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| author | FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> | 2010-07-03 17:45:32 +0900 |
|---|---|---|
| committer | Jens Axboe <jaxboe@fusionio.com> | 2010-08-07 18:23:53 +0200 |
| commit | 8749534fe6826596b71bc409c872b047a8e2755b (patch) | |
| tree | 29ceb928f03dfb33d3a03df1c00e4a51d22b55b3 /include/linux | |
| parent | 802447c1c0513a0ea0e29d6bda23b19ac0686654 (diff) | |
| download | lwn-8749534fe6826596b71bc409c872b047a8e2755b.tar.gz lwn-8749534fe6826596b71bc409c872b047a8e2755b.zip | |
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>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/bio.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h index 4d379c8250ae..f655b54c9ef3 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) |