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Re: [dm-devel] [PATCH] Add ALUA hardware handler



Reviewed the code, and did not find any generic issues (other than what
Mike Christie has stated).


On Wed, 2007-10-10 at 14:55 +0200, Hannes Reinecke wrote:
> Hi Alasdair,
> 
> this is a patch to add a SPC-3 hardware handler. SPC-3 ALUA has
> provisioning for 'explicit' port group state change via the
> SET TARGET GROUP STATES command, and some newer storage
> arrays do benefit from this.
> Eg HP EVAs and newer EMC Clariions already support explicit ALUA.
> 
> Please apply.
> 
> Cheers,
> 
> Hannes
> plain text document attachment (dm-mpath-alua-support)
> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
> index 531d4d1..3fa9df3 100644
> --- a/drivers/md/Kconfig
> +++ b/drivers/md/Kconfig
> @@ -267,6 +267,13 @@ config DM_MULTIPATH_RDAC
>  	---help---
>  	  Multipath support for LSI/Engenio RDAC.
> 
> +config DM_MULTIPATH_ALUA
> +	tristate "SPC-3 ALUA multipath support (EXPERIMENTAL)"
> +	depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
> +	---help---
> +	  Multipath support for SPC-3 Asymmetric Logical Unit
> +	  Access (ALUA).
> +
>  config DM_DELAY
>  	tristate "I/O delaying target (EXPERIMENTAL)"
>  	depends on BLK_DEV_DM && EXPERIMENTAL
> diff --git a/drivers/md/Makefile b/drivers/md/Makefile
> index c49366c..5013920 100644
> --- a/drivers/md/Makefile
> +++ b/drivers/md/Makefile
> @@ -8,6 +8,7 @@ dm-multipath-objs := dm-hw-handler.o dm-path-selector.o dm-mpath.o
>  dm-snapshot-objs := dm-snap.o dm-exception-store.o
>  dm-mirror-objs	:= dm-log.o dm-raid1.o
>  dm-rdac-objs	:= dm-mpath-rdac.o
> +dm-alua-objs	:= dm-mpath-alua.o
>  md-mod-objs     := md.o bitmap.o
>  raid456-objs	:= raid5.o raid6algos.o raid6recov.o raid6tables.o \
>  		   raid6int1.o raid6int2.o raid6int4.o \
> @@ -36,6 +37,7 @@ obj-$(CONFIG_DM_DELAY)		+= dm-delay.o
>  obj-$(CONFIG_DM_MULTIPATH)	+= dm-multipath.o dm-round-robin.o
>  obj-$(CONFIG_DM_MULTIPATH_EMC)	+= dm-emc.o
>  obj-$(CONFIG_DM_MULTIPATH_RDAC)	+= dm-rdac.o
> +obj-$(CONFIG_DM_MULTIPATH_ALUA)	+= dm-alua.o
>  obj-$(CONFIG_DM_SNAPSHOT)	+= dm-snapshot.o
>  obj-$(CONFIG_DM_MIRROR)		+= dm-mirror.o
>  obj-$(CONFIG_DM_ZERO)		+= dm-zero.o
> diff --git a/drivers/md/dm-mpath-alua.c b/drivers/md/dm-mpath-alua.c
> new file mode 100644
> index 0000000..40b9d4d
> --- /dev/null
> +++ b/drivers/md/dm-mpath-alua.c
> @@ -0,0 +1,662 @@
> +/*
> + * Generic SCSI-3 ALUA DM HW handler
> + *
> + * Copyright (C) 2007 Hannes Reinecke. 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 <scsi/scsi.h>
> +#include <scsi/scsi_cmnd.h>
> +#include <scsi/scsi_eh.h>
> +
> +#define DM_MSG_PREFIX "multipath alua"
> +
> +#include "dm.h"
> +#include "dm-hw-handler.h"
> +
> +#define ALUA_DM_HWH_NAME "alua"
> +#define ALUA_DM_HWH_VER "0.2"
> +
> +enum tpgs_state {
> +	TPGS_STATE_UNKNOWN = -1,
