Root/block/bsg.c

1/*
2 * bsg.c - block layer implementation of the sg v4 interface
3 *
4 * Copyright (C) 2004 Jens Axboe <axboe@suse.de> SUSE Labs
5 * Copyright (C) 2004 Peter M. Jones <pjones@redhat.com>
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License version 2. See the file "COPYING" in the main directory of this
9 * archive for more details.
10 *
11 */
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/file.h>
15#include <linux/blkdev.h>
16#include <linux/poll.h>
17#include <linux/cdev.h>
18#include <linux/jiffies.h>
19#include <linux/percpu.h>
20#include <linux/uio.h>
21#include <linux/idr.h>
22#include <linux/bsg.h>
23#include <linux/smp_lock.h>
24#include <linux/slab.h>
25
26#include <scsi/scsi.h>
27#include <scsi/scsi_ioctl.h>
28#include <scsi/scsi_cmnd.h>
29#include <scsi/scsi_device.h>
30#include <scsi/scsi_driver.h>
31#include <scsi/sg.h>
32
33#define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
34#define BSG_VERSION "0.4"
35
36struct bsg_device {
37    struct request_queue *queue;
38    spinlock_t lock;
39    struct list_head busy_list;
40    struct list_head done_list;
41    struct hlist_node dev_list;
42    atomic_t ref_count;
43    int queued_cmds;
44    int done_cmds;
45    wait_queue_head_t wq_done;
46    wait_queue_head_t wq_free;
47    char name[20];
48    int max_queue;
49    unsigned long flags;
50};
51
52enum {
53    BSG_F_BLOCK = 1,
54};
55
56#define BSG_DEFAULT_CMDS 64
57#define BSG_MAX_DEVS 32768
58
59#undef BSG_DEBUG
60
61#ifdef BSG_DEBUG
62#define dprintk(fmt, args...) printk(KERN_ERR "%s: " fmt, __func__, ##args)
63#else
64#define dprintk(fmt, args...)
65#endif
66
67static DEFINE_MUTEX(bsg_mutex);
68static DEFINE_IDR(bsg_minor_idr);
69
70#define BSG_LIST_ARRAY_SIZE 8
71static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
72
73static struct class *bsg_class;
74static int bsg_major;
75
76static struct kmem_cache *bsg_cmd_cachep;
77
78/*
79 * our internal command type
80 */
81struct bsg_command {
82    struct bsg_device *bd;
83    struct list_head list;
84    struct request *rq;
85    struct bio *bio;
86    struct bio *bidi_bio;
87    int err;
88    struct sg_io_v4 hdr;
89    char sense[SCSI_SENSE_BUFFERSIZE];
90};
91
92static void bsg_free_command(struct bsg_command *bc)
93{
94    struct bsg_device *bd = bc->bd;
95    unsigned long flags;
96
97    kmem_cache_free(bsg_cmd_cachep, bc);
98
99    spin_lock_irqsave(&bd->lock, flags);
100    bd->queued_cmds--;
101    spin_unlock_irqrestore(&bd->lock, flags);
102
103    wake_up(&bd->wq_free);
104}
105
106static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
107{
108    struct bsg_command *bc = ERR_PTR(-EINVAL);
109
110    spin_lock_irq(&bd->lock);
111
112    if (bd->queued_cmds >= bd->max_queue)
113        goto out;
114
115    bd->queued_cmds++;
116    spin_unlock_irq(&bd->lock);
117
118    bc = kmem_cache_zalloc(bsg_cmd_cachep, GFP_KERNEL);
119    if (unlikely(!bc)) {
120        spin_lock_irq(&bd->lock);
121        bd->queued_cmds--;
122        bc = ERR_PTR(-ENOMEM);
123        goto out;
124    }
125
126    bc->bd = bd;
127    INIT_LIST_HEAD(&bc->list);
128    dprintk("%s: returning free cmd %p\n", bd->name, bc);
129    return bc;
130out:
131    spin_unlock_irq(&bd->lock);
132    return bc;
133}
134
135static inline struct hlist_head *bsg_dev_idx_hash(int index)
136{
137    return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
138}
139
140static int bsg_io_schedule(struct bsg_device *bd)
141{
142    DEFINE_WAIT(wait);
143    int ret = 0;
144
145    spin_lock_irq(&bd->lock);
146
147    BUG_ON(bd->done_cmds > bd->queued_cmds);
148
149    /*
150     * -ENOSPC or -ENODATA? I'm going for -ENODATA, meaning "I have no
151     * work to do", even though we return -ENOSPC after this same test
152     * during bsg_write() -- there, it means our buffer can't have more
153     * bsg_commands added to it, thus has no space left.
