> -----Original Message----- > From: James Bottomley [mailto:jbottom...@parallels.com] > Sent: Friday, October 04, 2013 3:31 PM > To: KY Srinivasan > Cc: gre...@linuxfoundation.org; linux-ker...@vger.kernel.org; > de...@linuxdriverproject.org; oher...@suse.com; h...@infradead.org; > e...@purestorage.com; n...@linux-iscsi.org; linux-scsi@vger.kernel.org > Subject: Re: [PATCH 1/1] Drivers: scsi: Derive the FLUSH_TIMEOUT from the > basic > I/O timeout > > On Fri, 2013-10-04 at 22:01 +0000, KY Srinivasan wrote: > > > > > -----Original Message----- > > > From: James Bottomley [mailto:jbottom...@parallels.com] > > > Sent: Friday, October 04, 2013 2:42 PM > > > To: KY Srinivasan > > > Cc: gre...@linuxfoundation.org; linux-ker...@vger.kernel.org; > > > de...@linuxdriverproject.org; oher...@suse.com; h...@infradead.org; > > > e...@purestorage.com; n...@linux-iscsi.org; linux-scsi@vger.kernel.org > > > Subject: Re: [PATCH 1/1] Drivers: scsi: Derive the FLUSH_TIMEOUT from the > basic > > > I/O timeout > > > > > > 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) > > > > > > /* > > > > Thanks James. Given that you have already made the changes you want done > (in the > > Patch above), do you still want me to send you a fixed up patch? > > Either way is fine. I just need the patch to be on the mailing list for > my workflow (which it is now).
In that case, we will go with the patch you have. Thank you for taking the time on this. Regards, K. Y > > James > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
