From: Ira Weiny <ira.weiny@intel.com>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-kernel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Dan Williams <dan.j.williams@intel.com>,
Christoph Hellwig <hch@lst.de>,
"Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH V4 09/13] fs/xfs: Add write aops lock to xfs layer
Date: Mon, 24 Feb 2020 11:57:36 -0800 [thread overview]
Message-ID: <20200224195735.GA11565@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20200224003455.GY10776@dread.disaster.area>
On Mon, Feb 24, 2020 at 11:34:55AM +1100, Dave Chinner wrote:
> On Thu, Feb 20, 2020 at 04:41:30PM -0800, ira.weiny@intel.com wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> >
[snip]
> >
> > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> > index 35df324875db..5b014c428f0f 100644
> > --- a/fs/xfs/xfs_inode.c
> > +++ b/fs/xfs/xfs_inode.c
> > @@ -142,12 +142,12 @@ xfs_ilock_attr_map_shared(
> > *
> > * Basic locking order:
> > *
> > - * i_rwsem -> i_mmap_lock -> page_lock -> i_ilock
> > + * s_dax_sem -> i_rwsem -> i_mmap_lock -> page_lock -> i_ilock
> > *
> > * mmap_sem locking order:
> > *
> > * i_rwsem -> page lock -> mmap_sem
> > - * mmap_sem -> i_mmap_lock -> page_lock
> > + * s_dax_sem -> mmap_sem -> i_mmap_lock -> page_lock
> > *
> > * The difference in mmap_sem locking order mean that we cannot hold the
> > * i_mmap_lock over syscall based read(2)/write(2) based IO. These IO paths can
> > @@ -182,6 +182,9 @@ xfs_ilock(
> > (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
> > ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0);
> >
> > + if (lock_flags & XFS_DAX_EXCL)
> > + inode_aops_down_write(VFS_I(ip));
>
> I largely don't see the point of adding this to xfs_ilock/iunlock.
>
> It's only got one caller, so I don't see much point in adding it to
> an interface that has over a hundred other call sites that don't
> need or use this lock. just open code it where it is needed in the
> ioctl code.
I know it seems overkill but if we don't do this we need to code a flag to be
returned from xfs_ioctl_setattr_dax_invalidate(). This flag is then used in
xfs_ioctl_setattr_get_trans() to create the transaction log item which can then
be properly used to unlock the lock in xfs_inode_item_release()
I don't know of a cleaner way to communicate to xfs_inode_item_release() to
unlock i_aops_sem after the transaction is complete.
Ira
>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@fromorbit.com
next prev parent reply other threads:[~2020-02-24 19:57 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 0:41 [PATCH V4 00/13] Enable per-file/per-directory DAX operations V4 ira.weiny
2020-02-21 0:41 ` [PATCH V4 01/13] fs/xfs: Remove unnecessary initialization of i_rwsem ira.weiny
2020-02-21 1:26 ` Dave Chinner
2020-02-27 17:52 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 02/13] fs/xfs: Clarify lockdep dependency for xfs_isilocked() ira.weiny
2020-02-21 1:34 ` Dave Chinner
2020-02-21 23:00 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 03/13] fs: Remove unneeded IS_DAX() check ira.weiny
2020-02-21 1:42 ` Dave Chinner
2020-02-21 23:04 ` Ira Weiny
2020-02-21 17:42 ` Christoph Hellwig
2020-02-21 0:41 ` [PATCH V4 04/13] fs/stat: Define DAX statx attribute ira.weiny
2020-02-21 0:41 ` [PATCH V4 05/13] fs/xfs: Isolate the physical DAX flag from enabled ira.weiny
2020-02-21 0:41 ` [PATCH V4 06/13] fs/xfs: Create function xfs_inode_enable_dax() ira.weiny
2020-02-22 0:28 ` Darrick J. Wong
2020-02-23 15:07 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 07/13] fs: Add locking for a dynamic address space operations state ira.weiny
2020-02-21 17:44 ` Christoph Hellwig
2020-02-21 22:44 ` Dave Chinner
2020-02-21 23:26 ` Dan Williams
2020-02-24 17:56 ` Christoph Hellwig
2020-02-25 0:09 ` Dave Chinner
2020-02-25 17:36 ` Christoph Hellwig
2020-02-25 19:37 ` Jeff Moyer
2020-02-26 9:28 ` Jonathan Halliday
2020-02-26 11:31 ` Jan Kara
2020-02-26 11:56 ` Jonathan Halliday
2020-02-26 16:10 ` Ira Weiny
2020-02-26 16:46 ` Dan Williams
2020-02-26 17:20 ` Jan Kara
2020-02-26 17:54 ` Dan Williams
2020-02-25 21:03 ` Ira Weiny
2020-02-26 11:17 ` Jan Kara
2020-02-26 15:57 ` Ira Weiny
2020-02-22 0:33 ` Darrick J. Wong
2020-02-23 15:03 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 08/13] fs: Prevent DAX state change if file is mmap'ed ira.weiny
2020-02-21 0:41 ` [PATCH V4 09/13] fs/xfs: Add write aops lock to xfs layer ira.weiny
2020-02-22 0:31 ` Darrick J. Wong
2020-02-23 15:04 ` Ira Weiny
2020-02-24 0:34 ` Dave Chinner
2020-02-24 19:57 ` Ira Weiny [this message]
2020-02-24 22:32 ` Dave Chinner
2020-02-25 21:12 ` Ira Weiny
2020-02-25 22:59 ` Dave Chinner
2020-02-26 18:02 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 10/13] fs/xfs: Clean up locking in dax invalidate ira.weiny
2020-02-21 17:45 ` Christoph Hellwig
2020-02-21 18:06 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 11/13] fs/xfs: Allow toggle of effective DAX flag ira.weiny
2020-02-21 0:41 ` [PATCH V4 12/13] fs/xfs: Remove xfs_diflags_to_linux() ira.weiny
2020-02-21 0:41 ` [PATCH V4 13/13] Documentation/dax: Update Usage section ira.weiny
2020-02-26 22:48 ` [PATCH V4 00/13] Enable per-file/per-directory DAX operations V4 Jeff Moyer
2020-02-27 2:43 ` Ira Weiny
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