/*

   * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>

   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   *
   */

  #include <linux/kernel.h>
  #include <linux/blkdev.h>
  #include <linux/blktrace_api.h>
  #include <linux/percpu.h>
  #include <linux/init.h>
  #include <linux/mutex.h>
  #include <linux/debugfs.h>

  #include <linux/time.h>

  #include <trace/block.h>

  #include <asm/uaccess.h>

  static unsigned int blktrace_seq __read_mostly = 1;

  /* Global reference count of probes */
  static DEFINE_MUTEX(blk_probe_mutex);
  static atomic_t blk_probes_ref = ATOMIC_INIT(0);
  
  static int blk_register_tracepoints(void);
  static void blk_unregister_tracepoints(void);

  /*

   * Send out a notify message.
   */

  static void trace_note(struct blk_trace *bt, pid_t pid, int action,
  		       const void *data, size_t len)

  {
  	struct blk_io_trace *t;

  
  	t = relay_reserve(bt->rchan, sizeof(*t) + len);

  	if (t) {
  		const int cpu = smp_processor_id();
  
  		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;

  		t->time = ktime_to_ns(ktime_get());

  		t->device = bt->dev;
  		t->action = action;
  		t->pid = pid;
  		t->cpu = cpu;
  		t->pdu_len = len;
  		memcpy((void *) t + sizeof(*t), data, len);
  	}

  }
  
  /*

   * Send out a notify for this process, if we haven't done so since a trace
   * started
   */
  static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
  {

  	tsk->btrace_seq = blktrace_seq;
  	trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));

  }

  static void trace_note_time(struct blk_trace *bt)
  {
  	struct timespec now;
  	unsigned long flags;
  	u32 words[2];
  
  	getnstimeofday(&now);
  	words[0] = now.tv_sec;
  	words[1] = now.tv_nsec;
  
  	local_irq_save(flags);
  	trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
  	local_irq_restore(flags);

  }

  void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
  {
  	int n;
  	va_list args;

  	unsigned long flags;

  	char *buf;

  	local_irq_save(flags);

  	buf = per_cpu_ptr(bt->msg_data, smp_processor_id());

  	va_start(args, fmt);

  	n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);

  	va_end(args);

  	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);

  	local_irq_restore(flags);

  }
  EXPORT_SYMBOL_GPL(__trace_note_message);

  static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
  			 pid_t pid)
  {
  	if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
  		return 1;
  	if (sector < bt->start_lba || sector > bt->end_lba)
  		return 1;
  	if (bt->pid && pid != bt->pid)
  		return 1;
  
  	return 0;
  }
  
  /*
   * Data direction bit lookup
   */
  static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK_TC_WRITE) };

  /* The ilog2() calls fall out because they're constant */
  #define MASK_TC_BIT(rw, __name) ( (rw & (1 << BIO_RW_ ## __name)) << \
  	  (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - BIO_RW_ ## __name) )

  
  /*
   * The worker for the various blk_add_trace*() types. Fills out a
   * blk_io_trace structure and places it in a per-cpu subbuffer.
   */

  static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,

  		     int rw, u32 what, int error, int pdu_len, void *pdu_data)
  {
  	struct task_struct *tsk = current;
  	struct blk_io_trace *t;
  	unsigned long flags;
  	unsigned long *sequence;
  	pid_t pid;
  	int cpu;
  
  	if (unlikely(bt->trace_state != Blktrace_running))
  		return;
  
  	what |= ddir_act[rw & WRITE];

  	what |= MASK_TC_BIT(rw, BARRIER);
  	what |= MASK_TC_BIT(rw, SYNC);
  	what |= MASK_TC_BIT(rw, AHEAD);
  	what |= MASK_TC_BIT(rw, META);
  	what |= MASK_TC_BIT(rw, DISCARD);

  
  	pid = tsk->pid;
  	if (unlikely(act_log_check(bt, what, sector, pid)))
  		return;
  
  	/*
  	 * A word about the locking here - we disable interrupts to reserve
  	 * some space in the relay per-cpu buffer, to prevent an irq

  	 * from coming in and stepping on our toes.

