[Precise][SRU] zram: allow request end to coincide with disksize

[Luis Henriques]

From: Sergey Senozhatsky <sergey.senozhatsky at gmail.com>

BugLink: http://bugs.launchpad.net/bugs/1246664

Pass valid_io_request() checks if request end coincides with disksize
(end equals bound), only fail if we attempt to read beyond the bound.

mkfs.ext2 produces numerous errors:
[ 2164.632747] quiet_error: 1 callbacks suppressed
[ 2164.633260] Buffer I/O error on device zram0, logical block 153599
[ 2164.633265] lost page write due to I/O error on zram0

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(back ported from commit 75c7caf5a052ffd8db3312fa7864ee2d142890c4)
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/staging/zram/zram_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index d197b3e..e1a4994 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -553,7 +553,7 @@ static inline int valid_io_request(struct zram *zram, struct bio *bio)
 	end = start + (bio->bi_size >> SECTOR_SHIFT);
 	bound = zram->disksize >> SECTOR_SHIFT;
 	/* out of range range */
-	if (unlikely(start >= bound || end >= bound || start > end))
+	if (unlikely(start >= bound || end > bound || start > end))
 		return 0;
 
 	/* I/O request is valid */
-- 
1.8.3.2