* Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>:
> When ext4_insert_delayed block receives and recovers from an error from
> ext4_es_insert_delayed_block(), e.g., ENOMEM, it does not release the
> space it has reserved for that block insertion as it should. One effect
> of this bug is that s_dirtyclusters_counter is not decremented and
> remains incorrectly elevated until the file system has been unmounted.
> This can result in premature ENOSPC returns and apparent loss of free
> space.
>
> Another effect of this bug is that
> /sys/fs/ext4/<dev>/delayed_allocation_blocks can remain non-zero even
> after syncfs has been executed on the filesystem.
>
> Besides, add check for s_dirtyclusters_counter when inode is going to be
> evicted and freed. s_dirtyclusters_counter can still keep non-zero until
> inode is written back in .evict_inode(), and thus the check is delayed
> to .destroy_inode().
>
> Fixes: 51865fda28e5 ("ext4: let ext4 maintain extent status tree")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Suggested-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
> ---
> changes since v1:
> - improve commit log suggested by Eric Whitney
> - update "Suggested-by" title for Gao Xian, who actually found this bug
> code
> - add check for s_dirtyclusters_counter in .destroy_inode()
> ---
> fs/ext4/inode.c | 5 +++++
> fs/ext4/super.c | 6 ++++++
> 2 files changed, 11 insertions(+)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index d8de607849df..73daf9443e5e 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1640,6 +1640,7 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
> struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> int ret;
> bool allocated = false;
> + bool reserved = false;
>
> /*
> * If the cluster containing lblk is shared with a delayed,
> @@ -1656,6 +1657,7 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
> ret = ext4_da_reserve_space(inode);
> if (ret != 0) /* ENOSPC */
> goto errout;
> + reserved = true;
> } else { /* bigalloc */
> if (!ext4_es_scan_clu(inode, &ext4_es_is_delonly, lblk)) {
> if (!ext4_es_scan_clu(inode,
> @@ -1668,6 +1670,7 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
> ret = ext4_da_reserve_space(inode);
> if (ret != 0) /* ENOSPC */
> goto errout;
> + reserved = true;
> } else {
> allocated = true;
> }
> @@ -1678,6 +1681,8 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
> }
>
> ret = ext4_es_insert_delayed_block(inode, lblk, allocated);
> + if (ret && reserved)
> + ext4_da_release_space(inode, 1);
>
> errout:
> return ret;
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index dfa09a277b56..61bf52b58fca 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1351,6 +1351,12 @@ static void ext4_destroy_inode(struct inode *inode)
> true);
> dump_stack();
> }
> +
> + if (EXT4_I(inode)->i_reserved_data_blocks)
> + ext4_msg(inode->i_sb, KERN_ERR,
> + "Inode %lu (%p): i_reserved_data_blocks (%u) not cleared!",
> + inode->i_ino, EXT4_I(inode),
> + EXT4_I(inode)->i_reserved_data_blocks);
> }
>
> static void init_once(void *foo)
> --
> 2.27.0
>
Looks good, passed 4k xfstests-bld regression. Feel free to add:
Reviewed-by: Eric Whitney <enwlinux@xxxxxxxxx>
Eric
