[PATCH] blktrace: support for logging metadata reads

Signed-off-by: Jens Axboe <axboe@suse.de>

block/blktrace.c

@@ -69,7 +69,7 @@ static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK
 /*
  * Bio action bits of interest
  */
-static u32 bio_act[5] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC), 0, BLK_TC_ACT(BLK_TC_AHEAD) };
+static u32 bio_act[9] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC), 0, BLK_TC_ACT(BLK_TC_AHEAD), 0, 0, 0, BLK_TC_ACT(BLK_TC_META) };
 
 /*
  * More could be added as needed, taking care to increment the decrementer
@@ -81,6 +81,8 @@ static u32 bio_act[5] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_AC
 	(((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1))
 #define trace_ahead_bit(rw)	\
 	(((rw) & (1 << BIO_RW_AHEAD)) << (2 - BIO_RW_AHEAD))
+#define trace_meta_bit(rw)	\
+	(((rw) & (1 << BIO_RW_META)) >> (BIO_RW_META - 3))
 
 /*
  * The worker for the various blk_add_trace*() types. Fills out a
@@ -103,6 +105,7 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 	what |= bio_act[trace_barrier_bit(rw)];
 	what |= bio_act[trace_sync_bit(rw)];
 	what |= bio_act[trace_ahead_bit(rw)];
+	what |= bio_act[trace_meta_bit(rw)];
 
 	pid = tsk->pid;
 	if (unlikely(act_log_check(bt, what, sector, pid)))

include/linux/blktrace_api.h

@@ -20,6 +20,7 @@ enum blktrace_cat {
 	BLK_TC_PC	= 1 << 9,	/* pc requests */
 	BLK_TC_NOTIFY	= 1 << 10,	/* special message */
 	BLK_TC_AHEAD	= 1 << 11,	/* readahead */
+	BLK_TC_META	= 1 << 12,	/* metadata */
 
 	BLK_TC_END	= 1 << 15,	/* only 16-bits, reminder */
 };