diff options
Diffstat (limited to 'kernel/trace/blktrace.c')
| -rw-r--r-- | kernel/trace/blktrace.c | 2009 |
1 files changed, 2009 insertions, 0 deletions
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c new file mode 100644 index 000000000..75ea1a5be --- /dev/null +++ b/kernel/trace/blktrace.c @@ -0,0 +1,2009 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk> + * + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#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/slab.h> +#include <linux/debugfs.h> +#include <linux/export.h> +#include <linux/time.h> +#include <linux/uaccess.h> +#include <linux/list.h> +#include <linux/blk-cgroup.h> + +#include "../../block/blk.h" + +#include <trace/events/block.h> + +#include "trace_output.h" + +#ifdef CONFIG_BLK_DEV_IO_TRACE + +static unsigned int blktrace_seq __read_mostly = 1; + +static struct trace_array *blk_tr; +static bool blk_tracer_enabled __read_mostly; + +static LIST_HEAD(running_trace_list); +static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock); + +/* Select an alternative, minimalistic output than the original one */ +#define TRACE_BLK_OPT_CLASSIC 0x1 +#define TRACE_BLK_OPT_CGROUP 0x2 +#define TRACE_BLK_OPT_CGNAME 0x4 + +static struct tracer_opt blk_tracer_opts[] = { + /* Default disable the minimalistic output */ + { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) }, +#ifdef CONFIG_BLK_CGROUP + { TRACER_OPT(blk_cgroup, TRACE_BLK_OPT_CGROUP) }, + { TRACER_OPT(blk_cgname, TRACE_BLK_OPT_CGNAME) }, +#endif + { } +}; + +static struct tracer_flags blk_tracer_flags = { + .val = 0, + .opts = blk_tracer_opts, +}; + +/* Global reference count of probes */ +static DEFINE_MUTEX(blk_probe_mutex); +static int blk_probes_ref; + +static void 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, + union kernfs_node_id *cgid) +{ + struct blk_io_trace *t; + struct ring_buffer_event *event = NULL; + struct ring_buffer *buffer = NULL; + int pc = 0; + int cpu = smp_processor_id(); + bool blk_tracer = blk_tracer_enabled; + ssize_t cgid_len = cgid ? sizeof(*cgid) : 0; + + if (blk_tracer) { + buffer = blk_tr->trace_buffer.buffer; + pc = preempt_count(); + event = trace_buffer_lock_reserve(buffer, TRACE_BLK, + sizeof(*t) + len + cgid_len, + 0, pc); + if (!event) + return; + t = ring_buffer_event_data(event); + goto record_it; + } + + if (!bt->rchan) + return; + + t = relay_reserve(bt->rchan, sizeof(*t) + len + cgid_len); + if (t) { + t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; + t->time = ktime_to_ns(ktime_get()); +record_it: + t->device = bt->dev; + t->action = action | (cgid ? __BLK_TN_CGROUP : 0); + t->pid = pid; + t->cpu = cpu; + t->pdu_len = len + cgid_len; + if (cgid) + memcpy((void *)t + sizeof(*t), cgid, cgid_len); + memcpy((void *) t + sizeof(*t) + cgid_len, data, len); + + if (blk_tracer) + trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc); + } +} + +/* + * Send out a notify for this process, if we haven't done so since a trace + * started + */ +static void trace_note_tsk(struct task_struct *tsk) +{ + unsigned long flags; + struct blk_trace *bt; + + tsk->btrace_seq = blktrace_seq; + spin_lock_irqsave(&running_trace_lock, flags); + list_for_each_entry(bt, &running_trace_list, running_list) { + trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, + sizeof(tsk->comm), NULL); + } + spin_unlock_irqrestore(&running_trace_lock, flags); +} + +static void trace_note_time(struct blk_trace *bt) +{ + struct timespec64 now; + unsigned long flags; + u32 words[2]; + + /* need to check user space to see if this breaks in y2038 or y2106 */ + ktime_get_real_ts64(&now); + words[0] = (u32)now.tv_sec; + words[1] = now.tv_nsec; + + local_irq_save(flags); + trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words), NULL); + local_irq_restore(flags); +} + +void __trace_note_message(struct blk_trace *bt, struct blkcg *blkcg, + const char *fmt, ...) +{ + int n; + va_list args; + unsigned long flags; + char *buf; + + if (unlikely(bt->trace_state != Blktrace_running && + !blk_tracer_enabled)) + return; + + /* + * If the BLK_TC_NOTIFY action mask isn't set, don't send any note + * message to the trace. + */ + if (!(bt->act_mask & BLK_TC_NOTIFY)) + return; + + local_irq_save(flags); + buf = this_cpu_ptr(bt->msg_data); + va_start(args, fmt); + n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args); + va_end(args); + + if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP)) + blkcg = NULL; +#ifdef CONFIG_BLK_CGROUP + trace_note(bt, 0, BLK_TN_MESSAGE, buf, n, + blkcg ? cgroup_get_kernfs_id(blkcg->css.cgroup) : NULL); +#else + trace_note(bt, 0, BLK_TN_MESSAGE, buf, n, NULL); +#endif + 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 && (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 const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ), + BLK_TC_ACT(BLK_TC_WRITE) }; + +#define BLK_TC_RAHEAD BLK_TC_AHEAD +#define BLK_TC_PREFLUSH BLK_TC_FLUSH + +/* The ilog2() calls fall out because they're constant */ +#define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \ + (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __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 op, int op_flags, u32 what, int error, int pdu_len, + void *pdu_data, union kernfs_node_id *cgid) +{ + struct task_struct *tsk = current; + struct ring_buffer_event *event = NULL; + struct ring_buffer *buffer = NULL; + struct blk_io_trace *t; + unsigned long flags = 0; + unsigned long *sequence; + pid_t pid; + int cpu, pc = 0; + bool blk_tracer = blk_tracer_enabled; + ssize_t cgid_len = cgid ? sizeof(*cgid) : 0; + + if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer)) + return; + + what |= ddir_act[op_is_write(op) ? WRITE : READ]; + what |= MASK_TC_BIT(op_flags, SYNC); + what |= MASK_TC_BIT(op_flags, RAHEAD); + what |= MASK_TC_BIT(op_flags, META); + what |= MASK_TC_BIT(op_flags, PREFLUSH); + what |= MASK_TC_BIT(op_flags, FUA); + if (op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE) + what |= BLK_TC_ACT(BLK_TC_DISCARD); + if (op == REQ_OP_FLUSH) + what |= BLK_TC_ACT(BLK_TC_FLUSH); + if (cgid) + what |= __BLK_TA_CGROUP; + + pid = tsk->pid; + if (act_log_check(bt, what, sector, pid)) + return; + cpu = raw_smp_processor_id(); + + if (blk_tracer) { + tracing_record_cmdline(current); + + buffer = blk_tr->trace_buffer.buffer; + pc = preempt_count(); + event = trace_buffer_lock_reserve(buffer, TRACE_BLK, + sizeof(*t) + pdu_len + cgid_len, + 0, pc); + if (!event) + return; + t = ring_buffer_event_data(event); + goto record_it; + } + + if (unlikely(tsk->btrace_seq != blktrace_seq)) + trace_note_tsk(tsk); + + /* + * 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); + t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len + cgid_len); + if (t) { + 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()); +record_it: + /* + * These two are not needed in ftrace as they are in the + * generic trace_entry, filled by tracing_generic_entry_update, + * but for the trace_event->bin() synthesizer benefit we do it + * here too. + */ + t->cpu = cpu; + t->pid = pid; + + t->sector = sector; + t->bytes = bytes; + t->action = what; + t->device = bt->dev; + t->error = error; + t->pdu_len = pdu_len + cgid_len; + + if (cgid_len) + memcpy((void *)t + sizeof(*t), cgid, cgid_len); + if (pdu_len) + memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len); + + if (blk_tracer) { + trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc); + return; + } + } + + local_irq_restore(flags); +} + +static void blk_trace_free(struct blk_trace *bt) +{ + debugfs_remove(bt->msg_file); + debugfs_remove(bt->dropped_file); + relay_close(bt->rchan); + debugfs_remove(bt->dir); + free_percpu(bt->sequence); + free_percpu(bt->msg_data); + kfree(bt); +} + +static void get_probe_ref(void) +{ + mutex_lock(&blk_probe_mutex); + if (++blk_probes_ref == 1) + blk_register_tracepoints(); + mutex_unlock(&blk_probe_mutex); +} + +static void put_probe_ref(void) +{ + mutex_lock(&blk_probe_mutex); + if (!--blk_probes_ref) + blk_unregister_tracepoints(); + mutex_unlock(&blk_probe_mutex); +} + +static void blk_trace_cleanup(struct blk_trace *bt) +{ + synchronize_rcu(); + blk_trace_free(bt); + put_probe_ref(); +} + +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_running) + blk_trace_cleanup(bt); + + return 0; +} + +int blk_trace_remove(struct request_queue *q) +{ + int ret; + + mutex_lock(&q->blk_trace_mutex); + ret = __blk_trace_remove(q); + mutex_unlock(&q->blk_trace_mutex); + + return ret; +} +EXPORT_SYMBOL_GPL(blk_trace_remove); + +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 = simple_open, + .read = blk_dropped_read, + .llseek = default_llseek, +}; + +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 = memdup_user_nul(buffer, count); + if (IS_ERR(msg)) + return PTR_ERR(msg); + + bt = filp->private_data; + __trace_note_message(bt, NULL, "%s", msg); + kfree(msg); + + return count; +} + +static const struct file_operations blk_msg_fops = { + .owner = THIS_MODULE, + .open = simple_open, + .write = blk_msg_write, + .llseek = noop_llseek, +}; + +/* + * 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, + umode_t 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, +}; + +static void blk_trace_setup_lba(struct blk_trace *bt, + struct block_device *bdev) +{ + struct hd_struct *part = NULL; + + if (bdev) + part = bdev->bd_part; + + if (part) { + bt->start_lba = part->start_sect; + bt->end_lba = part->start_sect + part->nr_sects; + } else { + bt->start_lba = 0; + bt->end_lba = -1ULL; + } +} + +/* + * Setup everything required to start tracing + */ +static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, + struct block_device *bdev, + struct blk_user_trace_setup *buts) +{ + struct blk_trace *bt = NULL; + struct dentry *dir = NULL; + int ret; + + if (!buts->buf_size || !buts->buf_nr) + return -EINVAL; + + if (!blk_debugfs_root) + return -ENOENT; + + 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 + */ + strreplace(buts->name, '/', '_'); + + /* + * bdev can be NULL, as with scsi-generic, this is a helpful as + * we can be. + */ + if (q->blk_trace) { + pr_warn("Concurrent blktraces are not allowed on %s\n", + buts->name); + return -EBUSY; + } + + bt = kzalloc(sizeof(*bt), GFP_KERNEL); + if (!bt) + return -ENOMEM; + + ret = -ENOMEM; + bt->sequence = alloc_percpu(unsigned long); + if (!bt->sequence) + goto err; + + bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char)); + if (!bt->msg_data) + goto err; + +#ifdef CONFIG_BLK_DEBUG_FS + /* + * When tracing whole make_request drivers (multiqueue) block devices, + * reuse the existing debugfs directory created by the block layer on + * init. For request-based block devices, all partitions block devices, + * and scsi-generic block devices we create a temporary new debugfs + * directory that will be removed once the trace ends. + */ + if (q->mq_ops && bdev && bdev == bdev->bd_contains) + dir = q->debugfs_dir; + else +#endif + bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root); + if (!dir) + goto err; + + /* + * As blktrace relies on debugfs for its interface the debugfs