  	 */
  	local_irq_save(flags);
  
  	if (unlikely(tsk->btrace_seq != blktrace_seq))
  		trace_note_tsk(bt, tsk);
  
  	t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
  	if (t) {
  		cpu = smp_processor_id();
  		sequence = per_cpu_ptr(bt->sequence, cpu);
  
  		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
  		t->sequence = ++(*sequence);

  		t->time = ktime_to_ns(ktime_get());

  		t->sector = sector;
  		t->bytes = bytes;
  		t->action = what;
  		t->pid = pid;
  		t->device = bt->dev;
  		t->cpu = cpu;
  		t->error = error;
  		t->pdu_len = pdu_len;
  
  		if (pdu_len)
  			memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
  	}
  
  	local_irq_restore(flags);
  }

  static struct dentry *blk_tree_root;

  static DEFINE_MUTEX(blk_tree_mutex);

  static unsigned int root_users;
  
  static inline void blk_remove_root(void)
  {
  	if (blk_tree_root) {
  		debugfs_remove(blk_tree_root);
  		blk_tree_root = NULL;
  	}
  }
  
  static void blk_remove_tree(struct dentry *dir)
  {
  	mutex_lock(&blk_tree_mutex);
  	debugfs_remove(dir);
  	if (--root_users == 0)
  		blk_remove_root();
  	mutex_unlock(&blk_tree_mutex);
  }
  
  static struct dentry *blk_create_tree(const char *blk_name)
  {
  	struct dentry *dir = NULL;

  	int created = 0;

  
  	mutex_lock(&blk_tree_mutex);
  
  	if (!blk_tree_root) {
  		blk_tree_root = debugfs_create_dir("block", NULL);
  		if (!blk_tree_root)
  			goto err;

  		created = 1;

  	}
  
  	dir = debugfs_create_dir(blk_name, blk_tree_root);
  	if (dir)
  		root_users++;

  	else {
  		/* Delete root only if we created it */
  		if (created)
  			blk_remove_root();
  	}

  
  err:
  	mutex_unlock(&blk_tree_mutex);
  	return dir;
  }
  
  static void blk_trace_cleanup(struct blk_trace *bt)
  {
  	relay_close(bt->rchan);

  	debugfs_remove(bt->msg_file);

  	debugfs_remove(bt->dropped_file);
  	blk_remove_tree(bt->dir);
  	free_percpu(bt->sequence);

  	free_percpu(bt->msg_data);

  	kfree(bt);

  	mutex_lock(&blk_probe_mutex);
  	if (atomic_dec_and_test(&blk_probes_ref))
  		blk_unregister_tracepoints();
  	mutex_unlock(&blk_probe_mutex);

  }

  int blk_trace_remove(struct request_queue *q)

  {
  	struct blk_trace *bt;
  
  	bt = xchg(&q->blk_trace, NULL);
  	if (!bt)
  		return -EINVAL;
  
  	if (bt->trace_state == Blktrace_setup ||
  	    bt->trace_state == Blktrace_stopped)
  		blk_trace_cleanup(bt);
  
  	return 0;
  }

  EXPORT_SYMBOL_GPL(blk_trace_remove);

  
  static int blk_dropped_open(struct inode *inode, struct file *filp)
  {

  	filp->private_data = inode->i_private;

  
  	return 0;
  }
  
  static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
  				size_t count, loff_t *ppos)
  {
  	struct blk_trace *bt = filp->private_data;
  	char buf[16];
  
  	snprintf(buf, sizeof(buf), "%u
  ", atomic_read(&bt->dropped));
  
  	return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
  }

  static const struct file_operations blk_dropped_fops = {

  	.owner =	THIS_MODULE,
  	.open =		blk_dropped_open,
  	.read =		blk_dropped_read,
  };

  static int blk_msg_open(struct inode *inode, struct file *filp)
  {
  	filp->private_data = inode->i_private;
  
  	return 0;
  }
  
  static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
  				size_t count, loff_t *ppos)
  {
  	char *msg;
  	struct blk_trace *bt;
  
  	if (count > BLK_TN_MAX_MSG)
  		return -EINVAL;
  
  	msg = kmalloc(count, GFP_KERNEL);
  	if (msg == NULL)
  		return -ENOMEM;
  
  	if (copy_from_user(msg, buffer, count)) {
  		kfree(msg);
  		return -EFAULT;
  	}
  
  	bt = filp->private_data;
  	__trace_note_message(bt, "%s", msg);
  	kfree(msg);
  
  	return count;
  }
  
  static const struct file_operations blk_msg_fops = {
  	.owner =	THIS_MODULE,
  	.open =		blk_msg_open,
  	.write =	blk_msg_write,
  };