154     */
155    if (bd->done_cmds == bd->queued_cmds) {
156        ret = -ENODATA;
157        goto unlock;
158    }
159
160    if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
161        ret = -EAGAIN;
162        goto unlock;
163    }
164
165    prepare_to_wait(&bd->wq_done, &wait, TASK_UNINTERRUPTIBLE);
166    spin_unlock_irq(&bd->lock);
167    io_schedule();
168    finish_wait(&bd->wq_done, &wait);
169
170    return ret;
171unlock:
172    spin_unlock_irq(&bd->lock);
173    return ret;
174}
175
176static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
177                struct sg_io_v4 *hdr, struct bsg_device *bd,
178                fmode_t has_write_perm)
179{
180    if (hdr->request_len > BLK_MAX_CDB) {
181        rq->cmd = kzalloc(hdr->request_len, GFP_KERNEL);
182        if (!rq->cmd)
183            return -ENOMEM;
184    }
185
186    if (copy_from_user(rq->cmd, (void *)(unsigned long)hdr->request,
187               hdr->request_len))
188        return -EFAULT;
189
190    if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
191        if (blk_verify_command(rq->cmd, has_write_perm))
192            return -EPERM;
193    } else if (!capable(CAP_SYS_RAWIO))
194        return -EPERM;
195
196    /*
197     * fill in request structure
198     */
199    rq->cmd_len = hdr->request_len;
200    rq->cmd_type = REQ_TYPE_BLOCK_PC;
201
202    rq->timeout = msecs_to_jiffies(hdr->timeout);
203    if (!rq->timeout)
204        rq->timeout = q->sg_timeout;
205    if (!rq->timeout)
206        rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
207    if (rq->timeout < BLK_MIN_SG_TIMEOUT)
208        rq->timeout = BLK_MIN_SG_TIMEOUT;
209
210    return 0;
211}
212
213/*
214 * Check if sg_io_v4 from user is allowed and valid
215 */
216static int
217bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
218{
219    int ret = 0;
220
221    if (hdr->guard != 'Q')
222        return -EINVAL;
223
224    switch (hdr->protocol) {
225    case BSG_PROTOCOL_SCSI:
226        switch (hdr->subprotocol) {
227        case BSG_SUB_PROTOCOL_SCSI_CMD:
228        case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
229            break;
230        default:
231            ret = -EINVAL;
232        }
233        break;
234    default:
235        ret = -EINVAL;
236    }
237
238    *rw = hdr->dout_xfer_len ? WRITE : READ;
239    return ret;
240}
241
242/*
243 * map sg_io_v4 to a request.
