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/slab.h>
24
25#include <scsi/scsi.h>
26#include <scsi/scsi_ioctl.h>
27#include <scsi/scsi_cmnd.h>
28#include <scsi/scsi_device.h>
29#include <scsi/scsi_driver.h>
30#include <scsi/sg.h>
31
32#define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
33#define BSG_VERSION "0.4"
34
35struct bsg_device {
36    struct request_queue *queue;
37    spinlock_t lock;
38    struct list_head busy_list;
39    struct list_head done_list;
40    struct hlist_node dev_list;
41    atomic_t ref_count;
42    int queued_cmds;
43    int done_cmds;
44    wait_queue_head_t wq_done;
45    wait_queue_head_t wq_free;
46    char name[20];
47    int max_queue;
48    unsigned long flags;
49};
50
51enum {
52    BSG_F_BLOCK = 1,
53};
54
55#define BSG_DEFAULT_CMDS 64
56#define BSG_MAX_DEVS 32768
57
58#undef BSG_DEBUG
59
60#ifdef BSG_DEBUG
61#define dprintk(fmt, args...) printk(KERN_ERR "%s: " fmt, __func__, ##args)
62#else
63#define dprintk(fmt, args...)
64#endif
65
66static DEFINE_MUTEX(bsg_mutex);
67static DEFINE_IDR(bsg_minor_idr);
68
69#define BSG_LIST_ARRAY_SIZE 8
70static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
71
72static struct class *bsg_class;
73static int bsg_major;
74
75static struct kmem_cache *bsg_cmd_cachep;
76
77/*
78 * our internal command type
79 */
80struct bsg_command {
81    struct bsg_device *bd;
82    struct list_head list;
83    struct request *rq;
84    struct bio *bio;
85    struct bio *bidi_bio;
86    int err;
87    struct sg_io_v4 hdr;
88    char sense[SCSI_SENSE_BUFFERSIZE];
89};
90
91static void bsg_free_command(struct bsg_command *bc)
92{
93    struct bsg_device *bd = bc->bd;
94    unsigned long flags;
95
96    kmem_cache_free(bsg_cmd_cachep, bc);
97
98    spin_lock_irqsave(&bd->lock, flags);
99    bd->queued_cmds--;
100    spin_unlock_irqrestore(&bd->lock, flags);
101
102    wake_up(&bd->wq_free);
103}
104
105static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
106{
107    struct bsg_command *bc = ERR_PTR(-EINVAL);
108
109    spin_lock_irq(&bd->lock);
110
111    if (bd->queued_cmds >= bd->max_queue)
112        goto out;
113
114    bd->queued_cmds++;
115    spin_unlock_irq(&bd->lock);
116
117    bc = kmem_cache_zalloc(bsg_cmd_cachep, GFP_KERNEL);
118    if (unlikely(!bc)) {
119        spin_lock_irq(&bd->lock);
120        bd->queued_cmds--;
121        bc = ERR_PTR(-ENOMEM);
122        goto out;
123    }
124
125    bc->bd = bd;
126    INIT_LIST_HEAD(&bc->list);
127    dprintk("%s: returning free cmd %p\n", bd->name, bc);
128    return bc;
129out:
130    spin_unlock_irq(&bd->lock);
131    return bc;
132}
133
134static inline struct hlist_head *bsg_dev_idx_hash(int index)
135{
136    return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
137}
138
139static int bsg_io_schedule(struct bsg_device *bd)
140{
141    DEFINE_WAIT(wait);
142    int ret = 0;
143
144    spin_lock_irq(&bd->lock);
145
146    BUG_ON(bd->done_cmds > bd->queued_cmds);
147
148    /*
149     * -ENOSPC or -ENODATA? I'm going for -ENODATA, meaning "I have no
150     * work to do", even though we return -ENOSPC after this same test
151     * during bsg_write() -- there, it means our buffer can't have more
152     * bsg_commands added to it, thus has no space left.
