/* * 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 void blk_trace_cleanup(struct blk_trace *bt) { debugfs_remove(bt->msg_file); debugfs_remove(bt->dropped_file); relay_close(bt->rchan); 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\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, }; 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) { struct dentry *parent = dentry->d_parent; debugfs_remove(dentry); /* * this will fail for all but the last file, but that is ok. what we * care about is the top level buts->name directory going away, when * the last trace file is gone. Then we don't have to rmdir() that * manually on trace stop, so it nicely solves the issue with * force killing of running traces. */ debugfs_remove(parent); 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; if (!blk_tree_root) { blk_tree_root = debugfs_create_dir("block", NULL); if (!blk_tree_root) return -ENOMEM; } dir = debugfs_create_dir(buts->name, blk_tree_root); 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 (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(); }