On Mon, 15 Nov 2021 at 00:18, Dave Chinner <david@xxxxxxxxxxxxx> wrote: > I just can't see how this race condition is XFS specific and why > fixing it requires XFS to sepcifically handle it while we ignore > similar theoretical issues in other filesystems... It is XFS specific, because all other filesystems RCU free the in-core inode after eviction. XFS is the only one that reuses the in-core inode object and that is very much different from anything the other filesystems do and what the VFS expects. I don't see how clearing the quick link buffer in ext4_evict_inode() could do anything bad. The contents are irrelevant, the lookup will be restarted anyway, the important thing is that the buffer is not freed and that it's null terminated, and both hold for the ext4, AFAICS. I tend to agree with Brian and Ian at this point: return -ECHILD from xfs_vn_get_link_inline() until xfs's inode resue vs. rcu walk implications are fully dealt with. No way to fix this from VFS alone. Thanks, Miklos
