blktrace: export cgroup info in trace

Currently blktrace isn't cgroup aware. blktrace prints out task name of
current context, but the task of current context isn't always in the
cgroup where the BIO comes from. We can't use task name to find out IO
cgroup. For example, Writeback BIOs always comes from flusher thread but
the BIOs are for different blk cgroups. Request could be requeued and
dispatched from completely different tasks. MD/DM are another examples.

This patch tries to fix the gap. We print out cgroup fhandle info in
blktrace. Userspace can use open_by_handle_at() syscall to find the
cgroup by fhandle. Or userspace can use name_to_handle_at() syscall to
find fhandle for a cgroup and use a BPF program to filter out blktrace
for a specific cgroup.

We add a new 'blk_cgroup' trace option for blk tracer. It's default off.
Application which doesn't know the new option isn't affected.  When it's
on, we output fhandle info right after blk_io_trace with an extra bit
set in event action. So from application point of view, blktrace with
the option will output new actions.

I didn't change blk trace event yet, since I'm not sure if changing the
trace event output is an ABI issue. If not, I'll do it later.
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/uapi/linux/blktrace_api.h

@@ -52,6 +52,7 @@ enum blktrace_act {
 	__BLK_TA_REMAP,			/* bio was remapped */
 	__BLK_TA_ABORT,			/* request aborted */
 	__BLK_TA_DRV_DATA,		/* driver-specific binary data */
+	__BLK_TA_CGROUP = 1 << 8,	/* from a cgroup*/
 };
 
 /*
@@ -61,6 +62,7 @@ enum blktrace_notify {
 	__BLK_TN_PROCESS = 0,		/* establish pid/name mapping */
 	__BLK_TN_TIMESTAMP,		/* include system clock */
 	__BLK_TN_MESSAGE,		/* Character string message */
+	__BLK_TN_CGROUP = __BLK_TA_CGROUP, /* from a cgroup */
 };
 
 
@@ -107,6 +109,7 @@ struct blk_io_trace {
 	__u32 cpu;		/* on what cpu did it happen */
 	__u16 error;		/* completion error */
 	__u16 pdu_len;		/* length of data after this trace */
+	/* cgroup id will be stored here if exists */
 };
 
 /*

kernel/trace/blktrace.c

@@ -27,6 +27,7 @@
 #include <linux/time.h>
 #include <linux/uaccess.h>
 #include <linux/list.h>
+#include <linux/blk-cgroup.h>
 
 #include "../../block/blk.h"
 
@@ -46,10 +47,14 @@ 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
 
 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) },
+#endif
 	{ }
 };
 
@@ -68,7 +73,8 @@ 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)
+		       const void *data, size_t len,
+		       union kernfs_node_id *cgid)
 {
 	struct blk_io_trace *t;
 	struct ring_buffer_event *event = NULL;
@@ -76,12 +82,13 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 	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,
+						  sizeof(*t) + len + cgid_len,
 						  0, pc);
 		if (!event)
 			return;
@@ -92,17 +99,19 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 	if (!bt->rchan)
 		return;
 
-	t = relay_reserve(bt->rchan, sizeof(*t) + len);
+	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;
+		t->action = action | (cgid ? __BLK_TN_CGROUP : 0);
 		t->pid = pid;
 		t->cpu = cpu;
-		t->pdu_len = len;
-		memcpy((void *) t + sizeof(*t), data, len);
+		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);
@@ -122,7 +131,7 @@ static void trace_note_tsk(struct task_struct *tsk)
 	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));
+			   sizeof(tsk->comm), NULL);
 	}
 	spin_unlock_irqrestore(&running_trace_lock, flags);
 }
@@ -139,7 +148,7 @@ static void trace_note_time(struct blk_trace *bt)
 	words[1] = now.tv_nsec;
 
 	local_irq_save(flags);
-	trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
+	trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words), NULL);
 	local_irq_restore(flags);
 }
 
@@ -167,7 +176,7 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 	n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 	va_end(args);
 
-	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
+	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n, NULL);
 	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(__trace_note_message);
@@ -204,7 +213,7 @@ static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
  */
 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)
+		     void *pdu_data, union kernfs_node_id *cgid)
 {
 	struct task_struct *tsk = current;
 	struct ring_buffer_event *event = NULL;
@@ -215,6 +224,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 	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;
@@ -229,6 +239,8 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 		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))
@@ -241,7 +253,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 		buffer = blk_tr->trace_buffer.buffer;
 		pc = preempt_count();
 		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
-						  sizeof(*t) + pdu_len,
+						  sizeof(*t) + pdu_len + cgid_len,
 						  0, pc);
 		if (!event)
 			return;
@@ -258,7 +270,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 	 * from coming in and stepping on our toes.
 	 */
 	local_irq_save(flags);
-	t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
+	t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len + cgid_len);
 	if (t) {
 		sequence = per_cpu_ptr(bt->sequence, cpu);
 
@@ -280,10 +292,12 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 		t->action = what;
 		t->device = bt->dev;
 		t->error = error;
-		t->pdu_len = pdu_len;
+		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), pdu_data, 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);
@@ -684,6 +698,36 @@ void blk_trace_shutdown(struct request_queue *q)
 	}
 }
 
