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SubjectRe: [Ext2-devel] [PATCH 1/9] extents for ext4
On Thu, 10 Aug 2006 13:29:56 +0400 Alex Tomas wrote:

> AM> - The existing comments could benefit from some rework by a
> AM> native English speaker.
>
> could someone assist here, please?

See if this helps.
Patch applies on top of all ext4 patches from
http://ext2.sourceforge.net/48bitext3/patches/latest/.

---
From: Randy Dunlap <rdunlap@xenotime.net>
Clean up comments in ext4-extents patch.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
---
fs/ext4/extents.c | 226 ++++++++++++++++++++++------------------
include/linux/ext4_fs_extents.h | 54 ++++-----
include/linux/ext4_jbd2.h | 4
3 files changed, 157 insertions(+), 127 deletions(-)
--- linux-2618-rc4-ext4.orig/include/linux/ext4_jbd2.h
+++ linux-2618-rc4-ext4/include/linux/ext4_jbd2.h
@@ -28,8 +28,8 @@
* indirection blocks, the group and superblock summaries, and the data
* block to complete the transaction.
*
- * For extents-enabled fs we may have to allocate and modify upto
- * 5 levels of tree + root which is stored in inode. */
+ * For extents-enabled fs we may have to allocate and modify up to
+ * 5 levels of tree + root which are stored in the inode. */

#define EXT4_SINGLEDATA_TRANS_BLOCKS(sb) \
(EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS) \
--- linux-2618-rc4-ext4.orig/include/linux/ext4_fs_extents.h
+++ linux-2618-rc4-ext4/include/linux/ext4_fs_extents.h
@@ -22,29 +22,29 @@
#include <linux/ext4_fs.h>

/*
- * with AGRESSIVE_TEST defined capacity of index/leaf blocks
- * become very little, so index split, in-depth growing and
- * other hard changes happens much more often
- * this is for debug purposes only
+ * With AGRESSIVE_TEST defined, the capacity of index/leaf blocks
+ * becomes very small, so index split, in-depth growing and
+ * other hard changes happen much more often.
+ * This is for debug purposes only.
*/
#define AGRESSIVE_TEST_

/*
- * with EXTENTS_STATS defined number of blocks and extents
- * are collected in truncate path. they'll be showed at
- * umount time
+ * With EXTENTS_STATS defined, the number of blocks and extents
+ * are collected in the truncate path. They'll be shown at
+ * umount time.
*/
#define EXTENTS_STATS__

/*
- * if CHECK_BINSEARCH defined, then results of binary search
- * will be checked by linear search
+ * If CHECK_BINSEARCH is defined, then the results of the binary search
+ * will also be checked by linear search.
*/
#define CHECK_BINSEARCH__

/*
- * if EXT_DEBUG is defined you can use 'extdebug' mount option
- * to get lots of info what's going on
+ * If EXT_DEBUG is defined you can use the 'extdebug' mount option
+ * to get lots of info about what's going on.
*/
#define EXT_DEBUG__
#ifdef EXT_DEBUG
@@ -54,58 +54,58 @@
#endif

/*
- * if EXT_STATS is defined then stats numbers are collected
- * these number will be displayed at umount time
+ * If EXT_STATS is defined then stats numbers are collected.
+ * These number will be displayed at umount time.
*/
#define EXT_STATS_


/*
- * ext4_inode has i_block array (60 bytes total)
- * first 12 bytes store ext4_extent_header
- * the remain stores array of ext4_extent
+ * ext4_inode has i_block array (60 bytes total).
+ * The first 12 bytes store ext4_extent_header;
+ * the remainder stores an array of ext4_extent.
*/

/*
- * this is extent on-disk structure
- * it's used at the bottom of the tree
+ * This is the extent on-disk structure.
+ * It's used at the bottom of the tree.
*/
struct ext4_extent {
__le32 ee_block; /* first logical block extent covers */
__le16 ee_len; /* number of blocks covered by extent */
__le16 ee_start_hi; /* high 16 bits of physical block */
- __le32 ee_start; /* low 32 bigs of physical block */
+ __le32 ee_start; /* low 32 bits of physical block */
};

