocated blocks for given inode
    + *
    + * It's important to discard preallocations under i_data_sem
    + * We don't want another block to be served from the prealloc
    + * space when we are discarding the inode prealloc space.
    + *
    + * FIXME!! Make sure it is valid at all the call sites
    + */
    +void ext4_mb_discard_inode_preallocations(struct inode *inode)
    +{
    + struct ext4_inode_info *ei = EXT4_I(inode);
    + struct super_block *sb = inode->i_sb;
    + struct buffer_head *bitmap_bh = NULL;
    + struct ext4_prealloc_space *pa, *tmp;
    + ext4_group_t group = 0;
    + struct list_head list;
    + struct ext4_buddy e4b;
    + int err;
    +
    + if (!test_opt(sb, MBALLOC) || !S_ISREG(inode->i_mode)) {
    + /*BUG_ON(!list_empty(&ei->i_prealloc_list));*/
    + return;
    + }
    +
    + mb_debug("discard preallocation for inode %lu\n", inode->i_ino);
    +
    + INIT_LIST_HEAD(&list);
    +
    +repeat:
    + /* first, collect all pa's in the inode */
    + spin_lock(&ei->i_prealloc_lock);
    + while (!list_empty(&ei->i_prealloc_list)) {
    + pa = list_entry(ei->i_prealloc_list.next,
    + struct ext4_prealloc_space, pa_inode_list);
    + BUG_ON(pa->pa_obj_lock != &ei->i_prealloc_lock);
    + spin_lock(&pa->pa_lock);
    + if (atomic_read(&pa->pa_count)) {
    + /* this shouldn't happen often - nobody should
    + * use preallocation while we're discarding it */
    + spin_unlock(&pa->pa_lock);
    + spin_unlock(&ei->i_prealloc_lock);
    + printk(KERN_ERR "uh-oh! used pa while discarding\n");
    + dump_stack();
    + current->state = TASK_UNINTERRUPTIBLE;
    + schedule_timeout(HZ);
    + goto repeat;
    +
    + }
    + if (pa->pa_deleted == 0) {
    + pa->pa_deleted = 1;
    + spin_unlock(&pa->pa_lock);
    + list_del_rcu(&pa->pa_inode_list);
    + list_add(&pa->u.pa_tmp_list, &list);
    + continue;
    + }
    +
    + /* someone is deleting pa right now */
    + spin_unlock(&pa->pa_lock);
    + spin_unlock(&ei->i_prealloc_lock);
    +
    + /* we have to wait here because pa_deleted
    + * doesn't mean pa is already unlinked from
    + * the list. as we might be called from
    + * ->clear_inode() the inode will get freed
    + * and concurrent thread which is unlinking
    + * pa from inode's list may access already
    + * freed memory, bad-bad-bad */
    +
    + /* XXX: if this happens too often, we can
    + * add a flag to force wait only in case
    + * of ->clear_inode(), but not in case of
    + * regular truncate */
    + current->state = TASK_UNINTERRUPTIBLE;
    + schedule_timeout(HZ);
    + goto repeat;
    + }
    + spin_unlock(&ei->i_prealloc_lock);
    +
    + list_for_each_entry_safe(pa, tmp, &list, u.pa_tmp_list) {
    + BUG_ON(pa->pa_linear != 0);
    + ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, NULL);
    +
    + err = ext4_mb_load_buddy(sb, group, &e4b);
    + BUG_ON(err != 0); /* error handling here */
    +
    + bitmap_bh = read_block_bitmap(sb, group);
    + if (bitmap_bh == NULL) {
    + /* error handling here */
    + ext4_mb_release_desc(&e4b);
    + BUG_ON(bitmap_bh == NULL);
    + }
    +
    + ext4_lock_group(sb, group);
    + list_del_rcu(&pa->pa_group_list);
    + ext4_mb_release_inode_pa(&e4b, bitmap_bh, pa);
    + ext4_unlock_group(sb, group);
    +
    + ext4_mb_release_desc(&e4b);
    + brelse(bitmap_bh);
    +
    + list_del(&pa->u.pa_tmp_list);
    + mb_call_rcu(pa);
    + }
    +}
    +
    +/*
    + * finds all preallocated spaces and return blocks being freed to them
    + * if preallocated space becomes full (no block is used from the space)
    + * then the function frees space in buddy
    + * XXX: at the moment, truncate (which is the only way to free blocks)
    + * discards all preallocations
    + */
    +static void ext4_mb_return_to_preallocation(struct inode *inode,
    + struct ext4_buddy *e4b,
    + sector_t block, int count)
    +{
    + BUG_ON(!list_empty(&EXT4_I(inode)->i_prealloc_list));
    +}
    +#ifdef MB_DEBUG
    +static void ext4_mb_show_ac(struct ext4_allocation_context *ac)
    +{
    + struct super_block *sb = ac->ac_sb;
    + ext4_group_t i;
    +
    + printk(KERN_ERR "EXT4-fs: Can't allocate:"
    + " Allocation context details:\n");
    + printk(KERN_ERR "EXT4-fs: status %d flags %d\n",
