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>

diff --git a/block/bsg.c b/block/bsg.c
index e8bd2475682ab4c2d29f8f205e57b62427b7cfe2..e73e50daf3d0a36df8977cad29b550e3139fbef0 100644 (file)
--- 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 5963cf91a3a0c4f67dc709f9a6b98fdd87235f53..d0bb92cbefb9d698fc4756ec9041aeb2f5794005 100644 (file)
--- 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 6dcd30d806cd8539917fea7c0ae216160de0425d..031a315c0509e5aa9eaa73c080b7e76a44dc95a0 100644 (file)
--- 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);