On Tue 18 Jun 2024 10:52:55 AM +01, Luis Henriques wrote; > On Fri 14 Jun 2024 05:18:45 PM +01, Luis Henriques wrote; > [...} >>> >>> I can also reproduce this error message using the above script and: >>> >>> - Linux 6.10-rc2 >>> - A 2 GiB loopback devic instead of /dev/sdb >>> >>> I bisected this back to: >>> >>> commit 9725958bb75cdfa10f2ec11526fdb23e7485e8e4 >>> Author: Xin Yin <yinxi...@bytedance.com> >>> Date: Thu Dec 23 11:23:37 2021 +0800 >>> >>> ext4: fast commit may miss tracking unwritten range during ftruncate >>> >>> It is still possible to cleanly revert that commit from 6.10-rc2, and >>> doing so removes the error message. >> >> Because I recently fixed an issue in the fast commit code[1] I was hoping >> that you were hitting the same bug. I've executed the reproducer with the >> fix (which hasn't been merged yet) and realised it's definitely a >> different problem. >> >> Debugged the issue a bit, it seems to be related with the fact that >> ext4_fc_write_inode_data() isn't able to cope with the fact that >> 'ei->i_fc_lblk_len' is set to EXT_MAX_BLOCKS. > > OK, I've looked into this again. And something I didn't pay attention > before was that the filesystem was created with both fast_commit *and* > inline_data features. And after some more debugging, I _think_ the patch > bellow should be the fix for this bug. > > If I understand it correctly, when an inode has inlined data it means that > there's no inode data to be written and this case should be handled as if > the inode length was zero. > > I'll send out a patch later after running a few more tests just to make > sure it doesn't break something else. But it would awesome if you could > test it too.
Hmm... looking closer, this patch seems to work with this specific test script, but only because file data is probably small enough to fit in inode->i_block. However, it may actually truncate files that have inlined data if the file data is also stored in the extended attribute space (i.e. > 60 bytes). So, the correct fix is probably something like the below patch (which I'll send out soon). Cheers, -- Luís diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c index 87c009e0c59a..d3a67bc06d10 100644 --- a/fs/ext4/fast_commit.c +++ b/fs/ext4/fast_commit.c @@ -649,6 +649,12 @@ void ext4_fc_track_range(handle_t *handle, struct inode *inode, ext4_lblk_t star if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FC_INELIGIBLE)) return; + if (ext4_has_inline_data(inode)) { + ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR, + handle); + return; + } + args.start = start; args.end = end;