Enforce a minimum SG_IO timeout

There's no point in having too short SG_IO timeouts, since if the
command does end up timing out, we'll end up through the reset sequence
that is several seconds long in order to abort the command that timed
out.

As a result, shorter timeouts than a few seconds simply do not make
sense, as the recovery would be longer than the timeout itself.

Add a BLK_MIN_SG_TIMEOUT to match the existign BLK_DEFAULT_SG_TIMEOUT.

Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 5 insertions, 0 deletions

diff --git a/block/bsg.c b/block/bsg.c
index e8bd2475682a..e73e50daf3d0 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -202,6 +202,8 @@ static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
                 rq->timeout = q->sg_timeout;
         if (!rq->timeout)
                 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
+        if (rq->timeout < BLK_MIN_SG_TIMEOUT)
+                rq->timeout = BLK_MIN_SG_TIMEOUT;
 
         return 0;
 }
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 5963cf91a3a0..d0bb92cbefb9 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -208,6 +208,8 @@ static int blk_fill_sghdr_rq(struct request_queue *q, struct request *rq,
                 rq->timeout = q->sg_timeout;
         if (!rq->timeout)
                 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
+        if (rq->timeout < BLK_MIN_SG_TIMEOUT)
+                rq->timeout = BLK_MIN_SG_TIMEOUT;
 
         return 0;
 }
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6dcd30d806cd..031a315c0509 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -662,6 +662,7 @@ extern unsigned long blk_max_low_pfn, blk_max_pfn;
  * default timeout for SG_IO if none specified
  */
 #define BLK_DEFAULT_SG_TIMEOUT  (60 * HZ)
+#define BLK_MIN_SG_TIMEOUT      (7 * HZ)
 
 #ifdef CONFIG_BOUNCE
 extern int init_emergency_isa_pool(void);