  /*
   * Keep track of how many times we encountered a full subbuffer, to aid
   * the user space app in telling how many lost events there were.
   */
  static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
  				     void *prev_subbuf, size_t prev_padding)
  {
  	struct blk_trace *bt;
  
  	if (!relay_buf_full(buf))
  		return 1;
  
  	bt = buf->chan->private_data;
  	atomic_inc(&bt->dropped);
  	return 0;
  }
  
  static int blk_remove_buf_file_callback(struct dentry *dentry)
  {
  	debugfs_remove(dentry);
  	return 0;
  }
  
  static struct dentry *blk_create_buf_file_callback(const char *filename,
  						   struct dentry *parent,
  						   int mode,
  						   struct rchan_buf *buf,
  						   int *is_global)
  {
  	return debugfs_create_file(filename, mode, parent, buf,
  					&relay_file_operations);
  }
  
  static struct rchan_callbacks blk_relay_callbacks = {
  	.subbuf_start		= blk_subbuf_start_callback,
  	.create_buf_file	= blk_create_buf_file_callback,
  	.remove_buf_file	= blk_remove_buf_file_callback,
  };
  
  /*
   * Setup everything required to start tracing
   */

  int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,

  			struct blk_user_trace_setup *buts)

  {

  	struct blk_trace *old_bt, *bt = NULL;
  	struct dentry *dir = NULL;

  	int ret, i;

  	if (!buts->buf_size || !buts->buf_nr)

  		return -EINVAL;

  	strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
  	buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';

  
  	/*
  	 * some device names have larger paths - convert the slashes
  	 * to underscores for this to work as expected
  	 */

  	for (i = 0; i < strlen(buts->name); i++)
  		if (buts->name[i] == '/')
  			buts->name[i] = '_';

  
  	ret = -ENOMEM;
  	bt = kzalloc(sizeof(*bt), GFP_KERNEL);
  	if (!bt)
  		goto err;
  
  	bt->sequence = alloc_percpu(unsigned long);
  	if (!bt->sequence)
  		goto err;

  	bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG);
  	if (!bt->msg_data)
  		goto err;

  	ret = -ENOENT;

  	dir = blk_create_tree(buts->name);

  	if (!dir)
  		goto err;
  
  	bt->dir = dir;

  	bt->dev = dev;

  	atomic_set(&bt->dropped, 0);
  
  	ret = -EIO;
  	bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops);
  	if (!bt->dropped_file)
  		goto err;

  	bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
  	if (!bt->msg_file)
  		goto err;

  	bt->rchan = relay_open("trace", dir, buts->buf_size,
  				buts->buf_nr, &blk_relay_callbacks, bt);

  	if (!bt->rchan)
  		goto err;

  	bt->act_mask = buts->act_mask;

  	if (!bt->act_mask)
  		bt->act_mask = (u16) -1;

  	bt->start_lba = buts->start_lba;
  	bt->end_lba = buts->end_lba;

  	if (!bt->end_lba)
  		bt->end_lba = -1ULL;

  	bt->pid = buts->pid;

  	bt->trace_state = Blktrace_setup;

  	mutex_lock(&blk_probe_mutex);
  	if (atomic_add_return(1, &blk_probes_ref) == 1) {
  		ret = blk_register_tracepoints();
  		if (ret)
  			goto probe_err;
  	}
  	mutex_unlock(&blk_probe_mutex);

  	ret = -EBUSY;
  	old_bt = xchg(&q->blk_trace, bt);
  	if (old_bt) {
  		(void) xchg(&q->blk_trace, old_bt);
  		goto err;
  	}
  
  	return 0;

  probe_err:
  	atomic_dec(&blk_probes_ref);
  	mutex_unlock(&blk_probe_mutex);

  err:
  	if (dir)
  		blk_remove_tree(dir);
  	if (bt) {

  		if (bt->msg_file)
  			debugfs_remove(bt->msg_file);

  		if (bt->dropped_file)
  			debugfs_remove(bt->dropped_file);

  		free_percpu(bt->sequence);

  		free_percpu(bt->msg_data);

  		if (bt->rchan)
  			relay_close(bt->rchan);
  		kfree(bt);
  	}
  	return ret;
  }

  int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
  		    char __user *arg)

