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alistair23-linux/drivers/scsi/device_handler/scsi_dh_alua.c

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/*
* Generic SCSI-3 ALUA SCSI Device Handler
*
* Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <asm/unaligned.h>
#include <scsi/scsi.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_dh.h>
#define ALUA_DH_NAME "alua"
#define ALUA_DH_VER "1.3"
#define TPGS_STATE_OPTIMIZED 0x0
#define TPGS_STATE_NONOPTIMIZED 0x1
#define TPGS_STATE_STANDBY 0x2
#define TPGS_STATE_UNAVAILABLE 0x3
#define TPGS_STATE_LBA_DEPENDENT 0x4
#define TPGS_STATE_OFFLINE 0xe
#define TPGS_STATE_TRANSITIONING 0xf
#define TPGS_SUPPORT_NONE 0x00
#define TPGS_SUPPORT_OPTIMIZED 0x01
#define TPGS_SUPPORT_NONOPTIMIZED 0x02
#define TPGS_SUPPORT_STANDBY 0x04
#define TPGS_SUPPORT_UNAVAILABLE 0x08
#define TPGS_SUPPORT_LBA_DEPENDENT 0x10
#define TPGS_SUPPORT_OFFLINE 0x40
#define TPGS_SUPPORT_TRANSITION 0x80
#define RTPG_FMT_MASK 0x70
#define RTPG_FMT_EXT_HDR 0x10
#define TPGS_MODE_UNINITIALIZED -1
#define TPGS_MODE_NONE 0x0
#define TPGS_MODE_IMPLICIT 0x1
#define TPGS_MODE_EXPLICIT 0x2
#define ALUA_RTPG_SIZE 128
#define ALUA_FAILOVER_TIMEOUT 60
#define ALUA_FAILOVER_RETRIES 5
/* device handler flags */
#define ALUA_OPTIMIZE_STPG 1
#define ALUA_RTPG_EXT_HDR_UNSUPP 2
static LIST_HEAD(port_group_list);
static DEFINE_SPINLOCK(port_group_lock);
struct alua_port_group {
struct kref kref;
struct list_head node;
int group_id;
int tpgs;
int state;
int pref;
unsigned flags; /* used for optimizing STPG */
unsigned char transition_tmo;
};
struct alua_dh_data {
struct alua_port_group *pg;
int group_id;
int rel_port;
struct scsi_device *sdev;
activate_complete callback_fn;
void *callback_data;
};
#define ALUA_POLICY_SWITCH_CURRENT 0
#define ALUA_POLICY_SWITCH_ALL 1
static char print_alua_state(int);
static void release_port_group(struct kref *kref)
{
struct alua_port_group *pg;
pg = container_of(kref, struct alua_port_group, kref);
spin_lock(&port_group_lock);
list_del(&pg->node);
spin_unlock(&port_group_lock);
kfree(pg);
}
/*
* submit_rtpg - Issue a REPORT TARGET GROUP STATES command
* @sdev: sdev the command should be sent to
*/
static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff,
int bufflen, struct scsi_sense_hdr *sshdr, int flags)
{
u8 cdb[COMMAND_SIZE(MAINTENANCE_IN)];
int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
REQ_FAILFAST_DRIVER;
/* Prepare the command. */
memset(cdb, 0x0, COMMAND_SIZE(MAINTENANCE_IN));
cdb[0] = MAINTENANCE_IN;
if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP))
cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
else
cdb[1] = MI_REPORT_TARGET_PGS;
put_unaligned_be32(bufflen, &cdb[6]);
return scsi_execute_req_flags(sdev, cdb, DMA_FROM_DEVICE,
buff, bufflen, sshdr,
ALUA_FAILOVER_TIMEOUT * HZ,
ALUA_FAILOVER_RETRIES, NULL, req_flags);
}
/*
* submit_stpg - Issue a SET TARGET PORT GROUP command
*
* Currently we're only setting the current target port group state
* to 'active/optimized' and let the array firmware figure out
* the states of the remaining groups.
