Hannes,
On 03/01/2017 06:15 AM, Hannes Reinecke wrote:
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index f2cafae..cec439c 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -58,6 +58,7 @@
static int scsi_eh_try_stu(struct scsi_cmnd *scmd);
static int scsi_try_to_abort_cmd(struct scsi_host_template *,
struct scsi_cmnd *);
+static int scsi_eh_reset(struct scsi_cmnd *scmd);
/* called with shost->host_lock held */
void scsi_eh_wakeup(struct Scsi_Host *shost)
@@ -249,6 +250,7 @@ int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED)
eh_flag &= ~SCSI_EH_CANCEL_CMD;
scmd->eh_eflags |= eh_flag;
+ scsi_eh_reset(scmd);
list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
shost->host_failed++;
scsi_eh_wakeup(shost);
@@ -1107,7 +1109,19 @@ static int scsi_eh_action(struct scsi_cmnd *scmd, int rtn)
if (!blk_rq_is_passthrough(scmd->request)) {
struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
if (sdrv->eh_action)
- rtn = sdrv->eh_action(scmd, rtn);
+ rtn = sdrv->eh_action(scmd, rtn, false);
+ }
+ return rtn;
+}
+
+static int scsi_eh_reset(struct scsi_cmnd *scmd)
+{
+ int rtn = SUCCESS;
+
+ if (!blk_rq_is_passthrough(scmd->request)) {
+ struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
+ if (sdrv->eh_action)
+ rtn = sdrv->eh_action(scmd, rtn, true);
}
return rtn;
}
Apparently we can de-duplicate code in scsi_eh_reset()/scsi_eh_action(),
and change less of sd_eh_action() (i.e., no new parameter).
Something like this. Thoughts?
- Deduplicate code in scsi_eh_reset() and scsi_eh_action()
- A call to scsi_eh_reset() with reset == false calls into eh_action()
- A call to scsi_eh_reset() with reset == true returns early,
(as happens with/if sd_eh_action() is called in your patch)
- A call to scsi_eh_reset() in scsi_eh_scmd_add() uses SUCCESS just
for consistency with scsi_eh_reset() in your patch, as the return
value is ignored in it.
- Less changes to sd_eh_action()
- Removed one chunk in sd_eh_action() ('reset gate variable')
- No more parameter changes in sd_eh_action() (no 'reset' parameter)
- Removed forward declaration of scsi_eh_reset(), as already suggested
static int scsi_eh_reset(struct scsi_cmnd *scmd, int eh_disp, bool reset)
{
int rtn = eh_disp;
if (!blk_rq_is_passthrough(scmd->request)) {
struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
if (sdrv->eh_action) {
if (reset) {
struct scsi_disk *sdkp = scsi_disk(scmd->request->rq_disk);
/* New SCSI EH run, reset gate variable */
sdkp->medium_access_reset = 0;
return rtn;
}
rtn = sdrv->eh_action(scmd, rtn);
}
}
return rtn;
}
Plus,
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index f2cafae..cec439c 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -249,6 +250,7 @@ int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int
eh_flag)
if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED)
eh_flag &= ~SCSI_EH_CANCEL_CMD;
scmd->eh_eflags |= eh_flag;
+ scsi_eh_reset(scmd, SUCCESS, true); // return value is ignored (early
exit due to reset)
list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
shost->host_failed++;
scsi_eh_wakeup(shost);
@@ -1107,7 +1109,19 @@ static int scsi_eh_action(struct scsi_cmnd *scmd,
int rtn)
- if (!blk_rq_is_passthrough(scmd->request)) {
- struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
- if (sdrv->eh_action)
- rtn = sdrv->eh_action(scmd, rtn);
- }
- return rtn;
+ return scsi_eh_reset(scmd, rtn, false);
}
And the rest, without the 'reset' parameter.
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index c7839f6..c794686 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1689,X +1689,Y @@ static int sd_pr_clear(struct block_device *bdev,
u64 key)
* sd_eh_action - error handling callback
* @scmd: sd-issued command that has failed
* @eh_disp: The recovery disposition suggested by the midlayer
*
* This function is called by the SCSI midlayer upon completion of an
* error test command (currently TEST UNIT READY). The result of sending
* the eh command is passed in eh_disp. We're looking for devices that
* fail medium access commands but are OK with non access commands like
* test unit ready (so wrongly see the device as having a successful
- * recovery)
+ * recovery).
+ * We have to be careful to count a medium access failure only once
+ * per SCSI EH run; there might be several timed out commands which
+ * will cause the 'max_medium_access_timeouts' counter to trigger
+ * after the first SCSI EH run already and set the device to offline.
**/
@@ -1714,7 +1724,10 @@ static int sd_eh_action(struct scsi_cmnd *scmd,
int eh_disp)
* process of recovering or has it suffered an internal failure
* that prevents access to the storage medium.
*/
- sdkp->medium_access_timed_out++;
+ if (!sdkp->medium_access_reset) {
+ sdkp->medium_access_timed_out++;
+ sdkp->medium_access_reset = 1;
+ }
/*
* If the device keeps failing read/write commands but TEST UNIT
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 4dac35e..6a4f75a 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -106,6 +106,7 @@ struct scsi_disk {
unsigned rc_basis: 2;
unsigned zoned: 2;
unsigned urswrz : 1;
+ unsigned medium_access_reset : 1;
};
#define to_scsi_disk(obj) container_of(obj,struct scsi_disk,dev)
--
Mauricio Faria de Oliveira
IBM Linux Technology Center