> +	TPGS_STATE_OPTIMIZED = 0x0,
> +	TPGS_STATE_NONOPTIMIZED,
> +	TPGS_STATE_STANDBY,
> +	TPGS_STATE_UNAVAILABLE,
> +	TPGS_STATE_OFFLINE = 0xe,
> +	TPGS_STATE_TRANSITIONING,
> +};
> +
> +#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_OFFLINE		0x40
> +#define TPGS_SUPPORT_TRANSITION		0x80
> +
> +#define TPGS_MODE_UNINITIALIZED	-1
> +#define TPGS_MODE_NONE		0x0
> +#define TPGS_MODE_IMPLICIT	0x1
> +#define TPGS_MODE_EXPLICIT	0x2
> +
> +#define TPGS_INQUIRY_SIZE	36
> +#define TPGS_FAILOVER_TIMEOUT	(60 * HZ)
> +
> +struct alua_handler {
> +	struct dm_path		*path;
> +	int			debug;
> +	int			group_id;
> +	int			rel_port;
> +	int			tpgs;
> +	enum tpgs_state		state;
> +	unsigned char		inq[TPGS_INQUIRY_SIZE];
> +	unsigned char		*buff;
> +	int			bufflen;
> +	unsigned char		sense[SCSI_SENSE_BUFFERSIZE];
> +};
> +
> +#define ALUA_POLICY_SWITCH_CURRENT	0
> +#define ALUA_POLICY_SWITCH_ALL		1
> +
> +#define DPRINT(h, f, arg...) \
> +	if (h->debug) DMINFO("%s: " f, h->path->dev->name, arg)
> +
> +static inline int had_failures(int error)
> +{
> +	return (host_byte(error) != DID_OK ||
> +		msg_byte(error) != COMMAND_COMPLETE);
> +}
> +
> +static int realloc_buffer(struct alua_handler *h, unsigned len)
> +{
> +	if (h->buff && h->buff != h->inq)
> +		kfree(h->buff);
> +
> +	h->buff = kmalloc(len, GFP_ATOMIC);
> +	if (!h->buff) {
> +		DMINFO("%s: kmalloc buffer failed",__FUNCTION__);
> +		h->buff = h->inq;
> +		h->bufflen = TPGS_INQUIRY_SIZE;
> +		return 1;
> +	}
> +	h->bufflen = len;
> +	return 0;
> +}
> +
> +static struct request *prepare_req(struct alua_handler *h,
> +				   void *buffer, unsigned buflen, int rw)
> +{
> +	struct request *rq;
> +	struct request_queue *q = bdev_get_queue(h->path->dev->bdev);
> +
> +	if (!q) {
> +		DMWARN("%s: no queue", __FUNCTION__);
> +		return NULL;
> +	}
> +
> +	rq = blk_get_request(q, rw, GFP_KERNEL);
> +
> +	if (!rq) {
> +		DMINFO("%s: blk_get_request failed", __FUNCTION__);
> +		return NULL;
> +	}
> +
> +	if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_KERNEL)) {
> +		blk_put_request(rq);
> +		DMINFO("%s: blk_rq_map_kern failed", __FUNCTION__);
> +		return NULL;
> +	}
> +
> +	memset(&rq->cmd, 0, BLK_MAX_CDB);
> +	rq->sense = h->sense;
> +	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
> +	rq->sense_len = 0;
> +
> +	rq->timeout = TPGS_FAILOVER_TIMEOUT;
> +	rq->cmd_type = REQ_TYPE_BLOCK_PC;
> +	rq->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
> +	rq->end_io_data = h;
> +
> +	return rq;
> +}
> +
> +/*
> + * Issue a standard INQUIRY command
> + */
> +static int submit_std_inquiry(struct alua_handler *h)
> +{
> +	struct request *rq;
> +	unsigned err = (DRIVER_ERROR << 24);
> +
> +	rq = prepare_req(h, h->inq, TPGS_INQUIRY_SIZE, READ);
> +	if (!rq)
> +		return err;
> +
> +	/* Prepare the command. */
> +	rq->cmd[0] = INQUIRY;
> +	rq->cmd[1] = 0;
> +	rq->cmd[2] = 0;
