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authorK. Y. Srinivasan <kys@microsoft.com>2014-07-12 09:48:30 -0700
committerChristoph Hellwig <hch@lst.de>2014-07-25 17:17:03 -0400
commit56b26e69c8283121febedd12b3cc193384af46b9 (patch)
tree7e62acbb51256914944320c8aa54111bfbbf663f /drivers/scsi
parentadb6f9e1a8c6af1037232b59edb11277471537ea (diff)
downloadlinux-56b26e69c8283121febedd12b3cc193384af46b9.tar.bz2
Drivers: scsi: storvsc: Implement a eh_timed_out handler
On Azure, we have seen instances of unbounded I/O latencies. To deal with this issue, implement handler that can reset the timeout. Note that the host gaurantees that it will respond to each command that has been issued. Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Cc: <stable@vger.kernel.org> [hch: added a better comment explaining the issue] Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/storvsc_drv.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 7e8a64251681..2b8595b7ad45 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -33,6 +33,7 @@
#include <linux/device.h>
#include <linux/hyperv.h>
#include <linux/mempool.h>
+#include <linux/blkdev.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
@@ -1518,6 +1519,16 @@ static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd)
return SUCCESS;
}
+/*
+ * The host guarantees to respond to each command, although I/O latencies might
+ * be unbounded on Azure. Reset the timer unconditionally to give the host a
+ * chance to perform EH.
+ */
+static enum blk_eh_timer_return storvsc_eh_timed_out(struct scsi_cmnd *scmnd)
+{
+ return BLK_EH_RESET_TIMER;
+}
+
static bool storvsc_scsi_cmd_ok(struct scsi_cmnd *scmnd)
{
bool allowed = true;
@@ -1697,6 +1708,7 @@ static struct scsi_host_template scsi_driver = {
.bios_param = storvsc_get_chs,
.queuecommand = storvsc_queuecommand,
.eh_host_reset_handler = storvsc_host_reset_handler,
+ .eh_timed_out = storvsc_eh_timed_out,
.slave_alloc = storvsc_device_alloc,
.slave_destroy = storvsc_device_destroy,
.slave_configure = storvsc_device_configure,