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From: Dave Chinner <david@fromorbit.com>
To: ira.weiny@intel.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 01/13] fs/xfs: Remove unnecessary initialization of i_rwsem
Date: Fri, 21 Feb 2020 12:26:25 +1100
Message-ID: <20200221012625.GT10776@dread.disaster.area> (raw)
In-Reply-To: <20200221004134.30599-2-ira.weiny@intel.com>

On Thu, Feb 20, 2020 at 04:41:22PM -0800, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
> 
> xfs_reinit_inode() -> inode_init_always() already handles calling
> init_rwsem(i_rwsem).  Doing so again is unneeded.
> 
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>

Except that this inode has been destroyed and freed by the VFS, and
we are now recycling it back into the VFS before we actually
physically freed it.

Hence we have re-initialise the semaphore because the semaphore can
contain internal state that is specific to it's new life cycle (e.g.
the lockdep context) that will cause problems if we just assume that
the inode is the same inode as it was before we recycled it back
into the VFS caches.

So, yes, we actually do need to re-initialise the rwsem here.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

  reply index

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 [this message]
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
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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