> +	rq->cmd[4] = TPGS_INQUIRY_SIZE;
> +	rq->cmd_len = COMMAND_SIZE(INQUIRY);
> +
> +	blk_execute_rq(rq->q, NULL, rq, 1);
> +	err = rq->errors;
> +	blk_put_request(rq);
> +
> +	return err;
> +}
> +
> +/*
> + * Issue an INQUIRY VPD page 0x83 command
> + */
> +static int submit_vpd_inquiry(struct alua_handler *h)
> +{
> +	struct request *rq;
> +	unsigned err = (DRIVER_ERROR << 24);
> +
> +	rq = prepare_req(h, h->buff, h->bufflen, READ);
> +	if (!rq) {
> +		DMWARN("failed to send INQUIRY VPD page 0x83");
> +		return err;
> +	}
> +
> +	/* Prepare the command. */
> +	rq->cmd[0] = INQUIRY;
> +	rq->cmd[1] = 1;
> +	rq->cmd[2] = 0x83;
> +	rq->cmd[4] = h->bufflen;
> +	rq->cmd_len = COMMAND_SIZE(INQUIRY);
> +
> +	DPRINT(h, "submit INQUIRY VPD page 0x83 len %d", h->bufflen);
> +	blk_execute_rq(rq->q, NULL, rq, 1);
> +	err = rq->errors;
> +	blk_put_request(rq);
> +
> +	return err;
> +}
> +
> +/*
> + * Issue a REPORT TARGET GROUP STATES command.
> + */
> +static unsigned submit_rtpg(struct alua_handler *h)
> +{
> +	struct request *rq;
> +	unsigned err = (DRIVER_ERROR << 24);
> +
> +	rq = prepare_req(h, h->buff, h->bufflen, READ);
> +	if (!rq)
> +		return err;
> +
> +	/* Prepare the command. */
> +	rq->cmd[0] = MAINTENANCE_IN;
> +	rq->cmd[1] = MI_REPORT_TARGET_PGS;
> +	rq->cmd[6] = (h->bufflen >> 24) & 0xff;
> +	rq->cmd[7] = (h->bufflen >> 16) & 0xff;
> +	rq->cmd[8] = (h->bufflen >>  8) & 0xff;
> +	rq->cmd[9] = h->bufflen & 0xff;
> +	rq->cmd_len = COMMAND_SIZE(MAINTENANCE_IN);
> +
> +	DPRINT(h, "submit REPORT TARGET GROUP STATES len %d", h->bufflen);
> +	blk_execute_rq(rq->q, NULL, rq, 1);
> +	err = rq->errors;
> +	blk_put_request(rq);
> +
> +	return err;
> +}
> +
> +/*
> + * Issue a SET TARGET GROUP STATES 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 unsigned submit_stpg(struct alua_handler *h)
> +{
> +	struct request *rq;
> +	int stpg_len = 8;
> +	unsigned err = (DRIVER_ERROR << 24);
> +
> +	/* Prepare the data buffer */
> +	memset(h->buff, 0, stpg_len);
> +	h->buff[4] = TPGS_STATE_OPTIMIZED & 0x0f;
> +	h->buff[6] = (h->group_id >> 8) & 0x0f;
> +	h->buff[7] = h->group_id & 0x0f;
> +
> +	rq = prepare_req(h, h->buff, stpg_len, WRITE);
> +	if (!rq)
> +		return err;
> +
> +	/* Prepare the command. */
> +	rq->cmd[0] = MAINTENANCE_OUT;
> +	rq->cmd[1] = MO_SET_TARGET_PGS;
> +	rq->cmd[6] = (stpg_len >> 24) & 0xff;
> +	rq->cmd[7] = (stpg_len >> 16) & 0xff;
> +	rq->cmd[8] = (stpg_len >>  8) & 0xff;
> +	rq->cmd[9] = stpg_len & 0xff;
> +	rq->cmd_len = COMMAND_SIZE(MAINTENANCE_OUT);
> +
> +	if (h->debug)
> +		DMINFO("%s: submit SET TARGET GROUP STATES",
> +		       h->path->dev->name);
> +
> +	blk_execute_rq(rq->q, NULL, rq, 1);
> +	err = rq->errors;
> +	blk_put_request(rq);
> +
> +	return err;
> +}
> +
> +/*
> + * Evaluate standard INQUIRY command
> + *
> + * Just extract the TPGS setting to find out if ALUA
> + * is supported.
