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From: David Sterba <dsterba@suse.cz>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>,
	linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org,
	david@fromorbit.com, hch@lst.de, johannes.thumshirn@wdc.com,
	dsterba@suse.com, josef@toxicpanda.com,
	Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 04/14] iomap: Call inode_dio_end() before generic_write_sync()
Date: Mon, 28 Sep 2020 17:04:19 +0200	[thread overview]
Message-ID: <20200928150418.GC6756@twin.jikos.cz> (raw)
In-Reply-To: <20200926015108.GQ7964@magnolia>

On Fri, Sep 25, 2020 at 06:51:08PM -0700, Darrick J. Wong wrote:
> On Thu, Sep 24, 2020 at 11:39:11AM -0500, Goldwyn Rodrigues wrote:
> > From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> > 
> > iomap complete routine can deadlock with btrfs_fallocate because of the
> > call to generic_write_sync().
> > 
> > P0                      P1
> > inode_lock()            fallocate(FALLOC_FL_ZERO_RANGE)
> > __iomap_dio_rw()        inode_lock()
> >                         <block>
> > <submits IO>
> > <completes IO>
> > inode_unlock()
> >                         <gets inode_lock()>
> >                         inode_dio_wait()
> > iomap_dio_complete()
> >   generic_write_sync()
> >     btrfs_file_fsync()
> >       inode_lock()
> >       <deadlock>
> > 
> > inode_dio_end() is used to notify the end of DIO data in order
> > to synchronize with truncate. Call inode_dio_end() before calling
> > generic_write_sync(), so filesystems can lock i_rwsem during a sync.
> > 
> > This matches the way it is done in fs/direct-io.c:dio_complete().
> > 
> > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
> > Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> 
> Looks ok (at least with the fses that use either iomap or ye olde
> directio) to me...
> 
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> So, uh, do you want me to pull these two iomap patches in for 5.10?

That would be great, thanks. Once they land in 5.10-rc we'll be able to
base the rest on some master snapshot and target 5.11 for release.

  reply	other threads:[~2020-09-28 15:05 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-24 16:39 [PATCH 0/14 v3] BTRFS DIO inode locking/D_SYNC fix Goldwyn Rodrigues
2020-09-24 16:39 ` [PATCH 01/14] fs: remove dio_end_io() Goldwyn Rodrigues
2020-09-29 12:16   ` David Sterba
2020-09-24 16:39 ` [PATCH 02/14] btrfs: remove BTRFS_INODE_READDIO_NEED_LOCK Goldwyn Rodrigues
2020-09-24 16:39 ` [PATCH 03/14] iomap: Allow filesystem to call iomap_dio_complete without i_rwsem Goldwyn Rodrigues
2020-09-26  1:49   ` Darrick J. Wong
2020-09-24 16:39 ` [PATCH 04/14] iomap: Call inode_dio_end() before generic_write_sync() Goldwyn Rodrigues
2020-09-26  1:51   ` Darrick J. Wong
2020-09-28 15:04     ` David Sterba [this message]
2020-09-28 16:12       ` Darrick J. Wong
2020-09-24 16:39 ` [PATCH 05/14] btrfs: split btrfs_direct_IO to read and write Goldwyn Rodrigues
2020-09-24 16:39 ` [PATCH 06/14] btrfs: Move pos increment and pagecache extension to btrfs_buffered_write() Goldwyn Rodrigues
2020-09-24 16:39 ` [PATCH 07/14] btrfs: Move FS error state bit early during write Goldwyn Rodrigues
2020-09-24 16:39 ` [PATCH 08/14] btrfs: Introduce btrfs_write_check() Goldwyn Rodrigues
2020-10-09 14:21   ` Josef Bacik
2020-09-24 16:39 ` [PATCH 09/14] btrfs: Introduce btrfs_inode_lock()/unlock() Goldwyn Rodrigues
2020-09-24 16:39 ` [PATCH 10/14] btrfs: Push inode locking and unlocking into buffered/direct write Goldwyn Rodrigues
2020-09-24 16:39 ` [PATCH 11/14] btrfs: Use inode_lock_shared() for direct writes within EOF Goldwyn Rodrigues
2020-10-09 14:25   ` Josef Bacik
2020-09-24 16:39 ` [PATCH 12/14] btrfs: Remove dio_sem Goldwyn Rodrigues
2020-09-24 16:39 ` [PATCH 13/14] btrfs: Call iomap_dio_complete() without inode_lock Goldwyn Rodrigues
2020-09-24 16:39 ` [PATCH 14/14] btrfs: Revert 09745ff88d93 ("btrfs: dio iomap DSYNC workaround") Goldwyn Rodrigues

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