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Subject[PATCH 3/9] block: Refactor blk_update_request()
Date
Converts it to use bio_advance(), simplifying it quite a bit in the
process.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
---
block/blk-core.c | 84 +++++++++++---------------------------------------------
1 file changed, 16 insertions(+), 68 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 82aab28..94cbdcc 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -153,25 +153,19 @@ EXPORT_SYMBOL(blk_rq_init);
static void req_bio_endio(struct request *rq, struct bio *bio,
unsigned int nbytes, int error)
{
+ /*
+ * XXX: bio_endio() does this. only need this because of the weird
+ * flush seq thing.
+ */
if (error)
clear_bit(BIO_UPTODATE, &bio->bi_flags);
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))
@@ -2216,8 +2210,7 @@ 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;
@@ -2261,56 +2254,21 @@ 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))
- break;
- }
+ if (!nr_bytes)
+ break;
}

/*
@@ -2326,16 +2284,6 @@ 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);

--
1.7.12


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