  {
  	struct blk_user_trace_setup buts;
  	int ret;
  
  	ret = copy_from_user(&buts, arg, sizeof(buts));
  	if (ret)
  		return -EFAULT;

  	ret = do_blk_trace_setup(q, name, dev, &buts);

  	if (ret)
  		return ret;
  
  	if (copy_to_user(arg, &buts, sizeof(buts)))
  		return -EFAULT;
  
  	return 0;
  }

  EXPORT_SYMBOL_GPL(blk_trace_setup);

  int blk_trace_startstop(struct request_queue *q, int start)

  {
  	struct blk_trace *bt;
  	int ret;
  
  	if ((bt = q->blk_trace) == NULL)
  		return -EINVAL;
  
  	/*
  	 * For starting a trace, we can transition from a setup or stopped
  	 * trace. For stopping a trace, the state must be running
  	 */
  	ret = -EINVAL;
  	if (start) {
  		if (bt->trace_state == Blktrace_setup ||
  		    bt->trace_state == Blktrace_stopped) {
  			blktrace_seq++;
  			smp_mb();
  			bt->trace_state = Blktrace_running;

  
  			trace_note_time(bt);

  			ret = 0;
  		}
  	} else {
  		if (bt->trace_state == Blktrace_running) {
  			bt->trace_state = Blktrace_stopped;
  			relay_flush(bt->rchan);
  			ret = 0;
  		}
  	}
  
  	return ret;
  }

  EXPORT_SYMBOL_GPL(blk_trace_startstop);

  
  /**
   * blk_trace_ioctl: - handle the ioctls associated with tracing
   * @bdev:	the block device
   * @cmd: 	the ioctl cmd
   * @arg:	the argument data, if any
   *
   **/
  int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
  {

  	struct request_queue *q;

  	int ret, start = 0;

  	char b[BDEVNAME_SIZE];

  
  	q = bdev_get_queue(bdev);
  	if (!q)
  		return -ENXIO;
  
  	mutex_lock(&bdev->bd_mutex);
  
  	switch (cmd) {
  	case BLKTRACESETUP:

  		bdevname(bdev, b);

  		ret = blk_trace_setup(q, b, bdev->bd_dev, arg);

  		break;
  	case BLKTRACESTART:
  		start = 1;
  	case BLKTRACESTOP:
  		ret = blk_trace_startstop(q, start);
  		break;
  	case BLKTRACETEARDOWN:
  		ret = blk_trace_remove(q);
  		break;
  	default:
  		ret = -ENOTTY;
  		break;
  	}
  
  	mutex_unlock(&bdev->bd_mutex);
  	return ret;
  }
  
  /**
   * blk_trace_shutdown: - stop and cleanup trace structures
   * @q:    the request queue associated with the device
   *
   **/

  void blk_trace_shutdown(struct request_queue *q)

  {

  	if (q->blk_trace) {
  		blk_trace_startstop(q, 0);
  		blk_trace_remove(q);
  	}

  }

  
  /*
   * blktrace probes
   */
  
  /**
   * blk_add_trace_rq - Add a trace for a request oriented action
   * @q:		queue the io is for
   * @rq:		the source request
   * @what:	the action
   *
   * Description:
   *     Records an action against a request. Will log the bio offset + size.
   *
   **/
  static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
  				    u32 what)
  {
  	struct blk_trace *bt = q->blk_trace;
  	int rw = rq->cmd_flags & 0x03;
  
  	if (likely(!bt))
  		return;
  
  	if (blk_discard_rq(rq))
  		rw |= (1 << BIO_RW_DISCARD);
  
  	if (blk_pc_request(rq)) {
  		what |= BLK_TC_ACT(BLK_TC_PC);
  		__blk_add_trace(bt, 0, rq->data_len, rw, what, rq->errors,
  				sizeof(rq->cmd), rq->cmd);
  	} else  {
  		what |= BLK_TC_ACT(BLK_TC_FS);
  		__blk_add_trace(bt, rq->hard_sector, rq->hard_nr_sectors << 9,
  				rw, what, rq->errors, 0, NULL);
  	}
  }
  