*/
static int submit_stpg(struct scsi_device *sdev, int group_id,
struct scsi_sense_hdr *sshdr)
{
u8 cdb[COMMAND_SIZE(MAINTENANCE_OUT)];
unsigned char stpg_data[8];
int stpg_len = 8;
int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
REQ_FAILFAST_DRIVER;
/* Prepare the data buffer */
memset(stpg_data, 0, stpg_len);
stpg_data[4] = TPGS_STATE_OPTIMIZED & 0x0f;
put_unaligned_be16(group_id, &stpg_data[6]);
/* Prepare the command. */
memset(cdb, 0x0, COMMAND_SIZE(MAINTENANCE_OUT));
cdb[0] = MAINTENANCE_OUT;
cdb[1] = MO_SET_TARGET_PGS;
put_unaligned_be32(stpg_len, &cdb[6]);
return scsi_execute_req_flags(sdev, cdb, DMA_TO_DEVICE,
stpg_data, stpg_len,
sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
ALUA_FAILOVER_RETRIES, NULL, req_flags);
}
/*
* alua_alloc_pg - Allocate a new port_group structure
* @sdev: scsi device
* @h: alua device_handler data
* @group_id: port group id
*
* Allocate a new port_group structure for a given
* device.
*/
struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
int group_id, int tpgs)
{
struct alua_port_group *pg;
pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL);
if (!pg)
return NULL;
pg->group_id = group_id;
pg->tpgs = tpgs;
pg->state = TPGS_STATE_OPTIMIZED;
kref_init(&pg->kref);
spin_lock(&port_group_lock);
list_add(&pg->node, &port_group_list);
spin_unlock(&port_group_lock);
return pg;
}
/*
* alua_check_tpgs - Evaluate TPGS setting
* @sdev: device to be checked
*
* Examine the TPGS setting of the sdev to find out if ALUA
* is supported.
*/
static int alua_check_tpgs(struct scsi_device *sdev)
{
int tpgs = TPGS_MODE_NONE;
/*
* ALUA support for non-disk devices is fraught with
* difficulties, so disable it for now.
*/
if (sdev->type != TYPE_DISK) {
sdev_printk(KERN_INFO, sdev,
"%s: disable for non-disk devices\n",
ALUA_DH_NAME);
return tpgs;
}
tpgs = scsi_device_tpgs(sdev);
switch (tpgs) {
case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
sdev_printk(KERN_INFO, sdev,
"%s: supports implicit and explicit TPGS\n",
ALUA_DH_NAME);
break;
case TPGS_MODE_EXPLICIT:
sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
ALUA_DH_NAME);
break;
case TPGS_MODE_IMPLICIT:
sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
ALUA_DH_NAME);
break;
case TPGS_MODE_NONE:
sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
ALUA_DH_NAME);
break;
default:
sdev_printk(KERN_INFO, sdev,
"%s: unsupported TPGS setting %d\n",
ALUA_DH_NAME, tpgs);
tpgs = TPGS_MODE_NONE;
break;
}
return tpgs;
}
/*
* alua_check_vpd - Evaluate INQUIRY vpd page 0x83
* @sdev: device to be checked
*
* Extract the relative target port and the target port group
* descriptor from the list of identificators.
*/
static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h)
{
int rel_port = -1, group_id;
group_id = scsi_vpd_tpg_id(sdev, &rel_port);
if (group_id < 0) {
/*
* Internal error; TPGS supported but required
* VPD identification descriptors not present.
* Disable ALUA support
*/
sdev_printk(KERN_INFO, sdev,
"%s: No target port descriptors found\n",
ALUA_DH_NAME);
return SCSI_DH_DEV_UNSUPP;
}
h->group_id = group_id;
sdev_printk(KERN_INFO, sdev,
"%s: port group %02x rel port %02x\n",
ALUA_DH_NAME, h->group_id, h->rel_port);
return 0;
}
static char print_alua_state(int state)
{
switch (state) {
case TPGS_STATE_OPTIMIZED:
return 'A';
case TPGS_STATE_NONOPTIMIZED:
return 'N';
case TPGS_STATE_STANDBY:
return 'S';
case TPGS_STATE_UNAVAILABLE:
return 'U';
case TPGS_STATE_LBA_DEPENDENT:
return 'L';
case TPGS_STATE_OFFLINE:
return 'O';
case TPGS_STATE_TRANSITIONING:
return 'T';
default:
return 'X';
}
}
static int alua_check_sense(struct scsi_device *sdev,
struct scsi_sense_hdr *sense_hdr)
{
switch (sense_hdr->sense_key) {
case NOT_READY:
if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a)
/*
* LUN Not Accessible - ALUA state transition
*/
return ADD_TO_MLQUEUE;
break;
case UNIT_ATTENTION:
if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
/*
* Power On, Reset, or Bus Device Reset, just retry.