    + ac->ac_status, ac->ac_flags);
    + printk(KERN_ERR "EXT4-fs: orig %lu/%lu/%lu@%lu, goal %lu/%lu/%lu@%lu, "
    + "best %lu/%lu/%lu@%lu cr %d\n",
    + (unsigned long)ac->ac_o_ex.fe_group,
    + (unsigned long)ac->ac_o_ex.fe_start,
    + (unsigned long)ac->ac_o_ex.fe_len,
    + (unsigned long)ac->ac_o_ex.fe_logical,
    + (unsigned long)ac->ac_g_ex.fe_group,
    + (unsigned long)ac->ac_g_ex.fe_start,
    + (unsigned long)ac->ac_g_ex.fe_len,
    + (unsigned long)ac->ac_g_ex.fe_logical,
    + (unsigned long)ac->ac_b_ex.fe_group,
    + (unsigned long)ac->ac_b_ex.fe_start,
    + (unsigned long)ac->ac_b_ex.fe_len,
    + (unsigned long)ac->ac_b_ex.fe_logical,
    + (int)ac->ac_criteria);
    + printk(KERN_ERR "EXT4-fs: %lu scanned, %d found\n", ac->ac_ex_scanned,
    + ac->ac_found);
    + printk(KERN_ERR "EXT4-fs: groups: \n");
    + for (i = 0; i < EXT4_SB(sb)->s_groups_count; i++) {
    + struct ext4_group_info *grp = ext4_get_group_info(sb, i);
    + struct ext4_prealloc_space *pa;
    + ext4_grpblk_t start;
    + struct list_head *cur;
    + list_for_each_rcu(cur, &grp->bb_prealloc_list) {
    + pa = list_entry(cur, struct ext4_prealloc_space,
    + pa_group_list);
    + spin_lock(&pa->pa_lock);
    + ext4_get_group_no_and_offset(sb, pa->pa_pstart,
    + NULL, &start);
    + spin_unlock(&pa->pa_lock);
    + printk(KERN_ERR "PA:%lu:%d:%u \n", i,
    + start, pa->pa_len);
    + }
    +
    + if (grp->bb_free == 0)
    + continue;
    + printk(KERN_ERR "%lu: %d/%d \n",
    + i, grp->bb_free, grp->bb_fragments);
    + }
    + printk(KERN_ERR "\n");
    +}
    +#else
    +#define ext4_mb_show_ac(x)
    +#endif
    +
    +/*
    + * We use locality group preallocation for small size file. The size of the
    + * file is determined by the current size or the resulting size after
    + * allocation which ever is larger
    + *
    + * One can tune this size via /proc/fs/ext4/<partition>/stream_req
    + */
    +static void ext4_mb_group_or_file(struct ext4_allocation_context *ac)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
    + int bsbits = ac->ac_sb->s_blocksize_bits;
    + loff_t size, isize;
    +
    + if (!(ac->ac_flags & EXT4_MB_HINT_DATA))
    + return;
    +
    + size = ac->ac_o_ex.fe_logical + ac->ac_o_ex.fe_len;
    + isize = i_size_read(ac->ac_inode) >> bsbits;
    + if (size < isize)
    + size = isize;
    +
    + /* don't use group allocation for large files */
    + if (size >= sbi->s_mb_stream_request)
    + return;
    +
    + if (unlikely(ac->ac_flags & EXT4_MB_HINT_GOAL_ONLY))
    + return;
    +
    + BUG_ON(ac->ac_lg != NULL);
    + ac->ac_lg = &sbi->s_locality_groups[get_cpu()];
    + put_cpu();
    +
    + /* we're going to use group allocation */
    + ac->ac_flags |= EXT4_MB_HINT_GROUP_ALLOC;
    +
    + /* serialize all allocations in the group */
    + down(&ac->ac_lg->lg_sem);
    +}
    +
    +static int ext4_mb_initialize_context(struct ext4_allocation_context *ac,
    + struct ext4_allocation_request *ar)
    +{
    + struct super_block *sb = ar->inode->i_sb;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + struct ext4_super_block *es = sbi->s_es;
    + ext4_group_t group;
    + unsigned long len;
    + unsigned long goal;
    + ext4_grpblk_t block;
    +
    + /* we can't allocate > group size */
    + len = ar->len;
    +
    + /* just a dirty hack to filter too big requests */
    + if (len >= EXT4_BLOCKS_PER_GROUP(sb) - 10)
    + len = EXT4_BLOCKS_PER_GROUP(sb) - 10;
    +
    + /* start searching from the goal */
    + goal = ar->goal;
    + if (goal < le32_to_cpu(es->s_first_data_block) ||
    + goal >= ext4_blocks_count(es))
    + goal = le32_to_cpu(es->s_first_data_block);
    + ext4_get_group_no_and_offset(sb, goal, &group, &block);
    +
    + /* set up allocation goals */
    + ac->ac_b_ex.fe_logical = ar->logical;
    + ac->ac_b_ex.fe_group = 0;
    + ac->ac_b_ex.fe_start = 0;
    + ac->ac_b_ex.fe_len = 0;
    + ac->ac_status = AC_STATUS_CONTINUE;
    + ac->ac_groups_scanned = 0;
    + ac->ac_ex_scanned = 0;
    + ac->ac_found = 0;
    + ac->ac_sb = sb;
    + ac->ac_inode = ar->inode;
    + ac->ac_o_ex.fe_logical = ar->logical;
    + ac->ac_o_ex.fe_group = group;
    + ac->ac_o_ex.fe_start = block;
    + ac->ac_o_ex.fe_len = len;
