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authorJens Axboe <axboe@suse.de>2006-02-02 11:56:56 +0100
committerJens Axboe <axboe@suse.de>2006-02-02 11:56:56 +0100
commit210824c332e30b543676a537ddd34d380bc9c69d (patch)
treed5ed9e014865e2e612eefdd1631c6b2430cf9404 /kernel/blk-trace-2.6.16-rc1-git-U0
parent89482da65bbe96da701e2c873e3eeb3016b4e651 (diff)
downloadblktrace-210824c332e30b543676a537ddd34d380bc9c69d.tar.gz
blktrace-210824c332e30b543676a537ddd34d380bc9c69d.tar.bz2
[PATCH] Make the sequence per-CPU so the kernel side can be lockless
Diffstat (limited to 'kernel/blk-trace-2.6.16-rc1-git-U0')
-rw-r--r--kernel/blk-trace-2.6.16-rc1-git-U0997
1 files changed, 997 insertions, 0 deletions
diff --git a/kernel/blk-trace-2.6.16-rc1-git-U0 b/kernel/blk-trace-2.6.16-rc1-git-U0
new file mode 100644
index 0000000..677852b
--- /dev/null
+++ b/kernel/blk-trace-2.6.16-rc1-git-U0
@@ -0,0 +1,997 @@
+diff --git a/block/Kconfig b/block/Kconfig
+index 377f6dd..27eaed9 100644
+--- a/block/Kconfig
++++ b/block/Kconfig
+@@ -11,4 +11,15 @@ config LBD
+ your machine, or if you want to have a raid or loopback device
+ bigger than 2TB. Otherwise say N.
+
++config BLK_DEV_IO_TRACE
++ bool "Support for tracing block io actions"
++ select RELAYFS_FS
++ help
++ Say Y here, if you want to be able to trace the block layer actions
++ on a given queue. Tracing allows you to see any traffic happening
++ on a block device queue. For more information (and the user space
++ support tools needed), fetch the blktrace app from:
++
++ git://brick.kernel.dk/data/git/blktrace.git
++
+ source block/Kconfig.iosched
+diff --git a/block/Makefile b/block/Makefile
+index 7e4f93e..c05de0e 100644
+--- a/block/Makefile
++++ b/block/Makefile
+@@ -8,3 +8,5 @@ obj-$(CONFIG_IOSCHED_NOOP) += noop-iosch
+ obj-$(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
+diff --git a/block/blktrace.c b/block/blktrace.c
+new file mode 100644
+index 0000000..21b381d
+--- /dev/null
++++ b/block/blktrace.c
+@@ -0,0 +1,362 @@
++#include <linux/config.h>
++#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 <asm/uaccess.h>
++
++static DEFINE_PER_CPU(unsigned long long, blk_trace_cpu_offset) = { 0, };
++
++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 blk_io_trace *t;
++ unsigned long flags;
++ unsigned long *sequence;
++ pid_t pid;
++ int cpu;
++
++ if (rw & (1 << BIO_RW_BARRIER))
++ what |= BLK_TC_ACT(BLK_TC_BARRIER);
++ if (rw & (1 << BIO_RW_SYNC))
++ what |= BLK_TC_ACT(BLK_TC_SYNC);
++
++ if (rw & WRITE)
++ what |= BLK_TC_ACT(BLK_TC_WRITE);
++ else
++ what |= BLK_TC_ACT(BLK_TC_READ);
++
++ if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
++ return;
++ if (sector < bt->start_lba || sector > bt->end_lba)
++ return;
++
++ pid = current->pid;
++ if (bt->pid && pid != bt->pid)
++ return;
++
++ local_irq_save(flags);
++
++ t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
++ if (unlikely(!t)) {
++ local_irq_restore(flags);
++ return;
++ }
++
++ cpu = smp_processor_id();
++ sequence = per_cpu_ptr(bt->sequence, cpu);
++ t->sequence = ++(*sequence);
++ t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu);
++ t->cpu = cpu;
++
++ local_irq_restore(flags);
++
++ t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
++ t->device = bt->dev;
