On Wed, Aug 04, 2021 at 03:35:29PM +0200, Jan Kara wrote: > On Wed 04-08-21 20:50:44, yangerkun wrote: > > Our testcase(briefly described as fsstress on dm thin-provisioning which > > ext4 see volume size with 100G but actual size 10G) trigger a hungtask > > bug since ext4_writepages fall into a infinite loop: > > > > Got ENOSPC with follow stack: > > ... > > ext4_ext_map_blocks > > ext4_ext_convert_to_initialized > > ext4_ext_zeroout > > ext4_issue_zeroout > > ... > > submit_bio_wait <-- bio to thinpool will return ENOSPC > > > > Thanks for the patch. As a quick fix for the problem this is probably fine. > But longer term we might need to implement a configurable behavior for this > because just dropping data on the floor (which is what would happen here) > need not be what sysadmin wants and blocking until space is provisioned may be > actually a preferable behavior. Anyway for now feel free to add: > > Reviewed-by: Jan Kara <jack@xxxxxxx> Hmm, I wonder if this would be a better fix. (Not yet tested, may fry your file system, etc....) What do folks think? - Ted diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 92ad64b89d9b..501516cadc1b 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3569,7 +3569,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle, split_map.m_len - ee_block); err = ext4_ext_zeroout(inode, &zero_ex1); if (err) - goto out; + goto fallback; split_map.m_len = allocated; } if (split_map.m_lblk - ee_block + split_map.m_len < @@ -3583,7 +3583,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle, ext4_ext_pblock(ex)); err = ext4_ext_zeroout(inode, &zero_ex2); if (err) - goto out; + goto fallback; } split_map.m_len += split_map.m_lblk - ee_block; @@ -3592,6 +3592,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle, } } +fallback: err = ext4_split_extent(handle, inode, ppath, &split_map, split_flag, flags); if (err > 0)