153     */
154    if (bd->done_cmds == bd->queued_cmds) {
155        ret = -ENODATA;
156        goto unlock;
157    }
158
159    if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
160        ret = -EAGAIN;
161        goto unlock;
162    }
163
164    prepare_to_wait(&bd->wq_done, &wait, TASK_UNINTERRUPTIBLE);
165    spin_unlock_irq(&bd->lock);
166    io_schedule();
167    finish_wait(&bd->wq_done, &wait);
168
169    return ret;
170unlock:
171    spin_unlock_irq(&bd->lock);
172    return ret;
173}
174
175static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
176                struct sg_io_v4 *hdr, struct bsg_device *bd,
177                fmode_t has_write_perm)
178{
179    if (hdr->request_len > BLK_MAX_CDB) {
180        rq->cmd = kzalloc(hdr->request_len, GFP_KERNEL);
181        if (!rq->cmd)
182            return -ENOMEM;
183    }
184
185    if (copy_from_user(rq->cmd, (void *)(unsigned long)hdr->request,
186               hdr->request_len))
187        return -EFAULT;
188
189    if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
190        if (blk_verify_command(rq->cmd, has_write_perm))
191            return -EPERM;
192    } else if (!capable(CAP_SYS_RAWIO))
193        return -EPERM;
194
195    /*
196     * fill in request structure
197     */
198    rq->cmd_len = hdr->request_len;
199    rq->cmd_type = REQ_TYPE_BLOCK_PC;
200
201    rq->timeout = msecs_to_jiffies(hdr->timeout);
202    if (!rq->timeout)
203        rq->timeout = q->sg_timeout;
204    if (!rq->timeout)
205        rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
206    if (rq->timeout < BLK_MIN_SG_TIMEOUT)
207        rq->timeout = BLK_MIN_SG_TIMEOUT;
208
209    return 0;
210}
211
212/*
213 * Check if sg_io_v4 from user is allowed and valid
214 */
215static int
216bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
217{
218    int ret = 0;
219
220    if (hdr->guard != 'Q')
221        return -EINVAL;
222
223    switch (hdr->protocol) {
224    case BSG_PROTOCOL_SCSI:
225        switch (hdr->subprotocol) {
226        case BSG_SUB_PROTOCOL_SCSI_CMD:
227        case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
228            break;
229        default:
230            ret = -EINVAL;
231        }
232        break;
233    default:
234        ret = -EINVAL;
235    }
236
237    *rw = hdr->dout_xfer_len ? WRITE : READ;
238    return ret;
239}
240
241/*
242 * map sg_io_v4 to a request.
243 */
244static struct request *
245bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
246        u8 *sense)
247{
248    struct request_queue *q = bd->queue;
249    struct request *rq, *next_rq = NULL;
250    int ret, rw;
251    unsigned int dxfer_len;
252    void *dxferp = NULL;
253    struct bsg_class_device *bcd = &q->bsg_dev;
254
255    /* if the LLD has been removed then the bsg_unregister_queue will
256     * eventually be called and the class_dev was freed, so we can no
257     * longer use this request_queue. Return no such address.
