bio and request use the same set of failfast bits.  This patch makes

the following changes to simplify things.
* enumify BIO_RW* bits and reorder bits such that BIOS_RW_FAILFAST_*

  bits coincide with __REQ_FAILFAST_* bits.
* The above pushes BIO_RW_AHEAD out of sync with __REQ_FAILFAST_DEV

  but the matching is useless anyway.  init_request_from_bio() is

  responsible for setting FAILFAST bits on FS requests and non-FS

  requests never use BIO_RW_AHEAD.  Drop the code and comment from

  blk_rq_bio_prep().
* Define REQ_FAILFAST_MASK which is OR of all FAILFAST bits and

  simplify FAILFAST flags handling in init_request_from_bio().
Signed-off-by: Tejun Heo

Cc: Jens Axboe

---

 block/blk-core.c       |   19 +++++++------------

 include/linux/bio.h    |   43 +++++++++++++++++++++++--------------------

 include/linux/blkdev.h |    4 ++++

 3 files changed, 34 insertions(+), 32 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c

index 8f4b9e0..cd3b265 100644

--- a/block/blk-core.c

+++ b/block/blk-core.c

@@ -1119,17 +1119,13 @@ void init_request_from_bio(struct request *req, struct bio *bio)

 	req->cmd_type = REQ_TYPE_FS;
 	/*

-	 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)

+	 * Inherit FAILFAST from bio (for read-ahead, and explicit

+	 * FAILFAST).  FAILFAST flags are identical for req and bio.

 	 */

 	if (bio_rw_ahead(bio))

-		req->cmd_flags |= (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |

-				   REQ_FAILFAST_DRIVER);

-	if (bio_failfast_dev(bio))

-		req->cmd_flags |= REQ_FAILFAST_DEV;

-	if (bio_failfast_transport(bio))

-		req->cmd_flags |= REQ_FAILFAST_TRANSPORT;

-	if (bio_failfast_driver(bio))

-		req->cmd_flags |= REQ_FAILFAST_DRIVER;

+		req->cmd_flags |= REQ_FAILFAST_MASK;

+	else

+		req->cmd_flags |= bio->bi_rw & REQ_FAILFAST_MASK;
 	if (unlikely(bio_discard(bio))) {

 		req->cmd_flags |= REQ_DISCARD;

@@ -2247,9 +2243,8 @@ EXPORT_SYMBOL_GPL(__blk_end_request_cur);

 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,

 		     struct bio *bio)

 {

-	/* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw, and

-	   we want BIO_RW_AHEAD (bit 1) to imply REQ_FAILFAST (bit 1). */

-	rq->cmd_flags |= (bio->bi_rw & 3);

+	/* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */

+	rq->cmd_flags |= bio->bi_rw & REQ_RW;
 	if (bio_has_data(bio)) {

 		rq->nr_phys_segments = bio_phys_segments(q, bio);

diff --git a/include/linux/bio.h b/include/linux/bio.h

index 2892b71..a299ed3 100644

--- a/include/linux/bio.h

+++ b/include/linux/bio.h

@@ -142,37 +142,40 @@ struct bio {

  *

  * bit 0 -- data direction

  *	If not set, bio is a read from device. If set, it's a write to device.

- * bit 1 -- rw-ahead when set

- * bit 2 -- barrier

+ * bit 1 -- fail fast device errors

+ * bit 2 -- fail fast transport errors

+ * bit 3 -- fail fast driver errors

+ * bit 4 -- rw-ahead when set

+ * bit 5 -- barrier

  *	Insert a serialization point in the IO queue, forcing previously

  *	submitted IO to be completed before this one is issued.

- * bit 3 -- synchronous I/O hint.

- * bit 4 -- Unplug the device immediately after submitting this bio.

- * bit 5 -- metadata request

+ * bit 6 -- synchronous I/O hint.

+ * bit 7 -- Unplug the device immediately after submitting this bio.

+ * bit 8 -- metadata request

  *	Used for tracing to differentiate metadata and data IO. May also

  *	get some preferential treatment in the IO scheduler

- * bit 6 -- discard sectors

+ * bit 9 -- discard sectors

  *	Informs the lower level device that this range of sectors is no longer

  *	used by the file system and may thus be freed by the device. Used

  *	for flash based storage.

- * bit 7 -- fail fast device errors

- * bit 8 -- fail fast transport errors

- * bit 9 -- fail fast driver errors

  *	Don't want driver retries for any fast fail whatever the reason.

  * bit 10 -- Tell the IO scheduler not to wait for more requests after this

 	one has been submitted, even if it is a SYNC request.

  */

-#define BIO_RW		0	/* Must match RW in req flags (blkdev.h) */

-#define BIO_RW_AHEAD	1	/* Must match FAILFAST in req flags */

-#define BIO_RW_BARRIER	2

-#define BIO_RW_SYNCIO	3

-#define BIO_RW_UNPLUG	4

-#define BIO_RW_META	5

-#define BIO_RW_DISCARD	6

-#define BIO_RW_FAILFAST_DEV		7

-#define BIO_RW_FAILFAST_TRANSPORT	8

-#define BIO_RW_FAILFAST_DRIVER		9

-#define BIO_RW_NOIDLE	10

+enum bio_rw_flags {

+	BIO_RW,

+	BIO_RW_FAILFAST_DEV,

+	BIO_RW_FAILFAST_TRANSPORT,

+	BIO_RW_FAILFAST_DRIVER,

+	/* above flags must match REQ_* */

+	BIO_RW_AHEAD,

+	BIO_RW_BARRIER,

+	BIO_RW_SYNCIO,

+	BIO_RW_UNPLUG,

+	BIO_RW_META,

+	BIO_RW_DISCARD,

+	BIO_RW_NOIDLE,

+};
 #define bio_rw_flagged(bio, flag)	((bio)->bi_rw & (1 << (flag)))
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h

index 49ae079..a0e5ce1 100644

--- a/include/linux/blkdev.h

+++ b/include/linux/blkdev.h

@@ -98,6 +98,7 @@ enum rq_flag_bits {

 	__REQ_FAILFAST_DEV,	/* no driver retries of device errors */

 	__REQ_FAILFAST_TRANSPORT, /* no driver retries of transport errors */

 	__REQ_FAILFAST_DRIVER,	/* no driver retries of driver errors */

+	/* above flags must match BIO_RW_* */

 	__REQ_DISCARD,		/* request to discard sectors */

 	__REQ_SORTED,		/* elevator knows about this request */

 	__REQ_SOFTBARRIER,	/* may not be passed by ioscheduler */

@@ -148,6 +149,9 @@ enum rq_flag_bits {

 #define REQ_NOIDLE	(1 << __REQ_NOIDLE)

 #define REQ_IO_STAT	(1 << __REQ_IO_STAT)
+#define REQ_FAILFAST_MASK	(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | \

+				 REQ_FAILFAST_DRIVER)

+

 #define BLK_MAX_CDB	16
 /*

--

1.6.0.2
--

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