*/
return ADD_TO_MLQUEUE;
if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
/*
* Device internal reset
*/
return ADD_TO_MLQUEUE;
if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
/*
* Mode Parameters Changed
*/
return ADD_TO_MLQUEUE;
if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06)
/*
* ALUA state changed
*/
return ADD_TO_MLQUEUE;
if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07)
/*
* Implicit ALUA state transition failed
*/
return ADD_TO_MLQUEUE;
if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
/*
* Inquiry data has changed
*/
return ADD_TO_MLQUEUE;
if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
/*
* REPORTED_LUNS_DATA_HAS_CHANGED is reported
* when switching controllers on targets like
* Intel Multi-Flex. We can just retry.
*/
return ADD_TO_MLQUEUE;
break;
}
return SCSI_RETURN_NOT_HANDLED;
}
/*
* alua_rtpg - Evaluate REPORT TARGET GROUP STATES
* @sdev: the device to be evaluated.
* @wait_for_transition: if nonzero, wait ALUA_FAILOVER_TIMEOUT seconds for device to exit transitioning state
*
* Evaluate the Target Port Group State.
* Returns SCSI_DH_DEV_OFFLINED if the path is
* found to be unusable.
*/
static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg, int wait_for_transition)
{
struct scsi_sense_hdr sense_hdr;
int len, k, off, valid_states = 0, bufflen = ALUA_RTPG_SIZE;
unsigned char *ucp, *buff;
unsigned err, retval;
unsigned long expiry, interval = 0;
unsigned int tpg_desc_tbl_off;
unsigned char orig_transition_tmo;
if (!pg->transition_tmo)
expiry = round_jiffies_up(jiffies + ALUA_FAILOVER_TIMEOUT * HZ);
else
expiry = round_jiffies_up(jiffies + pg->transition_tmo * HZ);
buff = kzalloc(bufflen, GFP_KERNEL);
if (!buff)
return SCSI_DH_DEV_TEMP_BUSY;
retry:
retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags);
if (retval) {
if (!scsi_sense_valid(&sense_hdr)) {
sdev_printk(KERN_INFO, sdev,
"%s: rtpg failed, result %d\n",
ALUA_DH_NAME, retval);
kfree(buff);
if (driver_byte(retval) == DRIVER_ERROR)
return SCSI_DH_DEV_TEMP_BUSY;
return SCSI_DH_IO;
}
/*
* submit_rtpg() has failed on existing arrays
* when requesting extended header info, and
* the array doesn't support extended headers,
* even though it shouldn't according to T10.
* The retry without rtpg_ext_hdr_req set
* handles this.
*/
if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
sense_hdr.sense_key == ILLEGAL_REQUEST &&
sense_hdr.asc == 0x24 && sense_hdr.ascq == 0) {
pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
goto retry;
}
/*
* Retry on ALUA state transition or if any
* UNIT ATTENTION occurred.
*/
if (sense_hdr.sense_key == NOT_READY &&
sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
err = SCSI_DH_RETRY;
else if (sense_hdr.sense_key == UNIT_ATTENTION)
err = SCSI_DH_RETRY;
if (err == SCSI_DH_RETRY && time_before(jiffies, expiry)) {
sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
ALUA_DH_NAME);
scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
goto retry;
}
sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
ALUA_DH_NAME);
scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
kfree(buff);
return SCSI_DH_IO;
}
len = get_unaligned_be32(&buff[0]) + 4;
if (len > bufflen) {
/* Resubmit with the correct length */
kfree(buff);
bufflen = len;
buff = kmalloc(bufflen, GFP_KERNEL);
if (!buff) {
sdev_printk(KERN_WARNING, sdev,
"%s: kmalloc buffer failed\n",__func__);
/* Temporary failure, bypass */
return SCSI_DH_DEV_TEMP_BUSY;
}
goto retry;
}
orig_transition_tmo = pg->transition_tmo;
if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0)
pg->transition_tmo = buff[5];
else
pg->transition_tmo = ALUA_FAILOVER_TIMEOUT;
if (wait_for_transition &&
(orig_transition_tmo != pg->transition_tmo)) {
sdev_printk(KERN_INFO, sdev,
"%s: transition timeout set to %d seconds\n",
ALUA_DH_NAME, pg->transition_tmo);
expiry = jiffies + pg->transition_tmo * HZ;
}
if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
tpg_desc_tbl_off = 8;
else
tpg_desc_tbl_off = 4;
for (k = tpg_desc_tbl_off, ucp = buff + tpg_desc_tbl_off;
k < len;
