This block IO tracing belongs to the instrumentation category. Signed-off-by: Mathieu Desnoyers CC: Jens Axboe --- block/Makefile | 1 block/blktrace.c | 576 --------------------------------------------- instrumentation/Makefile | 1 instrumentation/blktrace.c | 576 +++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 577 insertions(+), 577 deletions(-) Index: linux-2.6-lttng.stable/block/Makefile =================================================================== --- linux-2.6-lttng.stable.orig/block/Makefile 2007-10-29 09:51:05.000000000 -0400 +++ linux-2.6-lttng.stable/block/Makefile 2007-10-29 09:53:17.000000000 -0400 @@ -10,5 +10,4 @@ obj-$(CONFIG_IOSCHED_AS) += as-iosched.o obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o -obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o Index: linux-2.6-lttng.stable/block/blktrace.c =================================================================== --- linux-2.6-lttng.stable.orig/block/blktrace.c 2007-10-29 09:51:05.000000000 -0400 +++ /dev/null 1970-01-01 00:00:00.000000000 +0000 @@ -1,576 +0,0 @@ -/* - * Copyright (C) 2006 Jens Axboe - * - * 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 -#include -#include -#include -#include -#include -#include -#include -#include - -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 = cpu_clock(cpu) - 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 = cpu_clock(cpu) - 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(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; -} - -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 - */ -int do_blk_trace_setup(struct request_queue *q, struct block_device *bdev, - 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 (!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] = '_'; - - 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_setup(struct request_queue *q, struct block_device *bdev, - 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, bdev, &buts); - if (ret) - return ret; - - if (copy_to_user(arg, &buts, sizeof(buts))) - return -EFAULT; - - return 0; -} - -static 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; -} - -/** - * 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; - - 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(struct request_queue *q) -{ - if (q->blk_trace) { - blk_trace_startstop(q, 0); - blk_trace_remove(q); - } -} - -/* - * Average offset over two calls to cpu_clock() with a gettimeofday() - * in the middle - */ -static void blk_check_time(unsigned long long *t, int this_cpu) -{ - unsigned long long a, b; - struct timeval tv; - - a = cpu_clock(this_cpu); - do_gettimeofday(&tv); - b = cpu_clock(this_cpu); - - *t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000; - *t -= (a + b) / 2; -} - -/* - * calibrate our inter-CPU timings - */ -static void blk_trace_check_cpu_time(void *data) -{ - unsigned long long *t; - int this_cpu = get_cpu(); - - t = &per_cpu(blk_trace_cpu_offset, this_cpu); - - /* - * Just call it twice, hopefully the second call will be cache hot - * and a little more precise - */ - blk_check_time(t, this_cpu); - blk_check_time(t, this_cpu); - - put_cpu(); -} - -static void blk_trace_set_ht_offsets(void) -{ -#if defined(CONFIG_SCHED_SMT) - int cpu, i; - - /* - * now make sure HT siblings have the same time offset - */ - preempt_disable(); - for_each_online_cpu(cpu) { - unsigned long long *cpu_off, *sibling_off; - - for_each_cpu_mask(i, per_cpu(cpu_sibling_map, cpu)) { - if (i == cpu) - continue; - - cpu_off = &per_cpu(blk_trace_cpu_offset, cpu); - sibling_off = &per_cpu(blk_trace_cpu_offset, i); - *sibling_off = *cpu_off; - } - } - preempt_enable(); -#endif -} - -static __init int blk_trace_init(void) -{ - mutex_init(&blk_tree_mutex); - on_each_cpu(blk_trace_check_cpu_time, NULL, 1, 1); - blk_trace_set_ht_offsets(); - - return 0; -} - -module_init(blk_trace_init); - Index: linux-2.6-lttng.stable/instrumentation/Makefile =================================================================== --- linux-2.6-lttng.stable.orig/instrumentation/Makefile 2007-10-29 09:53:14.000000000 -0400 +++ linux-2.6-lttng.stable/instrumentation/Makefile 2007-10-29 09:53:24.000000000 -0400 @@ -10,3 +10,4 @@ obj-$(CONFIG_LOCKDEP) += lockdep.o ifeq ($(CONFIG_PROC_FS),y) obj-$(CONFIG_LOCKDEP) += lockdep_proc.o endif +obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o Index: linux-2.6-lttng.stable/instrumentation/blktrace.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-2.6-lttng.stable/instrumentation/blktrace.c 2007-10-29 09:53:17.000000000 -0400 @@ -0,0 +1,576 @@ +/* + * Copyright (C) 2006 Jens Axboe + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include + +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 = cpu_clock(cpu) - 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 = cpu_clock(cpu) - 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(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; +} + +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 + */ +int do_blk_trace_setup(struct request_queue *q, struct block_device *bdev, + 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 (!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] = '_'; + + 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_setup(struct request_queue *q, struct block_device *bdev, + 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, bdev, &buts); + if (ret) + return ret; + + if (copy_to_user(arg, &buts, sizeof(buts))) + return -EFAULT; + + return 0; +} + +static 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; +} + +/** + * 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; + + 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(struct request_queue *q) +{ + if (q->blk_trace) { + blk_trace_startstop(q, 0); + blk_trace_remove(q); + } +} + +/* + * Average offset over two calls to cpu_clock() with a gettimeofday() + * in the middle + */ +static void blk_check_time(unsigned long long *t, int this_cpu) +{ + unsigned long long a, b; + struct timeval tv; + + a = cpu_clock(this_cpu); + do_gettimeofday(&tv); + b = cpu_clock(this_cpu); + + *t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000; + *t -= (a + b) / 2; +} + +/* + * calibrate our inter-CPU timings + */ +static void blk_trace_check_cpu_time(void *data) +{ + unsigned long long *t; + int this_cpu = get_cpu(); + + t = &per_cpu(blk_trace_cpu_offset, this_cpu); + + /* + * Just call it twice, hopefully the second call will be cache hot + * and a little more precise + */ + blk_check_time(t, this_cpu); + blk_check_time(t, this_cpu); + + put_cpu(); +} + +static void blk_trace_set_ht_offsets(void) +{ +#if defined(CONFIG_SCHED_SMT) + int cpu, i; + + /* + * now make sure HT siblings have the same time offset + */ + preempt_disable(); + for_each_online_cpu(cpu) { + unsigned long long *cpu_off, *sibling_off; + + for_each_cpu_mask(i, per_cpu(cpu_sibling_map, cpu)) { + if (i == cpu) + continue; + + cpu_off = &per_cpu(blk_trace_cpu_offset, cpu); + sibling_off = &per_cpu(blk_trace_cpu_offset, i); + *sibling_off = *cpu_off; + } + } + preempt_enable(); +#endif +} + +static __init int blk_trace_init(void) +{ + mutex_init(&blk_tree_mutex); + on_each_cpu(blk_trace_check_cpu_time, NULL, 1, 1); + blk_trace_set_ht_offsets(); + + return 0; +} + +module_init(blk_trace_init); + -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/