> + */
> +static void alua_std_inquiry(struct alua_handler *h)
> +{
> +	int error;
> +
> +	error = submit_std_inquiry(h);
> +
> +	if (had_failures(error)) {
> +		dm_pg_init_complete(h->path, MP_FAIL_PATH);
> +		return;
> +	}
> +
> +	/* Check TPGS setting */
> +	h->tpgs = (h->inq[5] >> 4) & 0x3;
> +	switch (h->tpgs) {
> +	case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
> +		DMWARN("%s: supports implicit and explicit TPGS",
> +		       h->path->dev->name);
> +		break;
> +	case TPGS_MODE_EXPLICIT:
> +		DMWARN("%s: supports explicit TPGS",
> +		       h->path->dev->name);
> +		break;
> +	case TPGS_MODE_IMPLICIT:
> +		DMWARN("%s: supports implicit TPGS",
> +		       h->path->dev->name);
> +		break;
> +	default:
> +		DMWARN("%s:TPGS not supported",
> +		       h->path->dev->name);
> +		break;
> +	}
> +
> +	if (h->tpgs == TPGS_MODE_NONE) {
> +		/*
> +		 * ALUA not supported
> +		 */
> +		dm_pg_init_complete(h->path, 0);
> +	}
> +	/*
> +	 * Don't call dm_pg_init_complete, continue
> +	 * with INQUIRY VPD page 0x83 command.
> +	 */
> +	return;
> +}
> +
> +/*
> + * Evaluate INQUIRY vpd page 0x83
> + *
> + * Extract the relative target port and the target port group
> + * descriptor from the list of identificators.
> + */
> +static void alua_vpd_inquiry(struct alua_handler *h)
> +{
> +	int len;
> +	unsigned error;
> +	unsigned char *d;
> +
> + retry:
> +	error = submit_vpd_inquiry(h);
> +
> +	if (had_failures(error)) {
> +		dm_pg_init_complete(h->path, MP_FAIL_PATH);
> +		return;
> +	}
> +
> +	/* Check if vpd page exceeds initial buffer */
> +	len = (h->buff[2] << 8) + h->buff[3] + 4;
> +	if (len > h->bufflen) {
> +		/* Resubmit with the correct length */
> +		if (realloc_buffer(h, len)) {
> +			DMINFO("%s: kmalloc buffer failed",__FUNCTION__);
> +			/* Temporary failure, bypass */
> +			dm_pg_init_complete(h->path, MP_BYPASS_PG);
> +			return;
> +		}
> +		goto retry;
> +	}
> +
> +	/*
> +	 * Now look for the correct descriptor.