258     */
259    if (!bcd->class_dev)
260        return ERR_PTR(-ENXIO);
261
262    dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
263        hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
264        hdr->din_xfer_len);
265
266    ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
267    if (ret)
268        return ERR_PTR(ret);
269
270    /*
271     * map scatter-gather elements separately and string them to request
272     */
273    rq = blk_get_request(q, rw, GFP_KERNEL);
274    if (!rq)
275        return ERR_PTR(-ENOMEM);
276    ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
277    if (ret)
278        goto out;
279
280    if (rw == WRITE && hdr->din_xfer_len) {
281        if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
282            ret = -EOPNOTSUPP;
283            goto out;
284        }
285
286        next_rq = blk_get_request(q, READ, GFP_KERNEL);
287        if (!next_rq) {
288            ret = -ENOMEM;
289            goto out;
290        }
291        rq->next_rq = next_rq;
292        next_rq->cmd_type = rq->cmd_type;
293
294        dxferp = (void*)(unsigned long)hdr->din_xferp;
295        ret = blk_rq_map_user(q, next_rq, NULL, dxferp,
296                       hdr->din_xfer_len, GFP_KERNEL);
297        if (ret)
298            goto out;
299    }
300
301    if (hdr->dout_xfer_len) {
302        dxfer_len = hdr->dout_xfer_len;
303        dxferp = (void*)(unsigned long)hdr->dout_xferp;
304    } else if (hdr->din_xfer_len) {
305        dxfer_len = hdr->din_xfer_len;
306        dxferp = (void*)(unsigned long)hdr->din_xferp;
307    } else
308        dxfer_len = 0;
309
310    if (dxfer_len) {
311        ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
312                      GFP_KERNEL);
313        if (ret)
314            goto out;
315    }
316
317    rq->sense = sense;
318    rq->sense_len = 0;
319
320    return rq;
321out:
322    if (rq->cmd != rq->__cmd)
323        kfree(rq->cmd);
324    blk_put_request(rq);
325    if (next_rq) {
326        blk_rq_unmap_user(next_rq->bio);
327        blk_put_request(next_rq);
328    }
329    return ERR_PTR(ret);
330}
331
332/*
333 * async completion call-back from the block layer, when scsi/ide/whatever
334 * calls end_that_request_last() on a request
335 */
336static void bsg_rq_end_io(struct request *rq, int uptodate)
337{
338    struct bsg_command *bc = rq->end_io_data;
339    struct bsg_device *bd = bc->bd;
340    unsigned long flags;
341
342    dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
343        bd->name, rq, bc, bc->bio, uptodate);
344
345    bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
346
347    spin_lock_irqsave(&bd->lock, flags);
348    list_move_tail(&bc->list, &bd->done_list);
349    bd->done_cmds++;
350    spin_unlock_irqrestore(&bd->lock, flags);
351
352    wake_up(&bd->wq_done);
353}
354
355/*
356 * do final setup of a 'bc' and submit the matching 'rq' to the block
357 * layer for io
358 */
359static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
360                struct bsg_command *bc, struct request *rq)
361{
362    int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
363
364    /*
365     * add bc command to busy queue and submit rq for io
366     */
367    bc->rq = rq;
368    bc->bio = rq->bio;
369    if (rq->next_rq)
370        bc->bidi_bio = rq->next_rq->bio;
371    bc->hdr.duration = jiffies;
372    spin_lock_irq(&bd->lock);
373    list_add_tail(&bc->list, &bd->busy_list);
374    spin_unlock_irq(&bd->lock);
375
376    dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
377
378    rq->end_io_data = bc;
379    blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
380}
381
382static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
383{
384    struct bsg_command *bc = NULL;
385
386    spin_lock_irq(&bd->lock);
387    if (bd->done_cmds) {
388        bc = list_first_entry(&bd->done_list, struct bsg_command, list);
389        list_del(&bc->list);
390        bd->done_cmds--;
391    }
392    spin_unlock_irq(&bd->lock);
393
394    return bc;
395}
396
397/*
398 * Get a finished command from the done list
399 */
400static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
401{
402    struct bsg_command *bc;
403    int ret;
404
405    do {
406        bc = bsg_next_done_cmd(bd);
407        if (bc)
408            break;
409
410        if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
411            bc = ERR_PTR(-EAGAIN);
412            break;
413        }
414
415        ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
416        if (ret) {
417            bc = ERR_PTR(-ERESTARTSYS);
418            break;
419        }
420    } while (1);
