I apologise for flooding, patch description in former email was for slightly different kernel version. Correct description is below: Existent implementation of ext4_free_blocks() always calls dquot_free_block This looks quite sensible in the most cases: blocks to be freed are associated with inode and were accounted in quota and i_blocks some time ago. However, there is a case when blocks to free were not accounted by the time calling ext4_free_blocks() yet: 1. delalloc is on, write_begin pre-allocated some space in quota 2. write-back happens, ext4 allocates some blocks in ext4_ext_map_blocks() 3. then ext4_ext_map_blocks() gets an error (e.g. ENOSPC) from ext4_ext_insert_extent() and calls ext4_free_blocks(). In this scenario, ext4_free_blocks() calls dquot_free_block() who, in turn, decrements i_blocks for blocks which were not accounted yet (due to delalloc) After clean umount, e2fsck reports something like: > Inode 21, i_blocks is 5080, should be 5128. Fix<y>? because i_blocks was erroneously decremented as explained above. The patch fixes the problem by passing EXT4_FREE_BLOCKS_SKIP_QUPD flag to ext4_free_blocks(). This flag forces ext4_free_blocks() to skip dquot_free_block() call. Signed-off-by: Maxim Patlasov <maxim.patlasov@xxxxxxxxx> On Fri, Jun 10, 2011 at 2:07 PM, Maxim Patlasov <maxim.patlasov@xxxxxxxxx> wrote: > Existent implementation of ext4_free_blocks() always calls vfs_dq_free_block > This looks quite sensible in the most cases: blocks to be freed are associated > with inode and were accounted in quota and i_blocks some time ago. > > However, there is a case when blocks to free were not accounted by the time > calling ext4_free_blocks() yet: > > 1. delalloc is on, write_begin pre-allocated some space in quota > 2. write-back happens, ext4 allocates some blocks in ext4_ext_get_blocks() > 3. then ext4_ext_get_blocks() gets an error (e.g. ENOSPC) from > ext4_ext_insert_extent() and calls ext4_free_blocks(). > > In this scenario, ext4_free_blocks() calls vfs_dq_free_block() who, in turn, > decrements i_blocks for blocks which were not accounted yet (due to delalloc) > After clean umount, e2fsck reports something like: > >> Inode 21, i_blocks is 5080, should be 5128. Fix<y>? > because i_blocks was erroneously decremented as explained above. > > The patch fixes the problem by passing EXT4_FREE_BLOCKS_SKIP_QUPD flag to > ext4_free_blocks(). This flag forces ext4_free_blocks() to skip > vfs_dq_free_block() call. > > Signed-off-by: Maxim Patlasov <maxim.patlasov@xxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