directory + * is required, contrary to the usual mantra of not checking for debugfs + * files or directories. + */ + if (IS_ERR_OR_NULL(dir)) { + pr_warn("debugfs_dir not present for %s so skipping\n", + buts->name); + ret = -ENOENT; + goto err; + } + + bt->dev = dev; + atomic_set(&bt->dropped, 0); + INIT_LIST_HEAD(&bt->running_list); + + 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; + + blk_trace_setup_lba(bt, bdev); + + /* overwrite with user settings */ + if (buts->start_lba) + bt->start_lba = buts->start_lba; + if (buts->end_lba) + bt->end_lba = buts->end_lba; + + bt->pid = buts->pid; + bt->trace_state = Blktrace_setup; + + ret = -EBUSY; + if (cmpxchg(&q->blk_trace, NULL, bt)) + goto err; + + get_probe_ref(); + + ret = 0; +err: + if (ret) + blk_trace_free(bt); + return ret; +} + +static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev, + 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, name, dev, bdev, &buts); + if (ret) + return ret; + + if (copy_to_user(arg, &buts, sizeof(buts))) { + __blk_trace_remove(q); + return -EFAULT; + } + return 0; +} + +int blk_trace_setup(struct request_queue *q, char *name, dev_t dev, + struct block_device *bdev, + char __user *arg) +{ + int ret; + + mutex_lock(&q->blk_trace_mutex); + ret = __blk_trace_setup(q, name, dev, bdev, arg); + mutex_unlock(&q->blk_trace_mutex); + + return ret; +} +EXPORT_SYMBOL_GPL(blk_trace_setup); + +#if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64) +static int compat_blk_trace_setup(struct request_queue *q, char *name, + dev_t dev, struct block_device *bdev, + char __user *arg) +{ + struct blk_user_trace_setup buts; + struct compat_blk_user_trace_setup cbuts; + int ret; + + if (copy_from_user(&cbuts, arg, sizeof(cbuts))) + return -EFAULT; + + buts = (struct blk_user_trace_setup) { + .act_mask = cbuts.act_mask, + .buf_size = cbuts.buf_size, + .buf_nr = cbuts.buf_nr, + .start_lba = cbuts.start_lba, + .end_lba = cbuts.end_lba, + .pid = cbuts.pid, + }; + + ret = do_blk_trace_setup(q, name, dev, bdev, &buts); + if (ret) + return ret; + + if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) { + __blk_trace_remove(q); + return -EFAULT; + } + + return 0; +} +#endif + +static int __blk_trace_startstop(struct request_queue *q, int start) +{ + int ret; + struct blk_trace *bt; + + bt = rcu_dereference_protected(q->blk_trace, + lockdep_is_held(&q->blk_trace_mutex)); + if (bt == 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; + spin_lock_irq(&running_trace_lock); + list_add(&bt->running_list, &running_trace_list); + spin_unlock_irq(&running_trace_lock); + + trace_note_time(bt); + ret = 0; + } + } else { + if (bt->trace_state == Blktrace_running) { + bt->trace_state = Blktrace_stopped; + spin_lock_irq(&running_trace_lock); + list_del_init(&bt->running_list); + spin_unlock_irq(&running_trace_lock); + relay_flush(bt->rchan); + ret = 0; + } + } + + return ret; +} + +int blk_trace_startstop(struct request_queue *q, int start) +{ + int ret; + + mutex_lock(&q->blk_trace_mutex); + ret = __blk_trace_startstop(q, start); + mutex_unlock(&q->blk_trace_mutex); + + return ret; +} +EXPORT_SYMBOL_GPL(blk_trace_startstop); + +/* + * When reading or writing the blktrace sysfs files, the references to the + * opened sysfs or device files should prevent the underlying block device + * from being removed. So no further delete protection is really needed. + */ + +/** + * 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(&q->blk_trace_mutex); + + switch (cmd) { + case BLKTRACESETUP: + bdevname(bdev, b); + ret = __blk_trace_setup(q, b, bdev->bd_dev, bdev, arg); + break; +#if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64) + case BLKTRACESETUP32: + bdevname(bdev, b); + ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg); + break; +#endif + 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(&q->blk_trace_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) +{ + mutex_lock(&q->blk_trace_mutex); + if (rcu_dereference_protected(q->blk_trace, + lockdep_is_held(&q->blk_trace_mutex))) { + __blk_trace_startstop(q, 0); + __blk_trace_remove(q); + } + + mutex_unlock(&q->blk_trace_mutex); +} + +#ifdef CONFIG_BLK_CGROUP +static union kernfs_node_id * +blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio) +{ + struct blk_trace *bt; + + /* We don't use the 'bt' value here except as an optimization... */ + bt = rcu_dereference_protected(q->blk_trace, 1); + if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP)) + return NULL; + + if (!bio->bi_css) + return NULL; + return cgroup_get_kernfs_id(bio->bi_css->cgroup); +} +#else +static union kernfs_node_id * +blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio) +{ + return NULL; +} +#endif + +static union kernfs_node_id * +blk_trace_request_get_cgid(struct request_queue *q, struct request *rq) +{ + if (!rq->bio) + return NULL; + /* Use the first bio */ + return blk_trace_bio_get_cgid(q, rq->bio); +} + +/* + * blktrace probes + */ + +/** + * blk_add_trace_rq - Add a trace for a request oriented action + * @rq: the source request + * @error: return status to log + * @nr_bytes: number of completed bytes + * @what: the action + * @cgid: the cgroup info + * + * Description: + * Records an action against a request. Will log the bio offset + size. + * + **/ +static void blk_add_trace_rq(struct request *rq, int error, + unsigned int nr_bytes, u32 what, + union kernfs_node_id *cgid) +{ + struct blk_trace *bt; + + rcu_read_lock(); + bt = rcu_dereference(rq->q->blk_trace); + if (likely(!bt)) { + rcu_read_unlock(); + return; + } + + if (blk_rq_is_passthrough(rq)) + what |= BLK_TC_ACT(BLK_TC_PC); + else + what |= BLK_TC_ACT(BLK_TC_FS); + + __blk_add_trace(bt, blk_rq_trace_sector(rq), nr_bytes, req_op(rq), + rq->cmd_flags, what, error, 0, NULL, cgid); + rcu_read_unlock(); +} + +static void blk_add_trace_rq_insert(void *ignore, + struct request_queue *q, struct request *rq) +{ + blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_INSERT, + blk_trace_request_get_cgid(q, rq)); +} + +static void blk_add_trace_rq_issue(void *ignore, + struct request_queue *q, struct request *rq) +{ + blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_ISSUE, + blk_trace_request_get_cgid(q, rq)); +} + +static void blk_add_trace_rq_requeue(void *ignore, + struct request_queue *q, + struct request *rq) +{ + blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_REQUEUE, + blk_trace_request_get_cgid(q, rq)); +} + +static void blk_add_trace_rq_complete(void *ignore, struct request *rq, + int error, unsigned int nr_bytes) +{ + blk_add_trace_rq(rq, error, nr_bytes, BLK_TA_COMPLETE, + blk_trace_request_get_cgid(rq->q, rq)); +} + +/** + * 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 + * @error: error, if any + * + * 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, int error) +{ + struct blk_trace *bt; + + rcu_read_lock(); + bt = rcu_dereference(q->blk_trace); + if (likely(!bt)) { + rcu_read_unlock(); + return; + } + + __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size, + bio_op(bio), bio->bi_opf, what, error, 0, NULL, + blk_trace_bio_get_cgid(q, bio)); + rcu_read_unlock(); +} + +static void blk_add_trace_bio_bounce(void *ignore, + struct request_queue *q, struct bio *bio) +{ + blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0); +} + +static void blk_add_trace_bio_complete(void *ignore, + struct request_queue *q, struct bio *bio, + int error) +{ + blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error); +} + +static void blk_add_trace_bio_backmerge(void *ignore, + struct request_queue *q, + struct request *rq, + struct bio *bio) +{ + blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0); +} + +static void blk_add_trace_bio_frontmerge(void *ignore, + struct request_queue *q, + struct request *rq, + struct bio *bio) +{ + blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0); +} + +static void blk_add_trace_bio_queue(void *ignore, + struct request_queue *q, struct bio *bio) +{ + blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0); +} + +static void blk_add_trace_getrq(void *ignore, + struct request_queue *q, + struct bio *bio, int rw) +{ + if (bio) + blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0); + else { + struct blk_trace *bt; + + rcu_read_lock(); + bt = rcu_dereference(q->blk_trace); + if (bt) + __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_GETRQ, 0, 0, + NULL, NULL); + rcu_read_unlock(); + } +} + + +static void blk_add_trace_sleeprq(void *ignore, + struct request_queue *q, + struct bio *bio, int rw) +{ + if (bio) + blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0); + else { + struct blk_trace *bt; + + rcu_read_lock(); + bt = rcu_dereference(q->blk_trace); + if (bt) + __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_SLEEPRQ, + 0, 0, NULL, NULL); + rcu_read_unlock(); + } +} + +static void blk_add_trace_plug(void *ignore, struct request_queue *q) +{ + struct blk_trace *bt; + + rcu_read_lock(); + bt = rcu_dereference(q->blk_trace); + if (bt) + __blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL, NULL); + rcu_read_unlock(); +} + +static void blk_add_trace_unplug(void *ignore, struct request_queue *q, + unsigned int depth, bool explicit) +{ + struct blk_trace *bt; + + rcu_read_lock(); + bt = rcu_dereference(q->blk_trace); + if (bt) { + __be64 rpdu = cpu_to_be64(depth); + u32 what; + + if (explicit) + what = BLK_TA_UNPLUG_IO; + else + what = BLK_TA_UNPLUG_TIMER; + + __blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu, NULL); + } + rcu_read_unlock(); +} + +static void blk_add_trace_split(void *ignore, + struct request_queue *q, struct bio *bio, + unsigned int pdu) +{ + struct blk_trace *bt; + + rcu_read_lock(); + bt = rcu_dereference(q->blk_trace); + if (bt) { + __be64 rpdu = cpu_to_be64(pdu); + + __blk_add_trace(bt, bio->bi_iter.bi_sector, + bio->bi_iter.bi_size, bio_op(bio), bio->bi_opf, + BLK_TA_SPLIT, + blk_status_to_errno(bio->bi_status), + sizeof(rpdu), &rpdu, + blk_trace_bio_get_cgid(q, bio)); + } + rcu_read_unlock(); +} + +/** + * blk_add_trace_bio_remap - Add a trace for a bio-remap operation + * @ignore: trace callback data parameter (not used) + * @q: queue the io is for + * @bio: the source bio + * @dev: target device + * @from: source 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_bio_remap(void *ignore, + struct request_queue *q, struct bio *bio, + dev_t dev, sector_t from) +{ + struct blk_trace *bt; + struct blk_io_trace_remap r; + + rcu_read_lock(); + bt = rcu_dereference(q->blk_trace); + if (likely(!bt)) { + rcu_read_unlock(); + return; + } + + r.device_from = cpu_to_be32(dev); + r.device_to = cpu_to_be32(bio_dev(bio)); + r.sector_from = cpu_to_be64(from); + + __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size, + bio_op(bio), bio->bi_opf, BLK_TA_REMAP, + blk_status_to_errno(bio->bi_status), + sizeof(r), &r, blk_trace_bio_get_cgid(q, bio)); + rcu_read_unlock(); +} + +/** + * blk_add_trace_rq_remap - Add a trace for a request-remap operation + * @ignore: trace callback data parameter (not used) + * @q: queue the io is for + * @rq: the source request + * @dev: