Commit f79ea416 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

block: Refactor blk_update_request() 



Converts it to use bio_advance(), simplifying it quite a bit in the
process.

Note that req_bio_endio() now always calls bio_advance() - which means
it always loops over the biovec, not just on partial completions. Don't
expect it to affect performance, but worth noting.

Tested it by forcing partial updates, and dumping before and after on
various bio/bvec fields when doing a partial update.

Signed-off-by: default avatarKent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
parent 054bdf64

block/blk-core.c

+12 −68
Original line number Diff line number Diff line
@@ -158,20 +158,10 @@ static void req_bio_endio(struct request *rq, struct bio *bio, 
	else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))

		error = -EIO;



	if (unlikely(nbytes > bio->bi_size)) {

		printk(KERN_ERR "%s: want %u bytes done, %u left\n",

		       __func__, nbytes, bio->bi_size);

		nbytes = bio->bi_size;

	}



	if (unlikely(rq->cmd_flags & REQ_QUIET))

		set_bit(BIO_QUIET, &bio->bi_flags);



	bio->bi_size -= nbytes;

	bio->bi_sector += (nbytes >> 9);



	if (bio_integrity(bio))

		bio_integrity_advance(bio, nbytes);

	bio_advance(bio, nbytes);



	/* don't actually finish bio if it's part of flush sequence */

	if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
@@ -2252,8 +2242,7 @@ EXPORT_SYMBOL(blk_fetch_request); 
 **/

bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)

{

	int total_bytes, bio_nbytes, next_idx = 0;

	struct bio *bio;

	int total_bytes;



	if (!req->bio)

		return false;
@@ -2299,57 +2288,22 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) 


	blk_account_io_completion(req, nr_bytes);



	total_bytes = bio_nbytes = 0;

	while ((bio = req->bio) != NULL) {

		int nbytes;

	total_bytes = 0;

	while (req->bio) {

		struct bio *bio = req->bio;

		unsigned bio_bytes = min(bio->bi_size, nr_bytes);



		if (nr_bytes >= bio->bi_size) {

		if (bio_bytes == bio->bi_size)

			req->bio = bio->bi_next;

			nbytes = bio->bi_size;

			req_bio_endio(req, bio, nbytes, error);

			next_idx = 0;

			bio_nbytes = 0;

		} else {

			int idx = bio->bi_idx + next_idx;



			if (unlikely(idx >= bio->bi_vcnt)) {

				blk_dump_rq_flags(req, "__end_that");

				printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n",

				       __func__, idx, bio->bi_vcnt);

				break;

			}



			nbytes = bio_iovec_idx(bio, idx)->bv_len;

			BIO_BUG_ON(nbytes > bio->bi_size);



			/*

			 * not a complete bvec done

			 */

			if (unlikely(nbytes > nr_bytes)) {

				bio_nbytes += nr_bytes;

				total_bytes += nr_bytes;

				break;

			}



			/*

			 * advance to the next vector

			 */

			next_idx++;

			bio_nbytes += nbytes;

		}

		req_bio_endio(req, bio, bio_bytes, error);



		total_bytes += nbytes;

		nr_bytes -= nbytes;

		total_bytes += bio_bytes;

		nr_bytes -= bio_bytes;



		bio = req->bio;

		if (bio) {

			/*

			 * end more in this run, or just return 'not-done'

			 */

			if (unlikely(nr_bytes <= 0))

		if (!nr_bytes)

			break;

	}

	}



	/*

	 * completely done
@@ -2364,16 +2318,6 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) 
		return false;

	}



	/*

	 * if the request wasn't completed, update state

	 */

	if (bio_nbytes) {

		req_bio_endio(req, bio, bio_nbytes, error);

		bio->bi_idx += next_idx;

		bio_iovec(bio)->bv_offset += nr_bytes;

		bio_iovec(bio)->bv_len -= nr_bytes;

	}



	req->__data_len -= total_bytes;

	req->buffer = bio_data(req->bio);

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