+#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 = q->blk_trace;
+
+	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
  */
@@ -694,13 +738,15 @@ void blk_trace_shutdown(struct request_queue *q)
  * @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)
+			     unsigned int nr_bytes, u32 what,
+			     union kernfs_node_id *cgid)
 {
 	struct blk_trace *bt = rq->q->blk_trace;
 
@@ -713,32 +759,36 @@ static void blk_add_trace_rq(struct request *rq, int error,
 		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);
+			rq->cmd_flags, what, error, 0, NULL, cgid);
 }
 
 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_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_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_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_add_trace_rq(rq, error, nr_bytes, BLK_TA_COMPLETE,
+			 blk_trace_request_get_cgid(rq->q, rq));
 }
 
 /**
@@ -753,7 +803,7 @@ static void blk_add_trace_rq_complete(void *ignore, struct request *rq,
  *
  **/
 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
-			      u32 what, int error)
+			      u32 what, int error, union kernfs_node_id *cgid)
 {
 	struct blk_trace *bt = q->blk_trace;
 
@@ -761,20 +811,22 @@ static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 		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);
+			bio_op(bio), bio->bi_opf, what, error, 0, NULL, cgid);
 }
 
 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);
+	blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0,
+			  blk_trace_bio_get_cgid(q, bio));
 }
 
 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);
+	blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error,
+			  blk_trace_bio_get_cgid(q, bio));
 }
 
 static void blk_add_trace_bio_backmerge(void *ignore,
@@ -782,7 +834,8 @@ static void blk_add_trace_bio_backmerge(void *ignore,
 					struct request *rq,
 					struct bio *bio)
 {
-	blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
+	blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0,
+			 blk_trace_bio_get_cgid(q, bio));
 }
 
 static void blk_add_trace_bio_frontmerge(void *ignore,
@@ -790,13 +843,15 @@ static void blk_add_trace_bio_frontmerge(void *ignore,
 					 struct request *rq,
 					 struct bio *bio)
 {
-	blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
+	blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0,
+			  blk_trace_bio_get_cgid(q, bio));
 }
 
 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);
+	blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0,
+			  blk_trace_bio_get_cgid(q, bio));
 }
 
 static void blk_add_trace_getrq(void *ignore,
@@ -804,13 +859,14 @@ static void blk_add_trace_getrq(void *ignore,
 				struct bio *bio, int rw)
 {
 	if (bio)
-		blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
+		blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0,
+				  blk_trace_bio_get_cgid(q, bio));
 	else {
 		struct blk_trace *bt = q->blk_trace;
 
 		if (bt)
 			__blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_GETRQ, 0, 0,
-					NULL);
+					NULL, NULL);
 	}
 }
 
@@ -820,13 +876,14 @@ static void blk_add_trace_sleeprq(void *ignore,
 				  struct bio *bio, int rw)
 {
 	if (bio)
-		blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
+		blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0,
+				  blk_trace_bio_get_cgid(q, bio));
 	else {
 		struct blk_trace *bt = q->blk_trace;
 
 		if (bt)
 			__blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_SLEEPRQ,
-					0, 0, NULL);
+					0, 0, NULL, NULL);
 	}
 }
 
@@ -835,7 +892,7 @@ static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 	struct blk_trace *bt = q->blk_trace;
 
 	if (bt)
-		__blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
+		__blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL, NULL);
 }
 
 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
@@ -852,7 +909,7 @@ static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 		else
 			what = BLK_TA_UNPLUG_TIMER;
 
-		__blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
+		__blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu, NULL);
 	}
 }
 
@@ -868,7 +925,7 @@ static void blk_add_trace_split(void *ignore,
 		__blk_add_trace(bt, bio->bi_iter.bi_sector,
 				bio->bi_iter.bi_size, bio_op(bio), bio->bi_opf,
 				BLK_TA_SPLIT, bio->bi_status, sizeof(rpdu),
-				&rpdu);
+				&rpdu, blk_trace_bio_get_cgid(q, bio));
 	}
 }
 
@@ -901,7 +958,7 @@ static void blk_add_trace_bio_remap(void *ignore,
 
 	__blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
 			bio_op(bio), bio->bi_opf, BLK_TA_REMAP, bio->bi_status,
-			sizeof(r), &r);
+			sizeof(r), &r, blk_trace_bio_get_cgid(q, bio));
 }
 
 /**
@@ -934,7 +991,7 @@ static void blk_add_trace_rq_remap(void *ignore,
 
 	__blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 			rq_data_dir(rq), 0, BLK_TA_REMAP, 0,
-			sizeof(r), &r);
+			sizeof(r), &r, blk_trace_request_get_cgid(q, rq));
 }
 
 /**
@@ -958,7 +1015,8 @@ void blk_add_driver_data(struct request_queue *q,
 		return;
 
