scsi: scsi_error: count medium access timeout only once per EH run

The current medium access timeout counter will be increased for
each command, so if there are enough failed commands we'll hit
the medium access timeout for even a single device failure and
the following kernel message is displayed:

sd H:C:T:L: [sdXY] Medium access timeout failure. Offlining disk!

Fix this by making the timeout per EH run, ie the counter will
only be increased once per device and EH run.

Fixes: 18a4d0a ("[SCSI] Handle disk devices which can not process medium access commands")
Cc: Ewan Milne <emilne@redhat.com>
Cc: Lawrence Obermann <loberman@redhat.com>
Cc: Benjamin Block <bblock@linux.vnet.ibm.com>
Cc: Steffen Maier <maier@linux.vnet.ibm.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index f2cafae150bcdb85292d86945cfb9d6e9fd7c340..370f6c045b60e32f6c20dae425dadd9b669789f8 100644 (file)
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -220,6 +220,23 @@ scsi_abort_command(struct scsi_cmnd *scmd)
        return SUCCESS;
 }
 
+/**
+ * scsi_eh_reset - call into ->eh_action to reset internal counters
+ * @scmd:      scmd to run eh on.
+ *
+ * The scsi driver might be carrying internal state about the
+ * devices, so we need to call into the driver to reset the
+ * internal state once the error handler is started.
+ */
+static void scsi_eh_reset(struct scsi_cmnd *scmd)
+{
+       if (!blk_rq_is_passthrough(scmd->request)) {
+               struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
+               if (sdrv->eh_reset)
+                       sdrv->eh_reset(scmd);
+       }
+}
+
 /**
  * scsi_eh_scmd_add - add scsi cmd to error handling.
  * @scmd:      scmd to run eh on.
@@ -249,6 +266,7 @@ 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);

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d277e8620e3e39794584ac29dc55cc3ce476a03a..bd2a38ef46f51211ca237e7517652a74cf2ad686 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -115,6 +115,7 @@ static void sd_rescan(struct device *);
 static int sd_init_command(struct scsi_cmnd *SCpnt);
 static void sd_uninit_command(struct scsi_cmnd *SCpnt);
 static int sd_done(struct scsi_cmnd *);
+static void sd_eh_reset(struct scsi_cmnd *);
 static int sd_eh_action(struct scsi_cmnd *, int);
 static void sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer);
 static void scsi_disk_release(struct device *cdev);
@@ -532,6 +533,7 @@ static struct scsi_driver sd_template = {
        .uninit_command         = sd_uninit_command,
        .done                   = sd_done,
        .eh_action              = sd_eh_action,
+       .eh_reset               = sd_eh_reset,
 };
 
 /*
@@ -1685,6 +1687,26 @@ static const struct block_device_operations sd_fops = {
        .pr_ops                 = &sd_pr_ops,
 };
 
+/**
+ *     sd_eh_reset - reset error handling callback
+ *     @scmd:          sd-issued command that has failed
+ *
+ *     This function is called by the SCSI midlayer before starting
+ *     SCSI EH. When counting medium access failures we have to be
+ *     careful to register it only only once per device and 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.
+ *     So this function resets the internal counter before starting SCSI EH.
+ **/
+static void sd_eh_reset(struct scsi_cmnd *scmd)
+{
+       struct scsi_disk *sdkp = scsi_disk(scmd->request->rq_disk);
+
+       /* New SCSI EH run, reset gate variable */
+       sdkp->ignore_medium_access_errors = false;
+}
+
 /**
  *     sd_eh_action - error handling callback
  *     @scmd:          sd-issued command that has failed
@@ -1714,7 +1736,10 @@ 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->ignore_medium_access_errors) {
+               sdkp->medium_access_timed_out++;
+               sdkp->ignore_medium_access_errors = true;
+       }
 
        /*
         * If the device keeps failing read/write commands but TEST UNIT

diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 4dac35e96a75baf833acbfe017c3edef8f8f23b8..0cf9680cb4698f3541adc39446d8a091d576e525 100644 (file)
--- 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        ignore_medium_access_errors : 1;
 };
 #define to_scsi_disk(obj) container_of(obj,struct scsi_disk,dev)
 

diff --git a/include/scsi/scsi_driver.h b/include/scsi/scsi_driver.h
index 891a658aa8673d03b5ad8ac848f3318662d39707..a5534ccad859d29069bff2b240ccfca4dd0c9567 100644 (file)
--- a/include/scsi/scsi_driver.h
+++ b/include/scsi/scsi_driver.h
@@ -16,6 +16,7 @@ struct scsi_driver {
        void (*uninit_command)(struct scsi_cmnd *);
        int (*done)(struct scsi_cmnd *);
        int (*eh_action)(struct scsi_cmnd *, int);
+       void (*eh_reset)(struct scsi_cmnd *);
 };
 #define to_scsi_driver(drv) \
        container_of((drv), struct scsi_driver, gendrv)