421
422    dprintk("%s: returning done %p\n", bd->name, bc);
423
424    return bc;
425}
426
427static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
428                    struct bio *bio, struct bio *bidi_bio)
429{
430    int ret = 0;
431
432    dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
433    /*
434     * fill in all the output members
435     */
436    hdr->device_status = rq->errors & 0xff;
437    hdr->transport_status = host_byte(rq->errors);
438    hdr->driver_status = driver_byte(rq->errors);
439    hdr->info = 0;
440    if (hdr->device_status || hdr->transport_status || hdr->driver_status)
441        hdr->info |= SG_INFO_CHECK;
442    hdr->response_len = 0;
443
444    if (rq->sense_len && hdr->response) {
445        int len = min_t(unsigned int, hdr->max_response_len,
446                    rq->sense_len);
447
448        ret = copy_to_user((void*)(unsigned long)hdr->response,
449                   rq->sense, len);
450        if (!ret)
451            hdr->response_len = len;
452        else
453            ret = -EFAULT;
454    }
455
456    if (rq->next_rq) {
457        hdr->dout_resid = rq->resid_len;
458        hdr->din_resid = rq->next_rq->resid_len;
459        blk_rq_unmap_user(bidi_bio);
460        blk_put_request(rq->next_rq);
461    } else if (rq_data_dir(rq) == READ)
462        hdr->din_resid = rq->resid_len;
463    else
464        hdr->dout_resid = rq->resid_len;
465
466    /*
467     * If the request generated a negative error number, return it
468     * (providing we aren't already returning an error); if it's
469     * just a protocol response (i.e. non negative), that gets
470     * processed above.
471     */
472    if (!ret && rq->errors < 0)
473        ret = rq->errors;
474
475    blk_rq_unmap_user(bio);
476    if (rq->cmd != rq->__cmd)
477        kfree(rq->cmd);
478    blk_put_request(rq);
479
480    return ret;
481}
482
483static int bsg_complete_all_commands(struct bsg_device *bd)
484{
485    struct bsg_command *bc;
486    int ret, tret;
487
488    dprintk("%s: entered\n", bd->name);
489
490    /*
491     * wait for all commands to complete
492     */
493    ret = 0;
494    do {
495        ret = bsg_io_schedule(bd);
496        /*
497         * look for -ENODATA specifically -- we'll sometimes get
498         * -ERESTARTSYS when we've taken a signal, but we can't
499         * return until we're done freeing the queue, so ignore
500         * it. The signal will get handled when we're done freeing
501         * the bsg_device.
502         */
503    } while (ret != -ENODATA);
504
505    /*
506     * discard done commands
507     */
508    ret = 0;
509    do {
510        spin_lock_irq(&bd->lock);
511        if (!bd->queued_cmds) {
512            spin_unlock_irq(&bd->lock);
513            break;
514        }
515        spin_unlock_irq(&bd->lock);
516
517        bc = bsg_get_done_cmd(bd);
518        if (IS_ERR(bc))
519            break;
520
521        tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
522                        bc->bidi_bio);
523        if (!ret)
524            ret = tret;
525
526        bsg_free_command(bc);
527    } while (1);
528
529    return ret;
530}
531
532static int
533__bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
534       const struct iovec *iov, ssize_t *bytes_read)
535{
536    struct bsg_command *bc;
537    int nr_commands, ret;
538
539    if (count % sizeof(struct sg_io_v4))
540        return -EINVAL;
541
542    ret = 0;
543    nr_commands = count / sizeof(struct sg_io_v4);
544    while (nr_commands) {
545        bc = bsg_get_done_cmd(bd);
546        if (IS_ERR(bc)) {
547            ret = PTR_ERR(bc);
548            break;
549        }
550
551        /*
552         * this is the only case where we need to copy data back
553         * after completing the request. so do that here,
554         * bsg_complete_work() cannot do that for us
555         */
556        ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
557                           bc->bidi_bio);
558
559        if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
560            ret = -EFAULT;
561
562        bsg_free_command(bc);
563
564        if (ret)
565            break;
566
567        buf += sizeof(struct sg_io_v4);
568        *bytes_read += sizeof(struct sg_io_v4);
569        nr_commands--;
570    }
571
572    return ret;
573}
574
575static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
576{
577    if (file->f_flags & O_NONBLOCK)
578        clear_bit(BSG_F_BLOCK, &bd->flags);
579    else
580        set_bit(BSG_F_BLOCK, &bd->flags);
581}
582
583/*
584 * Check if the error is a "real" error that we should return.