244 */
245static struct request *
246bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
247        u8 *sense)
248{
249    struct request_queue *q = bd->queue;
250    struct request *rq, *next_rq = NULL;
251    int ret, rw;
252    unsigned int dxfer_len;
253    void *dxferp = NULL;
254
255    dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
256        hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
257        hdr->din_xfer_len);
258
259    ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
260    if (ret)
261        return ERR_PTR(ret);
262
263    /*
264     * map scatter-gather elements separately and string them to request
265     */
266    rq = blk_get_request(q, rw, GFP_KERNEL);
267    if (!rq)
268        return ERR_PTR(-ENOMEM);
269    ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
270    if (ret)
271        goto out;
272
273    if (rw == WRITE && hdr->din_xfer_len) {
274        if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
275            ret = -EOPNOTSUPP;
276            goto out;
277        }
278
279        next_rq = blk_get_request(q, READ, GFP_KERNEL);
280        if (!next_rq) {
281            ret = -ENOMEM;
282            goto out;
283        }
284        rq->next_rq = next_rq;
285        next_rq->cmd_type = rq->cmd_type;
286
287        dxferp = (void*)(unsigned long)hdr->din_xferp;
288        ret = blk_rq_map_user(q, next_rq, NULL, dxferp,
289                       hdr->din_xfer_len, GFP_KERNEL);
290        if (ret)
291            goto out;
292    }
293
294    if (hdr->dout_xfer_len) {
295        dxfer_len = hdr->dout_xfer_len;
296        dxferp = (void*)(unsigned long)hdr->dout_xferp;
297    } else if (hdr->din_xfer_len) {
298        dxfer_len = hdr->din_xfer_len;
299        dxferp = (void*)(unsigned long)hdr->din_xferp;
300    } else
301        dxfer_len = 0;
302
303    if (dxfer_len) {
304        ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
305                      GFP_KERNEL);
306        if (ret)
307            goto out;
308    }
309
310    rq->sense = sense;
311    rq->sense_len = 0;
312
313    return rq;
314out:
315    if (rq->cmd != rq->__cmd)
316        kfree(rq->cmd);
317    blk_put_request(rq);
318    if (next_rq) {
319        blk_rq_unmap_user(next_rq->bio);
320        blk_put_request(next_rq);
321    }
322    return ERR_PTR(ret);
323}
324
325/*
326 * async completion call-back from the block layer, when scsi/ide/whatever
327 * calls end_that_request_last() on a request
328 */
329static void bsg_rq_end_io(struct request *rq, int uptodate)
330{
331    struct bsg_command *bc = rq->end_io_data;
332    struct bsg_device *bd = bc->bd;
333    unsigned long flags;
334
335    dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
336        bd->name, rq, bc, bc->bio, uptodate);
337
338    bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
339
340    spin_lock_irqsave(&bd->lock, flags);
341    list_move_tail(&bc->list, &bd->done_list);
342    bd->done_cmds++;
343    spin_unlock_irqrestore(&bd->lock, flags);
344
345    wake_up(&bd->wq_done);
346}
347
348/*
349 * do final setup of a 'bc' and submit the matching 'rq' to the block
350 * layer for io
351 */
352static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
353                struct bsg_command *bc, struct request *rq)
354{
355    int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
356
357    /*
358     * add bc command to busy queue and submit rq for io
359     */
360    bc->rq = rq;
361    bc->bio = rq->bio;
362    if (rq->next_rq)
363        bc->bidi_bio = rq->next_rq->bio;
364    bc->hdr.duration = jiffies;
365    spin_lock_irq(&bd->lock);
366    list_add_tail(&bc->list, &bd->busy_list);
367    spin_unlock_irq(&bd->lock);
368
369    dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
370
371    rq->end_io_data = bc;
372    blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
373}
374
375static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
376{
377    struct bsg_command *bc = NULL;
378
379    spin_lock_irq(&bd->lock);
380    if (bd->done_cmds) {
381        bc = list_first_entry(&bd->done_list, struct bsg_command, list);
382        list_del(&bc->list);
383        bd->done_cmds--;
384    }
385    spin_unlock_irq(&bd->lock);
386
387    return bc;
388}
389
390/*
391 * Get a finished command from the done list
392 */
393static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
394{
395    struct bsg_command *bc;
396    int ret;
397
398    do {
399        bc = bsg_next_done_cmd(bd);
400        if (bc)
401            break;
402
403        if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
404            bc = ERR_PTR(-EAGAIN);
405            break;
406        }
407
408        ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
409        if (ret) {
