/* * 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 <asm/uaccess.h> static DEFINE_PER_CPU(unsigned long long, blk_trace_cpu_offset) = { 0, };static unsigned int blktrace_seq __read_mostly = 1; /* * 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 = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu); 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);} 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) }; /* * Bio action bits of interest */static u32 bio_act[9] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC), 0, BLK_TC_ACT(BLK_TC_AHEAD), 0, 0, 0, BLK_TC_ACT(BLK_TC_META) }; /* * More could be added as needed, taking care to increment the decrementer * to get correct indexing */#define trace_barrier_bit(rw) \ (((rw) & (1 << BIO_RW_BARRIER)) >> (BIO_RW_BARRIER - 0))#define trace_sync_bit(rw) \ (((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1))#define trace_ahead_bit(rw) \ (((rw) & (1 << BIO_RW_AHEAD)) << (2 - BIO_RW_AHEAD))#define trace_meta_bit(rw) \ (((rw) & (1 << BIO_RW_META)) >> (BIO_RW_META - 3)) /* * The worker for the various blk_add_trace*() types. Fills out a * blk_io_trace structure and places it in a per-cpu subbuffer. */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 |= bio_act[trace_barrier_bit(rw)]; what |= bio_act[trace_sync_bit(rw)]; what |= bio_act[trace_ahead_bit(rw)]; what |= bio_act[trace_meta_bit(rw)]; 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. Once reserved, it's * enough to get preemption disabled to prevent read of this data * before we are through filling it. get_cpu()/put_cpu() does this * for us */ 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 = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu); 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);} EXPORT_SYMBOL_GPL(__blk_add_trace); static struct dentry *blk_tree_root;static struct 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; mutex_lock(&blk_tree_mutex); if (!blk_tree_root) { blk_tree_root = debugfs_create_dir("block", NULL); if (!blk_tree_root) goto err; } dir = debugfs_create_dir(blk_name, blk_tree_root); if (dir) root_users++; else 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->dropped_file); blk_remove_tree(bt->dir); free_percpu(bt->sequence); kfree(bt);} static int blk_trace_remove(request_queue_t *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;} 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\n", 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,}; /* * 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 */static int blk_trace_setup(request_queue_t *q, struct block_device *bdev, char __user *arg){ struct blk_user_trace_setup buts; struct blk_trace *old_bt, *bt = NULL; struct dentry *dir = NULL; char b[BDEVNAME_SIZE]; int ret, i; if (copy_from_user(&buts, arg, sizeof(buts))) return -EFAULT; if (!buts.buf_size || !buts.buf_nr) return -EINVAL; strcpy(buts.name, bdevname(bdev, b)); /* * 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] = '_'; if (copy_to_user(arg, &buts, sizeof(buts))) return -EFAULT; ret = -ENOMEM; bt = kzalloc(sizeof(*bt), GFP_KERNEL); if (!bt) goto err; bt->sequence = alloc_percpu(unsigned long); if (!bt->sequence) goto err; ret = -ENOENT; dir = blk_create_tree(buts.name); if (!dir) goto err; bt->dir = dir; bt->dev = bdev->bd_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->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; ret = -EBUSY; old_bt = xchg(&q->blk_trace, bt); if (old_bt) { (void) xchg(&q->blk_trace, old_bt); goto err; } return 0;err: if (dir) blk_remove_tree(dir); if (bt) { if (bt->dropped_file) debugfs_remove(bt->dropped_file); free_percpu(bt->sequence); if (bt->rchan) relay_close(bt->rchan); kfree(bt); } return ret;} static int blk_trace_startstop(request_queue_t *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;} /** * 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){ request_queue_t *q; int ret, start = 0; q = bdev_get_queue(bdev); if (!q) return -ENXIO; mutex_lock(&bdev->bd_mutex); switch (cmd) { case BLKTRACESETUP: ret = blk_trace_setup(q, bdev, 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(request_queue_t *q){ if (q->blk_trace) { blk_trace_startstop(q, 0); blk_trace_remove(q); }} /* * Average offset over two calls to sched_clock() with a gettimeofday() * in the middle */static void blk_check_time(unsigned long long *t){ unsigned long long a, b; struct timeval tv; a = sched_clock(); do_gettimeofday(&tv);Lines 1–500 of 562. 