585 */
586static inline int err_block_err(int ret)
587{
588    if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
589        return 1;
590
591    return 0;
592}
593
594static ssize_t
595bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
596{
597    struct bsg_device *bd = file->private_data;
598    int ret;
599    ssize_t bytes_read;
600
601    dprintk("%s: read %Zd bytes\n", bd->name, count);
602
603    bsg_set_block(bd, file);
604
605    bytes_read = 0;
606    ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
607    *ppos = bytes_read;
608
609    if (!bytes_read || (bytes_read && err_block_err(ret)))
610        bytes_read = ret;
611
612    return bytes_read;
613}
614
615static int __bsg_write(struct bsg_device *bd, const char __user *buf,
616               size_t count, ssize_t *bytes_written,
617               fmode_t has_write_perm)
618{
619    struct bsg_command *bc;
620    struct request *rq;
621    int ret, nr_commands;
622
623    if (count % sizeof(struct sg_io_v4))
624        return -EINVAL;
625
626    nr_commands = count / sizeof(struct sg_io_v4);
627    rq = NULL;
628    bc = NULL;
629    ret = 0;
630    while (nr_commands) {
631        struct request_queue *q = bd->queue;
632
633        bc = bsg_alloc_command(bd);
634        if (IS_ERR(bc)) {
635            ret = PTR_ERR(bc);
636            bc = NULL;
637            break;
638        }
639
640        if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
641            ret = -EFAULT;
642            break;
643        }
644
645        /*
646         * get a request, fill in the blanks, and add to request queue
647         */
648        rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
649        if (IS_ERR(rq)) {
650            ret = PTR_ERR(rq);
651            rq = NULL;
652            break;
653        }
654
655        bsg_add_command(bd, q, bc, rq);
656        bc = NULL;
657        rq = NULL;
658        nr_commands--;
659        buf += sizeof(struct sg_io_v4);
660        *bytes_written += sizeof(struct sg_io_v4);
661    }
662
663    if (bc)
664        bsg_free_command(bc);
665
666    return ret;
667}
668
669static ssize_t
670bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
671{
672    struct bsg_device *bd = file->private_data;
673    ssize_t bytes_written;
674    int ret;
675
676    dprintk("%s: write %Zd bytes\n", bd->name, count);
677
678    bsg_set_block(bd, file);
679
680    bytes_written = 0;
681    ret = __bsg_write(bd, buf, count, &bytes_written,
682              file->f_mode & FMODE_WRITE);
683
684    *ppos = bytes_written;
685
686    /*
687     * return bytes written on non-fatal errors
688     */
689    if (!bytes_written || (bytes_written && err_block_err(ret)))
690        bytes_written = ret;
691
692    dprintk("%s: returning %Zd\n", bd->name, bytes_written);
693    return bytes_written;
694}
695
696static struct bsg_device *bsg_alloc_device(void)
697{
698    struct bsg_device *bd;
699
700    bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
701    if (unlikely(!bd))
702        return NULL;
703
704    spin_lock_init(&bd->lock);
705
706    bd->max_queue = BSG_DEFAULT_CMDS;
707
708    INIT_LIST_HEAD(&bd->busy_list);
709    INIT_LIST_HEAD(&bd->done_list);
710    INIT_HLIST_NODE(&bd->dev_list);
711
712    init_waitqueue_head(&bd->wq_free);
713    init_waitqueue_head(&bd->wq_done);
714    return bd;
715}
716
717static void bsg_kref_release_function(struct kref *kref)
718{
719    struct bsg_class_device *bcd =
720        container_of(kref, struct bsg_class_device, ref);
721    struct device *parent = bcd->parent;
722
723    if (bcd->release)
