Root/block/bsg-lib.c

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 <linux/export.h>
29#include <scsi/scsi_cmnd.h>
30
31/**
32 * bsg_destroy_job - routine to teardown/delete a bsg job
33 * @job: bsg_job that is to be torn down
34 */
35static void bsg_destroy_job(struct bsg_job *job)
36{
37    put_device(job->dev); /* release reference for the request */
38
39    kfree(job->request_payload.sg_list);
40    kfree(job->reply_payload.sg_list);
41    kfree(job);
42}
43
44/**
45 * bsg_job_done - completion routine for bsg requests
46 * @job: bsg_job that is complete
47 * @result: job reply result
48 * @reply_payload_rcv_len: length of payload recvd
49 *
50 * The LLD should call this when the bsg job has completed.
51 */
52void bsg_job_done(struct bsg_job *job, int result,
53          unsigned int reply_payload_rcv_len)
54{
55    struct request *req = job->req;
56    struct request *rsp = req->next_rq;
57    int err;
58
59    err = job->req->errors = result;
60    if (err < 0)
61        /* we're only returning the result field in the reply */
62        job->req->sense_len = sizeof(u32);
63    else
64        job->req->sense_len = job->reply_len;
65    /* we assume all request payload was transferred, residual == 0 */
66    req->resid_len = 0;
67
68    if (rsp) {
69        WARN_ON(reply_payload_rcv_len > rsp->resid_len);
70
71        /* set reply (bidi) residual */
72        rsp->resid_len -= min(reply_payload_rcv_len, rsp->resid_len);
73    }
74    blk_complete_request(req);
75}
76EXPORT_SYMBOL_GPL(bsg_job_done);
77
78/**
79 * bsg_softirq_done - softirq done routine for destroying the bsg requests
80 * @rq: BSG request that holds the job to be destroyed
81 */
82static void bsg_softirq_done(struct request *rq)
83{
84    struct bsg_job *job = rq->special;
85
86    blk_end_request_all(rq, rq->errors);
87    bsg_destroy_job(job);
88}
89
90static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
91{
92    size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
93
94    BUG_ON(!req->nr_phys_segments);
95
96    buf->sg_list = kzalloc(sz, GFP_KERNEL);
97    if (!buf->sg_list)
98        return -ENOMEM;
99    sg_init_table(buf->sg_list, req->nr_phys_segments);
100    buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
101    buf->payload_len = blk_rq_bytes(req);
102    return 0;
103}
104
105/**
106 * bsg_create_job - create the bsg_job structure for the bsg request
107 * @dev: device that is being sent the bsg request
108 * @req: BSG request that needs a job structure
109 */
110static int bsg_create_job(struct device *dev, struct request *req)
111{
112    struct request *rsp = req->next_rq;
113    struct request_queue *q = req->q;
114    struct bsg_job *job;
115    int ret;
116
117    BUG_ON(req->special);
118
119    job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
120    if (!job)
121        return -ENOMEM;
122
123    req->special = job;
124    job->req = req;
125    if (q->bsg_job_size)
126        job->dd_data = (void *)&job[1];
127    job->request = req->cmd;
128    job->request_len = req->cmd_len;
129    job->reply = req->sense;
130    job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
131                         * allocated */
132    if (req->bio) {
133        ret = bsg_map_buffer(&job->request_payload, req);
134        if (ret)
135            goto failjob_rls_job;
136    }
137    if (rsp && rsp->bio) {
138        ret = bsg_map_buffer(&job->reply_payload, rsp);
139        if (ret)
140            goto failjob_rls_rqst_payload;
141    }
142    job->dev = dev;
143    /* take a reference for the request */
144    get_device(job->dev);
145    return 0;
146
147failjob_rls_rqst_payload:
148    kfree(job->request_payload.sg_list);
149failjob_rls_job:
150    kfree(job);
151    return -ENOMEM;
152}
153
154/**
155 * bsg_request_fn - generic handler for bsg requests
156 * @q: request queue to manage
157 *
158 * On error the create_bsg_job function should return a -Exyz error value
159 * that will be set to the req->errors.
160 *
161 * Drivers/subsys should pass this to the queue init function.
162 */
163void bsg_request_fn(struct request_queue *q)
164{
165    struct device *dev = q->queuedata;
166    struct request *req;
167    struct bsg_job *job;
168    int ret;
169
170    if (!get_device(dev))
171        return;
172
173    while (1) {
174        req = blk_fetch_request(q);
175        if (!req)
176            break;
177        spin_unlock_irq(q->queue_lock);
178
179        ret = bsg_create_job(dev, req);
180        if (ret) {
181            req->errors = ret;
182            blk_end_request_all(req, ret);
183            spin_lock_irq(q->queue_lock);
184            continue;
185        }
186
187        job = req->special;
188        ret = q->bsg_job_fn(job);
189        spin_lock_irq(q->queue_lock);
190        if (ret)
191            break;
192    }
193
194    spin_unlock_irq(q->queue_lock);
195    put_device(dev);
196    spin_lock_irq(q->queue_lock);
197}
198EXPORT_SYMBOL_GPL(bsg_request_fn);
199
200/**
201 * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
202 * @dev: device to attach bsg device to
203 * @q: request queue setup by caller
204 * @name: device to give bsg device
205 * @job_fn: bsg job handler
206 * @dd_job_size: size of LLD data needed for each job
207 *
208 * The caller should have setup the reuqest queue with bsg_request_fn
209 * as the request_fn.
210 */
211int bsg_setup_queue(struct device *dev, struct request_queue *q,
212            char *name, bsg_job_fn *job_fn, int dd_job_size)
213{
214    int ret;
215
216    q->queuedata = dev;
217    q->bsg_job_size = dd_job_size;
218    q->bsg_job_fn = job_fn;
219    queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
220    blk_queue_softirq_done(q, bsg_softirq_done);
221    blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
222
223    ret = bsg_register_queue(q, dev, name, NULL);
224    if (ret) {
225        printk(KERN_ERR "%s: bsg interface failed to "
226               "initialize - register queue\n", dev->kobj.name);
227        return ret;
228    }
229
230    return 0;
231}
232EXPORT_SYMBOL_GPL(bsg_setup_queue);
233

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