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authorFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>2010-07-03 17:45:32 +0900
committerJens Axboe <jaxboe@fusionio.com>2010-08-07 18:23:53 +0200
commit8749534fe6826596b71bc409c872b047a8e2755b (patch)
tree29ceb928f03dfb33d3a03df1c00e4a51d22b55b3
parent802447c1c0513a0ea0e29d6bda23b19ac0686654 (diff)
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block: introduce REQ_FLUSH flag
SCSI-ml needs a way to mark a request as flush request in q->prepare_flush_fn because it needs to identify them later (e.g. in q->request_fn or prep_rq_fn). queue_flush sets REQ_HARDBARRIER in rq->cmd_flags however the block layer also sends normal REQ_TYPE_FS requests with REQ_HARDBARRIER. So SCSI-ml can't use REQ_HARDBARRIER to identify flush requests. We could change the block layer to clear REQ_HARDBARRIER bit before sending non flush requests to the lower layers. However, intorudcing the new flag looks cleaner (surely easier). Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: James Bottomley <James.Bottomley@suse.de> Cc: David S. Miller <davem@davemloft.net> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Alasdair G Kergon <agk@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
-rw-r--r--block/blk-barrier.c2
-rw-r--r--include/linux/bio.h2
2 files changed, 3 insertions, 1 deletions
diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 7c6f4a7..a348242 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -143,7 +143,7 @@ static void queue_flush(struct request_queue *q, unsigned which)
}
blk_rq_init(q, rq);
- rq->cmd_flags = REQ_HARDBARRIER;
+ rq->cmd_flags = REQ_HARDBARRIER | REQ_FLUSH;
rq->rq_disk = q->bar_rq.rq_disk;
rq->end_io = end_io;
q->prepare_flush_fn(q, rq);
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 4d379c8..f655b54 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -174,6 +174,7 @@ enum rq_flag_bits {
__REQ_ALLOCED, /* request came from our alloc pool */
__REQ_COPY_USER, /* contains copies of user pages */
__REQ_INTEGRITY, /* integrity metadata has been remapped */
+ __REQ_FLUSH, /* request for cache flush */
__REQ_IO_STAT, /* account I/O stat */
__REQ_MIXED_MERGE, /* merge of different types, fail separately */
__REQ_NR_BITS, /* stops here */
@@ -213,6 +214,7 @@ enum rq_flag_bits {
#define REQ_ALLOCED (1 << __REQ_ALLOCED)
#define REQ_COPY_USER (1 << __REQ_COPY_USER)
#define REQ_INTEGRITY (1 << __REQ_INTEGRITY)
+#define REQ_FLUSH (1 << __REQ_FLUSH)
#define REQ_IO_STAT (1 << __REQ_IO_STAT)
#define REQ_MIXED_MERGE (1 << __REQ_MIXED_MERGE)