 	__blk_add_trace(bt, blk_rq_trace_sector(rq), blk_rq_bytes(rq), 0, 0,
-				BLK_TA_DRV_DATA, 0, len, data);
+				BLK_TA_DRV_DATA, 0, len, data,
+				blk_trace_request_get_cgid(q, rq));
 }
 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 
@@ -1031,7 +1089,7 @@ 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_MESSAGE) {
+	if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
 		rwbs[i++] = 'N';
 		goto out;
 	}
@@ -1066,9 +1124,21 @@ 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)
+static inline const void *pdu_start(const struct trace_entry *ent, bool has_cg)
 {
-	return te_blk_io_trace(ent) + 1;
+	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)
@@ -1096,16 +1166,16 @@ 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)
+static __u64 get_pdu_int(const struct trace_entry *ent, bool has_cg)
 {
-	const __u64 *val = pdu_start(ent);
+	const __u64 *val = pdu_start(ent, has_cg);
 	return be64_to_cpu(*val);
 }
 
 static void get_pdu_remap(const struct trace_entry *ent,
-			  struct blk_io_trace_remap *r)
+			  struct blk_io_trace_remap *r, bool has_cg)
 {
-	const struct blk_io_trace_remap *__r = pdu_start(ent);
+	const struct blk_io_trace_remap *__r = pdu_start(ent, has_cg);
 	__u64 sector_from = __r->sector_from;
 
 	r->device_from = be32_to_cpu(__r->device_from);
@@ -1113,9 +1183,11 @@ static void get_pdu_remap(const struct trace_entry *ent,
 	r->sector_from = be64_to_cpu(sector_from);
 }
 
-typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act);
+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)
+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;
@@ -1131,24 +1203,33 @@ static void blk_log_action_classic(struct trace_iterator *iter, const char *act)
 			 secs, nsec_rem, iter->ent->pid, act, rwbs);
 }
 
-static void blk_log_action(struct trace_iterator *iter, const char *act)
+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);
-	trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
-			 MAJOR(t->device), MINOR(t->device), act, rwbs);
+	if (has_cg) {
+		const union kernfs_node_id *id = cgid_start(iter->ent);
+
+		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)
+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);
-	pdu_len = te_blk_io_trace(ent)->pdu_len;
+	pdu_buf = pdu_start(ent, has_cg);
+	pdu_len = pdu_real_len(ent, has_cg);
 
 	if (!pdu_len)
 		return;
@@ -1179,7 +1260,7 @@ static void blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
 	trace_seq_puts(s, ") ");
 }
 
-static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
 {
 	char cmd[TASK_COMM_LEN];
 
@@ -1187,7 +1268,7 @@ static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
 
 	if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
 		trace_seq_printf(s, "%u ", t_bytes(ent));
-		blk_log_dump_pdu(s, ent);
+		blk_log_dump_pdu(s, ent, has_cg);
 		trace_seq_printf(s, "[%s]\n", cmd);
 	} else {
 		if (t_sec(ent))
@@ -1199,10 +1280,10 @@ static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
 }
 
 static void blk_log_with_error(struct trace_seq *s,
-			      const struct trace_entry *ent)
+			      const struct trace_entry *ent, bool has_cg)
 {
 	if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
-		blk_log_dump_pdu(s, ent);
+		blk_log_dump_pdu(s, ent, has_cg);
 		trace_seq_printf(s, "[%d]\n", t_error(ent));
 	} else {
 		if (t_sec(ent))
@@ -1215,18 +1296,18 @@ static void blk_log_with_error(struct trace_seq *s,
 	}
 }
 
-static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
 {
 	struct blk_io_trace_remap r = { .device_from = 0, };
 
-	get_pdu_remap(ent, &r);
+	get_pdu_remap(ent, &r, has_cg);
 	trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
 			 t_sector(ent), t_sec(ent),
 			 MAJOR(r.device_from), MINOR(r.device_from),
 			 (unsigned long long)r.sector_from);
 }
 
-static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
 {
 	char cmd[TASK_COMM_LEN];
 
@@ -1235,30 +1316,31 @@ static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
 	trace_seq_printf(s, "[%s]\n", cmd);
 }
 
-static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
+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));
+	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)
+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), cmd);
+			 get_pdu_int(ent, has_cg), cmd);
 }
 
-static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent,
+			bool has_cg)
 {
-	const struct blk_io_trace *t = te_blk_io_trace(ent);
 
-	trace_seq_putmem(s, t + 1, t->pdu_len);
+	trace_seq_putmem(s, pdu_start(ent, has_cg),
+		pdu_real_len(ent, has_cg));
 	trace_seq_putc(s, '\n');
 }
 
@@ -1298,7 +1380,8 @@ static void blk_tracer_reset(struct trace_array *tr)
 
 static const struct {
 	const char *act[2];
-	void	   (*print)(struct trace_seq *s, const struct trace_entry *ent);
+	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 },
@@ -1326,23 +1409,25 @@ static enum print_line_t print_one_line(struct trace_iterator *iter,
 	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);
+	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_MESSAGE) {
-		log_action(iter, long_act ? "message" : "m");
-		blk_log_msg(s, iter->ent);
+	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]);
-		what2act[what].print(s, iter->ent);
+		log_action(iter, what2act[what].act[long_act], has_cg);
+		what2act[what].print(s, iter->ent, has_cg);
 	}
 
 	return trace_handle_return(s);