    + ac->ac_g_ex.fe_logical = ar->logical;
    + ac->ac_g_ex.fe_group = group;
    + ac->ac_g_ex.fe_start = block;
    + ac->ac_g_ex.fe_len = len;
    + ac->ac_f_ex.fe_len = 0;
    + ac->ac_flags = ar->flags;
    + ac->ac_2order = 0;
    + ac->ac_criteria = 0;
    + ac->ac_pa = NULL;
    + ac->ac_bitmap_page = NULL;
    + ac->ac_buddy_page = NULL;
    + ac->ac_lg = NULL;
    +
    + /* we have to define context: we'll we work with a file or
    + * locality group. this is a policy, actually */
    + ext4_mb_group_or_file(ac);
    +
    + mb_debug("init ac: %u blocks @ %u, goal %u, flags %x, 2^%d, "
    + "left: %u/%u, right %u/%u to %swritable\n",
    + (unsigned) ar->len, (unsigned) ar->logical,
    + (unsigned) ar->goal, ac->ac_flags, ac->ac_2order,
    + (unsigned) ar->lleft, (unsigned) ar->pleft,
    + (unsigned) ar->lright, (unsigned) ar->pright,
    + atomic_read(&ar->inode->i_writecount) ? "" : "non-");
    + return 0;
    +
    +}
    +
    +/*
    + * release all resource we used in allocation
    + */
    +static int ext4_mb_release_context(struct ext4_allocation_context *ac)
    +{
    + if (ac->ac_pa) {
    + if (ac->ac_pa->pa_linear) {
    + /* see comment in ext4_mb_use_group_pa() */
    + spin_lock(&ac->ac_pa->pa_lock);
    + ac->ac_pa->pa_pstart += ac->ac_b_ex.fe_len;
    + ac->ac_pa->pa_lstart += ac->ac_b_ex.fe_len;
    + ac->ac_pa->pa_free -= ac->ac_b_ex.fe_len;
    + ac->ac_pa->pa_len -= ac->ac_b_ex.fe_len;
    + spin_unlock(&ac->ac_pa->pa_lock);
    + }
    + ext4_mb_put_pa(ac, ac->ac_sb, ac->ac_pa);
    + }
    + if (ac->ac_bitmap_page)
    + page_cache_release(ac->ac_bitmap_page);
    + if (ac->ac_buddy_page)
    + page_cache_release(ac->ac_buddy_page);
    + if (ac->ac_flags & EXT4_MB_HINT_GROUP_ALLOC)
    + up(&ac->ac_lg->lg_sem);
    + ext4_mb_collect_stats(ac);
    + return 0;
    +}
    +
    +static int ext4_mb_discard_preallocations(struct super_block *sb, int needed)
    +{
    + ext4_group_t i;
    + int ret;
    + int freed = 0;
    +
    + for (i = 0; i < EXT4_SB(sb)->s_groups_count && needed > 0; i++) {
    + ret = ext4_mb_discard_group_preallocations(sb, i, needed);
    + freed += ret;
    + needed -= ret;
    + }
    +
    + return freed;
    +}
    +
    +/*
    + * Main entry point into mballoc to allocate blocks
    + * it tries to use preallocation first, then falls back
    + * to usual allocation
    + */
    +ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
    + struct ext4_allocation_request *ar, int *errp)
    +{
    + struct ext4_allocation_context ac;
    + struct ext4_sb_info *sbi;
    + struct super_block *sb;
    + ext4_fsblk_t block = 0;
    + int freed;
    + int inquota;
    +
    + sb = ar->inode->i_sb;
    + sbi = EXT4_SB(sb);
    +
    + if (!test_opt(sb, MBALLOC)) {
    + block = ext4_new_blocks_old(handle, ar->inode, ar->goal,
    + &(ar->len), errp);
    + return block;
    + }
    +
    + while (ar->len && DQUOT_ALLOC_BLOCK(ar->inode, ar->len)) {
    + ar->flags |= EXT4_MB_HINT_NOPREALLOC;
    + ar->len--;
    + }
    + if (ar->len == 0) {
    + *errp = -EDQUOT;
    + return 0;
    + }
    + inquota = ar->len;
    +
    + ext4_mb_poll_new_transaction(sb, handle);
    +
    + *errp = ext4_mb_initialize_context(&ac, ar);
    + if (*errp) {
    + ar->len = 0;
    + goto out;
    + }
    +
    + ac.ac_op = EXT4_MB_HISTORY_PREALLOC;
    + if (!ext4_mb_use_preallocated(&ac)) {
    +
    + ac.ac_op = EXT4_MB_HISTORY_ALLOC;
    + ext4_mb_normalize_request(&ac, ar);
    +
    +repeat:
    + /* allocate space in core */
    + ext4_mb_regular_allocator(&ac);
    +
    + /* as we've just preallocated more space than
    + * user requested orinally, we store allocated
    + * space in a special descriptor */
    + if (ac.ac_status == AC_STATUS_FOUND &&
    + ac.ac_o_ex.fe_len < ac.ac_b_ex.fe_len)
    + ext4_mb_new_preallocation(&ac);
    + }
    +
    + if (likely(ac.ac_status == AC_STATUS_FOUND)) {
    + ext4_mb_mark_diskspace_used(&ac, handle);
    + *errp = 0;
    + block = ext4_grp_offs_to_block(sb, &ac.ac_b_ex);
    + ar->len = ac.ac_b_ex.fe_len;
    + } else {
    + freed = ext4_mb_discard_preallocations(sb, ac.ac_o_ex.fe_len);
    + if (freed)
    + goto repeat;
    + *errp = -ENOSPC;
    + ac.ac_b_ex.fe_len = 0;
    + ar->len = 0;
