From 207910ddeeda38fd54544d94f8c8ca5a9632cc25 Mon Sep 17 00:00:00 2001
From: Mark Fasheh <mfasheh@suse.de>
Date: Tue, 30 Jun 2015 14:42:04 -0700
Subject: [PATCH] btrfs: pass unaligned length to btrfs_cmp_data()

In the case that we dedupe the tail of a file, we might expand the dedupe
len out to the end of our last block. We don't want to compare data past
i_size however, so pass the original length to btrfs_cmp_data().

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
---
 fs/btrfs/ioctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index c86b835da7a87..55504338491d8 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2943,7 +2943,8 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
 		goto out_unlock;
 	}
 
-	ret = btrfs_cmp_data(src, loff, dst, dst_loff, len);
+	/* pass original length for comparison so we stay within i_size */
+	ret = btrfs_cmp_data(src, loff, dst, dst_loff, olen);
 	if (ret == 0)
 		ret = btrfs_clone(src, dst, loff, olen, len, dst_loff);
 
-- 
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