[PATCH 29/41] hpsa: allow user to disable accelerated i/o path

Stephen M. Cameron
2014-01-15T21:38:50Z

From: Scott Teel <scott.teel@hp.com>

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>
Acked-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
---
Documentation/ABI/testing/sysfs-class-scsi_host | 16 ++++++++
drivers/scsi/hpsa.c | 45 ++++++++++++++++++++++-
drivers/scsi/hpsa.h | 1 +
3 files changed, 61 insertions(+), 1 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-class-scsi_host b/Documentation/ABI/testing/sysfs-class-scsi_host
index 29a4f89..0eb255e 100644
--- 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 0109bf7..8e357f0 100644
--- 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,
};

@@ -3347,7 +3386,8 @@ 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)
@@ -6333,6 +6373,9 @@ 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 45bb1ea..1d3340d 100644
--- 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