From 56b26e69c8283121febedd12b3cc193384af46b9 Mon Sep 17 00:00:00 2001 From: "K. Y. Srinivasan" Date: Sat, 12 Jul 2014 09:48:30 -0700 Subject: [PATCH] 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 Reviewed-by: Hannes Reinecke Cc: [hch: added a better comment explaining the issue] Signed-off-by: Christoph Hellwig --- 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 7e8a64251681..2b8595b7ad45 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -33,6 +33,7 @@ #include #include #include +#include #include #include #include @@ -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,