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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Andreas Gruenbacher <agruenba@redhat.com>,
        Bob Peterson <rpeterso@redhat.com>
Subject: [PATCH 4.15 027/128] gfs2: Fixes to "Implement iomap for block_map" (2)
Date:   Fri, 16 Mar 2018 16:22:48 +0100
Message-Id: <20180316152337.877284662@linuxfoundation.org>
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4.15-stable review patch.  If anyone has any objections, please let me know.

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

From: Andreas Gruenbacher <agruenba@redhat.com>

commit 3b5da96e4585a2788da6a07619bda3518d76eb30 upstream.

It turns out that commit 3229c18c0d6b2 'Fixes to "Implement iomap for
block_map"' introduced another bug in gfs2_iomap_begin that can cause
gfs2_block_map to set bh->b_size of an actual buffer to 0.  This can
lead to arbitrary incorrect behavior including crashes or disk
corruption.  Revert the incorrect part of that commit.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/gfs2/bmap.c |    3 ---
 1 file changed, 3 deletions(-)

--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -811,9 +811,6 @@ do_alloc:
 			iomap->length = hole_size(inode, lblock, &mp);
 		else
 			iomap->length = size - pos;
-	} else {
-		if (height <= ip->i_height)
-			iomap->length = hole_size(inode, lblock, &mp);
 	}
 	goto out_release;
 }