410            bc = ERR_PTR(-ERESTARTSYS);
411            break;
412        }
413    } while (1);
414
415    dprintk("%s: returning done %p\n", bd->name, bc);
416
417    return bc;
418}
419
420static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
421                    struct bio *bio, struct bio *bidi_bio)
422{
423    int ret = 0;
424
425    dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
426    /*
427     * fill in all the output members
428     */
429    hdr->device_status = status_byte(rq->errors);
430    hdr->transport_status = host_byte(rq->errors);
431    hdr->driver_status = driver_byte(rq->errors);
432    hdr->info = 0;
433    if (hdr->device_status || hdr->transport_status || hdr->driver_status)
434        hdr->info |= SG_INFO_CHECK;
435    hdr->response_len = 0;
436
437    if (rq->sense_len && hdr->response) {
438        int len = min_t(unsigned int, hdr->max_response_len,
439                    rq->sense_len);
440
441        ret = copy_to_user((void*)(unsigned long)hdr->response,
442                   rq->sense, len);
443        if (!ret)
444            hdr->response_len = len;
445        else
446            ret = -EFAULT;
447    }
448
449    if (rq->next_rq) {
450        hdr->dout_resid = rq->resid_len;
451        hdr->din_resid = rq->next_rq->resid_len;
452        blk_rq_unmap_user(bidi_bio);
453        blk_put_request(rq->next_rq);
454    } else if (rq_data_dir(rq) == READ)
455        hdr->din_resid = rq->resid_len;
456    else
457        hdr->dout_resid = rq->resid_len;
458
459    /*
460     * If the request generated a negative error number, return it
461     * (providing we aren't already returning an error); if it's
462     * just a protocol response (i.e. non negative), that gets
463     * processed above.
464     */
465    if (!ret && rq->errors < 0)
466        ret = rq->errors;
467
468    blk_rq_unmap_user(bio);
469    if (rq->cmd != rq->__cmd)
470        kfree(rq->cmd);
471    blk_put_request(rq);
472
473    return ret;
474}
475
476static int bsg_complete_all_commands(struct bsg_device *bd)
477{
478    struct bsg_command *bc;
479    int ret, tret;
480
481    dprintk("%s: entered\n", bd->name);
482
483    /*
484     * wait for all commands to complete
485     */
486    ret = 0;
487    do {
488        ret = bsg_io_schedule(bd);
489        /*
490         * look for -ENODATA specifically -- we'll sometimes get
491         * -ERESTARTSYS when we've taken a signal, but we can't
492         * return until we're done freeing the queue, so ignore
493         * it. The signal will get handled when we're done freeing
494         * the bsg_device.
495         */
496    } while (ret != -ENODATA);
497
498    /*
499     * discard done commands
500     */
501    ret = 0;
502    do {
503        spin_lock_irq(&bd->lock);
504        if (!bd->queued_cmds) {
505            spin_unlock_irq(&bd->lock);
506            break;
507        }
508        spin_unlock_irq(&bd->lock);
509
510        bc = bsg_get_done_cmd(bd);
511        if (IS_ERR(bc))
512            break;
513
514        tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
515                        bc->bidi_bio);
516        if (!ret)
517            ret = tret;
518
519        bsg_free_command(bc);
520    } while (1);
521
522    return ret;
523}
524
525static int
526__bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
527       const struct iovec *iov, ssize_t *bytes_read)
528{
529    struct bsg_command *bc;
530    int nr_commands, ret;
531
532    if (count % sizeof(struct sg_io_v4))
533        return -EINVAL;
534
535    ret = 0;
536    nr_commands = count / sizeof(struct sg_io_v4);
537    while (nr_commands) {
538        bc = bsg_get_done_cmd(bd);
539        if (IS_ERR(bc)) {
540            ret = PTR_ERR(bc);
541            break;
542        }
543
544        /*
545         * this is the only case where we need to copy data back
546         * after completing the request. so do that here,
547         * bsg_complete_work() cannot do that for us
548         */
549        ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
550                           bc->bidi_bio);
551
552        if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
553            ret = -EFAULT;
554
555        bsg_free_command(bc);
556
557        if (ret)
558            break;
559
560        buf += sizeof(struct sg_io_v4);
561        *bytes_read += sizeof(struct sg_io_v4);
562        nr_commands--;
563    }
564
565    return ret;
566}
567
568static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
569{
570    if (file->f_flags & O_NONBLOCK)
571        clear_bit(BSG_F_BLOCK, &bd->flags);
572    else
573        set_bit(BSG_F_BLOCK, &bd->flags);
574}
575
576/*
577 * Check if the error is a "real" error that we should return.