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/* * 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 <asm/uaccess.h> static DEFINE_PER_CPU(unsigned long long, blk_trace_cpu_offset) = { 0, }; static unsigned int blktrace_seq __read_mostly = 1; /* * 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 = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu); 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); } 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) }; /* * Bio action bits of interest */ static u32 bio_act[9] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC), 0, BLK_TC_ACT(BLK_TC_AHEAD), 0, 0, 0, BLK_TC_ACT(BLK_TC_META) }; /* * More could be added as needed, taking care to increment the decrementer * to get correct indexing */ #define trace_barrier_bit(rw) \ (((rw) & (1 << BIO_RW_BARRIER)) >> (BIO_RW_BARRIER - 0)) #define trace_sync_bit(rw) \ (((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1)) #define trace_ahead_bit(rw) \ (((rw) & (1 << BIO_RW_AHEAD)) << (2 - BIO_RW_AHEAD)) #define trace_meta_bit(rw) \ (((rw) & (1 << BIO_RW_META)) >> (BIO_RW_META - 3)) /* * The worker for the various blk_add_trace*() types. Fills out a * blk_io_trace structure and places it in a per-cpu subbuffer. */ 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 |= bio_act[trace_barrier_bit(rw)]; what |= bio_act[trace_sync_bit(rw)]; what |= bio_act[trace_ahead_bit(rw)]; what |= bio_act[trace_meta_bit(rw)]; 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. Once reserved, it's * enough to get preemption disabled to prevent read of this data * before we are through filling it. get_cpu()/put_cpu() does this * for us */ 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 = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu); 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); } EXPORT_SYMBOL_GPL(__blk_add_trace); static struct dentry *blk_tree_root; static struct 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; mutex_lock(&blk_tree_mutex); if (!blk_tree_root) { blk_tree_root = debugfs_create_dir("block", NULL); if (!blk_tree_root) goto err; } dir = debugfs_create_dir(blk_name, blk_tree_root); if (dir) root_users++; else 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->dropped_file); blk_remove_tree(bt->dir); free_percpu(bt->sequence); kfree(bt); } static int blk_trace_remove(request_queue_t *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; } 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\n", 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, }; /* * 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 */ static int blk_trace_setup(request_queue_t *q, struct block_device *bdev, char __user *arg) { struct blk_user_trace_setup buts; struct blk_trace *old_bt, *bt = NULL; struct dentry *dir = NULL; char b[BDEVNAME_SIZE]; int ret, i; if (copy_from_user(&buts, arg, sizeof(buts))) return -EFAULT; if (!buts.buf_size || !buts.buf_nr) return -EINVAL; strcpy(buts.name, bdevname(bdev, b)); /* * 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] = '_'; if (copy_to_user(arg, &buts, sizeof(buts))) return -EFAULT; ret = -ENOMEM; bt = kzalloc(sizeof(*bt), GFP_KERNEL); if (!bt) goto err; bt->sequence = alloc_percpu(unsigned long); if (!bt->sequence) goto err; ret = -ENOENT; dir = blk_create_tree(buts.name); if (!dir) goto err; bt->dir = dir; bt->dev = bdev->bd_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->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; ret = -EBUSY; old_bt = xchg(&q->blk_trace, bt); if (old_bt) { (void) xchg(&q->blk_trace, old_bt); goto err; } return 0; err: if (dir) blk_remove_tree(dir); if (bt) { if (bt->dropped_file) debugfs_remove(bt->dropped_file); free_percpu(bt->sequence); if (bt->rchan) relay_close(bt->rchan); kfree(bt); } return ret; } static int blk_trace_startstop(request_queue_t *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; } /** * 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) { request_queue_t *q; int ret, start = 0; q = bdev_get_queue(bdev); if (!q) return -ENXIO; mutex_lock(&bdev->bd_mutex); switch (cmd) { case BLKTRACESETUP: ret = blk_trace_setup(q, bdev, 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(request_queue_t *q) { if (q->blk_trace) { blk_trace_startstop(q, 0); blk_trace_remove(q); } } /* * Average offset over two calls to sched_clock() with a gettimeofday() * in the middle */ static void blk_check_time(unsigned long long *t) { unsigned long long a, b; struct timeval tv; a = sched_clock(); do_gettimeofday(&tv);