From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Zheng Da <zhengda1936@gmail.com>, xfs@oss.sgi.com
Subject: Re: concurrent direct IO write in xfs
Date: Mon, 13 Feb 2012 12:48:06 -0500 [thread overview]
Message-ID: <20120213174806.GA7630@infradead.org> (raw)
In-Reply-To: <20120209060920.GF7479@dastard>
On Thu, Feb 09, 2012 at 05:09:20PM +1100, Dave Chinner wrote:
> if (create) {
> - lockmode = XFS_ILOCK_EXCL;
> + /*
> + * For direct IO, we lock in shared mode so that write
> + * operations that don't require allocation can occur
> + * concurrently. The ilock has to be dropped over the allocation
> + * transaction reservation, so the only thing the ilock is
> + * providing here is modification exclusion. i.e. there is no
> + * need to hold the lock exclusive.
> + *
> + * For buffered IO, if we need to do delayed allocation then
> + * hold the ilock exclusive so that the lookup and delalloc
> + * reservation is atomic.
> + */
> + if (direct)
> + lockmode = XFS_ILOCK_SHARED;
> + else
> + lockmode = XFS_ILOCK_EXCL;
> xfs_ilock(ip, lockmode);
> } else {
> lockmode = xfs_ilock_map_shared(ip);
We'll actually need to use xfs_ilock_map_shared for the the direct
create case too, to make sure we have the exclusive lock when we first
read the extent list in.
Also xfs_qm_dqattach_locked really wants the inode locked exclusively,
which your current code doesn't handle.
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next prev parent reply other threads:[~2012-02-13 17:48 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-16 0:01 concurrent direct IO write in xfs Zheng Da
2012-01-16 17:48 ` Christoph Hellwig
2012-01-16 19:44 ` Zheng Da
2012-01-16 23:25 ` Dave Chinner
2012-01-17 19:19 ` Zheng Da
2012-01-20 8:53 ` Linda Walsh
2012-01-20 15:07 ` Zheng Da
2012-01-23 5:11 ` Dave Chinner
2012-01-23 19:34 ` Zheng Da
2012-01-23 20:51 ` Zheng Da
2012-01-24 0:34 ` Stan Hoeppner
2012-01-24 1:40 ` Zheng Da
2012-01-24 3:54 ` Dave Chinner
2012-01-25 21:20 ` Zheng Da
2012-01-25 22:25 ` Dave Chinner
2012-02-09 6:09 ` Dave Chinner
2012-02-09 6:44 ` Zheng Da
2012-02-13 17:48 ` Christoph Hellwig [this message]
2012-02-13 23:07 ` Dave Chinner
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