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authorMike Christie <michaelc@cs.wisc.edu>2011-07-31 16:05:09 -0400
committerJens Axboe <jaxboe@fusionio.com>2011-07-31 16:05:09 -0400
commitaa387cc895672b00f807ad7c734a2defaf677712 (patch)
tree31c2c3f3e0d58ff2524cdf8f94abecc394f5eb49 /block
parent24c3047095fa3954f114bfff2e37b8fcbb216396 (diff)
block: add bsg helper library
This moves the FC classes bsg code to the block layer and makes it a lib so that other classes like iscsi and SAS can use it. It is helpful because working with the request queue, bios, creating scatterlists, etc are a pain that the LLD does not have to worry about with normal IOs and should not have to worry about for bsg requests. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block')
-rw-r--r--block/Kconfig10
-rw-r--r--block/Makefile1
-rw-r--r--block/bsg-lib.c297
3 files changed, 308 insertions, 0 deletions
diff --git a/block/Kconfig b/block/Kconfig
index 60be1e0455da..e97934eececa 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -65,6 +65,16 @@ config BLK_DEV_BSG
65 65
66 If unsure, say Y. 66 If unsure, say Y.
67 67
68config BLK_DEV_BSGLIB
69 bool "Block layer SG support v4 helper lib"
70 default n
71 select BLK_DEV_BSG
72 help
73 Subsystems will normally enable this if needed. Users will not
74 normally need to manually enable this.
75
76 If unsure, say N.
77
68config BLK_DEV_INTEGRITY 78config BLK_DEV_INTEGRITY
69 bool "Block layer data integrity support" 79 bool "Block layer data integrity support"
70 ---help--- 80 ---help---
diff --git a/block/Makefile b/block/Makefile
index 0fec4b3fab51..514c6e4f427a 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \
8 blk-iopoll.o blk-lib.o ioctl.o genhd.o scsi_ioctl.o 8 blk-iopoll.o blk-lib.o ioctl.o genhd.o scsi_ioctl.o
9 9
10obj-$(CONFIG_BLK_DEV_BSG) += bsg.o 10obj-$(CONFIG_BLK_DEV_BSG) += bsg.o
11obj-$(CONFIG_BLK_DEV_BSGLIB) += bsg-lib.o
11obj-$(CONFIG_BLK_CGROUP) += blk-cgroup.o 12obj-$(CONFIG_BLK_CGROUP) += blk-cgroup.o
12obj-$(CONFIG_BLK_DEV_THROTTLING) += blk-throttle.o 13obj-$(CONFIG_BLK_DEV_THROTTLING) += blk-throttle.o
13obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o 14obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
diff --git a/block/bsg-lib.c b/block/bsg-lib.c
new file mode 100644
index 000000000000..f8c0a61a529c
--- /dev/null
+++ b/block/bsg-lib.c
@@ -0,0 +1,297 @@
1/*
2 * BSG helper library
3 *
4 * Copyright (C) 2008 James Smart, Emulex Corporation
5 * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
6 * Copyright (C) 2011 Mike Christie
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 *
22 */
23#include <linux/slab.h>
24#include <linux/blkdev.h>
25#include <linux/delay.h>
26#include <linux/scatterlist.h>
27#include <linux/bsg-lib.h>
28#include <scsi/scsi_cmnd.h>
29
30/**
31 * bsg_destroy_job - routine to teardown/delete a bsg job
32 * @job: bsg_job that is to be torn down
33 */
34static void bsg_destroy_job(struct bsg_job *job)
35{
36 put_device(job->dev); /* release reference for the request */
37
38 kfree(job->request_payload.sg_list);
39 kfree(job->reply_payload.sg_list);
40 kfree(job);
41}
42
43/**
44 * bsg_job_done - completion routine for bsg requests
45 * @job: bsg_job that is complete
46 * @result: job reply result
47 * @reply_payload_rcv_len: length of payload recvd
48 *
49 * The LLD should call this when the bsg job has completed.
50 */
51void bsg_job_done(struct bsg_job *job, int result,
52 unsigned int reply_payload_rcv_len)
53{
54 struct request *req = job->req;
55 struct request *rsp = req->next_rq;
56 int err;
57
58 err = job->req->errors = result;
59 if (err < 0)
60 /* we're only returning the result field in the reply */
61 job->req->sense_len = sizeof(u32);
62 else
63 job->req->sense_len = job->reply_len;
64 /* we assume all request payload was transferred, residual == 0 */
65 req->resid_len = 0;
66
67 if (rsp) {
68 WARN_ON(reply_payload_rcv_len > rsp->resid_len);
69
70 /* set reply (bidi) residual */
71 rsp->resid_len -= min(reply_payload_rcv_len, rsp->resid_len);
72 }
73 blk_complete_request(req);
74}
75EXPORT_SYMBOL_GPL(bsg_job_done);
76
77/**
78 * bsg_softirq_done - softirq done routine for destroying the bsg requests
79 * @rq: BSG request that holds the job to be destroyed
80 */
81static void bsg_softirq_done(struct request *rq)
82{
83 struct bsg_job *job = rq->special;
84
85 blk_end_request_all(rq, rq->errors);
86 bsg_destroy_job(job);
87}
88
89static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
90{
91 size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
92
93 BUG_ON(!req->nr_phys_segments);
94
95 buf->sg_list = kzalloc(sz, GFP_KERNEL);
96 if (!buf->sg_list)
97 return -ENOMEM;
98 sg_init_table(buf->sg_list, req->nr_phys_segments);
99 buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
100 buf->payload_len = blk_rq_bytes(req);
101 return 0;
102}
103
104/**
105 * bsg_create_job - create the bsg_job structure for the bsg request
106 * @dev: device that is being sent the bsg request