578 */
579static inline int err_block_err(int ret)
580{
581    if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
582        return 1;
583
584    return 0;
585}
586
587static ssize_t
588bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
589{
590    struct bsg_device *bd = file->private_data;
591    int ret;
592    ssize_t bytes_read;
593
594    dprintk("%s: read %Zd bytes\n", bd->name, count);
595
596    bsg_set_block(bd, file);
597
598    bytes_read = 0;
599    ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
600    *ppos = bytes_read;
601
602    if (!bytes_read || (bytes_read && err_block_err(ret)))
603        bytes_read = ret;
604
605    return bytes_read;
606}
607
608static int __bsg_write(struct bsg_device *bd, const char __user *buf,
609               size_t count, ssize_t *bytes_written,
610               fmode_t has_write_perm)
611{
612    struct bsg_command *bc;
613    struct request *rq;
614    int ret, nr_commands;
615
616    if (count % sizeof(struct sg_io_v4))
617        return -EINVAL;
618
619    nr_commands = count / sizeof(struct sg_io_v4);
620    rq = NULL;
621    bc = NULL;
622    ret = 0;
623    while (nr_commands) {
624        struct request_queue *q = bd->queue;
625
626        bc = bsg_alloc_command(bd);
627        if (IS_ERR(bc)) {
628            ret = PTR_ERR(bc);
629            bc = NULL;
630            break;
631        }
632
633        if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
634            ret = -EFAULT;
635            break;
636        }
637
638        /*
639         * get a request, fill in the blanks, and add to request queue
640         */
641        rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
642        if (IS_ERR(rq)) {
643            ret = PTR_ERR(rq);
644            rq = NULL;
645            break;
646        }
647
648        bsg_add_command(bd, q, bc, rq);
649        bc = NULL;
650        rq = NULL;
651        nr_commands--;
652        buf += sizeof(struct sg_io_v4);
653        *bytes_written += sizeof(struct sg_io_v4);
654    }
655
656    if (bc)
657        bsg_free_command(bc);
658
659    return ret;
660}
661
662static ssize_t
663bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
664{
665    struct bsg_device *bd = file->private_data;
666    ssize_t bytes_written;
667    int ret;
668
669    dprintk("%s: write %Zd bytes\n", bd->name, count);
670
671    bsg_set_block(bd, file);
672
673    bytes_written = 0;
674    ret = __bsg_write(bd, buf, count, &bytes_written,
675              file->f_mode & FMODE_WRITE);
676
677    *ppos = bytes_written;
678
679    /*
680     * return bytes written on non-fatal errors
681     */
682    if (!bytes_written || (bytes_written && err_block_err(ret)))
683        bytes_written = ret;
684
685    dprintk("%s: returning %Zd\n", bd->name, bytes_written);
686    return bytes_written;
687}
688
689static struct bsg_device *bsg_alloc_device(void)
690{
691    struct bsg_device *bd;
692
693    bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
694    if (unlikely(!bd))
695        return NULL;
696
697    spin_lock_init(&bd->lock);
698
699    bd->max_queue = BSG_DEFAULT_CMDS;
700
701    INIT_LIST_HEAD(&bd->busy_list);
702    INIT_LIST_HEAD(&bd->done_list);
703    INIT_HLIST_NODE(&bd->dev_list);
704
705    init_waitqueue_head(&bd->wq_free);
706    init_waitqueue_head(&bd->wq_done);
707    return bd;
708}
709
710static void bsg_kref_release_function(struct kref *kref)
711{
712    struct bsg_class_device *bcd =
713        container_of(kref, struct bsg_class_device, ref);
714    struct device *parent = bcd->parent;
715
716    if (bcd->release)
