Fix up comments about matching flags between bio and rq

David Woodhouse committed 18 years ago

Commit d628eae1 parent 36144073 files · +5 −8Browse files

Unified · Split

3 files

 	blk_rq_init(q, rq);
-	/*
-	 * first three bits are identical in rq->cmd_flags and bio->bi_rw,
-	 * see bio.h and blkdev.h
-	 */
 	rq->cmd_flags = rw | REQ_ALLOCED;
 	if (priv) {
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 		     struct bio *bio)
 {
-	/* first two bits are identical in rq->cmd_flags and bio->bi_rw */
+	/* 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);
 	rq->nr_phys_segments = bio_phys_segments(q, bio);

@@ -150,8 +150,8 @@ struct bio { · 149 unmodified lines
150	* bit 3 -- fail fast, don't want low level driver retries	150	* bit 3 -- fail fast, don't want low level driver retries
151	* bit 4 -- synchronous I/O hint: the block layer will unplug immediately	151	* bit 4 -- synchronous I/O hint: the block layer will unplug immediately
152	*/	152	*/
153	#define BIO_RW 0	153	#define BIO_RW 0 /* Must match RW in req flags (blkdev.h) */
154	#define BIO_RW_AHEAD 1	154	#define BIO_RW_AHEAD 1 /* Must match FAILFAST in req flags */
155	#define BIO_RW_BARRIER 2	155	#define BIO_RW_BARRIER 2
156	#define BIO_RW_FAILFAST 3	156	#define BIO_RW_FAILFAST 3
157	#define BIO_RW_SYNC 4	157	#define BIO_RW_SYNC 4

@@ -84,7 +84,7 @@ enum { · 83 unmodified lines
84	};	84	};
85		85
86	/*	86	/*
87	* request type modified bits. first three bits match BIO_RW* bits, important	87	* request type modified bits. first two bits match BIO_RW* bits, important
88	*/	88	*/
89	enum rq_flag_bits {	89	enum rq_flag_bits {
90	__REQ_RW, /* not set, read. set, write */	90	__REQ_RW, /* not set, read. set, write */