++ t->sector = sector;
++ t->bytes = bytes;
++ t->action = what;
++ t->error = error;
++ t->pdu_len = pdu_len;
++
++ t->pid = pid;
++ memcpy(t->comm, current->comm, sizeof(t->comm));
++
++ if (pdu_len)
++ memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
++}
++
++EXPORT_SYMBOL_GPL(__blk_add_trace);
++
++static struct dentry *blk_tree_root;
++static struct mutex blk_tree_mutex;
++
++static inline void blk_remove_root(void)
++{
++ if (relayfs_remove_dir(blk_tree_root) != -ENOTEMPTY)
++ blk_tree_root = NULL;
++}
++
++static void blk_remove_tree(struct dentry *dir)
++{
++ mutex_lock(&blk_tree_mutex);
++ relayfs_remove_dir(dir);
++ 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 = relayfs_create_dir("block", NULL);
++ if (!blk_tree_root)
++ goto err;
++ }
++
++ dir = relayfs_create_dir(blk_name, blk_tree_root);
++ if (!dir)
++ blk_remove_root();
++
++err:
++ mutex_unlock(&blk_tree_mutex);
++ return dir;
++}
++
++void blk_cleanup_trace(struct blk_trace *bt)
++{
++ relay_close(bt->rchan);
++ relayfs_remove_file(bt->dropped_file);
++ blk_remove_tree(bt->dir);
++ kfree(bt);
++}
++
++int blk_stop_trace(struct block_device *bdev)
++{
++ request_queue_t *q = bdev_get_queue(bdev);
++ struct blk_trace *bt = NULL;
++ int ret = -EINVAL;
++
++ if (!q)
++ return -ENXIO;
++
++ down(&bdev->bd_sem);
++
++ if (q->blk_trace) {
++ bt = q->blk_trace;
++ q->blk_trace = NULL;
++ ret = 0;
++ }
++
++ up(&bdev->bd_sem);
++
++ if (bt)
++ blk_cleanup_trace(bt);
++
++ return ret;
++}
++
++static int blk_dropped_open(struct inode *inode, struct file *filp)
++{
++ filp->private_data = inode->u.generic_ip;
++
++ 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 struct file_operations blk_dropped_fops = {
++ .owner = THIS_MODULE,
++ .open = blk_dropped_open,
++ .read = blk_dropped_read,
++};
++
++static int blk_subbuf_start_callback (struct rchan_buf *buf,
++ void *subbuf,
++ void *prev_subbuf,
++ size_t prev_padding)
++{
++ if (relay_buf_full(buf)) {
++ struct blk_trace *bt = buf->chan->private_data;
++
++ atomic_inc(&bt->dropped);
++ return 0;
++ }
++
++ return 1;
++}
++
++static struct rchan_callbacks blk_relay_callbacks = {
++ .subbuf_start = blk_subbuf_start_callback,
++};
++
++int blk_start_trace(struct block_device *bdev, char __user *arg)
++{
++ request_queue_t *q = bdev_get_queue(bdev);
++ struct blk_user_trace_setup buts;
++ struct blk_trace *bt = NULL;
++ struct dentry *dir = NULL;
++ char b[BDEVNAME_SIZE];
++ int ret, i;
++
++ if (!q)
++ return -ENXIO;
++
++ if (copy_from_user(&buts, arg, sizeof(buts)))
++ return -EFAULT;
++
++ if (!buts.buf_size || !buts.buf_nr)
++ return -EINVAL;
++
++ strcpy(buts.name, bdevname(bdev, b));
++
++ /*
++ * some device names have larger paths - convert the slashes
++ * to underscores for this to work as expected
++ */
++ for (i = 0; i < strlen(buts.name); i++)
++ if (buts.name[i] == '/')
++ buts.name[i] = '_';
++
++ if (copy_to_user(arg, &buts, sizeof(buts)))
++ return -EFAULT;
++
++ down(&bdev->bd_sem);
++ ret = -EBUSY;
++ if (q->blk_trace)
++ goto err;
++
++ 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 = relayfs_create_file("dropped", dir, 0, &blk_dropped_fops, bt);
++ if (!bt->dropped_file)
++ goto err;
++
++ bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks);
