diff options
Diffstat (limited to 'drivers/md/dm-mpath-hp-sw.c')
| -rw-r--r-- | drivers/md/dm-mpath-hp-sw.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/drivers/md/dm-mpath-hp-sw.c b/drivers/md/dm-mpath-hp-sw.c new file mode 100644 index 00000000000..575317037ce --- /dev/null +++ b/drivers/md/dm-mpath-hp-sw.c @@ -0,0 +1,206 @@ +/* + * Copyright (C) 2005 Mike Christie, All rights reserved. + * Copyright (C) 2007 Red Hat, Inc. All rights reserved. + * Authors: Mike Christie + * Dave Wysochanski + * + * This file is released under the GPL. + * + * This module implements the specific path activation code for + * HP StorageWorks and FSC FibreCat Asymmetric (Active/Passive) + * storage arrays. + * These storage arrays have controller-based failover, not + * LUN-based failover. However, LUN-based failover is the design + * of dm-multipath. Thus, this module is written for LUN-based failover. + */ +#include <linux/blkdev.h> +#include <linux/list.h> +#include <linux/types.h> +#include <scsi/scsi.h> +#include <scsi/scsi_cmnd.h> + +#include "dm.h" +#include "dm-hw-handler.h" + +#define DM_MSG_PREFIX "multipath hp-sw" +#define DM_HP_HWH_NAME "hp-sw" +#define DM_HP_HWH_VER "0.0.3" + +struct hp_sw_context { + unsigned char sense[SCSI_SENSE_BUFFERSIZE]; +}; + +/* + * hp_sw_end_io - Completion handler for HP path activation. + * @req: path activation request + * @error: scsi-ml error + * + * Check sense data, free request structure, and notify dm that + * pg initialization has completed. + * + * Context: scsi-ml softirq + * + * Possible optimizations + * 1. Actually check sense data for retryable error (e.g. NOT_READY) + */ +static void hp_sw_end_io(struct request *req, int error) +{ + struct dm_path *path = req->end_io_data; + unsigned err_flags = 0; + + if (!error) + DMDEBUG("%s path activation command - success", + path->dev->name); + else { + DMWARN("%s path activation command - error=0x%x", + path->dev->name, error); + err_flags = MP_FAIL_PATH; + } + + req->end_io_data = NULL; + __blk_put_request(req->q, req); + dm_pg_init_complete(path, err_flags); +} + +/* + * hp_sw_get_request - Allocate an HP specific path activation request + * @path: path on which request will be sent (needed for request queue) + * + * The START command is used for path activation request. + * These arrays are controller-based failover, not LUN based. + * One START command issued to a single path will fail over all + * LUNs for the same controller. + * + * Possible optimizations + * 1. Make timeout configurable + * 2. Preallocate request + */ +static struct request *hp_sw_get_request(struct dm_path *path) +{ + struct request *req; + struct block_device *bdev = path->dev->bdev; + struct request_queue *q = bdev_get_queue(bdev); + struct hp_sw_context *h = path->hwhcontext; + + req = blk_get_request(q, WRITE, GFP_NOIO); + if (!req) + goto out; + + req->timeout = 60 * HZ; + + req->errors = 0; + req->cmd_type = REQ_TYPE_BLOCK_PC; + req->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE; + req->end_io_data = path; + req->sense = h->sense; + memset(req->sense, 0, SCSI_SENSE_BUFFERSIZE); + + memset(&req->cmd, 0, BLK_MAX_CDB); + req->cmd[0] = START_STOP; + req->cmd[4] = 1; + req->cmd_len = COMMAND_SIZE(req->cmd[0]); + +out: + return req; +} + +/* + * hp_sw_pg_init - HP path activation implementation. + * @hwh: hardware handler specific data + * @bypassed: unused; is the path group bypassed? (see dm-mpath.c) + * @path: path to send initialization command + * + * Send an HP-specific path activation command on 'path'. + * Do not try to optimize in any way, just send the activation command. + * More than one path activation command may be sent to the same controller. + * This seems to work fine for basic failover support. + * + * Possible optimizations + * 1. Detect an in-progress activation request and avoid submitting another one + * 2. Model the controller and only send a single activation request at a time + * 3. Determine the state of a path before sending an activation request + * + * Context: kmpathd (see process_queued_ios() in dm-mpath.c) + */ +static void hp_sw_pg_init(struct hw_handler *hwh, unsigned bypassed, + struct dm_path *path) +{ + struct request *req; + struct hp_sw_context *h; + + path->hwhcontext = hwh->context; + h = hwh->context; + + req = hp_sw_get_request(path); + if (!req) { + DMERR("%s path activation command - allocation fail", + path->dev->name); + goto fail; + } + + DMDEBUG("%s path activation command - sent", path->dev->name); + + blk_execute_rq_nowait(req->q, NULL, req, 1, hp_sw_end_io); + return; + +fail: + dm_pg_init_complete(path, MP_FAIL_PATH); +} + +static int hp_sw_create(struct hw_handler *hwh, unsigned argc, char **argv) +{ + struct hp_sw_context *h; + + h = kmalloc(sizeof(*h), GFP_KERNEL); + if (!h) + return -ENOMEM; + + hwh->context = h; + + return 0; +} + +static void hp_sw_destroy(struct hw_handler *hwh) +{ + struct hp_sw_context *h = hwh->context; + + kfree(h); +} + +static struct hw_handler_type hp_sw_hwh = { + .name = DM_HP_HWH_NAME, + .module = THIS_MODULE, + .create = hp_sw_create, + .destroy = hp_sw_destroy, + .pg_init = hp_sw_pg_init, +}; + +static int __init hp_sw_init(void) +{ + int r; + + r = dm_register_hw_handler(&hp_sw_hwh); + if (r < 0) + DMERR("register failed %d", r); + else + DMINFO("version " DM_HP_HWH_VER " loaded"); + + return r; +} + +static void __exit hp_sw_exit(void) +{ + int r; + + r = dm_unregister_hw_handler(&hp_sw_hwh); + if (r < 0) + DMERR("unregister failed %d", r); +} + +module_init(hp_sw_init); +module_exit(hp_sw_exit); + +MODULE_DESCRIPTION("DM Multipath HP StorageWorks / FSC FibreCat (A/P) support"); +MODULE_AUTHOR("Mike Christie, Dave Wysochanski <dm-devel@redhat.com>"); +MODULE_LICENSE("GPL"); +MODULE_VERSION(DM_HP_HWH_VER); |