/*
- * this is index on-disk structure
- * it's used at all the levels, but the bottom
+ * This is index on-disk structure.
+ * It's used at all the levels except the bottom.
*/
struct ext4_extent_idx {
__le32 ei_block; /* index covers logical blocks from 'block' */
__le32 ei_leaf; /* pointer to the physical block of the next *
- * level. leaf or next index could bet here */
+ * level. leaf or next index could be there */
__le16 ei_leaf_hi; /* high 16 bits of physical block */
__u16 ei_unused;
};

/*
- * each block (leaves and indexes), even inode-stored has header
+ * Each block (leaves and indexes), even inode-stored has header.
*/
struct ext4_extent_header {
__le16 eh_magic; /* probably will support different formats */
__le16 eh_entries; /* number of valid entries */
__le16 eh_max; /* capacity of store in entries */
- __le16 eh_depth; /* has tree real underlaying blocks? */
+ __le16 eh_depth; /* has tree real underlying blocks? */
__le32 eh_generation; /* generation of the tree */
};

#define EXT4_EXT_MAGIC cpu_to_le16(0xf30a)

/*
- * array of ext4_ext_path contains path to some extent
- * creation/lookup routines use it for traversal/splitting/etc
- * truncate uses it to simulate recursive walking
+ * Array of ext4_ext_path contains path to some extent.
+ * Creation/lookup routines use it for traversal/splitting/etc.
+ * Truncate uses it to simulate recursive walking.
*/
struct ext4_ext_path {
ext4_fsblk_t p_block;
--- linux-2618-rc4-ext4.orig/fs/ext4/extents.c
+++ linux-2618-rc4-ext4/fs/ext4/extents.c
@@ -44,7 +44,10 @@
#include <asm/uaccess.h>


-/* this macro combines low and hi parts of phys. blocknr into ext4_fsblk_t */
+/*
+ * ext_pblock:
+ * combine low and high parts of physical block number into ext4_fsblk_t
+ */
static inline ext4_fsblk_t ext_pblock(struct ext4_extent *ex)
{
ext4_fsblk_t block;
@@ -55,7 +58,10 @@ static inline ext4_fsblk_t ext_pblock(st
return block;
}

-/* this macro combines low and hi parts of phys. blocknr into ext4_fsblk_t */
+/*
+ * idx_pblock:
+ * combine low and high parts of a leaf physical block number into ext4_fsblk_t
+ */
static inline ext4_fsblk_t idx_pblock(struct ext4_extent_idx *ix)
{
ext4_fsblk_t block;
@@ -66,7 +72,11 @@ static inline ext4_fsblk_t idx_pblock(st
return block;
}

-/* the routine stores large phys. blocknr into extent breaking it into parts */
+/*
+ * ext4_ext_store_pblock:
+ * stores a large physical block number into an extent struct,
+ * breaking it into parts
+ */
static inline void ext4_ext_store_pblock(struct ext4_extent *ex, ext4_fsblk_t pb)
{
ex->ee_start = cpu_to_le32((unsigned long) (pb & 0xffffffff));
@@ -74,7 +84,11 @@ static inline void ext4_ext_store_pblock
ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff);
}

-/* the routine stores large phys. blocknr into index breaking it into parts */
+/*
+ * ext4_idx_store_pblock:
+ * stores a large physical block number into an index struct,
+ * breaking it into parts
+ */
static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix, ext4_fsblk_t pb)
{
ix->ei_leaf = cpu_to_le32((unsigned long) (pb & 0xffffffff));
@@ -179,8 +193,8 @@ static ext4_fsblk_t ext4_ext_find_goal(s
if ((ex = path[depth].p_ext))
return ext_pblock(ex)+(block-le32_to_cpu(ex->ee_block));