k += off, ucp += off) {
if (pg->group_id == get_unaligned_be16(&ucp[2])) {
pg->state = ucp[0] & 0x0f;
pg->pref = ucp[0] >> 7;
valid_states = ucp[1];
}
off = 8 + (ucp[7] * 4);
}
sdev_printk(KERN_INFO, sdev,
"%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
pg->pref ? "preferred" : "non-preferred",
valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
switch (pg->state) {
case TPGS_STATE_TRANSITIONING:
if (wait_for_transition) {
if (time_before(jiffies, expiry)) {
/* State transition, retry */
interval += 2000;
msleep(interval);
goto retry;
}
err = SCSI_DH_RETRY;
} else {
err = SCSI_DH_OK;
}
/* Transitioning time exceeded, set port to standby */
pg->state = TPGS_STATE_STANDBY;
break;
case TPGS_STATE_OFFLINE:
/* Path unusable */
err = SCSI_DH_DEV_OFFLINED;
break;
default:
/* Useable path if active */
err = SCSI_DH_OK;
break;
}
kfree(buff);
return err;
}
/*
* alua_stpg - Issue a SET TARGET PORT GROUP command
*
* Issue a SET TARGET PORT GROUP command and evaluate the
* response. Returns SCSI_DH_RETRY per default to trigger
* a re-evaluation of the target group state or SCSI_DH_OK
* if no further action needs to be taken.
*/
static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
{
int retval;
struct scsi_sense_hdr sense_hdr;
if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
/* Only implicit ALUA supported, retry */
return SCSI_DH_RETRY;
}
switch (pg->state) {
case TPGS_STATE_OPTIMIZED:
return SCSI_DH_OK;
case TPGS_STATE_NONOPTIMIZED:
if ((pg->flags & ALUA_OPTIMIZE_STPG) &&
!pg->pref &&
(pg->tpgs & TPGS_MODE_IMPLICIT))
return SCSI_DH_OK;
break;
case TPGS_STATE_STANDBY:
case TPGS_STATE_UNAVAILABLE:
break;
case TPGS_STATE_OFFLINE:
return SCSI_DH_IO;
case TPGS_STATE_TRANSITIONING:
break;
default:
sdev_printk(KERN_INFO, sdev,
"%s: stpg failed, unhandled TPGS state %d",
ALUA_DH_NAME, pg->state);
return SCSI_DH_NOSYS;
}
retval = submit_stpg(sdev, pg->group_id, &sense_hdr);
if (retval) {
if (!scsi_sense_valid(&sense_hdr)) {
sdev_printk(KERN_INFO, sdev,
"%s: stpg failed, result %d",
ALUA_DH_NAME, retval);
if (driver_byte(retval) == DRIVER_ERROR)
return SCSI_DH_DEV_TEMP_BUSY;
} else {
sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
ALUA_DH_NAME);
scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
}
}
/* Retry RTPG */
return SCSI_DH_RETRY;
}
/*
* alua_initialize - Initialize ALUA state
* @sdev: the device to be initialized
*
* For the prep_fn to work correctly we have
* to initialize the ALUA state for the device.
*/
static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
{
int err = SCSI_DH_DEV_UNSUPP, tpgs;
tpgs = alua_check_tpgs(sdev);
if (tpgs == TPGS_MODE_NONE)
goto out;
err = alua_check_vpd(sdev, h);
if (err != SCSI_DH_OK)
goto out;
h->pg = alua_alloc_pg(sdev, h->group_id, tpgs);
if (!h->pg) {
err = SCSI_DH_NOMEM;
goto out;
}
kref_get(&h->pg->kref);
err = alua_rtpg(sdev, h->pg, 0);
kref_put(&h->pg->kref, release_port_group);
out:
return err;
}
/*
* alua_set_params - set/unset the optimize flag
* @sdev: device on the path to be activated
* params - parameters in the following format
* "no_of_params\0param1\0param2\0param3\0...\0"
* For example, to set the flag pass the following parameters
* from multipath.conf
* hardware_handler "2 alua 1"
*/
static int alua_set_params(struct scsi_device *sdev, const char *params)
{
struct alua_dh_data *h = sdev->handler_data;
struct alua_port_group *pg = NULL;
unsigned int optimize = 0, argc;
const char *p = params;
int result = SCSI_DH_OK;
if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
return -EINVAL;
while (*p++)
;
if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
return -EINVAL;
pg = h->pg;
if (!pg)
return -ENXIO;
if (optimize)
pg->flags |= ALUA_OPTIMIZE_STPG;
else
pg->flags &= ~ALUA_OPTIMIZE_STPG;
return result;
}
static uint optimize_stpg;
module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0.");
/*
* alua_activate - activate a path
* @sdev: device on the path to be activated
*
* We're currently switching the port group to be activated only and
* let the array figure out the rest.