> +	 */
> +	d = h->buff + 4;
> +	while (d < h->buff + len) {
> +		switch (d[1] & 0xf) {
> +		case 0x4:
> +			/* Relative target port */
> +			h->rel_port = (d[6] << 8) + d[7];
> +			break;
> +		case 0x5:
> +			/* Target port group */
> +			h->group_id = (d[6] << 8) + d[7];
> +			break;
> +		default:
> +			break;
> +		}
> +		d += d[3] + 4;
> +	}
> +
> +	if (h->group_id == -1) {
> +		/*
> +		 * Internal error; TPGS supported but required
> +		 * VPD identification descriptors not present.
> +		 * Disable ALUA support
> +		 */
> +		DMWARN("%s: No target port descriptors in VPD page 0x83\n",
> +		       h->path->dev->name);
> +		h->state = TPGS_STATE_OPTIMIZED;
> +		h->tpgs = TPGS_MODE_NONE;
> +		dm_pg_init_complete(h->path, 0);
> +	} else {
> +		DMWARN("%s: port group %02x rel port %02x",
> +		       h->path->dev->name, h->group_id, h->rel_port);
> +	}
> +
> +	/*
> +	 * Don't call dm_pg_init_complete, continue
> +	 * with REPORT TARGET GROUP STATES command.
> +	 */
> +	return;
> +}
> +
> +static char print_alua_state(enum tpgs_state s)
> +{
> +	switch (s) {
> +	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_OFFLINE:
> +		return 'O';
> +	case TPGS_STATE_TRANSITIONING:
> +		return 'T';
> +	default:
> +		return 'X';
> +	}
> +}
> +
> +/*
> + * Evaluate SET TARGET GROUP STATES
> + *
> + * We only have to test here if we should resubmit the command;
> + * any other error is assumed as a failure.
> + * Maybe we should analyze the sensebuffer here, too.
> + */
> +static void alua_stpg(struct alua_handler *h, enum tpgs_state n)
> +{
> +	unsigned error;
> +	int retry = 5;
> +
> + retry:
> +	error = submit_stpg(h);
> +	switch(host_byte(error)) {
> +	case DID_BUS_BUSY:
> +		if (!retry)
> +			break;
> +		retry++;
> +	case DID_REQUEUE:
> +	case DID_IMM_RETRY:
> +		goto retry;
> +	}
> +
> +	if (had_failures(error)) {
> +		DMWARN("%s: stpg failed %x, disable path",
> +		       h->path->dev->name, error);
> +		dm_pg_init_complete(h->path, MP_FAIL_PATH);
> +	} else {
> +		h-state = n;
> +		DMWARN("%s: port group %02x new state %c",
> +		       h->path->dev->name, h->group_id,
> +		       print_alua_state(h->state) );
> +		dm_pg_init_complete(h->path, 0);
> +	}
> +}
> +
> +/*
> + * Evaluate REPORT TARGET GROUP STATES
> + *
> + * Set the Target Port Group State. If the state
> + * is not 'active/optimized' we will try to activate
> + * this group by sending a 'SET TARGET GROUP STATES'
> + * command.
> + * If the state is 'offline' we will just fail the
> + * path.