++ if (!bt->rchan)
++ goto err;
++ bt->rchan->private_data = bt;
++
++ 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;
++
++ q->blk_trace = bt;
++ up(&bdev->bd_sem);
++ return 0;
++err:
++ up(&bdev->bd_sem);
++ if (bt && bt->dropped_file)
++ relayfs_remove_file(bt->dropped_file);
++ if (dir)
++ blk_remove_tree(dir);
++ if (bt) {
++ if (bt->sequence)
++ free_percpu(bt->sequence);
++ kfree(bt);
++ }
++ return ret;
++}
++
++/*
++ * Average offset over two calls to sched_clock() with a gettimeofday()
++ * in the middle
++ */
++static void blk_check_time(unsigned long long *t)
++{
++ unsigned long long a, b;
++ struct timeval tv;
++
++ a = sched_clock();
++ do_gettimeofday(&tv);
++ b = sched_clock();
++
++ *t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
++ *t -= (a + b) / 2;
++}
++
++static void blk_trace_check_cpu_time(void *data)
++{
++ unsigned long long *t;
++ int cpu = get_cpu();
++
++ t = &per_cpu(blk_trace_cpu_offset, cpu);
++
++ /*
++ * Just call it twice, hopefully the second call will be cache hot
++ * and a little more precise
++ */
++ blk_check_time(t);
++ blk_check_time(t);
++
++ put_cpu();
++}
++
++/*
++ * Call blk_trace_check_cpu_time() on each CPU to calibrate our inter-CPU
++ * timings
++ */
++static void blk_trace_calibrate_offsets(void)
++{
++ unsigned long flags;
++
++ smp_call_function(blk_trace_check_cpu_time, NULL, 1, 1);
++ local_irq_save(flags);
++ blk_trace_check_cpu_time(NULL);
++ local_irq_restore(flags);
++}
++
++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, 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);
++ blk_trace_calibrate_offsets();
++ blk_trace_set_ht_offsets();
++
++ return 0;
++}
++
++module_init(blk_trace_init);
++
+diff --git a/block/elevator.c b/block/elevator.c
+index c9f424d..793c686 100644
+--- a/block/elevator.c
++++ b/block/elevator.c
+@@ -33,6 +33,7 @@
+ #include <linux/init.h>
+ #include <linux/compiler.h>
+ #include <linux/delay.h>
++#include <linux/blktrace_api.h>
+
+ #include <asm/uaccess.h>
+
+@@ -333,6 +334,8 @@ void __elv_add_request(request_queue_t *
+ struct list_head *pos;
+ unsigned ordseq;
+
++ blk_add_trace_rq(q, rq, BLK_TA_INSERT);
++
+ if (q->ordcolor)
+ rq->flags |= REQ_ORDERED_COLOR;
+
+@@ -491,6 +494,7 @@ struct request *elv_next_request(request
+ * not be passed by new incoming requests
+ */
+ rq->flags |= REQ_STARTED;
++ blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
+ }
+
+ if (!q->boundary_rq || q->boundary_rq == rq) {
+diff --git a/block/ioctl.c b/block/ioctl.c
+index e110949..63e67a2 100644
+--- a/block/ioctl.c
++++ b/block/ioctl.c
+@@ -5,6 +5,7 @@
+ #include <linux/backing-dev.h>
+ #include <linux/buffer_head.h>
+ #include <linux/smp_lock.h>
++#include <linux/blktrace_api.h>
+ #include <asm/uaccess.h>
+
+ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user *arg)
+@@ -189,6 +190,10 @@ static int blkdev_locked_ioctl(struct fi
+ return put_ulong(arg, bdev->bd_inode->i_size >> 9);
+ case BLKGETSIZE64:
+ return put_u64(arg, bdev->bd_inode->i_size);
++ case BLKSTARTTRACE:
++ return blk_start_trace(bdev, (char __user *) arg);
++ case BLKSTOPTRACE:
++ return blk_stop_trace(bdev);
+ }
+ return -ENOIOCTLCMD;
+ }
+diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
+index 8e27d0a..bfcde0f 100644