- /* it looks index is empty
- * try to find starting from index itself */
+ /* it looks like index is empty;
+ * try to find starting block from index itself */
if (path[depth].p_bh)
return path[depth].p_bh->b_blocknr;
}
@@ -317,7 +331,8 @@ static void ext4_ext_drop_refs(struct ex
}

/*
- * binary search for closest index by given block
+ * ext4_ext_binsearch_idx:
+ * binary search for the closest index of the given block
*/
static void
ext4_ext_binsearch_idx(struct inode *inode, struct ext4_ext_path *path, int block)
@@ -375,7 +390,8 @@ ext4_ext_binsearch_idx(struct inode *ino
}

/*
- * binary search for closest extent by given block
+ * ext4_ext_binsearch:
+ * binary search for closest extent of the given block
*/
static void
ext4_ext_binsearch(struct inode *inode, struct ext4_ext_path *path, int block)
@@ -388,8 +404,8 @@ ext4_ext_binsearch(struct inode *inode,

if (eh->eh_entries == 0) {
/*
- * this leaf is empty yet:
- * we get such a leaf in split/add case
+ * this leaf is empty:
+ * we get such a leaf in split/add case
*/
return;
}
@@ -520,8 +536,9 @@ err:
}

/*
- * insert new index [logical;ptr] into the block at cupr
- * it check where to insert: before curp or after curp
+ * ext4_ext_insert_index:
+ * insert new index [@logical;@ptr] into the block at @curp;
+ * check where to insert: before @curp or after @curp
*/
static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
struct ext4_ext_path *curp,
@@ -574,13 +591,14 @@ static int ext4_ext_insert_index(handle_
}

/*
- * routine inserts new subtree into the path, using free index entry
- * at depth 'at:
- * - allocates all needed blocks (new leaf and all intermediate index blocks)
- * - makes decision where to split
- * - moves remaining extens and index entries (right to the split point)
- * into the newly allocated blocks
- * - initialize subtree
+ * ext4_ext_split:
+ * inserts new subtree into the path, using free index entry
+ * at depth @at:
+ * - allocates all needed blocks (new leaf and all intermediate index blocks)
+ * - makes decision where to split
+ * - moves remaining extents and index entries (right to the split point)
+ * into the newly allocated blocks
+ * - initializes subtree
*/
static int ext4_ext_split(handle_t *handle, struct inode *inode,
struct ext4_ext_path *path,
@@ -598,14 +616,14 @@ static int ext4_ext_split(handle_t *hand
int err = 0;

/* make decision: where to split? */
- /* FIXME: now desicion is simplest: at current extent */
+ /* FIXME: now decision is simplest: at current extent */

- /* if current leaf will be splitted, then we should use
+ /* if current leaf will be split, then we should use
* border from split point */
BUG_ON(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr));
if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
border = path[depth].p_ext[1].ee_block;
- ext_debug("leaf will be splitted."
+ ext_debug("leaf will be split."
" next leaf starts at %d\n",
le32_to_cpu(border));
} else {
@@ -616,16 +634,16 @@ static int ext4_ext_split(handle_t *hand
}

/*
- * if error occurs, then we break processing
- * and turn filesystem read-only. so, index won't
+ * If error occurs, then we break processing
+ * and mark filesystem read-only. index won't
* be inserted and tree will be in consistent
- * state. next mount will repair buffers too
+ * state. Next mount will repair buffers too.
*/

/*
- * get array to track all allocated blocks
- * we need this to handle errors and free blocks
- * upon them
+ * Get array to track all allocated blocks.
+ * We need this to handle errors and free blocks
+ * upon them.
*/
ablocks = kmalloc(sizeof(ext4_fsblk_t) * depth, GFP_NOFS);
if (!ablocks)
@@ -661,7 +679,7 @@ static int ext4_ext_split(handle_t *hand
neh->eh_depth = 0;
ex = EXT_FIRST_EXTENT(neh);