target device + * @from: source sector + * + * Description: + * Device mapper remaps request to other devices. + * Add a trace for that action. + * + **/ +static void blk_add_trace_rq_remap(void *ignore, + struct request_queue *q, + struct request *rq, dev_t dev, + sector_t from) +{ + struct blk_trace *bt; + struct blk_io_trace_remap r; + + rcu_read_lock(); + bt = rcu_dereference(q->blk_trace); + if (likely(!bt)) { + rcu_read_unlock(); + return; + } + + r.device_from = cpu_to_be32(dev); + r.device_to = cpu_to_be32(disk_devt(rq->rq_disk)); + r.sector_from = cpu_to_be64(from); + + __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), + rq_data_dir(rq), 0, BLK_TA_REMAP, 0, + sizeof(r), &r, blk_trace_request_get_cgid(q, rq)); + rcu_read_unlock(); +} + +/** + * 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; + + rcu_read_lock(); + bt = rcu_dereference(q->blk_trace); + if (likely(!bt)) { + rcu_read_unlock(); + return; + } + + __blk_add_trace(bt, blk_rq_trace_sector(rq), blk_rq_bytes(rq), 0, 0, + BLK_TA_DRV_DATA, 0, len, data, + blk_trace_request_get_cgid(q, rq)); + rcu_read_unlock(); +} +EXPORT_SYMBOL_GPL(blk_add_driver_data); + +static void blk_register_tracepoints(void) +{ + int ret; + + ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL); + WARN_ON(ret); + ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL); + WARN_ON(ret); + ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL); + WARN_ON(ret); + ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL); + WARN_ON(ret); + ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL); + WARN_ON(ret); + ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL); + WARN_ON(ret); + ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL); + WARN_ON(ret); + ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL); + WARN_ON(ret); + ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL); + WARN_ON(ret); + ret = register_trace_block_getrq(blk_add_trace_getrq, NULL); + WARN_ON(ret); + ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL); + WARN_ON(ret); + ret = register_trace_block_plug(blk_add_trace_plug, NULL); + WARN_ON(ret); + ret = register_trace_block_unplug(blk_add_trace_unplug, NULL); + WARN_ON(ret); + ret = register_trace_block_split(blk_add_trace_split, NULL); + WARN_ON(ret); + ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL); + WARN_ON(ret); + ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL); + WARN_ON(ret); +} + +static void blk_unregister_tracepoints(void) +{ + unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL); + unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL); + unregister_trace_block_split(blk_add_trace_split, NULL); + unregister_trace_block_unplug(blk_add_trace_unplug, NULL); + unregister_trace_block_plug(blk_add_trace_plug, NULL); + unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL); + unregister_trace_block_getrq(blk_add_trace_getrq, NULL); + unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL); + unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL); + unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL); + unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL); + unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL); + unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL); + unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL); + unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL); + unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL); + + tracepoint_synchronize_unregister(); +} + +/* + * struct blk_io_tracer formatting routines + */ + +static void fill_rwbs(char *rwbs, const struct blk_io_trace *t) +{ + int i = 0; + int tc = t->action >> BLK_TC_SHIFT; + + if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) { + rwbs[i++] = 'N'; + goto out; + } + + if (tc & BLK_TC_FLUSH) + rwbs[i++] = 'F'; + + if (tc & BLK_TC_DISCARD) + rwbs[i++] = 'D'; + else if (tc & BLK_TC_WRITE) + rwbs[i++] = 'W'; + else if (t->bytes) + rwbs[i++] = 'R'; + else + rwbs[i++] = 'N'; + + if (tc & BLK_TC_FUA) + rwbs[i++] = 'F'; + if (tc & BLK_TC_AHEAD) + rwbs[i++] = 'A'; + if (tc & BLK_TC_SYNC) + rwbs[i++] = 'S'; + if (tc & BLK_TC_META) + rwbs[i++] = 'M'; +out: + rwbs[i] = '\0'; +} + +static inline +const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent) +{ + return (const struct blk_io_trace *)ent; +} + +static inline const void *pdu_start(const struct trace_entry *ent, bool has_cg) +{ + return (void *)(te_blk_io_trace(ent) + 1) + + (has_cg ? sizeof(union kernfs_node_id) : 0); +} + +static inline const void *cgid_start(const struct trace_entry *ent) +{ + return (void *)(te_blk_io_trace(ent) + 1); +} + +static inline int pdu_real_len(const struct trace_entry *ent, bool has_cg) +{ + return te_blk_io_trace(ent)->pdu_len - + (has_cg ? sizeof(union kernfs_node_id) : 0); +} + +static inline u32 t_action(const struct trace_entry *ent) +{ + return te_blk_io_trace(ent)->action; +} + +static inline u32 t_bytes(const struct trace_entry *ent) +{ + return te_blk_io_trace(ent)->bytes; +} + +static inline u32 t_sec(const struct trace_entry *ent) +{ + return te_blk_io_trace(ent)->bytes >> 9; +} + +static inline unsigned long long t_sector(const struct trace_entry *ent) +{ + return te_blk_io_trace(ent)->sector; +} + +static inline __u16 t_error(const struct trace_entry *ent) +{ + return te_blk_io_trace(ent)->error; +} + +static __u64 get_pdu_int(const struct trace_entry *ent, bool has_cg) +{ + const __be64 *val = pdu_start(ent, has_cg); + return be64_to_cpu(*val); +} + +typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act, + bool