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Subject[PATCH 1/3] block: introduce REQ_DIRECT to track direct io bio
Date
Introduce a new flag to identify if a bio has been generated for a
direct IO operation.

This flag is used by the blkio controller to identify if a write IO
request has been issued by the current task and can be limited directly
or if it has been generated from another IO context, as a result of a
buffered IO operation.

Signed-off-by: Andrea Righi <arighi@develer.com>
---
fs/direct-io.c | 1 +
include/linux/blk_types.h | 2 ++
2 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index b044705..fe364a4 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -361,6 +361,7 @@ static void dio_bio_submit(struct dio *dio)
unsigned long flags;

bio->bi_private = dio;
+ bio->bi_rw |= REQ_DIRECT;

spin_lock_irqsave(&dio->bio_lock, flags);
dio->refcount++;
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 46ad519..2f98c03 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -130,6 +130,7 @@ enum rq_flag_bits {
/* bio only flags */
__REQ_UNPLUG, /* unplug the immediately after submission */
__REQ_RAHEAD, /* read ahead, can fail anytime */
+ __REQ_DIRECT, /* direct io request */
__REQ_THROTTLED, /* This bio has already been subjected to
* throttling rules. Don't do it again. */

@@ -173,6 +174,7 @@ enum rq_flag_bits {
#define REQ_UNPLUG (1 << __REQ_UNPLUG)
#define REQ_RAHEAD (1 << __REQ_RAHEAD)
#define REQ_THROTTLED (1 << __REQ_THROTTLED)
+#define REQ_DIRECT (1 << __REQ_DIRECT)

#define REQ_SORTED (1 << __REQ_SORTED)
#define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
--
1.7.1


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