724        bcd->release(bcd->parent);
725
726    put_device(parent);
727}
728
729static int bsg_put_device(struct bsg_device *bd)
730{
731    int ret = 0, do_free;
732    struct request_queue *q = bd->queue;
733
734    mutex_lock(&bsg_mutex);
735
736    do_free = atomic_dec_and_test(&bd->ref_count);
737    if (!do_free) {
738        mutex_unlock(&bsg_mutex);
739        goto out;
740    }
741
742    hlist_del(&bd->dev_list);
743    mutex_unlock(&bsg_mutex);
744
745    dprintk("%s: tearing down\n", bd->name);
746
747    /*
748     * close can always block
749     */
750    set_bit(BSG_F_BLOCK, &bd->flags);
751
752    /*
753     * correct error detection baddies here again. it's the responsibility
754     * of the app to properly reap commands before close() if it wants
755     * fool-proof error detection
756     */
757    ret = bsg_complete_all_commands(bd);
758
759    kfree(bd);
760out:
761    kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
762    if (do_free)
763        blk_put_queue(q);
764    return ret;
765}
766
767static struct bsg_device *bsg_add_device(struct inode *inode,
768                     struct request_queue *rq,
769                     struct file *file)
770{
771    struct bsg_device *bd;
772    int ret;
773#ifdef BSG_DEBUG
774    unsigned char buf[32];
775#endif
776    ret = blk_get_queue(rq);
777    if (ret)
778        return ERR_PTR(-ENXIO);
779
780    bd = bsg_alloc_device();
781    if (!bd) {
782        blk_put_queue(rq);
783        return ERR_PTR(-ENOMEM);
784    }
785
786    bd->queue = rq;
787
788    bsg_set_block(bd, file);
789
790    atomic_set(&bd->ref_count, 1);
791    mutex_lock(&bsg_mutex);
792    hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
793
794    strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
795    dprintk("bound to <%s>, max queue %d\n",
796        format_dev_t(buf, inode->i_rdev), bd->max_queue);
797
798    mutex_unlock(&bsg_mutex);
799    return bd;
800}
801
802static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
803{
804    struct bsg_device *bd;
805    struct hlist_node *entry;
806
807    mutex_lock(&bsg_mutex);
808
809    hlist_for_each_entry(bd, entry, bsg_dev_idx_hash(minor), dev_list) {
810        if (bd->queue == q) {
811            atomic_inc(&bd->ref_count);
812            goto found;
813        }
814    }
815    bd = NULL;
816found:
817    mutex_unlock(&bsg_mutex);
818    return bd;
819}
820
821static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
822{
823    struct bsg_device *bd;
824    struct bsg_class_device *bcd;
825
826    /*
827     * find the class device
828     */
829    mutex_lock(&bsg_mutex);
830    bcd = idr_find(&bsg_minor_idr, iminor(inode));
831    if (bcd)
832        kref_get(&bcd->ref);
833    mutex_unlock(&bsg_mutex);
834
835    if (!bcd)
836        return ERR_PTR(-ENODEV);
837
838    bd = __bsg_get_device(iminor(inode), bcd->queue);
839    if (bd)
840        return bd;
841
842    bd = bsg_add_device(inode, bcd->queue, file);
843    if (IS_ERR(bd))
844        kref_put(&bcd->ref, bsg_kref_release_function);
845
846    return bd;
847}
848
849static int bsg_open(struct inode *inode, struct file *file)
850{
851    struct bsg_device *bd;
852
853    bd = bsg_get_device(inode, file);
854
855    if (IS_ERR(bd))
856        return PTR_ERR(bd);
857
858    file->private_data = bd;
859    return 0;
860}
861
862static int bsg_release(struct inode *inode, struct file *file)
863{
864    struct bsg_device *bd = file->private_data;
865
866    file->private_data = NULL;
867    return bsg_put_device(bd);
868}
869
870static unsigned int bsg_poll(struct file *file, poll_table *wait)