> + */
> +static void alua_rtpg(struct alua_handler *h)
> +{
> +	struct scsi_sense_hdr sense_hdr;
> +	int len, k, off, valid_states = 0, sense = 0;
> +	char *ucp;
> +	unsigned error;
> +
> + retry:
> +	error = submit_rtpg(h);
> +
> +	if (had_failures(error)) {
> +		dm_pg_init_complete(h->path, MP_FAIL_PATH);
> +		return;
> +	}
> +
> +	if (status_byte(error) == CHECK_CONDITION) {
> +		scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
> +				     &sense_hdr);
> +		/* Retry if not ready */
> +		if (sense_hdr.sense_key == NOT_READY) {
> +			DMWARN("%s: device not ready, retry",
> +			       h->path->dev->name);
> +			goto retry;
> +		}
> +		/* Retry on Unit Attention */
> +		sense = (sense_hdr.sense_key << 16) | (sense_hdr.asc << 8) |
> +				sense_hdr.ascq;
> +		if (sense == 0x62a06) {
> +			DMWARN("%s: unit attention after state transition",
> +			       h->path->dev->name);
> +			goto retry;
> +		}
> +	}
> +
> +	len = (h->buff[0] << 24) + (h->buff[1] << 16) +
> +		(h->buff[2] << 8) + h->buff[3] + 4;
> +
> +	if (len > h->bufflen) {
> +		/* Resubmit with the correct length */
> +		if (realloc_buffer(h, len)) {
> +			DMINFO("%s: kmalloc buffer failed",__FUNCTION__);
> +			/* Temporary failure, bypass */
> +			dm_pg_init_complete(h->path, MP_BYPASS_PG);
> +			return;
> +		}
> +		goto retry;
> +	}
> +
> +	for (k = 4, ucp = h->buff + 4; k < len; k += off, ucp += off) {
> +		if (h->group_id == (ucp[2] << 8) + ucp[3]) {
> +			h->state = ucp[0] & 0x0f;
> +			valid_states = ucp[1];
> +		}
> +		off = 8 + (ucp[7] * 4);
> +	}
> +
> +	DMWARN("%s: port group %02x state %c supports %c%c%c%c%c%c",
> +	       h->path->dev->name, h->group_id, print_alua_state(h->state),
> +	       valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
> +	       valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
> +	       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');
> +
> +	if (h->tpgs & TPGS_MODE_EXPLICIT) {
> +		switch (h->state) {
> +		case TPGS_STATE_TRANSITIONING:
> +			/* State transition, retry */
> +			goto retry;
> +			break;
> +		case TPGS_STATE_OPTIMIZED:
> +			/* Path in Active/Optmized state, all done */
> +			dm_pg_init_complete(h->path, 0);
> +			break;
> +		case TPGS_STATE_OFFLINE:
> +			/* Path is offline, fail */
> +			dm_pg_init_complete(h->path, MP_FAIL_PATH);
> +			break;
> +		default:
> +			/* Switch path to Active/Optimized */
> +			alua_stpg(h, TPGS_STATE_OPTIMIZED);
> +			break;
> +		}
> +	} else {
> +		/* Only Implicit ALUA support */
> +		if (h->state == TPGS_STATE_OPTIMIZED ||
> +		    h->state == TPGS_STATE_NONOPTIMIZED ||
> +		    h->state == TPGS_STATE_STANDBY)
> +			/* Useable path if active */
> +			dm_pg_init_complete(h->path, 0);
> +		else
> +			/* Path unuseable for unavailable/offline */
> +			dm_pg_init_complete(h->path, MP_FAIL_PATH);
> +	}
> +}
> +
> +/*
> + * We're currently switching the port group to be activated only and
> + * let the array figure out the rest.
> + * There may be others arrays which require us to switch all port groups
> + * based on a certain policy. But until we actually encounter them this
> + * should be okay.