- /* move remain of path[depth] to the new leaf */
+ /* move remainder of path[depth] to the new leaf */
BUG_ON(path[depth].p_hdr->eh_entries != path[depth].p_hdr->eh_max);
/* start copy from next extent */
/* TODO: we could do it by single memmove */
@@ -813,11 +831,12 @@ cleanup:
}

/*
- * routine implements tree growing procedure:
- * - allocates new block
- * - moves top-level data (index block or leaf) into the new block
- * - initialize new top-level, creating index that points to the
- * just created block
+ * ext4_ext_grow_indepth:
+ * implements tree growing procedure:
+ * - allocates new block
+ * - moves top-level data (index block or leaf) into the new block
+ * - initializes new top-level, creating index that points to the
+ * just created block
*/
static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
struct ext4_ext_path *path,
@@ -892,8 +911,9 @@ out:
}

/*
- * routine finds empty index and adds new leaf. if no free index found
- * then it requests in-depth growing
+ * ext4_ext_create_new_leaf:
+ * finds empty index and adds new leaf.
+ * if no free index is found, then it requests in-depth growing.
*/
static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
struct ext4_ext_path *path,
@@ -912,8 +932,8 @@ repeat:
curp--;
}

- /* we use already allocated block for index block
- * so, subsequent data blocks should be contigoues */
+ /* we use already allocated block for index block,
+ * so subsequent data blocks should be contiguous */
if (EXT_HAS_FREE_INDEX(curp)) {
/* if we found index with free entry, then use that
* entry: create all needed subtree and add new leaf */
@@ -943,12 +963,12 @@ repeat:
}

/*
- * only first (depth 0 -> 1) produces free space
- * in all other cases we have to split growed tree
+ * only first (depth 0 -> 1) produces free space;
+ * in all other cases we have to split the grown tree
*/
depth = ext_depth(inode);
if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
- /* now we need split */
+ /* now we need to split */
goto repeat;
}
}
@@ -958,10 +978,11 @@ out:
}

/*
- * returns allocated block in subsequent extent or EXT_MAX_BLOCK
- * NOTE: it consider block number from index entry as
- * allocated block. thus, index entries have to be consistent
- * with leafs
+ * ext4_ext_next_allocated_block:
+ * returns allocated block in subsequent extent or EXT_MAX_BLOCK.
+ * NOTE: it considers block number from index entry as
+ * allocated block. Thus, index entries have to be consistent
+ * with leaves.
*/
static unsigned long
ext4_ext_next_allocated_block(struct ext4_ext_path *path)
@@ -993,6 +1014,7 @@ ext4_ext_next_allocated_block(struct ext
}

/*
+ * ext4_ext_next_leaf_block:
* returns first allocated block from next leaf or EXT_MAX_BLOCK
*/
static unsigned ext4_ext_next_leaf_block(struct inode *inode,
@@ -1021,8 +1043,9 @@ static unsigned ext4_ext_next_leaf_block
}

/*
- * if leaf gets modified and modified extent is first in the leaf
- * then we have to correct all indexes above
+ * ext4_ext_correct_indexes:
+ * if leaf gets modified and modified extent is first in the leaf,
+ * then we have to correct all indexes above.
* TODO: do we need to correct tree in all cases?
*/
int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode,
@@ -1050,7 +1073,7 @@ int ext4_ext_correct_indexes(handle_t *h
}

/*
- * TODO: we need correction if border is smaller then current one
+ * TODO: we need correction if border is smaller than current one
*/
k = depth - 1;
border = path[depth].p_ext->ee_block;
@@ -1085,7 +1108,7 @@ ext4_can_extents_be_merged(struct inode
/*
* To allow future support for preallocated extents to be added
* as an RO_COMPAT feature, refuse to merge to extents if
- * can result in the top bit of ee_len being set
+ * this can result in the top bit of ee_len being set.
*/
if (le16_to_cpu(ex1->ee_len) + le16_to_cpu(ex2->ee_len) > EXT_MAX_LEN)
return 0;
@@ -1100,9 +1123,10 @@ ext4_can_extents_be_merged(struct inode
}