+--- a/block/ll_rw_blk.c
++++ b/block/ll_rw_blk.c
+@@ -28,6 +28,7 @@
+ #include <linux/writeback.h>
+ #include <linux/interrupt.h>
+ #include <linux/cpu.h>
++#include <linux/blktrace_api.h>
+
+ /*
+ * for max sense size
+@@ -1555,8 +1556,10 @@ void blk_plug_device(request_queue_t *q)
+ if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))
+ return;
+
+- if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
++ if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
+ mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
++ blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
++ }
+ }
+
+ EXPORT_SYMBOL(blk_plug_device);
+@@ -1620,14 +1623,21 @@ static void blk_backing_dev_unplug(struc
+ /*
+ * devices don't necessarily have an ->unplug_fn defined
+ */
+- if (q->unplug_fn)
++ if (q->unplug_fn) {
++ blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
++ q->rq.count[READ] + q->rq.count[WRITE]);
++
+ q->unplug_fn(q);
++ }
+ }
+
+ static void blk_unplug_work(void *data)
+ {
+ request_queue_t *q = data;
+
++ blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
++ q->rq.count[READ] + q->rq.count[WRITE]);
++
+ q->unplug_fn(q);
+ }
+
+@@ -1635,6 +1645,9 @@ static void blk_unplug_timeout(unsigned
+ {
+ request_queue_t *q = (request_queue_t *)data;
+
++ blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL,
++ q->rq.count[READ] + q->rq.count[WRITE]);
++
+ kblockd_schedule_work(&q->unplug_work);
+ }
+
+@@ -1757,6 +1770,11 @@ void blk_cleanup_queue(request_queue_t *
+ if (q->queue_tags)
+ __blk_queue_free_tags(q);
+
++ if (q->blk_trace) {
++ blk_cleanup_trace(q->blk_trace);
++ q->blk_trace = NULL;
++ }
++
+ kmem_cache_free(requestq_cachep, q);
+ }
+
+@@ -2108,6 +2126,8 @@ rq_starved:
+
+ rq_init(q, rq);
+ rq->rl = rl;
++
++ blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ);
+ out:
+ return rq;
+ }
+@@ -2136,6 +2156,8 @@ static struct request *get_request_wait(
+ if (!rq) {
+ struct io_context *ioc;
+
++ blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
++
+ __generic_unplug_device(q);
+ spin_unlock_irq(q->queue_lock);
+ io_schedule();
+@@ -2189,6 +2211,8 @@ EXPORT_SYMBOL(blk_get_request);
+ */
+ void blk_requeue_request(request_queue_t *q, struct request *rq)
+ {
++ blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
++
+ if (blk_rq_tagged(rq))
+ blk_queue_end_tag(q, rq);
+
+@@ -2820,6 +2844,8 @@ static int __make_request(request_queue_
+ if (!q->back_merge_fn(q, req, bio))
+ break;
+
++ blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
++
+ req->biotail->bi_next = bio;
+ req->biotail = bio;
+ req->nr_sectors = req->hard_nr_sectors += nr_sectors;
+@@ -2835,6 +2861,8 @@ static int __make_request(request_queue_
+ if (!q->front_merge_fn(q, req, bio))
+ break;
+
++ blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
++
+ bio->bi_next = req->bio;
+ req->bio = bio;
+
+@@ -2952,6 +2980,7 @@ void generic_make_request(struct bio *bi
+ request_queue_t *q;
+ sector_t maxsector;
+ int ret, nr_sectors = bio_sectors(bio);
++ dev_t old_dev;
+
+ might_sleep();
+ /* Test device or partition size, when known. */
+@@ -2978,6 +3007,8 @@ void generic_make_request(struct bio *bi
+ * NOTE: we don't repeat the blk_size check for each new device.
+ * Stacking drivers are expected to know what they are doing.
