[PATCH 3/3] blk-mq: support partial I/O completions

Christoph Hellwig
2014-02-20T23:32:38Z

[-- Attachment #1: 0003-blk-mq-support-partial-I-O-completions.patch --]
[-- Type: text/plain, Size: 2701 bytes --]

Add a new blk_mq_end_io_partial function to partially complete requests
as needed by the SCSI layer. We do this by reusing blk_update_request
to advance the bio instead of having a simplified version of it in
the blk-mq code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/blk-mq.c | 37 +++++--------------------------------
include/linux/blk-mq.h | 8 +++++++-
2 files changed, 12 insertions(+), 33 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 2af8405..1b8b50d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -283,38 +283,10 @@ void blk_mq_free_request(struct request *rq)
__blk_mq_free_request(hctx, ctx, rq);
}

-static void blk_mq_bio_endio(struct request *rq, struct bio *bio, int error)
+bool blk_mq_end_io_partial(struct request *rq, int error, unsigned int nr_bytes)
{
- if (error)
- clear_bit(BIO_UPTODATE, &bio->bi_flags);
- else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
- error = -EIO;
-
- if (unlikely(rq->cmd_flags & REQ_QUIET))
- set_bit(BIO_QUIET, &bio->bi_flags);
-
- /* don't actually finish bio if it's part of flush sequence */
- if (!(rq->cmd_flags & REQ_FLUSH_SEQ))
- bio_endio(bio, error);
-}
-
-void blk_mq_end_io(struct request *rq, int error)
-{
- struct bio *bio = rq->bio;
- unsigned int bytes = 0;
-
- trace_block_rq_complete(rq->q, rq);
-
- while (bio) {
- struct bio *next = bio->bi_next;
-
- bio->bi_next = NULL;
- bytes += bio->bi_iter.bi_size;
- blk_mq_bio_endio(rq, bio, error);
- bio = next;
- }
-
- blk_account_io_completion(rq, bytes);
+ if (blk_update_request(rq, error, blk_rq_bytes(rq)))
+ return true;

blk_account_io_done(rq);

@@ -322,8 +294,9 @@ void blk_mq_end_io(struct request *rq, int error)
rq->end_io(rq, error);
else
blk_mq_free_request(rq);
+ return false;
}
-EXPORT_SYMBOL(blk_mq_end_io);
+EXPORT_SYMBOL(blk_mq_end_io_partial);

static void __blk_mq_complete_request_remote(void *data)
{
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index ff28fe3..2ff2e8d 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -133,7 +133,13 @@ struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *, const int ctx_ind
struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_reg *, unsigned int);
void blk_mq_free_single_hw_queue(struct blk_mq_hw_ctx *, unsigned int);

-void blk_mq_end_io(struct request *rq, int error);
+bool blk_mq_end_io_partial(struct request *rq, int error,
+ unsigned int nr_bytes);
+static inline void blk_mq_end_io(struct request *rq, int error)
+{
+ bool done = !blk_mq_end_io_partial(rq, error, blk_rq_bytes(rq));
+ BUG_ON(!done);
+}

void blk_mq_complete_request(struct request *rq);

--
1.7.10.4