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From: Dave Jiang <dave.jiang@intel.com>
To: tytso@mit.edu, darrick.wong@oracle.com, jack@suse.cz, zwisler@kernel.org
Cc: linux-nvdimm@lists.01.org, david@fromorbit.com,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	lczerner@redhat.com, linux-ext4@vger.kernel.org, hch@lst.de
Subject: [PATCH 2/2] [PATCH] xfs: Close race between direct IO and xfs_break_layouts()
Date: Tue, 07 Aug 2018 15:11:43 -0700	[thread overview]
Message-ID: <153367990333.37314.16218849614019392916.stgit@djiang5-desk3.ch.intel.com> (raw)
In-Reply-To: <153367989755.37314.6889218648604435494.stgit@djiang5-desk3.ch.intel.com>

This patch is the duplicate of ross's fix for ext4 for xfs.

If the refcount of a page is lowered between the time that it is returned
by dax_busy_page() and when the refcount is again checked in
xfs_break_layouts() => ___wait_var_event(), the waiting function
xfs_wait_dax_page() will never be called.  This means that
xfs_break_layouts() will still have 'retry' set to false, so we'll stop
looping and never check the refcount of other pages in this inode.

Instead, always continue looping as long as dax_layout_busy_page() gives us
a page which it found with an elevated refcount.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 fs/xfs/xfs_file.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index a3e7767a5715..666c93fe5284 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -721,12 +721,10 @@ xfs_file_write_iter(
 
 static void
 xfs_wait_dax_page(
-	struct inode		*inode,
-	bool			*did_unlock)
+	struct inode		*inode)
 {
 	struct xfs_inode        *ip = XFS_I(inode);
 
-	*did_unlock = true;
 	xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
 	schedule();
 	xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
@@ -746,9 +744,10 @@ xfs_break_dax_layouts(
 	if (!page)
 		return 0;
 
+	*did_unlock = true;
 	return ___wait_var_event(&page->_refcount,
 			atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
-			0, 0, xfs_wait_dax_page(inode, did_unlock));
+			0, 0, xfs_wait_dax_page(inode));
 }
 
 int

  reply	other threads:[~2018-08-08  0:28 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-07 22:11 [PATCH 1/2] ext4: Close race between direct IO and ext4_break_layouts() Dave Jiang
2018-08-07 22:11 ` Dave Jiang [this message]
2018-08-08  8:53   ` [PATCH 2/2] [PATCH] xfs: Close race between direct IO and xfs_break_layouts() Jan Kara
2018-08-08 15:47     ` Dave Jiang
2018-08-08  8:49 ` [PATCH 1/2] ext4: Close race between direct IO and ext4_break_layouts() Jan Kara

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