bsg.c

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    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 
   35 struct 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 
   51 enum {
   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 
   66 static DEFINE_MUTEX(bsg_mutex);
   67 static DEFINE_IDR(bsg_minor_idr);
   68 
   69 #define BSG_LIST_ARRAY_SIZE     8
   70 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
   71 
   72 static struct class *bsg_class;
   73 static int bsg_major;
   74 
   75 static struct kmem_cache *bsg_cmd_cachep;
   76 
   77 /*
   78  * our internal command type
   79  */
   80 struct 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 
   91 static 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 
  105 static 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;
  129 out:
  130         spin_unlock_irq(&bd->lock);
  131         return bc;
  132 }
  133 
  134 static inline struct hlist_head *bsg_dev_idx_hash(int index)
  135 {
  136         return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
  137 }
  138 
  139 static 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;
  170 unlock:
  171         spin_unlock_irq(&bd->lock);
  172         return ret;
  173 }
  174 
  175 static 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 __user *)(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  */
  215 static int
  216 bsg_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  */
  244 static struct request *
  245 bsg_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 __user *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 __user *)(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 __user *)(unsigned long)hdr->dout_xferp;
  304         } else if (hdr->din_xfer_len) {
  305                 dxfer_len = hdr->din_xfer_len;
  306                 dxferp = (void __user *)(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;
  321 out:
  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  */
  336 static 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  */
  359 static 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 
  382 static 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  */
  400 static 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 
  427 static 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 __user *)(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 
  483 static 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 
  532 static 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 
  575 static 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  */
  586 static 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 
  594 static ssize_t
  595 bsg_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 || err_block_err(ret))
  610                 bytes_read = ret;
  611 
  612         return bytes_read;
  613 }
  614 
  615 static 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 
  669 static ssize_t
  670 bsg_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 || 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 
  696 static 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 
  717 static 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 
  729 static 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);
  760 out:
  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 
  767 static 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 #ifdef BSG_DEBUG
  773         unsigned char buf[32];
  774 #endif
  775         if (!blk_get_queue(rq))
  776                 return ERR_PTR(-ENXIO);
  777 
  778         bd = bsg_alloc_device();
  779         if (!bd) {
  780                 blk_put_queue(rq);
  781                 return ERR_PTR(-ENOMEM);
  782         }
  783 
  784         bd->queue = rq;
  785 
  786         bsg_set_block(bd, file);
  787 
  788         atomic_set(&bd->ref_count, 1);
  789         mutex_lock(&bsg_mutex);
  790         hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
  791 
  792         strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
  793         dprintk("bound to <%s>, max queue %d\n",
  794                 format_dev_t(buf, inode->i_rdev), bd->max_queue);
  795 
  796         mutex_unlock(&bsg_mutex);
  797         return bd;
  798 }
  799 
  800 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
  801 {
  802         struct bsg_device *bd;
  803         struct hlist_node *entry;
  804 
  805         mutex_lock(&bsg_mutex);
  806 
  807         hlist_for_each_entry(bd, entry, bsg_dev_idx_hash(minor), dev_list) {
  808                 if (bd->queue == q) {
  809                         atomic_inc(&bd->ref_count);
  810                         goto found;
  811                 }
  812         }
  813         bd = NULL;
  814 found:
  815         mutex_unlock(&bsg_mutex);
  816         return bd;
  817 }
  818 
  819 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
  820 {
  821         struct bsg_device *bd;
  822         struct bsg_class_device *bcd;
  823 
  824         /*
  825          * find the class device
  826          */
  827         mutex_lock(&bsg_mutex);
