btrfs: pass unaligned length to btrfs_cmp_data()

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>
(Cherry picked from commit 207910ddeeda38fd54544d94f8c8ca5a9632cc25)

Orabug: 26251039

Signed-off-by: Shan Hai <shan.hai@oracle.com>
Acked-by: Shannon Nelson <shannon.nelson@oracle.com>
Acked-by: John Haxby <john.haxby@oracle.com>