[PATCH] blktrace: readahead support
Provide the needed kernel support for distinguishing readahead
from regular read requests when tracing block devices.
Signed-off-by: Nathan Scott <nathans@sgi.com>
Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/block/blktrace.c b/block/blktrace.c
index 92925e7..b8c07027 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -69,7 +69,7 @@
/*
* Bio action bits of interest
*/
-static u32 bio_act[3] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC) };
+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) };
/*
* More could be added as needed, taking care to increment the decrementer
@@ -79,6 +79,8 @@
(((rw) & (1 << BIO_RW_BARRIER)) >> (BIO_RW_BARRIER - 0))
#define trace_sync_bit(rw) \
(((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1))
+#define trace_ahead_bit(rw) \
+ (((rw) & (1 << BIO_RW_AHEAD)) << (BIO_RW_AHEAD - 0))
/*
* The worker for the various blk_add_trace*() types. Fills out a
@@ -100,6 +102,7 @@
what |= ddir_act[rw & WRITE];
what |= bio_act[trace_barrier_bit(rw)];
what |= bio_act[trace_sync_bit(rw)];
+ what |= bio_act[trace_ahead_bit(rw)];
pid = tsk->pid;
if (unlikely(act_log_check(bt, what, sector, pid)))
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index d95615f..2346a1d 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -19,6 +19,7 @@
BLK_TC_FS = 1 << 8, /* fs requests */
BLK_TC_PC = 1 << 9, /* pc requests */
BLK_TC_NOTIFY = 1 << 10, /* special message */
+ BLK_TC_AHEAD = 1 << 11, /* readahead */
BLK_TC_END = 1 << 15, /* only 16-bits, reminder */
};