871{
872    struct bsg_device *bd = file->private_data;
873    unsigned int mask = 0;
874
875    poll_wait(file, &bd->wq_done, wait);
876    poll_wait(file, &bd->wq_free, wait);
877
878    spin_lock_irq(&bd->lock);
879    if (!list_empty(&bd->done_list))
880        mask |= POLLIN | POLLRDNORM;
881    if (bd->queued_cmds >= bd->max_queue)
882        mask |= POLLOUT;
883    spin_unlock_irq(&bd->lock);
884
885    return mask;
886}
887
888static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
889{
890    struct bsg_device *bd = file->private_data;
891    int __user *uarg = (int __user *) arg;
892    int ret;
893
894    switch (cmd) {
895        /*
896         * our own ioctls
897         */
898    case SG_GET_COMMAND_Q:
899        return put_user(bd->max_queue, uarg);
900    case SG_SET_COMMAND_Q: {
901        int queue;
902
903        if (get_user(queue, uarg))
904            return -EFAULT;
905        if (queue < 1)
906            return -EINVAL;
907
908        spin_lock_irq(&bd->lock);
909        bd->max_queue = queue;
910        spin_unlock_irq(&bd->lock);
911        return 0;
912    }
913
914    /*
915     * SCSI/sg ioctls
916     */
917    case SG_GET_VERSION_NUM:
918    case SCSI_IOCTL_GET_IDLUN:
919    case SCSI_IOCTL_GET_BUS_NUMBER:
920    case SG_SET_TIMEOUT:
921    case SG_GET_TIMEOUT:
922    case SG_GET_RESERVED_SIZE:
923    case SG_SET_RESERVED_SIZE:
924    case SG_EMULATED_HOST:
925    case SCSI_IOCTL_SEND_COMMAND: {
926        void __user *uarg = (void __user *) arg;
927        return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
928    }
929    case SG_IO: {
930        struct request *rq;
931        struct bio *bio, *bidi_bio = NULL;
932        struct sg_io_v4 hdr;
933        int at_head;
934        u8 sense[SCSI_SENSE_BUFFERSIZE];
935
936        if (copy_from_user(&hdr, uarg, sizeof(hdr)))
937            return -EFAULT;
938
939        rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
940        if (IS_ERR(rq))
941            return PTR_ERR(rq);
942
943        bio = rq->bio;
944        if (rq->next_rq)
945            bidi_bio = rq->next_rq->bio;
946
947        at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
948        blk_execute_rq(bd->queue, NULL, rq, at_head);
949        ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
950
951        if (copy_to_user(uarg, &hdr, sizeof(hdr)))
952            return -EFAULT;
953
954        return ret;
955    }
956    /*
957     * block device ioctls
958     */
959    default:
960#if 0
961        return ioctl_by_bdev(bd->bdev, cmd, arg);
962#else
963        return -ENOTTY;
964#endif
965    }
966}
967
968static const struct file_operations bsg_fops = {
969    .read = bsg_read,
970    .write = bsg_write,
971    .poll = bsg_poll,
972    .open = bsg_open,
973    .release = bsg_release,
974    .unlocked_ioctl = bsg_ioctl,
975    .owner = THIS_MODULE,
976    .llseek = default_llseek,
977};
978
979void bsg_unregister_queue(struct request_queue *q)
980{
981    struct bsg_class_device *bcd = &q->bsg_dev;
982
983    if (!bcd->class_dev)
984        return;
985
986    mutex_lock(&bsg_mutex);
987    idr_remove(&bsg_minor_idr, bcd->minor);
988    sysfs_remove_link(&q->kobj, "bsg");
989    device_unregister(bcd->class_dev);
990    bcd->class_dev = NULL;
991    kref_put(&bcd->ref, bsg_kref_release_function);
992    mutex_unlock(&bsg_mutex);
993}
994EXPORT_SYMBOL_GPL(bsg_unregister_queue);
995
996int bsg_register_queue(struct request_queue *q, struct device *parent,
997               const char *name, void (*release)(struct device *))
998{
999    struct bsg_class_device *bcd;
