linux-kernel - [PATCH 4.9 34/48] xfs: evict CoW fork extents when performing finsert/fcollapse

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Date:   Tue, 24 Oct 2017 15:03:47 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Amir Goldstein <amir73il@...il.com>,
        Carlos Maiolino <cmaiolino@...hat.com>,
        Christoph Hellwig <hch@....de>,
        "Darrick J. Wong" <darrick.wong@...cle.com>
Subject: [PATCH 4.9 34/48] xfs: evict CoW fork extents when performing finsert/fcollapse

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Darrick J. Wong <darrick.wong@...cle.com>

commit 3af423b03435c81036fa710623d3ae92fbe346a3 upstream.

When we perform an finsert/fcollapse operation, cancel all the CoW
extents for the affected file offset range so that they don't end up
pointing to the wrong blocks.

Reported-by: Amir Goldstein <amir73il@...il.com>
Reviewed-by: Carlos Maiolino <cmaiolino@...hat.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/xfs/xfs_bmap_util.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1445,7 +1445,19 @@ xfs_shift_file_space(
 		return error;
 
 	/*
-	 * The extent shiting code works on extent granularity. So, if
+	 * Clean out anything hanging around in the cow fork now that
+	 * we've flushed all the dirty data out to disk to avoid having
+	 * CoW extents at the wrong offsets.
+	 */
+	if (xfs_is_reflink_inode(ip)) {
+		error = xfs_reflink_cancel_cow_range(ip, offset, NULLFILEOFF,
+				true);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * The extent shifting code works on extent granularity. So, if
 	 * stop_fsb is not the starting block of extent, we need to split
 	 * the extent at stop_fsb.
 	 */