On 8/24/21 4:30 AM, Eric Whitney wrote:
> * 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>
Hi tytso, it's a bug fix and it would be great if it could be merged to
5.15.
--
Thanks,
Jeffle