* There may be other arrays which require us to switch all port groups
* based on a certain policy. But until we actually encounter them it
* should be okay.
*/
static int alua_activate(struct scsi_device *sdev,
activate_complete fn, void *data)
{
struct alua_dh_data *h = sdev->handler_data;
int err = SCSI_DH_OK;
if (!h->pg)
goto out;
kref_get(&h->pg->kref);
if (optimize_stpg)
h->pg->flags |= ALUA_OPTIMIZE_STPG;
err = alua_rtpg(sdev, h->pg, 1);
if (err != SCSI_DH_OK) {
kref_put(&h->pg->kref, release_port_group);
goto out;
}
err = alua_stpg(sdev, h->pg);
if (err == SCSI_DH_RETRY)
err = alua_rtpg(sdev, h->pg, 1);
kref_put(&h->pg->kref, release_port_group);
out:
if (fn)
fn(data, err);
return 0;
}
/*
* alua_prep_fn - request callback
*
* Fail I/O to all paths not in state
* active/optimized or active/non-optimized.
*/
static int alua_prep_fn(struct scsi_device *sdev, struct request *req)
{
struct alua_dh_data *h = sdev->handler_data;
int state;
int ret = BLKPREP_OK;
if (!h->pg)
return ret;
kref_get(&h->pg->kref);
state = h->pg->state;
kref_put(&h->pg->kref, release_port_group);
if (state == TPGS_STATE_TRANSITIONING)
ret = BLKPREP_DEFER;
else if (state != TPGS_STATE_OPTIMIZED &&
state != TPGS_STATE_NONOPTIMIZED &&
state != TPGS_STATE_LBA_DEPENDENT) {
ret = BLKPREP_KILL;
req->cmd_flags |= REQ_QUIET;
}
return ret;
}
/*
* alua_bus_attach - Attach device handler
* @sdev: device to be attached to
*/
static int alua_bus_attach(struct scsi_device *sdev)
{
struct alua_dh_data *h;
int err, ret = -EINVAL;
h = kzalloc(sizeof(*h) , GFP_KERNEL);
if (!h)
return -ENOMEM;
h->pg = NULL;
h->rel_port = -1;
h->sdev = sdev;
err = alua_initialize(sdev, h);
if (err == SCSI_DH_NOMEM)
ret = -ENOMEM;
if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
goto failed;
sdev->handler_data = h;
return 0;
failed:
kfree(h);
return ret;
}
/*
* alua_bus_detach - Detach device handler
* @sdev: device to be detached from
*/
static void alua_bus_detach(struct scsi_device *sdev)
{
struct alua_dh_data *h = sdev->handler_data;
if (h->pg) {
kref_put(&h->pg->kref, release_port_group);
h->pg = NULL;
}
sdev->handler_data = NULL;
kfree(h);
}
static struct scsi_device_handler alua_dh = {
.name = ALUA_DH_NAME,
.module = THIS_MODULE,
.attach = alua_bus_attach,
.detach = alua_bus_detach,
.prep_fn = alua_prep_fn,
.check_sense = alua_check_sense,
.activate = alua_activate,
.set_params = alua_set_params,
};
static int __init alua_init(void)
{
int r;
r = scsi_register_device_handler(&alua_dh);
if (r != 0)
printk(KERN_ERR "%s: Failed to register scsi device handler",
ALUA_DH_NAME);
return r;
}
static void __exit alua_exit(void)
{
scsi_unregister_device_handler(&alua_dh);
}
module_init(alua_init);
module_exit(alua_exit);
MODULE_DESCRIPTION("DM Multipath ALUA support");
MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
MODULE_LICENSE("GPL");
MODULE_VERSION(ALUA_DH_VER);
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