    + ext4_mb_show_ac(&ac);
    + }
    +
    + ext4_mb_release_context(&ac);
    +
    +out:
    + if (ar->len < inquota)
    + DQUOT_FREE_BLOCK(ar->inode, inquota - ar->len);
    +
    + return block;
    +}
    +static void ext4_mb_poll_new_transaction(struct super_block *sb,
    + handle_t *handle)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    +
    + if (sbi->s_last_transaction == handle->h_transaction->t_tid)
    + return;
    +
    + /* new transaction! time to close last one and free blocks for
    + * committed transaction. we know that only transaction can be
    + * active, so previos transaction can be being logged and we
    + * know that transaction before previous is known to be already
    + * logged. this means that now we may free blocks freed in all
    + * transactions before previous one. hope I'm clear enough ... */
    +
    + spin_lock(&sbi->s_md_lock);
    + if (sbi->s_last_transaction != handle->h_transaction->t_tid) {
    + mb_debug("new transaction %lu, old %lu\n",
    + (unsigned long) handle->h_transaction->t_tid,
    + (unsigned long) sbi->s_last_transaction);
    + list_splice_init(&sbi->s_closed_transaction,
    + &sbi->s_committed_transaction);
    + list_splice_init(&sbi->s_active_transaction,
    + &sbi->s_closed_transaction);
    + sbi->s_last_transaction = handle->h_transaction->t_tid;
    + }
    + spin_unlock(&sbi->s_md_lock);
    +
    + ext4_mb_free_committed_blocks(sb);
    +}
    +
    +static int ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
    + ext4_group_t group, ext4_grpblk_t block, int count)
    +{
    + struct ext4_group_info *db = e4b->bd_info;
    + struct super_block *sb = e4b->bd_sb;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + struct ext4_free_metadata *md;
    + int i;
    +
    + BUG_ON(e4b->bd_bitmap_page == NULL);
    + BUG_ON(e4b->bd_buddy_page == NULL);
    +
    + ext4_lock_group(sb, group);
    + for (i = 0; i < count; i++) {
    + md = db->bb_md_cur;
    + if (md && db->bb_tid != handle->h_transaction->t_tid) {
    + db->bb_md_cur = NULL;
    + md = NULL;
    + }
    +
    + if (md == NULL) {
    + ext4_unlock_group(sb, group);
    + md = kmalloc(sizeof(*md), GFP_KERNEL);
    + if (md == NULL)
    + return -ENOMEM;
    + md->num = 0;
    + md->group = group;
    +
    + ext4_lock_group(sb, group);
    + if (db->bb_md_cur == NULL) {
    + spin_lock(&sbi->s_md_lock);
    + list_add(&md->list, &sbi->s_active_transaction);
    + spin_unlock(&sbi->s_md_lock);
    + /* protect buddy cache from being freed,
    + * otherwise we'll refresh it from
    + * on-disk bitmap and lose not-yet-available
    + * blocks */
    + page_cache_get(e4b->bd_buddy_page);
    + page_cache_get(e4b->bd_bitmap_page);
    + db->bb_md_cur = md;
    + db->bb_tid = handle->h_transaction->t_tid;
    + mb_debug("new md 0x%p for group %lu\n",
    + md, md->group);
    + } else {
    + kfree(md);
    + md = db->bb_md_cur;
    + }
    + }
    +
    + BUG_ON(md->num >= EXT4_BB_MAX_BLOCKS);
    + md->blocks[md->num] = block + i;
    + md->num++;
    + if (md->num == EXT4_BB_MAX_BLOCKS) {
    + /* no more space, put full container on a sb's list */
    + db->bb_md_cur = NULL;
    + }
    + }
    + ext4_unlock_group(sb, group);
    + return 0;
    +}
    +
    +/*
    + * Main entry point into mballoc to free blocks
    + */
    +void ext4_mb_free_blocks(handle_t *handle, struct inode *inode,
    + unsigned long block, unsigned long count,
    + int metadata, unsigned long *freed)
    +{
    + struct buffer_head *bitmap_bh = NULL;
    + struct super_block *sb = inode->i_sb;
    + struct ext4_allocation_context ac;
    + struct ext4_group_desc *gdp;
    + struct ext4_super_block *es;
    + unsigned long overflow;
    + ext4_grpblk_t bit;
    + struct buffer_head *gd_bh;
    + ext4_group_t block_group;
    + struct ext4_sb_info *sbi;
    + struct ext4_buddy e4b;
    + int err = 0;
    + int ret;
    +
    + *freed = 0;
    +
    + ext4_mb_poll_new_transaction(sb, handle);
    +
    + sbi = EXT4_SB(sb);
    + es = EXT4_SB(sb)->s_es;
    + if (block < le32_to_cpu(es->s_first_data_block) ||
    + block + count < block ||
    + block + count > ext4_blocks_count(es)) {
    + ext4_error(sb, __FUNCTION__,
    + "Freeing blocks not in datazone - "
