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authorDave Wysochanski <dwysocha@redhat.com>2007-10-19 17:47:54 -0400
committerAlasdair G Kergon <agk@redhat.com>2007-10-19 21:01:19 -0400
commit16ebbf358477b762115fec2f85d9b9496a5cae76 (patch)
treef25ad7881636aa21e85027be00056f5675a45de5 /drivers/md/dm-mpath-hp-sw.c
parentc9e45581ad530cc1ca4b5d4add44a5b625234ada (diff)
dm mpath: add hp handler
This patch adds the most basic dm-multipath hardware support for the HP active/passive arrays. Signed-off-by: Dave Wysochanski <dwysocha@redhat.com> Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Acked-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-mpath-hp-sw.c')
-rw-r--r--drivers/md/dm-mpath-hp-sw.c206
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 000000000000..575317037ce2
--- /dev/null
+++ b/drivers/md/dm-mpath-hp-sw.c
@@ -0,0 +1,206 @@
1/*
2 * Copyright (C) 2005 Mike Christie, All rights reserved.
3 * Copyright (C) 2007 Red Hat, Inc. All rights reserved.
4 * Authors: Mike Christie
5 * Dave Wysochanski
6 *
7 * This file is released under the GPL.
8 *
9 * This module implements the specific path activation code for
10 * HP StorageWorks and FSC FibreCat Asymmetric (Active/Passive)
11 * storage arrays.
12 * These storage arrays have controller-based failover, not
13 * LUN-based failover. However, LUN-based failover is the design
14 * of dm-multipath. Thus, this module is written for LUN-based failover.
15 */
16#include <linux/blkdev.h>
17#include <linux/list.h>
18#include <linux/types.h>
19#include <scsi/scsi.h>
20#include <scsi/scsi_cmnd.h>
21
22#include "dm.h"
23#include "dm-hw-handler.h"
24
25#define DM_MSG_PREFIX "multipath hp-sw"
26#define DM_HP_HWH_NAME "hp-sw"
27#define DM_HP_HWH_VER "0.0.3"
28
29struct hp_sw_context {
30 unsigned char sense[SCSI_SENSE_BUFFERSIZE];
31};
32
33/*
34 * hp_sw_end_io - Completion handler for HP path activation.
35 * @req: path activation request
36 * @error: scsi-ml error
37 *
38 * Check sense data, free request structure, and notify dm that
39 * pg initialization has completed.
40 *
41 * Context: scsi-ml softirq
42 *
43 * Possible optimizations
44 * 1. Actually check sense data for retryable error (e.g. NOT_READY)
45 */
46static void hp_sw_end_io(struct request *req, int error)
47{
48 struct dm_path *path = req->end_io_data;
49 unsigned err_flags = 0;
50
51 if (!error)
52 DMDEBUG("%s path activation command - success",
53 path->dev->name);
54 else {
55 DMWARN("%s path activation command - error=0x%x",
56 path->dev->name, error);
57 err_flags = MP_FAIL_PATH;
58 }
59
60 req->end_io_data = NULL;
61 __blk_put_request(req->q, req);
62 dm_pg_init_complete(path, err_flags);
63}
64
65/*
66 * hp_sw_get_request - Allocate an HP specific path activation request
67 * @path: path on which request will be sent (needed for request queue)
68 *
69 * The START command is used for path activation request.
70 * These arrays are controller-based failover, not LUN based.
71 * One START command issued to a single path will fail over all
72 * LUNs for the same controller.
