blktrace: port to tracepoints

This was a forward port of work done by Mathieu Desnoyers, I changed it to
encode the 'what' parameter on the tracepoint name, so that one can register
interest in specific events and not on classes of events to then check the
'what' parameter.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 329 insertions, 3 deletions

diff --git a/block/blktrace.c b/block/blktrace.c
index 85049a7e7a17..b0a2cae886db 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -23,10 +23,18 @@
 #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.
  */
@@ -119,7 +127,7 @@ static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK
  * The worker for the various blk_add_trace*() types. Fills out a
  * blk_io_trace structure and places it in a per-cpu subbuffer.
  */
-void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
+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;
@@ -177,8 +185,6 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
         local_irq_restore(flags);
 }
 
-EXPORT_SYMBOL_GPL(__blk_add_trace);
-
 static struct dentry *blk_tree_root;
 static DEFINE_MUTEX(blk_tree_mutex);
 static unsigned int root_users;
@@ -237,6 +243,10 @@ static void blk_trace_cleanup(struct blk_trace *bt)
         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)
@@ -428,6 +438,14 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
         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) {
@@ -436,6 +454,9 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
         }
 
         return 0;
+probe_err:
+        atomic_dec(&blk_probes_ref);
+        mutex_unlock(&blk_probe_mutex);
 err:
         if (dir)
                 blk_remove_tree(dir);
@@ -562,3 +583,308 @@ void blk_trace_shutdown(struct request_queue *q)
                 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();
+}