[SCSI] hpsa: allow user to disable accelerated i/o path

Allow SSD Smart Path for a controller to be disabled by
the user, regardless of settings in controller firmware
or array configuration.

To disable:     echo 0 > /sys/class/scsi_host/host<id>/acciopath_status
To re-enable:   echo 1 > /sys/class/scsi_host/host<id>/acciopath_status
To check state: cat /sys/class/scsi_host/host<id>/acciopath_status

Signed-off-by: Scott Teel <scott.teel@hp.com>
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

diff --git a/Documentation/ABI/testing/sysfs-class-scsi_host b/Documentation/ABI/testing/sysfs-class-scsi_host
index 29a4f892e433c42810d2e510eb15b71303d1ad7f..0eb255e7db123c84ebcd08d04f2cd867ee6bffa0 100644 (file)
--- a/Documentation/ABI/testing/sysfs-class-scsi_host
+++ b/Documentation/ABI/testing/sysfs-class-scsi_host
@@ -11,3 +11,19 @@ Description:
                guaranteed.  The 'isci_id' attribute unambiguously identifies
                the controller index: '0' for the first controller,
                '1' for the second.
+
+What:          /sys/class/scsi_host/hostX/acciopath_status
+Date:          November 2013
+Contact:       Stephen M. Cameron <scameron@beardog.cce.hp.com>
+Description:   This file contains the current status of the "SSD Smart Path"
+               feature of HP Smart Array RAID controllers using the hpsa
+               driver.  SSD Smart Path, when enabled permits the driver to
+               send i/o requests directly to physical devices that are part
+               of a logical drive, bypassing the controllers firmware RAID
+               stack for a performance advantage when possible.  A value of
+               '1' indicates the feature is enabled, and the controller may
+               use the direct i/o path to physical devices.  A value of zero
+               means the feature is disabled and the controller may not use
+               the direct i/o path to physical devices.  This setting is
+               controller wide, affecting all configured logical drives on the
+               controller.  This file is readable and writable.

diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index 7cd28714d8dd5d625d809d3cf3ae381f3132b2ac..a599a7b51a921cfcabca6e9c6c1141ea051ec086 100644 (file)
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -287,6 +287,30 @@ static int check_for_busy(struct ctlr_info *h, struct CommandList *c)
        return 1;
 }
 
+static ssize_t host_store_hp_ssd_smart_path_status(struct device *dev,
+                                        struct device_attribute *attr,
+                                        const char *buf, size_t count)
+{
+       int status, len;
+       struct ctlr_info *h;
+       struct Scsi_Host *shost = class_to_shost(dev);
+       char tmpbuf[10];
+
+       if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
+               return -EACCES;
+       len = count > sizeof(tmpbuf) - 1 ? sizeof(tmpbuf) - 1 : count;
+       strncpy(tmpbuf, buf, len);
+       tmpbuf[len] = '\0';
+       if (sscanf(tmpbuf, "%d", &status) != 1)
+               return -EINVAL;
+       h = shost_to_hba(shost);
+       h->acciopath_status = !!status;
+       dev_warn(&h->pdev->dev,
+               "hpsa: HP SSD Smart Path %s via sysfs update.\n",
+               h->acciopath_status ? "enabled" : "disabled");
+       return count;
+}
+
 static ssize_t host_store_rescan(struct device *dev,
                                 struct device_attribute *attr,
                                 const char *buf, size_t count)
@@ -334,6 +358,17 @@ static ssize_t host_show_transport_mode(struct device *dev,
                        "performant" : "simple");
 }
 
+static ssize_t host_show_hp_ssd_smart_path_status(struct device *dev,
+       struct device_attribute *attr, char *buf)
+{
+       struct ctlr_info *h;
+       struct Scsi_Host *shost = class_to_shost(dev);
+
+       h = shost_to_hba(shost);
+       return snprintf(buf, 30, "HP SSD Smart Path %s\n",
+               (h->acciopath_status == 1) ?  "enabled" : "disabled");
+}
+
 /* List of controllers which cannot be hard reset on kexec with reset_devices */
 static u32 unresettable_controller[] = {
        0x324a103C, /* Smart Array P712m */
@@ -546,6 +581,9 @@ static DEVICE_ATTR(unique_id, S_IRUGO, unique_id_show, NULL);
 static DEVICE_ATTR(rescan, S_IWUSR, NULL, host_store_rescan);
 static DEVICE_ATTR(hp_ssd_smart_path_enabled, S_IRUGO,
                        host_show_hp_ssd_smart_path_enabled, NULL);
+static DEVICE_ATTR(hp_ssd_smart_path_status, S_IWUSR|S_IRUGO|S_IROTH,
+               host_show_hp_ssd_smart_path_status,
+               host_store_hp_ssd_smart_path_status);
 static DEVICE_ATTR(firmware_revision, S_IRUGO,
        host_show_firmware_revision, NULL);
 static DEVICE_ATTR(commands_outstanding, S_IRUGO,
@@ -569,6 +607,7 @@ static struct device_attribute *hpsa_shost_attrs[] = {
        &dev_attr_commands_outstanding,
        &dev_attr_transport_mode,
        &dev_attr_resettable,
+       &dev_attr_hp_ssd_smart_path_status,
        NULL,
 };
 
@@ -3341,7 +3380,8 @@ static int hpsa_scsi_queue_command_lck(struct scsi_cmnd *cmd,
         * Retries always go down the normal I/O path.
         */
        if (likely(cmd->retries == 0 &&
-               cmd->request->cmd_type == REQ_TYPE_FS)) {
+               cmd->request->cmd_type == REQ_TYPE_FS &&
+               h->acciopath_status)) {
                if (dev->offload_enabled) {
                        rc = hpsa_scsi_ioaccel_raid_map(h, c);
                        if (rc == 0)
@@ -6326,6 +6366,9 @@ reinit_after_soft_reset:
                goto reinit_after_soft_reset;
        }
 
+       /* Enable Accelerated IO path at driver layer */
+       h->acciopath_status = 1;
+
        /* Turn the interrupts on so we can service requests */
        h->access.set_intr_mask(h, HPSA_INTR_ON);
 

diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
index 45bb1ea6835e85c5298c45ad057dbb307bd85bc9..1d3340dbe31081f5c41e1efbcabf4377a041375c 100644 (file)
--- a/drivers/scsi/hpsa.h
+++ b/drivers/scsi/hpsa.h
@@ -181,6 +181,7 @@ struct ctlr_info {
 #define HPSATMF_LOG_QRY_TSET    (1 << 24)
 #define HPSATMF_LOG_QRY_ASYNC   (1 << 25)
        u32 events;
+       int     acciopath_status;
 };
 #define HPSA_ABORT_MSG 0
 #define HPSA_DEVICE_RESET_MSG 1