has_cg); + +static void blk_log_action_classic(struct trace_iterator *iter, const char *act, + bool has_cg) +{ + char rwbs[RWBS_LEN]; + unsigned long long ts = iter->ts; + unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC); + unsigned secs = (unsigned long)ts; + const struct blk_io_trace *t = te_blk_io_trace(iter->ent); + + fill_rwbs(rwbs, t); + + trace_seq_printf(&iter->seq, + "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ", + MAJOR(t->device), MINOR(t->device), iter->cpu, + secs, nsec_rem, iter->ent->pid, act, rwbs); +} + +static void blk_log_action(struct trace_iterator *iter, const char *act, + bool has_cg) +{ + char rwbs[RWBS_LEN]; + const struct blk_io_trace *t = te_blk_io_trace(iter->ent); + + fill_rwbs(rwbs, t); + if (has_cg) { + const union kernfs_node_id *id = cgid_start(iter->ent); + + if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) { + char blkcg_name_buf[NAME_MAX + 1] = "<...>"; + + cgroup_path_from_kernfs_id(id, blkcg_name_buf, + sizeof(blkcg_name_buf)); + trace_seq_printf(&iter->seq, "%3d,%-3d %s %2s %3s ", + MAJOR(t->device), MINOR(t->device), + blkcg_name_buf, act, rwbs); + } else + trace_seq_printf(&iter->seq, + "%3d,%-3d %x,%-x %2s %3s ", + MAJOR(t->device), MINOR(t->device), + id->ino, id->generation, act, rwbs); + } else + trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ", + MAJOR(t->device), MINOR(t->device), act, rwbs); +} + +static void blk_log_dump_pdu(struct trace_seq *s, + const struct trace_entry *ent, bool has_cg) +{ + const unsigned char *pdu_buf; + int pdu_len; + int i, end; + + pdu_buf = pdu_start(ent, has_cg); + pdu_len = pdu_real_len(ent, has_cg); + + if (!pdu_len) + return; + + /* find the last zero that needs to be printed */ + for (end = pdu_len - 1; end >= 0; end--) + if (pdu_buf[end]) + break; + end++; + + trace_seq_putc(s, '('); + + for (i = 0; i < pdu_len; i++) { + + trace_seq_printf(s, "%s%02x", + i == 0 ? "" : " ", pdu_buf[i]); + + /* + * stop when the rest is just zeroes and indicate so + * with a ".." appended + */ + if (i == end && end != pdu_len - 1) { + trace_seq_puts(s, " ..) "); + return; + } + } + + trace_seq_puts(s, ") "); +} + +static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent, bool has_cg) +{ + char cmd[TASK_COMM_LEN]; + + trace_find_cmdline(ent->pid, cmd); + + if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) { + trace_seq_printf(s, "%u ", t_bytes(ent)); + blk_log_dump_pdu(s, ent, has_cg); + trace_seq_printf(s, "[%s]\n", cmd); + } else { + if (t_sec(ent)) + trace_seq_printf(s, "%llu + %u [%s]\n", + t_sector(ent), t_sec(ent), cmd); + else + trace_seq_printf(s, "[%s]\n", cmd); + } +} + +static void blk_log_with_error(struct trace_seq *s, + const struct trace_entry *ent, bool has_cg) +{ + if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) { + blk_log_dump_pdu(s, ent, has_cg); + trace_seq_printf(s, "[%d]\n", t_error(ent)); + } else { + if (t_sec(ent)) + trace_seq_printf(s, "%llu + %u [%d]\n", + t_sector(ent), + t_sec(ent), t_error(ent)); + else + trace_seq_printf(s, "%llu [%d]\n", + t_sector(ent), t_error(ent)); + } +} + +static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent, bool has_cg) +{ + const struct blk_io_trace_remap *__r = pdu_start(ent, has_cg); + + trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n", + t_sector(ent), t_sec(ent), + MAJOR(be32_to_cpu(__r->device_from)), + MINOR(be32_to_cpu(__r->device_from)), + be64_to_cpu(__r->sector_from)); +} + +static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg) +{ + char cmd[TASK_COMM_LEN]; + + trace_find_cmdline(ent->pid, cmd); + + trace_seq_printf(s, "[%s]\n", cmd); +} + +static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg) +{ + char cmd[TASK_COMM_LEN]; + + trace_find_cmdline(ent->pid, cmd); + + trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent, has_cg)); +} + +static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent, bool has_cg) +{ + char cmd[TASK_COMM_LEN]; + + trace_find_cmdline(ent->pid, cmd); + + trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent), + get_pdu_int(ent, has_cg), cmd); +} + +static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent, + bool has_cg) +{ + + trace_seq_putmem(s, pdu_start(ent, has_cg), + pdu_real_len(ent, has_cg)); + trace_seq_putc(s, '\n'); +} + +/* + * struct tracer operations + */ + +static void blk_tracer_print_header(struct seq_file *m) +{ + if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC)) + return; + seq_puts(m, "# DEV CPU TIMESTAMP PID ACT FLG\n" + "# | | | | | |\n"); +} + +static void blk_tracer_start(struct trace_array *tr) +{ + blk_tracer_enabled = true; +} + +static int blk_tracer_init(struct trace_array *tr) +{ + blk_tr = tr; + blk_tracer_start(tr); + return 0; +} + +static void blk_tracer_stop(struct trace_array *tr) +{ + blk_tracer_enabled = false; +} + +static void blk_tracer_reset(struct trace_array *tr) +{ + blk_tracer_stop(tr); +} + +static const struct { + const char *act[2]; + void (*print)(struct trace_seq *s, const struct trace_entry *ent, + bool has_cg); +} what2act[] = { + [__BLK_TA_QUEUE] = {{ "Q", "queue" }, blk_log_generic }, + [__BLK_TA_BACKMERGE] = {{ "M", "backmerge" }, blk_log_generic }, + [__BLK_TA_FRONTMERGE] = {{ "F", "frontmerge" }, blk_log_generic }, + [__BLK_TA_GETRQ] = {{ "G", "getrq" }, blk_log_generic }, + [__BLK_TA_SLEEPRQ] = {{ "S", "sleeprq" }, blk_log_generic }, + [__BLK_TA_REQUEUE] = {{ "R", "requeue" }, blk_log_with_error }, + [__BLK_TA_ISSUE] = {{ "D", "issue" }, blk_log_generic }, + [__BLK_TA_COMPLETE] = {{ "C", "complete" }, blk_log_with_error }, + [__BLK_TA_PLUG] = {{ "P", "plug" }, blk_log_plug }, + [__BLK_TA_UNPLUG_IO] = {{ "U", "unplug_io" }, blk_log_unplug }, + [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug }, + [__BLK_TA_INSERT] = {{ "I", "insert" }, blk_log_generic }, + [__BLK_TA_SPLIT] = {{ "X", "split" }, blk_log_split }, + [__BLK_TA_BOUNCE] = {{ "B", "bounce" }, blk_log_generic }, + [__BLK_TA_REMAP] = {{ "A", "remap" }, blk_log_remap }, +}; + +static enum print_line_t print_one_line(struct trace_iterator *iter, + bool classic) +{ + struct trace_array *tr = iter->tr; + struct trace_seq *s = &iter->seq; + const struct blk_io_trace *t; + u16 what; + bool long_act; + blk_log_action_t *log_action; + bool has_cg; + + t = te_blk_io_trace(iter->ent); + what = (t->action & ((1 << BLK_TC_SHIFT) - 1)) & ~__BLK_TA_CGROUP; + long_act = !!(tr->trace_flags & TRACE_ITER_VERBOSE); + log_action = classic ? &blk_log_action_classic : &blk_log_action; + has_cg = t->action & __BLK_TA_CGROUP; + + if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) { + log_action(iter, long_act ? "message" : "m", has_cg); + blk_log_msg(s, iter->ent, has_cg); + return trace_handle_return(s); + } + + if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act))) + trace_seq_printf(s, "Unknown action %x\n", what); + else { + log_action(iter, what2act[what].act[long_act], has_cg); + what2act[what].print(s, iter->ent, has_cg); + } + + return trace_handle_return(s); +} + +static enum print_line_t blk_trace_event_print(struct trace_iterator *iter, + int flags, struct trace_event *event) +{ + return print_one_line(iter, false); +} + +static void blk_trace_synthesize_old_trace(struct trace_iterator *iter) +{ + struct trace_seq *s = &iter->seq; + struct blk_io_trace *t = (struct blk_io_trace *)iter->ent; + const int offset = offsetof(struct blk_io_trace, sector); + struct blk_io_trace old = { + .magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION, + .time = iter->ts, + }; + + trace_seq_putmem(s, &old, offset); + trace_seq_putmem(s, &t->sector, + sizeof(old) - offset + t->pdu_len); +} + +static enum print_line_t +blk_trace_event_print_binary(struct trace_iterator *iter, int flags, + struct trace_event *event) +{ + blk_trace_synthesize_old_trace(iter); + + return trace_handle_return(&iter->seq); +} + +static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter) +{ + if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC)) + return TRACE_TYPE_UNHANDLED; + + return print_one_line(iter, true); +} + +static int +blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) +{ + /* don't output context-info for blk_classic output */ + if (bit == TRACE_BLK_OPT_CLASSIC) { + if (set) + tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO; + else + tr->trace_flags |= TRACE_ITER_CONTEXT_INFO; + } + return 0; +} + +static struct tracer blk_tracer __read_mostly = { + .name = "blk", + .init = blk_tracer_init, + .reset = blk_tracer_reset, + .start = blk_tracer_start, + .stop = blk_tracer_stop, + .print_header = blk_tracer_print_header, + .print_line = blk_tracer_print_line, + .flags = &blk_tracer_flags, + .set_flag = blk_tracer_set_flag, +}; + +static struct trace_event_functions trace_blk_event_funcs = { + .trace = blk_trace_event_print, + .binary = blk_trace_event_print_binary, +}; + +static struct trace_event trace_blk_event = { + .type = TRACE_BLK, + .funcs = &trace_blk_event_funcs, +}; + +static int __init init_blk_tracer(void) +{ + if (!register_trace_event(&trace_blk_event)) { + pr_warn("Warning: could not register block events\n"); + return 1; + } + + if (register_tracer(&blk_tracer) != 0) { + pr_warn("Warning: could not register the block tracer\n"); + unregister_trace_event(&trace_blk_event); + return 1; + } + + return 0; +} + +device_initcall(init_blk_tracer); + +static int blk_trace_remove_queue(struct request_queue *q) +{ + struct blk_trace *bt; + + bt = xchg(&q->blk_trace, NULL); + if (bt == NULL) + return -EINVAL; + + if (bt->trace_state == Blktrace_running) { + bt->trace_state = Blktrace_stopped; + spin_lock_irq(&running_trace_lock); + list_del_init(&bt->running_list); + spin_unlock_irq(&running_trace_lock); + relay_flush(bt->rchan); + } + + put_probe_ref(); + synchronize_rcu(); + blk_trace_free(bt); + return 0; +} + +/* + * Setup everything required to start tracing + */ +static int blk_trace_setup_queue(struct request_queue *q, + struct block_device *bdev) +{ + struct blk_trace *bt = NULL; + int ret = -ENOMEM; + + bt = kzalloc(sizeof(*bt), GFP_KERNEL); + if (!bt) + return -ENOMEM; + + bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char)); + if (!bt->msg_data) + goto free_bt; + + bt->dev = bdev->bd_dev; + bt->act_mask = (u16)-1; + + blk_trace_setup_lba(bt, bdev); + + ret = -EBUSY; + if (cmpxchg(&q->blk_trace, NULL, bt)) + goto free_bt; + + get_probe_ref(); + return 0; + +free_bt: + blk_trace_free(bt); + return ret; +} + +/* + * sysfs interface to enable and configure tracing + */ + +static ssize_t sysfs_blk_trace_attr_show(struct device *dev, + struct device_attribute *attr, + char *buf); +static ssize_t sysfs_blk_trace_attr_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count); +#define BLK_TRACE_DEVICE_ATTR(_name) \ + DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \ + sysfs_blk_trace_attr_show, \ + sysfs_blk_trace_attr_store) + +static BLK_TRACE_DEVICE_ATTR(enable); +static BLK_TRACE_DEVICE_ATTR(act_mask); +static BLK_TRACE_DEVICE_ATTR(pid); +static BLK_TRACE_DEVICE_ATTR(start_lba); +static BLK_TRACE_DEVICE_ATTR(end_lba); + +static struct attribute *blk_trace_attrs[] = { + &dev_attr_enable.attr, + &dev_attr_act_mask.attr, + &dev_attr_pid.attr, + &dev_attr_start_lba.attr, + &dev_attr_end_lba.attr, + NULL +}; + +struct attribute_group blk_trace_attr_group = { + .name = "trace", + .attrs = blk_trace_attrs, +}; + +static const struct { + int mask; + const char *str; +} mask_maps[] = { + { BLK_TC_READ, "read" }, + { BLK_TC_WRITE, "write" }, + { BLK_TC_FLUSH, "flush" }, + { BLK_TC_SYNC, "sync" }, + { BLK_TC_QUEUE, "queue" }, + { BLK_TC_REQUEUE, "requeue" }, + { BLK_TC_ISSUE, "issue" }, + { BLK_TC_COMPLETE, "complete" }, + { BLK_TC_FS, "fs" }, + { BLK_TC_PC, "pc" }, + { BLK_TC_NOTIFY, "notify" }, + { BLK_TC_AHEAD, "ahead" }, + { BLK_TC_META, "meta" }, + { BLK_TC_DISCARD, "discard" }, + { BLK_TC_DRV_DATA, "drv_data" }, + { BLK_TC_FUA, "fua" }, +}; + +static int blk_trace_str2mask(const char *str) +{ + int i; + int mask = 0; + char *buf, *s, *token; + + buf = kstrdup(str, GFP_KERNEL); + if (buf == NULL) + return -ENOMEM; + s = strstrip(buf); + + while (1) { + token = strsep(&s, ","); + if (token == NULL) + break; + + if (*token == '\0') + continue; + + for (i = 0; i < ARRAY_SIZE(mask_maps); i++) { + if (strcasecmp(token, mask_maps[i].str) == 0) { + mask |= mask_maps[i].mask; + break; + } + } + if (i == ARRAY_SIZE(mask_maps)) { + mask = -EINVAL; + break; + } + } + kfree(buf); + + return mask; +} + +static ssize_t blk_trace_mask2str(char *buf, int mask) +{ + int i; + char *p = buf; + + for (i = 0; i < ARRAY_SIZE(mask_maps); i++) { + if (mask & mask_maps[i].mask) { + p += sprintf(p, "%s%s", + (p == buf) ? "" : ",", mask_maps[i].str); + } + } + *p++ = '\n'; + + return p - buf; +} + +static struct request_queue *blk_trace_get_queue(struct block_device *bdev) +{ + if (bdev->bd_disk == NULL) + return NULL; + + return bdev_get_queue(bdev); +} + +static ssize_t sysfs_blk_trace_attr_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct hd_struct *p = dev_to_part(dev); + struct request_queue *q; + struct block_device *bdev; + struct blk_trace *bt; + ssize_t ret = -ENXIO; + + bdev = bdget(part_devt(p)); + if (bdev == NULL) + goto out; + + q = blk_trace_get_queue(bdev); + if (q == NULL) + goto out_bdput; + + mutex_lock(&q->blk_trace_mutex); + + bt = rcu_dereference_protected(q->blk_trace, + lockdep_is_held(&q->blk_trace_mutex)); + if (attr == &dev_attr_enable) { + ret = sprintf(buf, "%u\n", !!bt); + goto out_unlock_bdev; + } + + if (bt == NULL) + ret = sprintf(buf, "disabled\n"); + else if (attr == &dev_attr_act_mask) + ret = blk_trace_mask2str(buf, bt->act_mask); + else if (attr == &dev_attr_pid) + ret = sprintf(buf, "%u\n", bt->pid); + else if (attr == &dev_attr_start_lba) + ret = sprintf(buf, "%llu\n", bt->start_lba); + else if (attr == &dev_attr_end_lba) + ret = sprintf(buf, "%llu\n", bt->end_lba); + +out_unlock_bdev: + mutex_unlock(&q->blk_trace_mutex); +out_bdput: + bdput(bdev); +out: + return ret; +} + +static ssize_t sysfs_blk_trace_attr_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct block_device *bdev; + struct request_queue *q; + struct hd_struct *p; + struct blk_trace *bt; + u64 value; + ssize_t ret = -EINVAL; + + if (count == 0) + goto out; + + if (attr == &dev_attr_act_mask) { + if (kstrtoull(buf, 0, &value)) { + /* Assume it is a list of trace category names */ + ret = blk_trace_str2mask(buf); + if (ret < 0) + goto out; + value = ret; + } + } else if (kstrtoull(buf, 0, &value)) + goto out; + + ret = -ENXIO; + + p = dev_to_part(dev); + bdev = bdget(part_devt(p)); + if (bdev == NULL) + goto out; + + q = blk_trace_get_queue(bdev); + if (q == NULL) + goto out_bdput; + + mutex_lock(&q->blk_trace_mutex); + + bt = rcu_dereference_protected(q->blk_trace, + lockdep_is_held(&q->blk_trace_mutex)); + if (attr == &dev_attr_enable) { + if (!!value == !!bt) { + ret = 0; + goto out_unlock_bdev; + } + if (value) + ret = blk_trace_setup_queue(q, bdev); + else + ret = blk_trace_remove_queue(q); + goto out_unlock_bdev; + } + + ret = 0; + if (bt == NULL) { + ret = blk_trace_setup_queue(q, bdev); + bt = rcu_dereference_protected(q->blk_trace, + lockdep_is_held(&q->blk_trace_mutex)); + } + + if (ret == 0) { + if (attr == &dev_attr_act_mask) + bt->act_mask = value; + else if (attr == &dev_attr_pid) + bt->pid = value; + else if (attr == &dev_attr_start_lba) + bt->start_lba = value; + else if (attr == &dev_attr_end_lba) + bt->end_lba = value; + } + +out_unlock_bdev: + mutex_unlock(&q->blk_trace_mutex); +out_bdput: + bdput(bdev); +out: + return ret ? ret : count; +} + +int blk_trace_init_sysfs(struct device *dev) +{ + return sysfs_create_group(&dev->kobj, &blk_trace_attr_group); +} + +void blk_trace_remove_sysfs(struct device *dev) +{ + sysfs_remove_group(&dev->kobj, &blk_trace_attr_group); +} + +#endif /* CONFIG_BLK_DEV_IO_TRACE */ + +#ifdef CONFIG_EVENT_TRACING + +void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes) +{ + int i = 0; + + if (op & REQ_PREFLUSH) + rwbs[i++] = 'F'; + + switch (op & REQ_OP_MASK) { + case REQ_OP_WRITE: + case REQ_OP_WRITE_SAME: + rwbs[i++] = 'W'; + break; + case REQ_OP_DISCARD: + rwbs[i++] = 'D'; + break; + case REQ_OP_SECURE_ERASE: + rwbs[i++] = 'D'; + rwbs[i++] = 'E'; + break; + case REQ_OP_FLUSH: + rwbs[i++] = 'F'; + break; + case REQ_OP_READ: + rwbs[i++] = 'R'; + break; + default: + rwbs[i++] = 'N'; + } + + if (op & REQ_FUA) + rwbs[i++] = 'F'; + if (op & REQ_RAHEAD) + rwbs[i++] = 'A'; + if (op & REQ_SYNC) + rwbs[i++] = 'S'; + if (op & REQ_META) + rwbs[i++] = 'M'; + + rwbs[i] = '\0'; +} +EXPORT_SYMBOL_GPL(blk_fill_rwbs); + +#endif /* CONFIG_EVENT_TRACING */ + |