    + "block = %lu, count = %lu", block, count);
    + goto error_return;
    + }
    +
    + ext4_debug("freeing block %lu\n", block);
    +
    + ac.ac_op = EXT4_MB_HISTORY_FREE;
    + ac.ac_inode = inode;
    + ac.ac_sb = sb;
    +
    +do_more:
    + overflow = 0;
    + ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
    +
    + /*
    + * Check to see if we are freeing blocks across a group
    + * boundary.
    + */
    + if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
    + overflow = bit + count - EXT4_BLOCKS_PER_GROUP(sb);
    + count -= overflow;
    + }
    + brelse(bitmap_bh);
    + bitmap_bh = read_block_bitmap(sb, block_group);
    + if (!bitmap_bh)
    + goto error_return;
    + gdp = ext4_get_group_desc(sb, block_group, &gd_bh);
    + if (!gdp)
    + goto error_return;
    +
    + if (in_range(ext4_block_bitmap(sb, gdp), block, count) ||
    + in_range(ext4_inode_bitmap(sb, gdp), block, count) ||
    + in_range(block, ext4_inode_table(sb, gdp),
    + EXT4_SB(sb)->s_itb_per_group) ||
    + in_range(block + count - 1, ext4_inode_table(sb, gdp),
    + EXT4_SB(sb)->s_itb_per_group)) {
    +
    + ext4_error(sb, __FUNCTION__,
    + "Freeing blocks in system zone - "
    + "Block = %lu, count = %lu", block, count);
    + }
    +
    + BUFFER_TRACE(bitmap_bh, "getting write access");
    + err = ext4_journal_get_write_access(handle, bitmap_bh);
    + if (err)
    + goto error_return;
    +
    + /*
    + * We are about to modify some metadata. Call the journal APIs
    + * to unshare ->b_data if a currently-committing transaction is
    + * using it
    + */
    + BUFFER_TRACE(gd_bh, "get_write_access");
    + err = ext4_journal_get_write_access(handle, gd_bh);
    + if (err)
    + goto error_return;
    +
    + err = ext4_mb_load_buddy(sb, block_group, &e4b);
    + if (err)
    + goto error_return;
    +
    +#ifdef AGGRESSIVE_CHECK
    + {
    + int i;
    + for (i = 0; i < count; i++)
    + BUG_ON(!mb_test_bit(bit + i, bitmap_bh->b_data));
    + }
    +#endif
    + mb_clear_bits(sb_bgl_lock(sbi, block_group), bitmap_bh->b_data,
    + bit, count);
    +
    + /* We dirtied the bitmap block */
    + BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
    + err = ext4_journal_dirty_metadata(handle, bitmap_bh);
    +
    + ac.ac_b_ex.fe_group = block_group;
    + ac.ac_b_ex.fe_start = bit;
    + ac.ac_b_ex.fe_len = count;
    + ext4_mb_store_history(&ac);
    +
    + if (metadata) {
    + /* blocks being freed are metadata. these blocks shouldn't
    + * be used until this transaction is committed */
    + ext4_mb_free_metadata(handle, &e4b, block_group, bit, count);
    + } else {
    + ext4_lock_group(sb, block_group);
    + err = mb_free_blocks(inode, &e4b, bit, count);
    + ext4_mb_return_to_preallocation(inode, &e4b, block, count);
    + ext4_unlock_group(sb, block_group);
    + BUG_ON(err != 0);
    + }
    +
    + spin_lock(sb_bgl_lock(sbi, block_group));
    + gdp->bg_free_blocks_count =
    + cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) + count);
    + gdp->bg_checksum = ext4_group_desc_csum(sbi, block_group, gdp);
    + spin_unlock(sb_bgl_lock(sbi, block_group));
    + percpu_counter_add(&sbi->s_freeblocks_counter, count);
    +
    + ext4_mb_release_desc(&e4b);
    +
    + *freed += count;
    +
    + /* And the group descriptor block */
    + BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
    + ret = ext4_journal_dirty_metadata(handle, gd_bh);
    + if (!err)
    + err = ret;
    +
    + if (overflow && !err) {
    + block += count;
    + count = overflow;
    + goto do_more;
    + }
    + sb->s_dirt = 1;
    +error_return:
    + brelse(bitmap_bh);
    + ext4_std_error(sb, err);
    + return;
    +}
    diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
    index 7203d3d..6b40f55 100644
    --- a/fs/ext4/migrate.c
    +++ b/fs/ext4/migrate.c
    @@ -253,11 +253,11 @@ static int free_dind_blocks(handle_t *handle,
    for (i = 0; i < max_entries; i++) {
    if (tmp_idata[i]) {
    ext4_free_blocks(handle, inode,
    - le32_to_cpu(tmp_idata[i]), 1);
    + le32_to_cpu(tmp_idata[i]), 1, 1);
    }
    }
    brelse(bh);
    - ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1);
    + ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);

