On Fri, 2013-10-04 at 12:38 -0700, K. Y. Srinivasan wrote:
> Rather than having a separate constant for specifying the timeout on FLUSH
> operations, use the basic I/O timeout value that is already configurable
> on a per target basis to derive the FLUSH timeout. Looking at the current
> definitions of these timeout values, the FLUSH operation is supposed to have
> a value that is twice the normal timeout value. This patch preserves this
> relationship while leveraging the flexibility of specifying the I/O timeout.
>
> I would like to thank Eric Seppanen <e...@purestorage.com> and
> Nicholas A. Bellinger <n...@linux-iscsi.org> for their help in resolving
> this issue.
>
> Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
> ---
> drivers/scsi/sd.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index e62d17d..8aff306 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -829,7 +829,7 @@ static int sd_setup_write_same_cmnd(struct scsi_device
> *sdp, struct request *rq)
>
> static int scsi_setup_flush_cmnd(struct scsi_device *sdp, struct request *rq)
> {
> - rq->timeout = SD_FLUSH_TIMEOUT;
> + rq->timeout *= 2;
> rq->retries = SD_MAX_RETRIES;
> rq->cmd[0] = SYNCHRONIZE_CACHE;
> rq->cmd_len = 10;
> @@ -1433,6 +1433,7 @@ static int sd_sync_cache(struct scsi_disk *sdkp)
> {
> int retries, res;
> struct scsi_device *sdp = sdkp->device;
> + unsigned int timeout = sdp->request_queue->rq_timeout;
The timeout is signed in the function prototype
> struct scsi_sense_hdr sshdr;
>
> if (!scsi_device_online(sdp))
> @@ -1448,7 +1449,7 @@ static int sd_sync_cache(struct scsi_disk *sdkp)
> * flush everything.
> */
> res = scsi_execute_req_flags(sdp, cmd, DMA_NONE, NULL, 0,
> - &sshdr, SD_FLUSH_TIMEOUT,
> + &sshdr, timeout * 2,
> SD_MAX_RETRIES, NULL, REQ_PM);
> if (res == 0)
> break;
Not like this, please: you now leave us with a dangling #define whose
name makes you think it should be related to flushing and a couple of
curious magic constants. It's almost hand crafted to confuse people
reading the code.
Please do it like this instead: with a comment explaining what we're
doing above the #define and a name that clearly relates to the actions.
James
---
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index e62d17d..5c9496d 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -829,7 +829,7 @@ static int sd_setup_write_same_cmnd(struct scsi_device
*sdp, struct request *rq)
static int scsi_setup_flush_cmnd(struct scsi_device *sdp, struct request *rq)
{
- rq->timeout = SD_FLUSH_TIMEOUT;
+ rq->timeout *= SD_FLUSH_TIMEOUT_MULTIPLIER;
rq->retries = SD_MAX_RETRIES;
rq->cmd[0] = SYNCHRONIZE_CACHE;
rq->cmd_len = 10;
@@ -1433,6 +1433,8 @@ static int sd_sync_cache(struct scsi_disk *sdkp)
{
int retries, res;
struct scsi_device *sdp = sdkp->device;
+ const int timeout = sdp->request_queue->rq_timeout
+ * SD_FLUSH_TIMEOUT_MULTIPLIER;
struct scsi_sense_hdr sshdr;
if (!scsi_device_online(sdp))
@@ -1448,8 +1450,8 @@ static int sd_sync_cache(struct scsi_disk *sdkp)
* flush everything.
*/
res = scsi_execute_req_flags(sdp, cmd, DMA_NONE, NULL, 0,
- &sshdr, SD_FLUSH_TIMEOUT,
- SD_MAX_RETRIES, NULL, REQ_PM);
+ &sshdr, timeout, SD_MAX_RETRIES,
+ NULL, REQ_PM);
if (res == 0)
break;
}
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 7a049de..7f7999c 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -13,7 +13,11 @@
*/
#define SD_TIMEOUT (30 * HZ)
#define SD_MOD_TIMEOUT (75 * HZ)
-#define SD_FLUSH_TIMEOUT (60 * HZ)
+/*
+ * Flush timeout is a multiplier over the standard device timeout which is
+ * user modifiable via sysfs but initially set to SD_TIMEOUT
+ */
+#define SD_FLUSH_TIMEOUT_MULTIPLIER 2
#define SD_WRITE_SAME_TIMEOUT (120 * HZ)
/*
--
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