1000    dev_t dev;
1001    int ret, minor;
1002    struct device *class_dev = NULL;
1003    const char *devname;
1004
1005    if (name)
1006        devname = name;
1007    else
1008        devname = dev_name(parent);
1009
1010    /*
1011     * we need a proper transport to send commands, not a stacked device
1012     */
1013    if (!q->request_fn)
1014        return 0;
1015
1016    bcd = &q->bsg_dev;
1017    memset(bcd, 0, sizeof(*bcd));
1018
1019    mutex_lock(&bsg_mutex);
1020
1021    ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
1022    if (!ret) {
1023        ret = -ENOMEM;
1024        goto unlock;
1025    }
1026
1027    ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
1028    if (ret < 0)
1029        goto unlock;
1030
1031    if (minor >= BSG_MAX_DEVS) {
1032        printk(KERN_ERR "bsg: too many bsg devices\n");
1033        ret = -EINVAL;
1034        goto remove_idr;
1035    }
1036
1037    bcd->minor = minor;
1038    bcd->queue = q;
1039    bcd->parent = get_device(parent);
1040    bcd->release = release;
1041    kref_init(&bcd->ref);
1042    dev = MKDEV(bsg_major, bcd->minor);
1043    class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1044    if (IS_ERR(class_dev)) {
1045        ret = PTR_ERR(class_dev);
1046        goto put_dev;
1047    }
1048    bcd->class_dev = class_dev;
1049
1050    if (q->kobj.sd) {
1051        ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1052        if (ret)
1053            goto unregister_class_dev;
1054    }
1055
1056    mutex_unlock(&bsg_mutex);
1057    return 0;
1058
1059unregister_class_dev:
1060    device_unregister(class_dev);
1061put_dev:
1062    put_device(parent);
1063remove_idr:
1064    idr_remove(&bsg_minor_idr, minor);
1065unlock:
1066    mutex_unlock(&bsg_mutex);
1067    return ret;
1068}
1069EXPORT_SYMBOL_GPL(bsg_register_queue);
1070
1071static struct cdev bsg_cdev;
1072
1073static char *bsg_devnode(struct device *dev, mode_t *mode)
1074{
1075    return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
1076}
1077
1078static int __init bsg_init(void)
1079{
1080    int ret, i;
1081    dev_t devid;
1082
1083    bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1084                sizeof(struct bsg_command), 0, 0, NULL);
1085    if (!bsg_cmd_cachep) {
1086        printk(KERN_ERR "bsg: failed creating slab cache\n");
1087        return -ENOMEM;
1088    }
1089
1090    for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1091        INIT_HLIST_HEAD(&bsg_device_list[i]);
1092
1093    bsg_class = class_create(THIS_MODULE, "bsg");
1094    if (IS_ERR(bsg_class)) {
1095        ret = PTR_ERR(bsg_class);
1096        goto destroy_kmemcache;
1097    }
1098    bsg_class->devnode = bsg_devnode;
1099
1100    ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1101    if (ret)
1102        goto destroy_bsg_class;
1103
1104    bsg_major = MAJOR(devid);
1105
1106    cdev_init(&bsg_cdev, &bsg_fops);
1107    ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1108    if (ret)
1109        goto unregister_chrdev;
1110
1111    printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1112           " loaded (major %d)\n", bsg_major);
1113    return 0;
1114unregister_chrdev:
1115    unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1116destroy_bsg_class:
1117    class_destroy(bsg_class);
1118destroy_kmemcache:
1119    kmem_cache_destroy(bsg_cmd_cachep);
1120    return ret;
1121}
1122
1123MODULE_AUTHOR("Jens Axboe");
1124MODULE_DESCRIPTION(BSG_DESCRIPTION);
1125MODULE_LICENSE("GPL");
1126
1127device_initcall(bsg_init);
1128

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