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>
---
fs/ext4/ext4.h | 1 +
fs/ext4/extents.c | 4 +++-
fs/ext4/mballoc.c | 2 +-
3 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 1921392..2cff50c 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -526,6 +526,7 @@ struct ext4_new_group_data {
#define EXT4_FREE_BLOCKS_METADATA 0x0001
#define EXT4_FREE_BLOCKS_FORGET 0x0002
#define EXT4_FREE_BLOCKS_VALIDATED 0x0004
+#define EXT4_FREE_BLOCKS_SKIP_QUPD 0x0008
/*
* ioctl commands
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 5199bac..4d17497 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3601,12 +3601,14 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
err = ext4_ext_insert_extent(handle, inode, path, &newex, flags);
if (err) {
+ int fb_flags = flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE ?
+ EXT4_FREE_BLOCKS_SKIP_QUPD : 0;
/* 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_discard_preallocations(inode);
ext4_free_blocks(handle, inode, NULL, ext4_ext_pblock(&newex),
- ext4_ext_get_actual_len(&newex), 0);
+ ext4_ext_get_actual_len(&newex), fb_flags);
goto out2;
}
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 859f2ae..ba391c6 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4637,7 +4637,7 @@ do_more:
}
ext4_mark_super_dirty(sb);
error_return:
- if (freed)
+ if (freed && !(flags & EXT4_FREE_BLOCKS_SKIP_QUPD))
dquot_free_block(inode, freed);
brelse(bitmap_bh);
ext4_std_error(sb, err);
--
1.7.4.4
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