+ */
++ maxsector = -1;
++ old_dev = 0;
+ do {
+ char b[BDEVNAME_SIZE];
+
+@@ -3010,6 +3041,15 @@ end_io:
+ */
+ blk_partition_remap(bio);
+
++ if (maxsector != -1)
++ blk_add_trace_remap(q, bio, old_dev, bio->bi_sector,
++ maxsector);
++
++ blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
++
++ maxsector = bio->bi_sector;
++ old_dev = bio->bi_bdev->bd_dev;
++
+ ret = q->make_request_fn(q, bio);
+ } while (ret);
+ }
+@@ -3129,6 +3169,8 @@ static int __end_that_request_first(stru
+ int total_bytes, bio_nbytes, error, next_idx = 0;
+ struct bio *bio;
+
++ blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE);
++
+ /*
+ * extend uptodate bool to allow < 0 value to be direct io error
+ */
+diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
+index 12d7b9b..880892a 100644
+--- a/drivers/block/cciss.c
++++ b/drivers/block/cciss.c
+@@ -38,6 +38,7 @@
+ #include <linux/hdreg.h>
+ #include <linux/spinlock.h>
+ #include <linux/compat.h>
++#include <linux/blktrace_api.h>
+ #include <asm/uaccess.h>
+ #include <asm/io.h>
+
+@@ -2330,6 +2331,7 @@ static inline void complete_command( ctl
+
+ cmd->rq->completion_data = cmd;
+ cmd->rq->errors = status;
++ blk_add_trace_rq(cmd->rq->q, cmd->rq, BLK_TA_COMPLETE);
+ blk_complete_request(cmd->rq);
+ }
+
+diff --git a/drivers/md/dm.c b/drivers/md/dm.c
+index 8c16359..8c979c2 100644
+--- a/drivers/md/dm.c
++++ b/drivers/md/dm.c
+@@ -17,6 +17,7 @@
+ #include <linux/mempool.h>
+ #include <linux/slab.h>
+ #include <linux/idr.h>
++#include <linux/blktrace_api.h>
+
+ static const char *_name = DM_NAME;
+
+@@ -303,6 +304,8 @@ static void dec_pending(struct dm_io *io
+ /* nudge anyone waiting on suspend queue */
+ wake_up(&io->md->wait);
+
++ blk_add_trace_bio(io->md->queue, io->bio, BLK_TA_COMPLETE);
++
+ bio_endio(io->bio, io->bio->bi_size, io->error);
+ free_io(io->md, io);
+ }
+@@ -361,6 +364,7 @@ static void __map_bio(struct dm_target *
+ struct target_io *tio)
+ {
+ int r;
++ sector_t sector;
+
+ /*
+ * Sanity checks.
+@@ -376,10 +380,17 @@ static void __map_bio(struct dm_target *
+ * this io.
+ */
+ atomic_inc(&tio->io->io_count);
++ sector = clone->bi_sector;
+ r = ti->type->map(ti, clone, &tio->info);
+- if (r > 0)
++ if (r > 0) {
+ /* the bio has been remapped so dispatch it */
++
++ blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone,
++ tio->io->bio->bi_bdev->bd_dev, sector,
++ clone->bi_sector);
++
+ generic_make_request(clone);
++ }
+
+ else if (r < 0) {
+ /* error the io and bail out */
+diff --git a/fs/bio.c b/fs/bio.c
+index bbc442b..8a1b0b6 100644
+--- a/fs/bio.c
++++ b/fs/bio.c
+@@ -25,6 +25,7 @@
+ #include <linux/module.h>
+ #include <linux/mempool.h>
+ #include <linux/workqueue.h>
++#include <linux/blktrace_api.h>
+ #include <scsi/sg.h> /* for struct sg_iovec */
+
+ #define BIO_POOL_SIZE 256
+@@ -1094,6 +1095,9 @@ struct bio_pair *bio_split(struct bio *b
+ if (!bp)
+ return bp;
+
