From 83cdadd8b0559c93728d065d23ca3485fa567e54 Mon Sep 17 00:00:00 2001
From: Brian Foster <bfoster@redhat.com>
Date: Fri, 22 Feb 2013 13:32:56 -0500
Subject: xfs: fix potential infinite loop in xfs_iomap_prealloc_size()

If freesp == 0, we could end up in an infinite loop while squashing
the preallocation. Break the loop when we've killed the prealloc
entirely.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

(cherry picked from commit e78c420bfc2608bb5f9a0b9165b1071c1e31166a)

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 912d83d..b0b0f44 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -413,7 +413,7 @@ xfs_iomap_prealloc_size(
 		 * have a large file on a small filesystem and the above
 		 * lowspace thresholds are smaller than MAXEXTLEN.
 		 */
-		while (alloc_blocks >= freesp)
+		while (alloc_blocks && alloc_blocks >= freesp)
 			alloc_blocks >>= 4;
 	}
 
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