/*
- * this routine tries to merge requsted extent into the existing
- * extent or inserts requested extent as new one into the tree,
- * creating new leaf in no-space case
+ * ext4_ext_insert_extent:
+ * tries to merge requsted extent into the existing extent or
+ * inserts requested extent as new one into the tree,
+ * creating new leaf in the no-space case.
*/
int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
struct ext4_ext_path *path,
@@ -1163,8 +1187,8 @@ repeat:
}

/*
- * there is no free space in found leaf
- * we're gonna add new leaf in the tree
+ * There is no free space in the found leaf.
+ * We're gonna add a new leaf in the tree.
*/
err = ext4_ext_create_new_leaf(handle, inode, path, newext);
if (err)
@@ -1377,7 +1401,8 @@ ext4_ext_put_in_cache(struct inode *inod
}

/*
- * this routine calculate boundaries of the gap requested block fits into
+ * ext4_ext_put_gap_in_cache:
+ * calculate boundaries of the gap that the requested block fits into
* and cache this gap
*/
static inline void
@@ -1452,9 +1477,10 @@ ext4_ext_in_cache(struct inode *inode, u
}

/*
- * routine removes index from the index block
- * it's used in truncate case only. thus all requests are for
- * last index in the block only
+ * ext4_ext_rm_idx:
+ * removes index from the index block.
+ * It's used in truncate case only, thus all requests are for
+ * last index in the block only.
*/
int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
struct ext4_ext_path *path)
@@ -1480,11 +1506,12 @@ int ext4_ext_rm_idx(handle_t *handle, st
}

/*
- * This routine returns max. credits extent tree can consume.
+ * ext4_ext_calc_credits_for_insert:
+ * This routine returns max. credits that the extent tree can consume.
* It should be OK for low-performance paths like ->writepage()
- * To allow many writing process to fit a single transaction,
- * caller should calculate credits under truncate_mutex and
- * pass actual path.
+ * To allow many writing processes to fit into a single transaction,
+ * the caller should calculate credits under truncate_mutex and
+ * pass the actual path.
*/
int inline ext4_ext_calc_credits_for_insert(struct inode *inode,
struct ext4_ext_path *path)
@@ -1500,9 +1527,9 @@ int inline ext4_ext_calc_credits_for_ins
}

/*
- * given 32bit logical block (4294967296 blocks), max. tree
+ * given 32-bit logical block (4294967296 blocks), max. tree
* can be 4 levels in depth -- 4 * 340^4 == 53453440000.
- * let's also add one more level for imbalance.
+ * Let's also add one more level for imbalance.
*/
depth = 5;

@@ -1510,13 +1537,13 @@ int inline ext4_ext_calc_credits_for_ins
needed = 2;

/*
- * tree can be full, so it'd need to grow in depth:
+ * tree can be full, so it would need to grow in depth:
* allocation + old root + new root
*/
needed += 2 + 1 + 1;

/*
- * Index split can happen, we'd need:
+ * Index split can happen, we would need:
* allocate intermediate indexes (bitmap + group)
* + change two blocks at each level, but root (already included)
*/
@@ -1634,7 +1661,7 @@ ext4_ext_rm_leaf(handle_t *handle, struc
BUG_ON(b != ex_ee_block + ex_ee_len - 1);
}

- /* at present, extent can't cross block group */
+ /* at present, extent can't cross block group: */
/* leaf + bitmap + group desc + sb + inode */
credits = 5;
if (ex == EXT_FIRST_EXTENT(eh)) {
@@ -1660,7 +1687,7 @@ ext4_ext_rm_leaf(handle_t *handle, struc
goto out;

if (num == 0) {
- /* this extent is removed entirely mark slot unused */
+ /* this extent is removed; mark slot entirely unused */
ext4_ext_store_pblock(ex, 0);
eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)-1);
}
@@ -1692,7 +1719,8 @@ out:
}