717        bcd->release(bcd->parent);
718
719    put_device(parent);
720}
721
722static int bsg_put_device(struct bsg_device *bd)
723{
724    int ret = 0, do_free;
725    struct request_queue *q = bd->queue;
726
727    mutex_lock(&bsg_mutex);
728
729    do_free = atomic_dec_and_test(&bd->ref_count);
730    if (!do_free) {
731        mutex_unlock(&bsg_mutex);
732        goto out;
733    }
734
735    hlist_del(&bd->dev_list);
736    mutex_unlock(&bsg_mutex);
737
738    dprintk("%s: tearing down\n", bd->name);
739
740    /*
741     * close can always block
742     */
743    set_bit(BSG_F_BLOCK, &bd->flags);
744
745    /*
746     * correct error detection baddies here again. it's the responsibility
747     * of the app to properly reap commands before close() if it wants
748     * fool-proof error detection
749     */
750    ret = bsg_complete_all_commands(bd);
751
752    kfree(bd);
753out:
754    kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
755    if (do_free)
756        blk_put_queue(q);
757    return ret;
758}
759
760static struct bsg_device *bsg_add_device(struct inode *inode,
761                     struct request_queue *rq,
762                     struct file *file)
763{
764    struct bsg_device *bd;
765    int ret;
766#ifdef BSG_DEBUG
767    unsigned char buf[32];
768#endif
769    ret = blk_get_queue(rq);
770    if (ret)
771        return ERR_PTR(-ENXIO);
772
773    bd = bsg_alloc_device();
774    if (!bd) {
775        blk_put_queue(rq);
776        return ERR_PTR(-ENOMEM);
777    }
778
779    bd->queue = rq;
780
781    bsg_set_block(bd, file);
782
783    atomic_set(&bd->ref_count, 1);
784    mutex_lock(&bsg_mutex);
785    hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
786
787    strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
788    dprintk("bound to <%s>, max queue %d\n",
789        format_dev_t(buf, inode->i_rdev), bd->max_queue);
790
791    mutex_unlock(&bsg_mutex);
792    return bd;
793}
794
795static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
796{
797    struct bsg_device *bd;
798    struct hlist_node *entry;
799
800    mutex_lock(&bsg_mutex);
801
802    hlist_for_each_entry(bd, entry, bsg_dev_idx_hash(minor), dev_list) {
803        if (bd->queue == q) {
804            atomic_inc(&bd->ref_count);
805            goto found;
806        }
807    }
808    bd = NULL;
809found:
810    mutex_unlock(&bsg_mutex);
811    return bd;
812}
813
814static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
815{
816    struct bsg_device *bd;
817    struct bsg_class_device *bcd;
818
819    /*
820     * find the class device
821     */
822    mutex_lock(&bsg_mutex);
823    bcd = idr_find(&bsg_minor_idr, iminor(inode));
824    if (bcd)
825        kref_get(&bcd->ref);
826    mutex_unlock(&bsg_mutex);
827
828    if (!bcd)
829        return ERR_PTR(-ENODEV);
830
831    bd = __bsg_get_device(iminor(inode), bcd->queue);
832    if (bd)
833        return bd;
834
835    bd = bsg_add_device(inode, bcd->queue, file);
836    if (IS_ERR(bd))
837        kref_put(&bcd->ref, bsg_kref_release_function);
838
839    return bd;
840}
841
842static int bsg_open(struct inode *inode, struct file *file)
843{
844    struct bsg_device *bd;
845
846    lock_kernel();
847    bd = bsg_get_device(inode, file);
848    unlock_kernel();
849
850    if (IS_ERR(bd))
851        return PTR_ERR(bd);
852
853    file->private_data = bd;
854    return 0;
855}
856
857static int bsg_release(struct inode *inode, struct file *file)
858{
859    struct bsg_device *bd = file->private_data;
860
861    file->private_data = NULL;
862    return bsg_put_device(bd);
863}
864