    return 0;

    @@ -289,7 +289,7 @@ static int free_tind_blocks(handle_t *handle,
    }
    }
    brelse(bh);
    - ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1);
    + ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);

    return 0;

    @@ -304,7 +304,7 @@ static int free_ind_block(handle_t *handle, struct inode *inode)
    if (ei->i_data[EXT4_IND_BLOCK]) {

    ext4_free_blocks(handle, inode,
    - le32_to_cpu(ei->i_data[EXT4_IND_BLOCK]), 1);
    + le32_to_cpu(ei->i_data[EXT4_IND_BLOCK]), 1, 1);

    }

    @@ -402,7 +402,7 @@ static int free_ext_idx(handle_t *handle, struct inode *inode,
    if (eh->eh_depth == 0) {

    brelse(bh);
    - ext4_free_blocks(handle, inode, block, 1);
    + ext4_free_blocks(handle, inode, block, 1, 1);

    } else {

    diff --git a/fs/ext4/super.c b/fs/ext4/super.c
    index 64fc7f1..136d095 100644
    --- a/fs/ext4/super.c
    +++ b/fs/ext4/super.c
    @@ -503,6 +503,7 @@ static void ext4_put_super (struct super_block * sb)
    struct ext4_super_block *es = sbi->s_es;
    int i;

    + ext4_mb_release(sb);
    ext4_ext_release(sb);
    ext4_xattr_put_super(sb);
    jbd2_journal_destroy(sbi->s_journal);
    @@ -569,6 +570,8 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
    ei->i_block_alloc_info = NULL;
    ei->vfs_inode.i_version = 1;
    memset(&ei->i_cached_extent, 0, sizeof(struct ext4_ext_cache));
    + INIT_LIST_HEAD(&ei->i_prealloc_list);
    + spin_lock_init(&ei->i_prealloc_lock);
    return &ei->vfs_inode;
    }

    @@ -881,6 +884,7 @@ enum {
    Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota,
    Opt_ignore, Opt_barrier, Opt_err, Opt_resize, Opt_usrquota,
    Opt_grpquota, Opt_extents, Opt_noextents, Opt_i_version,
    + Opt_mballoc, Opt_nomballoc, Opt_stripe,
    };

    static match_table_t tokens = {
    @@ -935,6 +939,9 @@ static match_table_t tokens = {
    {Opt_extents, "extents"},
    {Opt_noextents, "noextents"},
    {Opt_i_version, "i_version"},
    + {Opt_mballoc, "mballoc"},
    + {Opt_nomballoc, "nomballoc"},
    + {Opt_stripe, "stripe=%u"},
    {Opt_err, NULL},
    {Opt_resize, "resize"},
    };
    @@ -1284,6 +1291,19 @@ clear_qf_name:
    set_opt(sbi->s_mount_opt, I_VERSION);
    sb->s_flags |= MS_I_VERSION;
    break;
    + case Opt_mballoc:
    + set_opt(sbi->s_mount_opt, MBALLOC);
    + break;
    + case Opt_nomballoc:
    + clear_opt(sbi->s_mount_opt, MBALLOC);
    + break;
    + case Opt_stripe:
    + if (match_int(&args[0], &option))
    + return 0;
    + if (option < 0)
    + return 0;
    + sbi->s_stripe = option;
    + break;
    default:
    printk (KERN_ERR
    "EXT4-fs: Unrecognized mount option \"%s\" "
    @@ -1742,6 +1762,33 @@ static ext4_fsblk_t descriptor_loc(struct super_block *sb,
    return (has_super + ext4_group_first_block_no(sb, bg));
    }

    +/**
    + * ext4_get_stripe_size: Get the stripe size.
    + * @sbi: In memory super block info
    + *
    + * If we have specified it via mount option, then
    + * use the mount option value. If the value specified at mount time is
    + * greater than the blocks per group use the super block value.
    + * If the super block value is greater than blocks per group return 0.
    + * Allocator needs it be less than blocks per group.
    + *
    + */
    +static unsigned long ext4_get_stripe_size(struct ext4_sb_info *sbi)
    +{
    + unsigned long stride = le16_to_cpu(sbi->s_es->s_raid_stride);
    + unsigned long stripe_width =
    + le32_to_cpu(sbi->s_es->s_raid_stripe_width);
    +
    + if (sbi->s_stripe && sbi->s_stripe <= sbi->s_blocks_per_group) {
    + return sbi->s_stripe;
    + } else if (stripe_width <= sbi->s_blocks_per_group) {
    + return stripe_width;
    + } else if (stride <= sbi->s_blocks_per_group) {
    + return stride;
    + }
    +
    + return 0;
    +}

    static int ext4_fill_super (struct super_block *sb, void *data, int silent)
    __releases(kernel_sem)
    @@ -2091,6 +2138,8 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
    sbi->s_rsv_window_head.rsv_goal_size = 0;
    ext4_rsv_window_add(sb, &sbi->s_rsv_window_head);

    + sbi->s_stripe = ext4_get_stripe_size(sbi);
    +
    /*
    * set up enough so that it can read an inode
    */
    @@ -2250,6 +2299,7 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
    "writeback");

    ext4_ext_init(sb);
    + ext4_mb_init(sb, needs_recovery);

    lock_kernel();
    return 0;
    @@ -3232,9 +3282,15 @@ static struct file_system_type ext4dev_fs_type = {

    static int __init init_ext4_fs(void)
    {
    - int err = init_ext4_xattr();
    + int err;
    +
    + err = init_ext4_mballoc();
    if (err)
    return err;
    +
    + err = init_ext4_xattr();
    + if (err)
    + goto out2;
    err = init_inodecache();
    if (err)
    goto out1;
    @@ -3246,6 +3302,8 @@ out:
    destroy_inodecache();
    out1:
    exit_ext4_xattr();
    +out2:
    + exit_ext4_mballoc();
    return err;
    }