/*
- * returns 1 if current index have to be freed (even partial)
+ * ext4_ext_more_to_rm:
+ * returns 1 if current index has to be freed (even partial)
*/
static int inline
ext4_ext_more_to_rm(struct ext4_ext_path *path)
@@ -1703,7 +1731,7 @@ ext4_ext_more_to_rm(struct ext4_ext_path
return 0;

/*
- * if truncate on deeper level happened it it wasn't partial
+ * if truncate on deeper level happened, it wasn't partial,
* so we have to consider current index for truncation
*/
if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block)
@@ -1729,8 +1757,8 @@ int ext4_ext_remove_space(struct inode *
ext4_ext_invalidate_cache(inode);

/*
- * we start scanning from right side freeing all the blocks
- * after i_size and walking into the deep
+ * We start scanning from right side, freeing all the blocks
+ * after i_size and walking into the tree depth-wise.
*/
path = kmalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_KERNEL);
if (path == NULL) {
@@ -1749,7 +1777,7 @@ int ext4_ext_remove_space(struct inode *
if (i == depth) {
/* this is leaf block */
err = ext4_ext_rm_leaf(handle, inode, path, start);
- /* root level have p_bh == NULL, brelse() eats this */
+ /* root level has p_bh == NULL, brelse() eats this */
brelse(path[i].p_bh);
path[i].p_bh = NULL;
i--;
@@ -1772,14 +1800,14 @@ int ext4_ext_remove_space(struct inode *
BUG_ON(path[i].p_hdr->eh_magic != EXT4_EXT_MAGIC);

if (!path[i].p_idx) {
- /* this level hasn't touched yet */
+ /* this level hasn't been touched yet */
path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr);
path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1;
ext_debug("init index ptr: hdr 0x%p, num %d\n",
path[i].p_hdr,
le16_to_cpu(path[i].p_hdr->eh_entries));
} else {
- /* we've already was here, see at next index */
+ /* we were already here, see at next index */
path[i].p_idx--;
}

@@ -1799,19 +1827,19 @@ int ext4_ext_remove_space(struct inode *
break;
}

- /* put actual number of indexes to know is this
- * number got changed at the next iteration */
+ /* save actual number of indexes since this
+ * number is changed at the next iteration */
path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries);
i++;
} else {
- /* we finish processing this index, go up */
+ /* we finished processing this index, go up */
if (path[i].p_hdr->eh_entries == 0 && i > 0) {
- /* index is empty, remove it
+ /* index is empty, remove it;
* handle must be already prepared by the
* truncatei_leaf() */
err = ext4_ext_rm_idx(handle, inode, path + i);
}
- /* root level have p_bh == NULL, brelse() eats this */
+ /* root level has p_bh == NULL, brelse() eats this */
brelse(path[i].p_bh);
path[i].p_bh = NULL;
i--;
@@ -1822,8 +1850,8 @@ int ext4_ext_remove_space(struct inode *
/* TODO: flexible tree reduction should be here */
if (path->p_hdr->eh_entries == 0) {
/*
- * truncate to zero freed all the tree
- * so, we need to correct eh_depth
+ * truncate to zero freed all the tree,
+ * so we need to correct eh_depth
*/
err = ext4_ext_get_access(handle, inode, path);
if (err == 0) {
@@ -1911,7 +1939,7 @@ int ext4_ext_get_blocks(handle_t *handle
if (goal == EXT4_EXT_CACHE_GAP) {
if (!create) {
/* block isn't allocated yet and
- * user don't want to allocate it */
+ * user doesn't want to allocate it */
goto out2;
}
/* we should allocate requested block */
@@ -1920,7 +1948,7 @@ int ext4_ext_get_blocks(handle_t *handle
newblock = iblock
- le32_to_cpu(newex.ee_block)
+ ext_pblock(&newex);
- /* number of remain blocks in the extent */
+ /* number of remaining blocks in the extent */
allocated = le16_to_cpu(newex.ee_len) -
(iblock - le32_to_cpu(newex.ee_block));
goto out;
@@ -1940,8 +1968,8 @@ int ext4_ext_get_blocks(handle_t *handle
depth = ext_depth(inode);