73 *
74 * Possible optimizations
75 * 1. Make timeout configurable
76 * 2. Preallocate request
77 */
78static struct request *hp_sw_get_request(struct dm_path *path)
79{
80 struct request *req;
81 struct block_device *bdev = path->dev->bdev;
82 struct request_queue *q = bdev_get_queue(bdev);
83 struct hp_sw_context *h = path->hwhcontext;
84
85 req = blk_get_request(q, WRITE, GFP_NOIO);
86 if (!req)
87 goto out;
88
89 req->timeout = 60 * HZ;
90
91 req->errors = 0;
92 req->cmd_type = REQ_TYPE_BLOCK_PC;
93 req->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
94 req->end_io_data = path;
95 req->sense = h->sense;
96 memset(req->sense, 0, SCSI_SENSE_BUFFERSIZE);
97
98 memset(&req->cmd, 0, BLK_MAX_CDB);
99 req->cmd[0] = START_STOP;
100 req->cmd[4] = 1;
101 req->cmd_len = COMMAND_SIZE(req->cmd[0]);
102
103out:
104 return req;
105}
106
107/*
108 * hp_sw_pg_init - HP path activation implementation.
109 * @hwh: hardware handler specific data
110 * @bypassed: unused; is the path group bypassed? (see dm-mpath.c)
111 * @path: path to send initialization command
112 *
113 * Send an HP-specific path activation command on 'path'.
114 * Do not try to optimize in any way, just send the activation command.
115 * More than one path activation command may be sent to the same controller.
116 * This seems to work fine for basic failover support.
117 *
118 * Possible optimizations
119 * 1. Detect an in-progress activation request and avoid submitting another one
120 * 2. Model the controller and only send a single activation request at a time
121 * 3. Determine the state of a path before sending an activation request
122 *
123 * Context: kmpathd (see process_queued_ios() in dm-mpath.c)
124 */
125static void hp_sw_pg_init(struct hw_handler *hwh, unsigned bypassed,
126 struct dm_path *path)
127{
128 struct request *req;
129 struct hp_sw_context *h;
130
131 path->hwhcontext = hwh->context;
132 h = hwh->context;
133
134 req = hp_sw_get_request(path);
135 if (!req) {
136 DMERR("%s path activation command - allocation fail",
137 path->dev->name);
138 goto fail;
139 }
140
141 DMDEBUG("%s path activation command - sent", path->dev->name);
142
143 blk_execute_rq_nowait(req->q, NULL, req, 1, hp_sw_end_io);
144 return;
145
146fail:
147 dm_pg_init_complete(path, MP_FAIL_PATH);
148}
149
150static int hp_sw_create(struct hw_handler *hwh, unsigned argc, char **argv)
151{
152 struct hp_sw_context *h;
153
154 h = kmalloc(sizeof(*h), GFP_KERNEL);
155 if (!h)
156 return -ENOMEM;
157
158 hwh->context = h;
159
160 return 0;
161}
162
163static void hp_sw_destroy(struct hw_handler *hwh)
164{
165 struct hp_sw_context *h = hwh->context;
166
167 kfree(h);
168}
169
170static struct hw_handler_type hp_sw_hwh = {
171 .name = DM_HP_HWH_NAME,
172 .module = THIS_MODULE,
173 .create = hp_sw_create,
174 .destroy = hp_sw_destroy,
175 .pg_init = hp_sw_pg_init,
176};
177
178static int __init hp_sw_init(void)
179{
180 int r;
181
182 r = dm_register_hw_handler(&hp_sw_hwh);
183 if (r < 0)
184 DMERR("register failed %d", r);
185 else
186 DMINFO("version " DM_HP_HWH_VER " loaded");
187
188 return r;
189}
190
191static void __exit hp_sw_exit(void)
192{
193 int r;
194
195 r = dm_unregister_hw_handler(&hp_sw_hwh);
196 if (r < 0)
197 DMERR("unregister failed %d", r);
198}
199
200module_init(hp_sw_init);
201module_exit(hp_sw_exit);
202
203MODULE_DESCRIPTION("DM Multipath HP StorageWorks / FSC FibreCat (A/P) support");
204MODULE_AUTHOR("Mike Christie, Dave Wysochanski <dm-devel@redhat.com>");
205MODULE_LICENSE("GPL");
206MODULE_VERSION(DM_HP_HWH_VER);