107 * @req: BSG request that needs a job structure
108 */
109static int bsg_create_job(struct device *dev, struct request *req)
110{
111 struct request *rsp = req->next_rq;
112 struct request_queue *q = req->q;
113 struct bsg_job *job;
114 int ret;
115
116 BUG_ON(req->special);
117
118 job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
119 if (!job)
120 return -ENOMEM;
121
122 req->special = job;
123 job->req = req;
124 if (q->bsg_job_size)
125 job->dd_data = (void *)&job[1];
126 job->request = req->cmd;
127 job->request_len = req->cmd_len;
128 job->reply = req->sense;
129 job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
130 * allocated */
131 if (req->bio) {
132 ret = bsg_map_buffer(&job->request_payload, req);
133 if (ret)
134 goto failjob_rls_job;
135 }
136 if (rsp && rsp->bio) {
137 ret = bsg_map_buffer(&job->reply_payload, rsp);
138 if (ret)
139 goto failjob_rls_rqst_payload;
140 }
141 job->dev = dev;
142 /* take a reference for the request */
143 get_device(job->dev);
144 return 0;
145
146failjob_rls_rqst_payload:
147 kfree(job->request_payload.sg_list);
148failjob_rls_job:
149 kfree(job);
150 return -ENOMEM;
151}
152
153/*
154 * bsg_goose_queue - restart queue in case it was stopped
155 * @q: request q to be restarted
156 */
157void bsg_goose_queue(struct request_queue *q)
158{
159 if (!q)
160 return;
161
162 blk_run_queue_async(q);
163}
164EXPORT_SYMBOL_GPL(bsg_goose_queue);
165
166/**
167 * bsg_request_fn - generic handler for bsg requests
168 * @q: request queue to manage
169 *
170 * On error the create_bsg_job function should return a -Exyz error value
171 * that will be set to the req->errors.
172 *
173 * Drivers/subsys should pass this to the queue init function.
174 */
175void bsg_request_fn(struct request_queue *q)
176{
177 struct device *dev = q->queuedata;
178 struct request *req;
179 struct bsg_job *job;
180 int ret;
181
182 if (!get_device(dev))
183 return;
184
185 while (1) {
186 req = blk_fetch_request(q);
187 if (!req)
188 break;
189 spin_unlock_irq(q->queue_lock);
190
191 ret = bsg_create_job(dev, req);
192 if (ret) {
193 req->errors = ret;
194 blk_end_request_all(req, ret);
195 spin_lock_irq(q->queue_lock);
196 continue;
197 }
198
199 job = req->special;
200 ret = q->bsg_job_fn(job);
201 spin_lock_irq(q->queue_lock);
202 if (ret)
203 break;
204 }
205
206 spin_unlock_irq(q->queue_lock);
207 put_device(dev);
208 spin_lock_irq(q->queue_lock);
209}
210EXPORT_SYMBOL_GPL(bsg_request_fn);
211
212/**
213 * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
214 * @dev: device to attach bsg device to
215 * @q: request queue setup by caller
216 * @name: device to give bsg device
217 * @job_fn: bsg job handler
218 * @dd_job_size: size of LLD data needed for each job
219 *
220 * The caller should have setup the reuqest queue with bsg_request_fn
221 * as the request_fn.
222 */
223int bsg_setup_queue(struct device *dev, struct request_queue *q,
224 char *name, bsg_job_fn *job_fn, int dd_job_size)
225{
226 int ret;
227
228 q->queuedata = dev;
229 q->bsg_job_size = dd_job_size;
230 q->bsg_job_fn = job_fn;
231 queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
232 blk_queue_softirq_done(q, bsg_softirq_done);
233 blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
234
235 ret = bsg_register_queue(q, dev, name, NULL);
236 if (ret) {
237 printk(KERN_ERR "%s: bsg interface failed to "
238 "initialize - register queue\n", dev->kobj.name);
239 return ret;
240 }
241
242 return 0;
243}
244EXPORT_SYMBOL_GPL(bsg_setup_queue);
245
246/**
247 * bsg_remove_queue - Deletes the bsg dev from the q
248 * @q: the request_queue that is to be torn down.
249 *
250 * Notes:
251 * Before unregistering the queue empty any requests that are blocked
252 */
253void bsg_remove_queue(struct request_queue *q)
254{
255 struct request *req; /* block request */
256 int counts; /* totals for request_list count and starved */
257
258 if (!q)
259 return;
260
261 /* Stop taking in new requests */
262 spin_lock_irq(q->queue_lock);
263 blk_stop_queue(q);
264
265 /* drain all requests in the queue */
266 while (1) {
267 /* need the lock to fetch a request
268 * this may fetch the same reqeust as the previous pass
269 */
270 req = blk_fetch_request(q);
271 /* save requests in use and starved */
272 counts = q->rq.count[0] + q->rq.count[1] +
273 q->rq.starved[0] + q->rq.starved[1];
274 spin_unlock_irq(q->queue_lock);
275 /* any requests still outstanding? */
276 if (counts == 0)
277 break;
278
279 /* This may be the same req as the previous iteration,
280 * always send the blk_end_request_all after a prefetch.
281 * It is not okay to not end the request because the
282 * prefetch started the request.
283 */
284 if (req) {
285 /* return -ENXIO to indicate that this queue is
286 * going away
287 */
288 req->errors = -ENXIO;
289 blk_end_request_all(req, -ENXIO);
290 }
291
292 msleep(200); /* allow bsg to possibly finish */
293 spin_lock_irq(q->queue_lock);
294 }
295 bsg_unregister_queue(q);
296}
297EXPORT_SYMBOL_GPL(bsg_remove_queue);