865static unsigned int bsg_poll(struct file *file, poll_table *wait)
866{
867    struct bsg_device *bd = file->private_data;
868    unsigned int mask = 0;
869
870    poll_wait(file, &bd->wq_done, wait);
871    poll_wait(file, &bd->wq_free, wait);
872
873    spin_lock_irq(&bd->lock);
874    if (!list_empty(&bd->done_list))
875        mask |= POLLIN | POLLRDNORM;
876    if (bd->queued_cmds >= bd->max_queue)
877        mask |= POLLOUT;
878    spin_unlock_irq(&bd->lock);
879
880    return mask;
881}
882
883static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
884{
885    struct bsg_device *bd = file->private_data;
886    int __user *uarg = (int __user *) arg;
887    int ret;
888
889    switch (cmd) {
890        /*
891         * our own ioctls
892         */
893    case SG_GET_COMMAND_Q:
894        return put_user(bd->max_queue, uarg);
895    case SG_SET_COMMAND_Q: {
896        int queue;
897
898        if (get_user(queue, uarg))
899            return -EFAULT;
900        if (queue < 1)
901            return -EINVAL;
902
903        spin_lock_irq(&bd->lock);
904        bd->max_queue = queue;
905        spin_unlock_irq(&bd->lock);
906        return 0;
907    }
908
909    /*
910     * SCSI/sg ioctls
911     */
912    case SG_GET_VERSION_NUM:
913    case SCSI_IOCTL_GET_IDLUN:
914    case SCSI_IOCTL_GET_BUS_NUMBER:
915    case SG_SET_TIMEOUT:
916    case SG_GET_TIMEOUT:
917    case SG_GET_RESERVED_SIZE:
918    case SG_SET_RESERVED_SIZE:
919    case SG_EMULATED_HOST:
920    case SCSI_IOCTL_SEND_COMMAND: {
921        void __user *uarg = (void __user *) arg;
922        return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
923    }
924    case SG_IO: {
925        struct request *rq;
926        struct bio *bio, *bidi_bio = NULL;
927        struct sg_io_v4 hdr;
928        int at_head;
929        u8 sense[SCSI_SENSE_BUFFERSIZE];
930
931        if (copy_from_user(&hdr, uarg, sizeof(hdr)))
932            return -EFAULT;
933
934        rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
935        if (IS_ERR(rq))
936            return PTR_ERR(rq);
937
938        bio = rq->bio;
939        if (rq->next_rq)
940            bidi_bio = rq->next_rq->bio;
941
942        at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
943        blk_execute_rq(bd->queue, NULL, rq, at_head);
944        ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
945
946        if (copy_to_user(uarg, &hdr, sizeof(hdr)))
947            return -EFAULT;
948
949        return ret;
950    }
951    /*
952     * block device ioctls
953     */
954    default:
955#if 0
956        return ioctl_by_bdev(bd->bdev, cmd, arg);
957#else
958        return -ENOTTY;
959#endif
960    }
961}
962
963static const struct file_operations bsg_fops = {
964    .read = bsg_read,
965    .write = bsg_write,
966    .poll = bsg_poll,
967    .open = bsg_open,
968    .release = bsg_release,
969    .unlocked_ioctl = bsg_ioctl,
970    .owner = THIS_MODULE,
971};
972
973void bsg_unregister_queue(struct request_queue *q)
974{
975    struct bsg_class_device *bcd = &q->bsg_dev;
976
977    if (!bcd->class_dev)
978        return;
979
980    mutex_lock(&bsg_mutex);
981    idr_remove(&bsg_minor_idr, bcd->minor);
982    sysfs_remove_link(&q->kobj, "bsg");
983    device_unregister(bcd->class_dev);
984    bcd->class_dev = NULL;
985    kref_put(&bcd->ref, bsg_kref_release_function);
986    mutex_unlock(&bsg_mutex);
987}
988EXPORT_SYMBOL_GPL(bsg_unregister_queue);
989
990int bsg_register_queue(struct request_queue *q, struct device *parent,
991               const char *name, void (*release)(struct device *))
992{
993    struct bsg_class_device *bcd;