++ blk_add_trace_pdu_int(bdev_get_queue(bi->bi_bdev), BLK_TA_SPLIT, bi,
++ bi->bi_sector + first_sectors);
++
+ BUG_ON(bi->bi_vcnt != 1);
+ BUG_ON(bi->bi_idx != 0);
+ atomic_set(&bp->cnt, 3);
+diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
+index 5dd0207..010e02b 100644
+--- a/fs/compat_ioctl.c
++++ b/fs/compat_ioctl.c
+@@ -72,6 +72,7 @@
+ #include <linux/i2c-dev.h>
+ #include <linux/wireless.h>
+ #include <linux/atalk.h>
++#include <linux/blktrace_api.h>
+
+ #include <net/sock.h> /* siocdevprivate_ioctl */
+ #include <net/bluetooth/bluetooth.h>
+diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
+index 02a585f..195c3b9 100644
+--- a/include/linux/blkdev.h
++++ b/include/linux/blkdev.h
+@@ -22,6 +22,7 @@ typedef struct request_queue request_que
+ struct elevator_queue;
+ typedef struct elevator_queue elevator_t;
+ struct request_pm_state;
++struct blk_trace;
+
+ #define BLKDEV_MIN_RQ 4
+ #define BLKDEV_MAX_RQ 128 /* Default maximum */
+@@ -416,6 +417,8 @@ struct request_queue
+ unsigned int sg_reserved_size;
+ int node;
+
++ struct blk_trace *blk_trace;
++
+ /*
+ * reserved for flush operations
+ */
+diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
+new file mode 100644
+index 0000000..026b995
+--- /dev/null
++++ b/include/linux/blktrace_api.h
+@@ -0,0 +1,215 @@
++#ifndef BLKTRACE_H
++#define BLKTRACE_H
++
++#include <linux/config.h>
++#include <linux/blkdev.h>
++#include <linux/relayfs_fs.h>
++
++/*
++ * Trace categories
++ */
++enum blktrace_cat {
++ BLK_TC_READ = 1 << 0, /* reads */
++ BLK_TC_WRITE = 1 << 1, /* writes */
++ BLK_TC_BARRIER = 1 << 2, /* barrier */
++ BLK_TC_SYNC = 1 << 3, /* barrier */
++ BLK_TC_QUEUE = 1 << 4, /* queueing/merging */
++ BLK_TC_REQUEUE = 1 << 5, /* requeueing */
++ BLK_TC_ISSUE = 1 << 6, /* issue */
++ BLK_TC_COMPLETE = 1 << 7, /* completions */
++ BLK_TC_FS = 1 << 8, /* fs requests */
++ BLK_TC_PC = 1 << 9, /* pc requests */
++
++ BLK_TC_END = 1 << 15, /* only 16-bits, reminder */
++};
++
++#define BLK_TC_SHIFT (16)
++#define BLK_TC_ACT(act) ((act) << BLK_TC_SHIFT)
++
++/*
++ * Basic trace actions
++ */
++enum blktrace_act {
++ __BLK_TA_QUEUE = 1, /* queued */
++ __BLK_TA_BACKMERGE, /* back merged to existing rq */
++ __BLK_TA_FRONTMERGE, /* front merge to existing rq */
++ __BLK_TA_GETRQ, /* allocated new request */
++ __BLK_TA_SLEEPRQ, /* sleeping on rq allocation */
++ __BLK_TA_REQUEUE, /* request requeued */
++ __BLK_TA_ISSUE, /* sent to driver */
++ __BLK_TA_COMPLETE, /* completed by driver */
++ __BLK_TA_PLUG, /* queue was plugged */
++ __BLK_TA_UNPLUG_IO, /* queue was unplugged by io */
++ __BLK_TA_UNPLUG_TIMER, /* queue was unplugged by timer */
++ __BLK_TA_INSERT, /* insert request */
++ __BLK_TA_SPLIT, /* bio was split */
++ __BLK_TA_BOUNCE, /* bio was bounced */
++ __BLK_TA_REMAP, /* bio was remapped */
++};
++
++/*
++ * Trace actions in full. Additionally, read or write is masked
++ */
