Re: [PATCH v2 5/5] btrfs: Add a lockdep model for the ordered extents wait event

[Josef Bacik <josef@toxicpanda.com>]

On Mon, Jul 18, 2022 at 09:10:00PM -0700, Ioannis Angelakopoulos wrote:
> This wait event is very similar to the pending_ordered wait event in the
> sense that it occurs in a different context than the condition signaling
> for the event. The signaling occurs in btrfs_remove_ordered_extent() while
> the wait event is implemented in btrfs_start_ordered_extent() in
> fs/btrfs/ordered-data.c
> 
> However, in this case a thread must not acquire the lockdep map for the
> ordered extents wait event when the ordered extent is related to a free
> space inode. That is because lockdep creates dependencies between locks
> acquired both in execution paths related to normal inodes and paths related
> to free space inodes, thus leading to false positives.
> 
> Also to prevent false positives related to free space inodes and normal
> inodes, the lockdep map class for the inode->mapping->invalidate_lock is
> reinitialized in load_free_space_cache() in fs/btrfs/free-space-cache.c
> 

Make this bit a separate patch, put it before this one with an explanation of
why so we have a commit per logical change.  Thanks,

Josef