994    dev_t dev;
995    int ret, minor;
996    struct device *class_dev = NULL;
997    const char *devname;
998
999    if (name)
1000        devname = name;
1001    else
1002        devname = dev_name(parent);
1003
1004    /*
1005     * we need a proper transport to send commands, not a stacked device
1006     */
1007    if (!q->request_fn)
1008        return 0;
1009
1010    bcd = &q->bsg_dev;
1011    memset(bcd, 0, sizeof(*bcd));
1012
1013    mutex_lock(&bsg_mutex);
1014
1015    ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
1016    if (!ret) {
1017        ret = -ENOMEM;
1018        goto unlock;
1019    }
1020
1021    ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
1022    if (ret < 0)
1023        goto unlock;
1024
1025    if (minor >= BSG_MAX_DEVS) {
1026        printk(KERN_ERR "bsg: too many bsg devices\n");
1027        ret = -EINVAL;
1028        goto remove_idr;
1029    }
1030
1031    bcd->minor = minor;
1032    bcd->queue = q;
1033    bcd->parent = get_device(parent);
1034    bcd->release = release;
1035    kref_init(&bcd->ref);
1036    dev = MKDEV(bsg_major, bcd->minor);
1037    class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1038    if (IS_ERR(class_dev)) {
1039        ret = PTR_ERR(class_dev);
1040        goto put_dev;
1041    }
1042    bcd->class_dev = class_dev;
1043
1044    if (q->kobj.sd) {
1045        ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1046        if (ret)
1047            goto unregister_class_dev;
1048    }
1049
1050    mutex_unlock(&bsg_mutex);
1051    return 0;
1052
1053unregister_class_dev:
1054    device_unregister(class_dev);
1055put_dev:
1056    put_device(parent);
1057remove_idr:
1058    idr_remove(&bsg_minor_idr, minor);
1059unlock:
1060    mutex_unlock(&bsg_mutex);
1061    return ret;
1062}
1063EXPORT_SYMBOL_GPL(bsg_register_queue);
1064
1065static struct cdev bsg_cdev;
1066
1067static char *bsg_devnode(struct device *dev, mode_t *mode)
1068{
1069    return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
1070}
1071
1072static int __init bsg_init(void)
1073{
1074    int ret, i;
1075    dev_t devid;
1076
1077    bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1078                sizeof(struct bsg_command), 0, 0, NULL);
1079    if (!bsg_cmd_cachep) {
1080        printk(KERN_ERR "bsg: failed creating slab cache\n");
1081        return -ENOMEM;
1082    }
1083
1084    for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1085        INIT_HLIST_HEAD(&bsg_device_list[i]);
1086
1087    bsg_class = class_create(THIS_MODULE, "bsg");
1088    if (IS_ERR(bsg_class)) {
1089        ret = PTR_ERR(bsg_class);
1090        goto destroy_kmemcache;
1091    }
1092    bsg_class->devnode = bsg_devnode;
1093
1094    ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1095    if (ret)
1096        goto destroy_bsg_class;
1097
1098    bsg_major = MAJOR(devid);
1099
1100    cdev_init(&bsg_cdev, &bsg_fops);
1101    ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1102    if (ret)
1103        goto unregister_chrdev;
1104
1105    printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1106           " loaded (major %d)\n", bsg_major);
1107    return 0;
1108unregister_chrdev:
1109    unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1110destroy_bsg_class:
1111    class_destroy(bsg_class);
1112destroy_kmemcache:
1113    kmem_cache_destroy(bsg_cmd_cachep);
1114    return ret;
1115}
1116
1117MODULE_AUTHOR("Jens Axboe");
1118MODULE_DESCRIPTION(BSG_DESCRIPTION);
1119MODULE_LICENSE("GPL");
1120
1121device_initcall(bsg_init);
1122

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