On Wed, May 26, 2021 at 12:18:40PM +0200, Jan Kara wrote:

On Tue 25-05-21 14:37:29, Darrick J. Wong wrote:

quoted

On Tue, May 25, 2021 at 03:50:44PM +0200, Jan Kara wrote:

quoted

Use invalidate_lock instead of XFS internal i_mmap_lock. The intended
purpose of invalidate_lock is exactly the same. Note that the locking in
__xfs_filemap_fault() slightly changes as filemap_fault() already takes
invalidate_lock.

Reviewed-by: Christoph Hellwig <hch@lst.de>
CC: <redacted>
CC: "Darrick J. Wong" <redacted>

It's djwong@kernel.org now.

OK, updated.

quoted

quoted

@@ -355,8 +358,11 @@ xfs_isilocked(
 
 	if (lock_flags & (XFS_MMAPLOCK_EXCL|XFS_MMAPLOCK_SHARED)) {
 		if (!(lock_flags & XFS_MMAPLOCK_SHARED))
-			return !!ip->i_mmaplock.mr_writer;
-		return rwsem_is_locked(&ip->i_mmaplock.mr_lock);
+			return !debug_locks ||
+				lockdep_is_held_type(
+					&VFS_I(ip)->i_mapping->invalidate_lock,
+					0);
+		return rwsem_is_locked(&VFS_I(ip)->i_mapping->invalidate_lock);

This doesn't look right...

If lockdep is disabled, we always return true for
xfs_isilocked(ip, XFS_MMAPLOCK_EXCL) even if nobody holds the lock?

Granted, you probably just copy-pasted from the IOLOCK_SHARED clause
beneath it.  Er... oh right, preichl was messing with all that...

https://lore.kernel.org/linux-xfs/20201016021005.548850-2-preichl@redhat.com/ (local)

Indeed copy-paste programming ;) It certainly makes the assertions happy
but useless. Should I pull the patch you reference into the series? It
seems to have been uncontroversial and reviewed. Or will you pull the
series to xfs tree so I can just rebase on top?

The full conversion series introduced assertion failures because lockdep
can't handle some of the ILOCK usage patterns, specifically the fact
that a thread sometimes takes the ILOCK but then hands the inode to a
workqueue to avoid overflowing the first thread's stack.  That's why it
never got merged into the xfs tree.

However, that kind of switcheroo isn't done with the
MMAPLOCK/invalidate_lock, so you could simply pull the patch I linked
above into your series.

--D

								Honza
-- 
Jan Kara [off-list ref]
SUSE Labs, CR