  static void blk_add_trace_rq_abort(struct request_queue *q, struct request *rq)
  {
  	blk_add_trace_rq(q, rq, BLK_TA_ABORT);
  }
  
  static void blk_add_trace_rq_insert(struct request_queue *q, struct request *rq)
  {
  	blk_add_trace_rq(q, rq, BLK_TA_INSERT);
  }
  
  static void blk_add_trace_rq_issue(struct request_queue *q, struct request *rq)
  {
  	blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
  }
  
  static void blk_add_trace_rq_requeue(struct request_queue *q, struct request *rq)
  {
  	blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
  }
  
  static void blk_add_trace_rq_complete(struct request_queue *q, struct request *rq)
  {
  	blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
  }
  
  /**
   * blk_add_trace_bio - Add a trace for a bio oriented action
   * @q:		queue the io is for
   * @bio:	the source bio
   * @what:	the action
   *
   * Description:
   *     Records an action against a bio. Will log the bio offset + size.
   *
   **/
  static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
  				     u32 what)
  {
  	struct blk_trace *bt = q->blk_trace;
  
  	if (likely(!bt))
  		return;
  
  	__blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
  			!bio_flagged(bio, BIO_UPTODATE), 0, NULL);
  }
  
  static void blk_add_trace_bio_bounce(struct request_queue *q, struct bio *bio)
  {
  	blk_add_trace_bio(q, bio, BLK_TA_BOUNCE);
  }
  
  static void blk_add_trace_bio_complete(struct request_queue *q, struct bio *bio)
  {
  	blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
  }
  
  static void blk_add_trace_bio_backmerge(struct request_queue *q, struct bio *bio)
  {
  	blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
  }
  
  static void blk_add_trace_bio_frontmerge(struct request_queue *q, struct bio *bio)
  {
  	blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
  }
  
  static void blk_add_trace_bio_queue(struct request_queue *q, struct bio *bio)
  {
  	blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
  }
  
  static void blk_add_trace_getrq(struct request_queue *q, struct bio *bio, int rw)
  {
  	if (bio)
  		blk_add_trace_bio(q, bio, BLK_TA_GETRQ);
  	else {
  		struct blk_trace *bt = q->blk_trace;
  
  		if (bt)
  			__blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
  	}
  }
  
  
  static void blk_add_trace_sleeprq(struct request_queue *q, struct bio *bio, int rw)
  {
  	if (bio)
  		blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ);
  	else {
  		struct blk_trace *bt = q->blk_trace;
  
  		if (bt)
  			__blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ, 0, 0, NULL);
  	}
  }
  
  static void blk_add_trace_plug(struct request_queue *q)
  {
  	struct blk_trace *bt = q->blk_trace;
  
  	if (bt)
  		__blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
  }
  
  static void blk_add_trace_unplug_io(struct request_queue *q)
  {
  	struct blk_trace *bt = q->blk_trace;
  
  	if (bt) {
  		unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
  		__be64 rpdu = cpu_to_be64(pdu);
  
  		__blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0,
  				sizeof(rpdu), &rpdu);
  	}
  }
  
  static void blk_add_trace_unplug_timer(struct request_queue *q)
  {
  	struct blk_trace *bt = q->blk_trace;
  
  	if (bt) {
  		unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
  		__be64 rpdu = cpu_to_be64(pdu);
  
  		__blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_TIMER, 0,
  				sizeof(rpdu), &rpdu);
  	}
  }
  
  static void blk_add_trace_split(struct request_queue *q, struct bio *bio,
  				unsigned int pdu)
  {
  	struct blk_trace *bt = q->blk_trace;
  
  	if (bt) {
  		__be64 rpdu = cpu_to_be64(pdu);
  
  		__blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
  				BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
  				sizeof(rpdu), &rpdu);
  	}
  }
  
  /**
   * blk_add_trace_remap - Add a trace for a remap operation
   * @q:		queue the io is for
   * @bio:	the source bio
   * @dev:	target device
   * @from:	source sector
   * @to:		target sector
   *
   * Description:
   *     Device mapper or raid target sometimes need to split a bio because
   *     it spans a stripe (or similar). Add a trace for that action.
   *
   **/
  static void blk_add_trace_remap(struct request_queue *q, struct bio *bio,
  				       dev_t dev, sector_t from, sector_t to)
  {
  	struct blk_trace *bt = q->blk_trace;
  	struct blk_io_trace_remap r;
  
  	if (likely(!bt))
  		return;
  
  	r.device = cpu_to_be32(dev);
  	r.device_from = cpu_to_be32(bio->bi_bdev->bd_dev);
  	r.sector = cpu_to_be64(to);
  