++#define BLK_TA_QUEUE (__BLK_TA_QUEUE | BLK_TC_ACT(BLK_TC_QUEUE))
++#define BLK_TA_BACKMERGE (__BLK_TA_BACKMERGE | BLK_TC_ACT(BLK_TC_QUEUE))
++#define BLK_TA_FRONTMERGE (__BLK_TA_FRONTMERGE | BLK_TC_ACT(BLK_TC_QUEUE))
++#define BLK_TA_GETRQ (__BLK_TA_GETRQ | BLK_TC_ACT(BLK_TC_QUEUE))
++#define BLK_TA_SLEEPRQ (__BLK_TA_SLEEPRQ | BLK_TC_ACT(BLK_TC_QUEUE))
++#define BLK_TA_REQUEUE (__BLK_TA_REQUEUE | BLK_TC_ACT(BLK_TC_REQUEUE))
++#define BLK_TA_ISSUE (__BLK_TA_ISSUE | BLK_TC_ACT(BLK_TC_ISSUE))
++#define BLK_TA_COMPLETE (__BLK_TA_COMPLETE| BLK_TC_ACT(BLK_TC_COMPLETE))
++#define BLK_TA_PLUG (__BLK_TA_PLUG | BLK_TC_ACT(BLK_TC_QUEUE))
++#define BLK_TA_UNPLUG_IO (__BLK_TA_UNPLUG_IO | BLK_TC_ACT(BLK_TC_QUEUE))
++#define BLK_TA_UNPLUG_TIMER (__BLK_TA_UNPLUG_TIMER | BLK_TC_ACT(BLK_TC_QUEUE))
++#define BLK_TA_INSERT (__BLK_TA_INSERT | BLK_TC_ACT(BLK_TC_QUEUE))
++#define BLK_TA_SPLIT (__BLK_TA_SPLIT)
++#define BLK_TA_BOUNCE (__BLK_TA_BOUNCE)
++#define BLK_TA_REMAP (__BLK_TA_REMAP | BLK_TC_ACT(BLK_TC_QUEUE))
++
++#define BLK_IO_TRACE_MAGIC 0x65617400
++#define BLK_IO_TRACE_VERSION 0x06
++
++/*
++ * The trace itself
++ */
++struct blk_io_trace {
++ u32 magic; /* MAGIC << 8 | version */
++ u32 sequence; /* event number */
++ u64 time; /* in microseconds */
++ u64 sector; /* disk offset */
++ u32 bytes; /* transfer length */
++ u32 action; /* what happened */
++ u32 pid; /* who did it */
++ u32 cpu; /* on what cpu did it happen */
++ u16 error; /* completion error */
++ u16 pdu_len; /* length of data after this trace */
++ u32 device; /* device number */
++ char comm[16]; /* task command name (TASK_COMM_LEN) */
++};
++
++/*
++ * The remap event
++ */
++struct blk_io_trace_remap {
++ u32 device;
++ u32 __pad;
++ u64 sector;
++};
++
++struct blk_trace {
++ struct dentry *dir;
++ struct rchan *rchan;
++ struct dentry *dropped_file;
++ atomic_t dropped;
++ unsigned long *sequence;
++ u32 dev;
++ u16 act_mask;
++ u64 start_lba;
++ u64 end_lba;
++ u32 pid;
++};
++
++/*
++ * User setup structure passed with BLKSTARTTRACE
++ */
++struct blk_user_trace_setup {
++ char name[BDEVNAME_SIZE]; /* output */
++ u16 act_mask; /* input */
++ u32 buf_size; /* input */
++ u32 buf_nr; /* input */
++ u64 start_lba;
++ u64 end_lba;
++ u32 pid;
++};
++
++#if defined(CONFIG_BLK_DEV_IO_TRACE)
++extern int blk_start_trace(struct block_device *, char __user *);
++extern int blk_stop_trace(struct block_device *);
++extern void blk_cleanup_trace(struct blk_trace *);
++extern void __blk_add_trace(struct blk_trace *, sector_t, int, int, u32, int, int, void *);
++
++static inline void blk_add_trace_rq(struct request_queue *q, struct request *rq,
++ u32 what)
++{
++ struct blk_trace *bt = q->blk_trace;
++ int rw = rq->flags & 0x07;
++
++ if (likely(!bt))
++ return;
++
++ 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 inline 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 inline void blk_add_trace_generic(struct request_queue *q,