> + */
> +static int alua_create(struct hw_handler *hwh, unsigned argc, char **argv)
> +{
> +	struct alua_handler *h;
> +	int debug = 0;
> +
> +	if (argc == 0) {
> +		/* No arguments: use defaults */
> +		debug = 0;
> +	} else if (argc != 1) {
> +		DMWARN("incorrect number of arguments");
> +		return -EINVAL;
> +	} else {
> +		if (sscanf(argv[1], "%u", &debug) != 1) {
> +			DMWARN("invalid debug value");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	h = kzalloc(sizeof(*h), GFP_KERNEL);
> +	if (!h)
> +		return -ENOMEM;
> +
> +	hwh->context = h;
> +	h->debug = debug;
> +	h->tpgs = TPGS_MODE_UNINITIALIZED;
> +	h->group_id = -1;
> +	h->rel_port = -1;
> +	h->state = TPGS_STATE_UNKNOWN;
> +	h->buff = h->inq;
> +	h->bufflen = TPGS_INQUIRY_SIZE;
> +
> +	return 0;
> +}
> +
> +static void alua_destroy(struct hw_handler *hwh)
> +{
> +	struct alua_handler *h = hwh->context;
> +
> +	if (h->buff && h->inq != h->buff)
> +		kfree(h->buff);
> +	kfree(h);
> +	hwh->context = NULL;
> +}
> +
> +static unsigned alua_error(struct hw_handler *hwh, struct bio *bio)
> +{
> +	/* Try default handler */
> +	return dm_scsi_err_handler(hwh, bio);
> +}
> +
> +static void alua_pg_init(struct hw_handler *hwh, unsigned bypassed,
> +			struct dm_path *path)
> +{
> +	struct alua_handler *h = hwh->context;
> +
> +	h->path = path;
> +	if (h->tpgs == TPGS_MODE_UNINITIALIZED)
> +		alua_std_inquiry(h);
> +	if (h->tpgs & (TPGS_MODE_IMPLICIT | TPGS_MODE_EXPLICIT))
> +		alua_vpd_inquiry(h);
> +	if (h->group_id != -1)
> +		alua_rtpg(h);
> +}
> +
> +static struct hw_handler_type alua_handler = {
> +	.name = ALUA_DM_HWH_NAME,
> +	.module = THIS_MODULE,
> +	.create = alua_create,
> +	.destroy = alua_destroy,
> +	.pg_init = alua_pg_init,
> +	.error = alua_error,
> +};
> +
> +static int __init alua_init(void)
> +{
> +	int r = dm_register_hw_handler(&alua_handler);
> +
> +	if (r < 0) {
> +		DMERR("%s: register failed %d", ALUA_DM_HWH_NAME, r);
> +		return r;
> +	}
> +
> +	DMINFO("%s: version %s loaded", ALUA_DM_HWH_NAME, ALUA_DM_HWH_VER);
> +	return 0;
> +}
> +
> +static void __exit alua_exit(void)
> +{
> +	int r = dm_unregister_hw_handler(&alua_handler);
> +
> +	if (r < 0)
> +		DMERR("%s: unregister failed %d", ALUA_DM_HWH_NAME, r);
> +}
> +
> +module_init(alua_init);
> +module_exit(alua_exit);
> +
> +MODULE_DESCRIPTION("DM Multipath ALUA support");
> +MODULE_AUTHOR("Hannes Reinecke");
> +MODULE_LICENSE("GPL");
> +MODULE_VERSION(ALUA_DM_HWH_VER);
> diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
> index 9f8f80a..4e87c84 100644
> --- a/include/scsi/scsi.h
> +++ b/include/scsi/scsi.h
> @@ -98,6 +98,7 @@ extern const unsigned char scsi_command_size[8];
>  #define PERSISTENT_RESERVE_OUT 0x5f
>  #define REPORT_LUNS           0xa0
>  #define MAINTENANCE_IN        0xa3
> +#define MAINTENANCE_OUT       0xa4
>  #define MOVE_MEDIUM           0xa5
>  #define EXCHANGE_MEDIUM       0xa6
>  #define READ_12               0xa8
> @@ -117,6 +118,8 @@ extern const unsigned char scsi_command_size[8];
>  #define	SAI_READ_CAPACITY_16  0x10
>  /* values for maintenance in */
>  #define MI_REPORT_TARGET_PGS  0x0a
> +/* values for maintenance out */
> +#define MO_SET_TARGET_PGS     0x0a
> 
>  /* Values for T10/04-262r7 */
>  #define	ATA_16		      0x85	/* 16-byte pass-thru */
> --
> dm-devel mailing list
> dm-devel redhat com
> https://www.redhat.com/mailman/listinfo/dm-devel
-- 

----------------------------------------------------------------------
    Chandra Seetharaman               | Be careful what you choose....
              - sekharan us ibm com   |      .......you may get it.
----------------------------------------------------------------------



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