  828         bcd = idr_find(&bsg_minor_idr, iminor(inode));
  829         if (bcd)
  830                 kref_get(&bcd->ref);
  831         mutex_unlock(&bsg_mutex);
  832 
  833         if (!bcd)
  834                 return ERR_PTR(-ENODEV);
  835 
  836         bd = __bsg_get_device(iminor(inode), bcd->queue);
  837         if (bd)
  838                 return bd;
  839 
  840         bd = bsg_add_device(inode, bcd->queue, file);
  841         if (IS_ERR(bd))
  842                 kref_put(&bcd->ref, bsg_kref_release_function);
  843 
  844         return bd;
  845 }
  846 
  847 static int bsg_open(struct inode *inode, struct file *file)
  848 {
  849         struct bsg_device *bd;
  850 
  851         bd = bsg_get_device(inode, file);
  852 
  853         if (IS_ERR(bd))
  854                 return PTR_ERR(bd);
  855 
  856         file->private_data = bd;
  857         return 0;
  858 }
  859 
  860 static int bsg_release(struct inode *inode, struct file *file)
  861 {
  862         struct bsg_device *bd = file->private_data;
  863 
  864         file->private_data = NULL;
  865         return bsg_put_device(bd);
  866 }
  867 
  868 static unsigned int bsg_poll(struct file *file, poll_table *wait)
  869 {
  870         struct bsg_device *bd = file->private_data;
  871         unsigned int mask = 0;
  872 
  873         poll_wait(file, &bd->wq_done, wait);
  874         poll_wait(file, &bd->wq_free, wait);
  875 
  876         spin_lock_irq(&bd->lock);
  877         if (!list_empty(&bd->done_list))
  878                 mask |= POLLIN | POLLRDNORM;
  879         if (bd->queued_cmds < bd->max_queue)
  880                 mask |= POLLOUT;
  881         spin_unlock_irq(&bd->lock);
  882 
  883         return mask;
  884 }
  885 
  886 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  887 {
  888         struct bsg_device *bd = file->private_data;
  889         int __user *uarg = (int __user *) arg;
  890         int ret;
  891 
  892         switch (cmd) {
  893                 /*
  894                  * our own ioctls
  895                  */
  896         case SG_GET_COMMAND_Q:
  897                 return put_user(bd->max_queue, uarg);
  898         case SG_SET_COMMAND_Q: {
  899                 int queue;
  900 
  901                 if (get_user(queue, uarg))
  902                         return -EFAULT;
  903                 if (queue < 1)
  904                         return -EINVAL;
  905 
  906                 spin_lock_irq(&bd->lock);
  907                 bd->max_queue = queue;
  908                 spin_unlock_irq(&bd->lock);
  909                 return 0;
  910         }
  911 
  912         /*
  913          * SCSI/sg ioctls
  914          */
  915         case SG_GET_VERSION_NUM:
  916         case SCSI_IOCTL_GET_IDLUN:
  917         case SCSI_IOCTL_GET_BUS_NUMBER:
  918         case SG_SET_TIMEOUT:
  919         case SG_GET_TIMEOUT:
  920         case SG_GET_RESERVED_SIZE:
  921         case SG_SET_RESERVED_SIZE:
  922         case SG_EMULATED_HOST:
  923         case SCSI_IOCTL_SEND_COMMAND: {
  924                 void __user *uarg = (void __user *) arg;
  925                 return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
  926         }
  927         case SG_IO: {
  928                 struct request *rq;
  929                 struct bio *bio, *bidi_bio = NULL;
  930                 struct sg_io_v4 hdr;
  931                 int at_head;
  932                 u8 sense[SCSI_SENSE_BUFFERSIZE];
  933 
  934                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
  935                         return -EFAULT;
  936 
  937                 rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
  938                 if (IS_ERR(rq))
  939                         return PTR_ERR(rq);
  940 
  941                 bio = rq->bio;
  942                 if (rq->next_rq)
  943                         bidi_bio = rq->next_rq->bio;
  944 
  945                 at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
  946                 blk_execute_rq(bd->queue, NULL, rq, at_head);
  947                 ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
  948 
  949                 if (copy_to_user(uarg, &hdr, sizeof(hdr)))
  950                         return -EFAULT;
  951 
  952                 return ret;
  953         }
  954         /*
  955          * block device ioctls
  956          */
  957         default:
  958 #if 0
  959                 return ioctl_by_bdev(bd->bdev, cmd, arg);
  960 #else
  961                 return -ENOTTY;
  962 #endif
  963         }
  964 }
  965 
  966 static const struct file_operations bsg_fops = {
  967         .read           =       bsg_read,
  968         .write          =       bsg_write,
  969         .poll           =       bsg_poll,
  970         .open           =       bsg_open,
  971         .release        =       bsg_release,
  972         .unlocked_ioctl =       bsg_ioctl,
  973         .owner          =       THIS_MODULE,
  974         .llseek         =       default_llseek,
  975 };
  976 
  977 void bsg_unregister_queue(struct request_queue *q)
  978 {
  979         struct bsg_class_device *bcd = &q->bsg_dev;
