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    Subject[PATCH 3.16.y-ckt 026/170] ext4: move error report out of atomic context in ext4_init_block_bitmap()
    Date
    3.16.7-ckt1 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Dmitry Monakhov <dmonakhov@openvz.org>

    commit aef4885ae14f1df75b58395c5314d71f613d26d9 upstream.

    Error report likely result in IO so it is bad idea to do it from
    atomic context.

    This patch should fix following issue:

    BUG: sleeping function called from invalid context at include/linux/buffer_head.h:349
    in_atomic(): 1, irqs_disabled(): 0, pid: 137, name: kworker/u128:1
    5 locks held by kworker/u128:1/137:
    #0: ("writeback"){......}, at: [<ffffffff81085618>] process_one_work+0x228/0x4d0
    #1: ((&(&wb->dwork)->work)){......}, at: [<ffffffff81085618>] process_one_work+0x228/0x4d0
    #2: (jbd2_handle){......}, at: [<ffffffff81242622>] start_this_handle+0x712/0x7b0
    #3: (&ei->i_data_sem){......}, at: [<ffffffff811fa387>] ext4_map_blocks+0x297/0x430
    #4: (&(&bgl->locks[i].lock)->rlock){......}, at: [<ffffffff811f3180>] ext4_read_block_bitmap_nowait+0x5d0/0x630
    CPU: 3 PID: 137 Comm: kworker/u128:1 Not tainted 3.17.0-rc2-00184-g82752e4 #165
    Hardware name: Intel Corporation W2600CR/W2600CR, BIOS SE5C600.86B.99.99.x028.061320111235 06/13/2011
    Workqueue: writeback bdi_writeback_workfn (flush-1:0)
    0000000000000411 ffff880813777288 ffffffff815c7fdc ffff880813777288
    ffff880813a8bba0 ffff8808137772a8 ffffffff8108fb30 ffff880803e01e38
    ffff880803e01e38 ffff8808137772c8 ffffffff811a8d53 ffff88080ecc6000
    Call Trace:
    [<ffffffff815c7fdc>] dump_stack+0x51/0x6d
    [<ffffffff8108fb30>] __might_sleep+0xf0/0x100
    [<ffffffff811a8d53>] __sync_dirty_buffer+0x43/0xe0
    [<ffffffff811a8e03>] sync_dirty_buffer+0x13/0x20
    [<ffffffff8120f581>] ext4_commit_super+0x1d1/0x230
    [<ffffffff8120fa03>] save_error_info+0x23/0x30
    [<ffffffff8120fd06>] __ext4_error+0xb6/0xd0
    [<ffffffff8120f260>] ? ext4_group_desc_csum+0x140/0x190
    [<ffffffff811f2d8c>] ext4_read_block_bitmap_nowait+0x1dc/0x630
    [<ffffffff8122e23a>] ext4_mb_init_cache+0x21a/0x8f0
    [<ffffffff8113ae95>] ? lru_cache_add+0x55/0x60
    [<ffffffff8112e16c>] ? add_to_page_cache_lru+0x6c/0x80
    [<ffffffff8122eaa0>] ext4_mb_init_group+0x190/0x280
    [<ffffffff8122ec51>] ext4_mb_good_group+0xc1/0x190
    [<ffffffff8123309a>] ext4_mb_regular_allocator+0x17a/0x410
    [<ffffffff8122c821>] ? ext4_mb_use_preallocated+0x31/0x380
    [<ffffffff81233535>] ? ext4_mb_new_blocks+0x205/0x8e0
    [<ffffffff8116ed5c>] ? kmem_cache_alloc+0xfc/0x180
    [<ffffffff812335b0>] ext4_mb_new_blocks+0x280/0x8e0
    [<ffffffff8116f2c4>] ? __kmalloc+0x144/0x1c0
    [<ffffffff81221797>] ? ext4_find_extent+0x97/0x320
    [<ffffffff812257f4>] ext4_ext_map_blocks+0xbc4/0x1050
    [<ffffffff811fa387>] ? ext4_map_blocks+0x297/0x430
    [<ffffffff811fa3ab>] ext4_map_blocks+0x2bb/0x430
    [<ffffffff81200e43>] ? ext4_init_io_end+0x23/0x50
    [<ffffffff811feb44>] ext4_writepages+0x564/0xaf0
    [<ffffffff815cde3b>] ? _raw_spin_unlock+0x2b/0x40
    [<ffffffff810ac7bd>] ? lock_release_non_nested+0x2fd/0x3c0
    [<ffffffff811a009e>] ? writeback_sb_inodes+0x10e/0x490
    [<ffffffff811a009e>] ? writeback_sb_inodes+0x10e/0x490
    [<ffffffff811377e3>] do_writepages+0x23/0x40
    [<ffffffff8119c8ce>] __writeback_single_inode+0x9e/0x280
    [<ffffffff811a026b>] writeback_sb_inodes+0x2db/0x490
    [<ffffffff811a0664>] wb_writeback+0x174/0x2d0
    [<ffffffff810ac359>] ? lock_release_holdtime+0x29/0x190
    [<ffffffff811a0863>] wb_do_writeback+0xa3/0x200
    [<ffffffff811a0a40>] bdi_writeback_workfn+0x80/0x230
    [<ffffffff81085618>] ? process_one_work+0x228/0x4d0
    [<ffffffff810856cd>] process_one_work+0x2dd/0x4d0
    [<ffffffff81085618>] ? process_one_work+0x228/0x4d0
    [<ffffffff81085c1d>] worker_thread+0x35d/0x460
    [<ffffffff810858c0>] ? process_one_work+0x4d0/0x4d0
    [<ffffffff810858c0>] ? process_one_work+0x4d0/0x4d0
    [<ffffffff8108a885>] kthread+0xf5/0x100
    [<ffffffff810990e5>] ? local_clock+0x25/0x30
    [<ffffffff8108a790>] ? __init_kthread_worker+0x70/0x70
    [<ffffffff815ce2ac>] ret_from_fork+0x7c/0xb0
    [<ffffffff8108a790>] ? __init_kthread_work

    Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
    Signed-off-by: Theodore Ts'o <tytso@mit.edu>
    Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
    ---
    fs/ext4/balloc.c | 12 ++++++++----
    1 file changed, 8 insertions(+), 4 deletions(-)

    diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
    index fca382037ddd..06b65be20d48 100644
    --- a/fs/ext4/balloc.c
    +++ b/fs/ext4/balloc.c
    @@ -176,7 +176,7 @@ static unsigned int num_clusters_in_group(struct super_block *sb,
    }

    /* Initializes an uninitialized block bitmap */
    -static void ext4_init_block_bitmap(struct super_block *sb,
    +static int ext4_init_block_bitmap(struct super_block *sb,
    struct buffer_head *bh,
    ext4_group_t block_group,
    struct ext4_group_desc *gdp)
    @@ -192,7 +192,6 @@ static void ext4_init_block_bitmap(struct super_block *sb,
    /* If checksum is bad mark all blocks used to prevent allocation
    * essentially implementing a per-group read-only flag. */
    if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
    - ext4_error(sb, "Checksum bad for group %u", block_group);
    grp = ext4_get_group_info(sb, block_group);
    if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
    percpu_counter_sub(&sbi->s_freeclusters_counter,
    @@ -205,7 +204,7 @@ static void ext4_init_block_bitmap(struct super_block *sb,
    count);
    }
    set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
    - return;
    + return -EIO;
    }
    memset(bh->b_data, 0, sb->s_blocksize);

    @@ -243,6 +242,7 @@ static void ext4_init_block_bitmap(struct super_block *sb,
    sb->s_blocksize * 8, bh->b_data);
    ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
    ext4_group_desc_csum_set(sb, block_group, gdp);
    + return 0;
    }

    /* Return the number of free blocks in a block group. It is used when
    @@ -438,11 +438,15 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
    }
    ext4_lock_group(sb, block_group);
    if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
    - ext4_init_block_bitmap(sb, bh, block_group, desc);
    + int err;
    +
    + err = ext4_init_block_bitmap(sb, bh, block_group, desc);
    set_bitmap_uptodate(bh);
    set_buffer_uptodate(bh);
    ext4_unlock_group(sb, block_group);
    unlock_buffer(bh);
    + if (err)
    + ext4_error(sb, "Checksum bad for grp %u", block_group);
    return bh;
    }
    ext4_unlock_group(sb, block_group);
    --
    2.1.0


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