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Date: Wed, 26 May 2021 08:32:51 -0700 From: "Darrick J. Wong" <djwong@...nel.org> To: Jan Kara <jack@...e.cz> Cc: linux-fsdevel@...r.kernel.org, Christoph Hellwig <hch@...radead.org>, Dave Chinner <david@...morbit.com>, ceph-devel@...r.kernel.org, Chao Yu <yuchao0@...wei.com>, Damien Le Moal <damien.lemoal@....com>, "Darrick J. Wong" <darrick.wong@...cle.com>, Jaegeuk Kim <jaegeuk@...nel.org>, Jeff Layton <jlayton@...nel.org>, Johannes Thumshirn <jth@...nel.org>, linux-cifs@...r.kernel.org, linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net, linux-mm@...ck.org, linux-xfs@...r.kernel.org, Miklos Szeredi <miklos@...redi.hu>, Steve French <sfrench@...ba.org>, Ted Tso <tytso@....edu>, Matthew Wilcox <willy@...radead.org>, Christoph Hellwig <hch@....de> Subject: Re: [PATCH 07/13] xfs: Convert to use invalidate_lock 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: > > On Tue, May 25, 2021 at 03:50:44PM +0200, Jan Kara wrote: > > > 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@....de> > > > CC: <linux-xfs@...r.kernel.org> > > > CC: "Darrick J. Wong" <darrick.wong@...cle.com> > > > > It's djwong@...nel.org now. > > OK, updated. > > > > @@ -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/ > > 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 <jack@...e.com> > SUSE Labs, CR
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