    @@ -3254,6 +3312,7 @@ static void __exit exit_ext4_fs(void)
    unregister_filesystem(&ext4dev_fs_type);
    destroy_inodecache();
    exit_ext4_xattr();
    + exit_ext4_mballoc();
    }

    MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");
    diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
    index 8638730..d796213 100644
    --- a/fs/ext4/xattr.c
    +++ b/fs/ext4/xattr.c
    @@ -480,7 +480,7 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode,
    ea_bdebug(bh, "refcount now=0; freeing");
    if (ce)
    mb_cache_entry_free(ce);
    - ext4_free_blocks(handle, inode, bh->b_blocknr, 1);
    + ext4_free_blocks(handle, inode, bh->b_blocknr, 1, 1);
    get_bh(bh);
    ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
    } else {
    @@ -821,7 +821,7 @@ inserted:
    new_bh = sb_getblk(sb, block);
    if (!new_bh) {
    getblk_failed:
    - ext4_free_blocks(handle, inode, block, 1);
    + ext4_free_blocks(handle, inode, block, 1, 1);
    error = -EIO;
    goto cleanup;
    }
    diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
    index d0b7ca9..1852313 100644
    --- a/include/linux/ext4_fs.h
    +++ b/include/linux/ext4_fs.h
    @@ -20,6 +20,8 @@
    #include <linux/blkdev.h>
    #include <linux/magic.h>

    +#include <linux/ext4_fs_i.h>
    +
    /*
    * The second extended filesystem constants/structures
    */
    @@ -51,6 +53,50 @@
    #define ext4_debug(f, a...) do {} while (0)
    #endif

    +#define EXT4_MULTIBLOCK_ALLOCATOR 1
    +
    +/* prefer goal again. length */
    +#define EXT4_MB_HINT_MERGE 1
    +/* blocks already reserved */
    +#define EXT4_MB_HINT_RESERVED 2
    +/* metadata is being allocated */
    +#define EXT4_MB_HINT_METADATA 4
    +/* first blocks in the file */
    +#define EXT4_MB_HINT_FIRST 8
    +/* search for the best chunk */
    +#define EXT4_MB_HINT_BEST 16
    +/* data is being allocated */
    +#define EXT4_MB_HINT_DATA 32
    +/* don't preallocate (for tails) */
    +#define EXT4_MB_HINT_NOPREALLOC 64
    +/* allocate for locality group */
    +#define EXT4_MB_HINT_GROUP_ALLOC 128
    +/* allocate goal blocks or none */
    +#define EXT4_MB_HINT_GOAL_ONLY 256
    +/* goal is meaningful */
    +#define EXT4_MB_HINT_TRY_GOAL 512
    +
    +struct ext4_allocation_request {
    + /* target inode for block we're allocating */
    + struct inode *inode;
    + /* logical block in target inode */
    + ext4_lblk_t logical;
    + /* phys. target (a hint) */
    + ext4_fsblk_t goal;
    + /* the closest logical allocated block to the left */
    + ext4_lblk_t lleft;
    + /* phys. block for ^^^ */
    + ext4_fsblk_t pleft;
    + /* the closest logical allocated block to the right */
    + ext4_lblk_t lright;
    + /* phys. block for ^^^ */
    + ext4_fsblk_t pright;
    + /* how many blocks we want to allocate */
    + unsigned long len;
    + /* flags. see above EXT4_MB_HINT_* */
    + unsigned long flags;
    +};
    +
    /*
    * Special inodes numbers
    */
    @@ -474,6 +520,7 @@ do { \
    #define EXT4_MOUNT_JOURNAL_CHECKSUM 0x800000 /* Journal checksums */
    #define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT 0x1000000 /* Journal Async Commit */
    #define EXT4_MOUNT_I_VERSION 0x2000000 /* i_version support */
    +#define EXT4_MOUNT_MBALLOC 0x4000000 /* Buddy allocation support */
    /* Compatibility, for having both ext2_fs.h and ext4_fs.h included at once */
    #ifndef _LINUX_EXT2_FS_H
    #define clear_opt(o, opt) o &= ~EXT4_MOUNT_##opt
    @@ -912,7 +959,7 @@ extern ext4_fsblk_t ext4_new_blocks (handle_t *handle, struct inode *inode,
    extern ext4_fsblk_t ext4_new_blocks_old(handle_t *handle, struct inode *inode,
    ext4_fsblk_t goal, unsigned long *count, int *errp);
    extern void ext4_free_blocks (handle_t *handle, struct inode *inode,
    - ext4_fsblk_t block, unsigned long count);
    + ext4_fsblk_t block, unsigned long count, int metadata);
    extern void ext4_free_blocks_sb (handle_t *handle, struct super_block *sb,
    ext4_fsblk_t block, unsigned long count,
    unsigned long *pdquot_freed_blocks);
    @@ -950,6 +997,20 @@ extern unsigned long ext4_count_dirs (struct super_block *);
    extern void ext4_check_inodes_bitmap (struct super_block *);
    extern unsigned long ext4_count_free (struct buffer_head *, unsigned);