++ struct bio *bio, int rw, u32 what)
++{
++ struct blk_trace *bt = q->blk_trace;
++
++ if (likely(!bt))
++ return;
++
++ if (bio)
++ blk_add_trace_bio(q, bio, what);
++ else
++ __blk_add_trace(bt, 0, 0, rw, what, 0, 0, NULL);
++}
++
++static inline void blk_add_trace_pdu_int(struct request_queue *q, u32 what,
++ struct bio *bio, unsigned int pdu)
++{
++ struct blk_trace *bt = q->blk_trace;
++ u64 rpdu = cpu_to_be64(pdu);
++
++ if (likely(!bt))
++ return;
++
++ if (bio)
++ __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what, !bio_flagged(bio, BIO_UPTODATE), sizeof(rpdu), &rpdu);
++ else
++ __blk_add_trace(bt, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
++}
++
++static inline 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.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);
++}
++
++#else /* !CONFIG_BLK_DEV_IO_TRACE */
++#define blk_start_trace(bdev, arg) (-EINVAL)
++#define blk_stop_trace(bdev) (-EINVAL)
++#define blk_cleanup_trace(bt) do { } while (0)
++#define blk_add_trace_rq(q, rq, what) do { } while (0)
++#define blk_add_trace_bio(q, rq, what) do { } while (0)
++#define blk_add_trace_generic(q, rq, rw, what) do { } while (0)
++#define blk_add_trace_pdu_int(q, what, bio, pdu) do { } while (0)
++#define blk_add_trace_remap(q, bio, dev, f, t) do {} while (0)
++#endif /* CONFIG_BLK_DEV_IO_TRACE */
++
++#endif
+diff --git a/include/linux/compat_ioctl.h b/include/linux/compat_ioctl.h
+index 8fad50f..5bed09a 100644
+--- a/include/linux/compat_ioctl.h
++++ b/include/linux/compat_ioctl.h
+@@ -97,6 +97,8 @@ COMPATIBLE_IOCTL(BLKRRPART)
+ COMPATIBLE_IOCTL(BLKFLSBUF)
+ COMPATIBLE_IOCTL(BLKSECTSET)
+ COMPATIBLE_IOCTL(BLKSSZGET)
++COMPATIBLE_IOCTL(BLKSTARTTRACE)
++COMPATIBLE_IOCTL(BLKSTOPTRACE)
+ ULONG_IOCTL(BLKRASET)
+ ULONG_IOCTL(BLKFRASET)
+ /* RAID */
+diff --git a/include/linux/fs.h b/include/linux/fs.h
+index b77f260..5575284 100644
+--- a/include/linux/fs.h
++++ b/include/linux/fs.h
+@@ -196,6 +196,8 @@ extern int dir_notify_enable;
+ #define BLKBSZGET _IOR(0x12,112,size_t)
+ #define BLKBSZSET _IOW(0x12,113,size_t)
+ #define BLKGETSIZE64 _IOR(0x12,114,size_t) /* return device size in bytes (u64 *arg) */
++#define BLKSTARTTRACE _IOWR(0x12,115,struct blk_user_trace_setup)
++#define BLKSTOPTRACE _IO(0x12,116)
+
+ #define BMAP_IOCTL 1 /* obsolete - kept for compatibility */
+ #define FIBMAP _IO(0x00,1) /* bmap access */
+diff --git a/mm/highmem.c b/mm/highmem.c
+index ce2e7e8..d0ea1ee 100644
+--- a/mm/highmem.c
++++ b/mm/highmem.c
+@@ -26,6 +26,7 @@
+ #include <linux/init.h>
+ #include <linux/hash.h>
+ #include <linux/highmem.h>
++#include <linux/blktrace_api.h>
+ #include <asm/tlbflush.h>
+
+ static mempool_t *page_pool, *isa_page_pool;
+@@ -483,6 +484,8 @@ void blk_queue_bounce(request_queue_t *q
+ pool = isa_page_pool;
+ }
+
++ blk_add_trace_bio(q, *bio_orig, BLK_TA_BOUNCE);
++
+ /*
+ * slow path
+ */