  980 
  981         if (!bcd->class_dev)
  982                 return;
  983 
  984         mutex_lock(&bsg_mutex);
  985         idr_remove(&bsg_minor_idr, bcd->minor);
  986         if (q->kobj.sd)
  987                 sysfs_remove_link(&q->kobj, "bsg");
  988         device_unregister(bcd->class_dev);
  989         bcd->class_dev = NULL;
  990         kref_put(&bcd->ref, bsg_kref_release_function);
  991         mutex_unlock(&bsg_mutex);
  992 }
  993 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
  994 
  995 int bsg_register_queue(struct request_queue *q, struct device *parent,
  996                        const char *name, void (*release)(struct device *))
  997 {
  998         struct bsg_class_device *bcd;
  999         dev_t dev;
 1000         int ret, minor;
 1001         struct device *class_dev = NULL;
 1002         const char *devname;
 1003 
 1004         if (name)
 1005                 devname = name;
 1006         else
 1007                 devname = dev_name(parent);
 1008 
 1009         /*
 1010          * we need a proper transport to send commands, not a stacked device
 1011          */
 1012         if (!q->request_fn)
 1013                 return 0;
 1014 
 1015         bcd = &q->bsg_dev;
 1016         memset(bcd, 0, sizeof(*bcd));
 1017 
 1018         mutex_lock(&bsg_mutex);
 1019 
 1020         ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
 1021         if (!ret) {
 1022                 ret = -ENOMEM;
 1023                 goto unlock;
 1024         }
 1025 
 1026         ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
 1027         if (ret < 0)
 1028                 goto unlock;
 1029 
 1030         if (minor >= BSG_MAX_DEVS) {
 1031                 printk(KERN_ERR "bsg: too many bsg devices\n");
 1032                 ret = -EINVAL;
 1033                 goto remove_idr;
 1034         }
 1035 
 1036         bcd->minor = minor;
 1037         bcd->queue = q;
 1038         bcd->parent = get_device(parent);
 1039         bcd->release = release;
 1040         kref_init(&bcd->ref);
 1041         dev = MKDEV(bsg_major, bcd->minor);
 1042         class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
 1043         if (IS_ERR(class_dev)) {
 1044                 ret = PTR_ERR(class_dev);
 1045                 goto put_dev;
 1046         }
 1047         bcd->class_dev = class_dev;
 1048 
 1049         if (q->kobj.sd) {
 1050                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
 1051                 if (ret)
 1052                         goto unregister_class_dev;
 1053         }
 1054 
 1055         mutex_unlock(&bsg_mutex);
 1056         return 0;
 1057 
 1058 unregister_class_dev:
 1059         device_unregister(class_dev);
 1060 put_dev:
 1061         put_device(parent);
 1062 remove_idr:
 1063         idr_remove(&bsg_minor_idr, minor);
 1064 unlock:
 1065         mutex_unlock(&bsg_mutex);
 1066         return ret;
 1067 }
 1068 EXPORT_SYMBOL_GPL(bsg_register_queue);
 1069 
 1070 static struct cdev bsg_cdev;
 1071 
 1072 static char *bsg_devnode(struct device *dev, umode_t *mode)
 1073 {
 1074         return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
 1075 }
 1076 
 1077 static int __init bsg_init(void)
 1078 {
 1079         int ret, i;
 1080         dev_t devid;
 1081 
 1082         bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
 1083                                 sizeof(struct bsg_command), 0, 0, NULL);
 1084         if (!bsg_cmd_cachep) {
 1085                 printk(KERN_ERR "bsg: failed creating slab cache\n");
 1086                 return -ENOMEM;
 1087         }
 1088 
 1089         for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
 1090                 INIT_HLIST_HEAD(&bsg_device_list[i]);
 1091 
 1092         bsg_class = class_create(THIS_MODULE, "bsg");
 1093         if (IS_ERR(bsg_class)) {
 1094                 ret = PTR_ERR(bsg_class);
 1095                 goto destroy_kmemcache;
 1096         }
 1097         bsg_class->devnode = bsg_devnode;
 1098 
 1099         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
 1100         if (ret)
 1101                 goto destroy_bsg_class;
 1102 
 1103         bsg_major = MAJOR(devid);
 1104 
 1105         cdev_init(&bsg_cdev, &bsg_fops);
 1106         ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
 1107         if (ret)
 1108                 goto unregister_chrdev;
 1109 
 1110         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
 1111                " loaded (major %d)\n", bsg_major);
 1112         return 0;
 1113 unregister_chrdev:
 1114         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
 1115 destroy_bsg_class:
 1116         class_destroy(bsg_class);
 1117 destroy_kmemcache:
 1118         kmem_cache_destroy(bsg_cmd_cachep);
 1119         return ret;
 1120 }
 1121 
 1122 MODULE_AUTHOR("Jens Axboe");
 1123 MODULE_DESCRIPTION(BSG_DESCRIPTION);
 1124 MODULE_LICENSE("GPL");
 1125 
 1126 device_initcall(bsg_init);
Cache object: dfe912a1335c589c6d6722ba98261e05
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FreeBSD/Linux Kernel Cross Reference sys/block/bsg.c

FreeBSD/Linux Kernel Cross Reference
sys/block/bsg.c