    +/* mballoc.c */
    +extern long ext4_mb_stats;
    +extern long ext4_mb_max_to_scan;
    +extern int ext4_mb_init(struct super_block *, int);
    +extern int ext4_mb_release(struct super_block *);
    +extern ext4_fsblk_t ext4_mb_new_blocks(handle_t *,
    + struct ext4_allocation_request *, int *);
    +extern int ext4_mb_reserve_blocks(struct super_block *, int);
    +extern void ext4_mb_discard_inode_preallocations(struct inode *);
    +extern int __init init_ext4_mballoc(void);
    +extern void exit_ext4_mballoc(void);
    +extern void ext4_mb_free_blocks(handle_t *, struct inode *,
    + unsigned long, unsigned long, int, unsigned long *);
    +

    /* inode.c */
    int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
    @@ -1080,6 +1141,19 @@ static inline void ext4_isize_set(struct ext4_inode *raw_inode, loff_t i_size)
    raw_inode->i_size_high = cpu_to_le32(i_size >> 32);
    }

    +static inline
    +struct ext4_group_info *ext4_get_group_info(struct super_block *sb,
    + ext4_group_t group)
    +{
    + struct ext4_group_info ***grp_info;
    + long indexv, indexh;
    + grp_info = EXT4_SB(sb)->s_group_info;
    + indexv = group >> (EXT4_DESC_PER_BLOCK_BITS(sb));
    + indexh = group & ((EXT4_DESC_PER_BLOCK(sb)) - 1);
    + return grp_info[indexv][indexh];
    +}
    +
    +
    #define ext4_std_error(sb, errno) \
    do { \
    if ((errno)) \
    diff --git a/include/linux/ext4_fs_i.h b/include/linux/ext4_fs_i.h
    index 4377d24..d5508d3 100644
    --- a/include/linux/ext4_fs_i.h
    +++ b/include/linux/ext4_fs_i.h
    @@ -158,6 +158,10 @@ struct ext4_inode_info {
    * struct timespec i_{a,c,m}time in the generic inode.
    */
    struct timespec i_crtime;
    +
    + /* mballoc */
    + struct list_head i_prealloc_list;
    + spinlock_t i_prealloc_lock;
    };

    #endif /* _LINUX_EXT4_FS_I */
    diff --git a/include/linux/ext4_fs_sb.h b/include/linux/ext4_fs_sb.h
    index 38a47ec..abaae2c 100644
    --- a/include/linux/ext4_fs_sb.h
    +++ b/include/linux/ext4_fs_sb.h
    @@ -91,6 +91,58 @@ struct ext4_sb_info {
    unsigned long s_ext_blocks;
    unsigned long s_ext_extents;
    #endif
    +
    + /* for buddy allocator */
    + struct ext4_group_info ***s_group_info;
    + struct inode *s_buddy_cache;
    + long s_blocks_reserved;
    + spinlock_t s_reserve_lock;
    + struct list_head s_active_transaction;
    + struct list_head s_closed_transaction;
    + struct list_head s_committed_transaction;
    + spinlock_t s_md_lock;
    + tid_t s_last_transaction;
    + unsigned short *s_mb_offsets, *s_mb_maxs;
    +
    + /* tunables */
    + unsigned long s_stripe;
    + unsigned long s_mb_stream_request;
    + unsigned long s_mb_max_to_scan;
    + unsigned long s_mb_min_to_scan;
    + unsigned long s_mb_stats;
    + unsigned long s_mb_order2_reqs;
    + unsigned long s_mb_group_prealloc;
    + /* where last allocation was done - for stream allocation */
    + unsigned long s_mb_last_group;
    + unsigned long s_mb_last_start;
    +
    + /* history to debug policy */
    + struct ext4_mb_history *s_mb_history;
    + int s_mb_history_cur;
    + int s_mb_history_max;
    + int s_mb_history_num;
    + struct proc_dir_entry *s_mb_proc;
    + spinlock_t s_mb_history_lock;
    + int s_mb_history_filter;
    +
    + /* stats for buddy allocator */
    + spinlock_t s_mb_pa_lock;
    + atomic_t s_bal_reqs; /* number of reqs with len > 1 */
    + atomic_t s_bal_success; /* we found long enough chunks */
    + atomic_t s_bal_allocated; /* in blocks */
    + atomic_t s_bal_ex_scanned; /* total extents scanned */
    + atomic_t s_bal_goals; /* goal hits */
    + atomic_t s_bal_breaks; /* too long searches */
    + atomic_t s_bal_2orders; /* 2^order hits */
    + spinlock_t s_bal_lock;
    + unsigned long s_mb_buddies_generated;
    + unsigned long long s_mb_generation_time;
    + atomic_t s_mb_lost_chunks;
    + atomic_t s_mb_preallocated;
    + atomic_t s_mb_discarded;
    +
    + /* locality groups */
    + struct ext4_locality_group *s_locality_groups;
    };

    #endif /* _LINUX_EXT4_FS_SB */
    --
    1.5.4.rc3.31.g1271-dirty


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