bcache: print number of keys in trace_bcache_journal_write

Sometimes flush journal may be very frequent, so it's useful to dump
number of keys every time write journal.
Signed-off-by: Guoju Fang <fangguoju@gmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/bcache/journal.c

@@ -663,7 +663,7 @@ static void journal_write_unlocked(struct closure *cl)
 				 REQ_SYNC|REQ_META|REQ_PREFLUSH|REQ_FUA);
 		bch_bio_map(bio, w->data);
 
-		trace_bcache_journal_write(bio);
+		trace_bcache_journal_write(bio, w->data->keys);
 		bio_list_add(&list, bio);
 
 		SET_PTR_OFFSET(k, i, PTR_OFFSET(k, i) + sectors);

include/trace/events/bcache.h

@@ -221,9 +221,30 @@ DEFINE_EVENT(cache_set, bcache_journal_entry_full,
 	TP_ARGS(c)
 );
 
-DEFINE_EVENT(bcache_bio, bcache_journal_write,
-	TP_PROTO(struct bio *bio),
-	TP_ARGS(bio)
+TRACE_EVENT(bcache_journal_write,
+	TP_PROTO(struct bio *bio, u32 keys),
+	TP_ARGS(bio, keys),
+
+	TP_STRUCT__entry(
+		__field(dev_t,		dev			)
+		__field(sector_t,	sector			)
+		__field(unsigned int,	nr_sector		)
+		__array(char,		rwbs,	6		)
+		__field(u32,		nr_keys			)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= bio_dev(bio);
+		__entry->sector		= bio->bi_iter.bi_sector;
+		__entry->nr_sector	= bio->bi_iter.bi_size >> 9;
+		__entry->nr_keys	= keys;
+		blk_fill_rwbs(__entry->rwbs, bio->bi_opf, bio->bi_iter.bi_size);
+	),
+
+	TP_printk("%d,%d  %s %llu + %u keys %u",
+		  MAJOR(__entry->dev), MINOR(__entry->dev), __entry->rwbs,
+		  (unsigned long long)__entry->sector, __entry->nr_sector,
+		  __entry->nr_keys)
 );
 
 /* Btree */