| From | Jiri Slaby <> | Subject | [PATCH 3.12 058/142] Drivers: scsi: storvsc: Implement a eh_timed_out handler | Date | Fri, 26 Sep 2014 11:44:29 +0200 |
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From: "K. Y. Srinivasan" <kys@microsoft.com>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit 56b26e69c8283121febedd12b3cc193384af46b9 upstream.
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> [hch: added a better comment explaining the issue] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- drivers/scsi/storvsc_drv.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index 9969fa1ef7c4..a14a1f7cd577 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; @@ -1687,6 +1698,7 @@ 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, -- 2.1.0
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