  	__blk_add_trace(bt, from, bio->bi_size, bio->bi_rw, BLK_TA_REMAP,
  			!bio_flagged(bio, BIO_UPTODATE), sizeof(r), &r);
  }
  
  /**
   * blk_add_driver_data - Add binary message with driver-specific data
   * @q:		queue the io is for
   * @rq:		io request
   * @data:	driver-specific data
   * @len:	length of driver-specific data
   *
   * Description:
   *     Some drivers might want to write driver-specific data per request.
   *
   **/
  void blk_add_driver_data(struct request_queue *q,
  			 struct request *rq,
  			 void *data, size_t len)
  {
  	struct blk_trace *bt = q->blk_trace;
  
  	if (likely(!bt))
  		return;
  
  	if (blk_pc_request(rq))
  		__blk_add_trace(bt, 0, rq->data_len, 0, BLK_TA_DRV_DATA,
  				rq->errors, len, data);
  	else
  		__blk_add_trace(bt, rq->hard_sector, rq->hard_nr_sectors << 9,
  				0, BLK_TA_DRV_DATA, rq->errors, len, data);
  }
  EXPORT_SYMBOL_GPL(blk_add_driver_data);
  
  static int blk_register_tracepoints(void)
  {
  	int ret;
  
  	ret = register_trace_block_rq_abort(blk_add_trace_rq_abort);
  	WARN_ON(ret);
  	ret = register_trace_block_rq_insert(blk_add_trace_rq_insert);
  	WARN_ON(ret);
  	ret = register_trace_block_rq_issue(blk_add_trace_rq_issue);
  	WARN_ON(ret);
  	ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue);
  	WARN_ON(ret);
  	ret = register_trace_block_rq_complete(blk_add_trace_rq_complete);
  	WARN_ON(ret);
  	ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce);
  	WARN_ON(ret);
  	ret = register_trace_block_bio_complete(blk_add_trace_bio_complete);
  	WARN_ON(ret);
  	ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
  	WARN_ON(ret);
  	ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
  	WARN_ON(ret);
  	ret = register_trace_block_bio_queue(blk_add_trace_bio_queue);
  	WARN_ON(ret);
  	ret = register_trace_block_getrq(blk_add_trace_getrq);
  	WARN_ON(ret);
  	ret = register_trace_block_sleeprq(blk_add_trace_sleeprq);
  	WARN_ON(ret);
  	ret = register_trace_block_plug(blk_add_trace_plug);
  	WARN_ON(ret);
  	ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer);
  	WARN_ON(ret);
  	ret = register_trace_block_unplug_io(blk_add_trace_unplug_io);
  	WARN_ON(ret);
  	ret = register_trace_block_split(blk_add_trace_split);
  	WARN_ON(ret);
  	ret = register_trace_block_remap(blk_add_trace_remap);
  	WARN_ON(ret);
  	return 0;
  }
  
  static void blk_unregister_tracepoints(void)
  {
  	unregister_trace_block_remap(blk_add_trace_remap);
  	unregister_trace_block_split(blk_add_trace_split);
  	unregister_trace_block_unplug_io(blk_add_trace_unplug_io);
  	unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer);
  	unregister_trace_block_plug(blk_add_trace_plug);
  	unregister_trace_block_sleeprq(blk_add_trace_sleeprq);
  	unregister_trace_block_getrq(blk_add_trace_getrq);
  	unregister_trace_block_bio_queue(blk_add_trace_bio_queue);
  	unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
  	unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
  	unregister_trace_block_bio_complete(blk_add_trace_bio_complete);
  	unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce);
  	unregister_trace_block_rq_complete(blk_add_trace_rq_complete);
  	unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue);
  	unregister_trace_block_rq_issue(blk_add_trace_rq_issue);
  	unregister_trace_block_rq_insert(blk_add_trace_rq_insert);
  	unregister_trace_block_rq_abort(blk_add_trace_rq_abort);
  
  	tracepoint_synchronize_unregister();
  }