/*
- * consistent leaf must not be empty
- * this situations is possible, though, _during_ tree modification
+ * consistent leaf must not be empty;
+ * this situation is possible, though, _during_ tree modification;
* this is why assert can't be put in ext4_ext_find_extent()
*/
BUG_ON(path[depth].p_ext == NULL && depth != 0);
@@ -1959,10 +1987,10 @@ int ext4_ext_get_blocks(handle_t *handle
*/
if (ee_len > EXT_MAX_LEN)
goto out2;
- /* if found exent covers block, simple return it */
+ /* if found extent covers block, simply return it */
if (iblock >= ee_block && iblock < ee_block + ee_len) {
newblock = iblock - ee_block + ee_start;
- /* number of remain blocks in the extent */
+ /* number of remaining blocks in the extent */
allocated = ee_len - (iblock - ee_block);
ext_debug("%d fit into %lu:%d -> "E3FSBLK"\n", (int) iblock,
ee_block, ee_len, newblock);
@@ -1973,17 +2001,18 @@ int ext4_ext_get_blocks(handle_t *handle
}

/*
- * requested block isn't allocated yet
+ * requested block isn't allocated yet;
* we couldn't try to create block if create flag is zero
*/
if (!create) {
- /* put just found gap into cache to speedup subsequest reqs */
+ /* put just found gap into cache to speed up
+ * subsequent requests */
ext4_ext_put_gap_in_cache(inode, path, iblock);
goto out2;
}
/*
* Okay, we need to do block allocation. Lazily initialize the block
- * allocation info here if necessary
+ * allocation info here if necessary.
*/
if (S_ISREG(inode->i_mode) && (!EXT4_I(inode)->i_block_alloc_info))
ext4_init_block_alloc_info(inode);
@@ -2061,9 +2090,9 @@ void ext4_ext_truncate(struct inode * in
ext4_ext_invalidate_cache(inode);

/*
- * TODO: optimization is possible here
- * probably we need not scaning at all,
- * because page truncation is enough
+ * TODO: optimization is possible here.
+ * Probably we need not scan at all,
+ * because page truncation is enough.
*/
if (ext4_orphan_add(handle, inode))
goto out_stop;
@@ -2077,13 +2106,13 @@ void ext4_ext_truncate(struct inode * in
err = ext4_ext_remove_space(inode, last_block);

/* In a multi-transaction truncate, we only make the final
- * transaction synchronous */
+ * transaction synchronous. */
if (IS_SYNC(inode))
handle->h_sync = 1;

out_stop:
/*
- * If this was a simple ftruncate(), and the file will remain alive
+ * If this was a simple ftruncate() and the file will remain alive,
* then we need to clear up the orphan record which we created above.
* However, if this was a real unlink then we were called by
* ext4_delete_inode(), and we allow that function to clean up the
@@ -2097,7 +2126,8 @@ out_stop:
}

/*
- * this routine calculate max number of blocks we could modify
+ * ext4_ext_writepage_trans_blocks:
+ * calculate max number of blocks we could modify
* in order to allocate new block for an inode
*/
int ext4_ext_writepage_trans_blocks(struct inode *inode, int num)
@@ -2106,7 +2136,7 @@ int ext4_ext_writepage_trans_blocks(stru

needed = ext4_ext_calc_credits_for_insert(inode, NULL);

- /* caller want to allocate num blocks, but note it includes sb */
+ /* caller wants to allocate num blocks, but note it includes sb */
needed = needed * num - (num - 1);

#ifdef CONFIG_QUOTA
-
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