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block: Consolidate command flag and queue limit checks for merges 

- blk_check_merge_flags() verifies that cmd_flags / bi_rw are
   compatible. This function is called for both req-req and req-bio
   merging.

 - blk_rq_get_max_sectors() and blk_queue_get_max_sectors() can be used
   to query the maximum sector count for a given request or queue. The
   calls will return the right value from the queue limits given the
   type of command (RW, discard, write same, etc.)

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Martin K. Petersen 2012-09-18 12:19:26 -04:00 committed by Jens Axboe
parent e2a60da74f
commit f31dc1cd49
3 changed files with 44 additions and 20 deletions
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3
block/blk-core.c
View File

@ -1866,8 +1866,7 @@ int blk_rq_check_limits(struct request_queue *q, struct request *rq)
if (!rq_mergeable(rq))
return 0;
if (blk_rq_sectors(rq) > queue_max_sectors(q) ||
blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 9) {
if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) {
printk(KERN_ERR "%s: over max size limit.\n", __func__);
return -EIO;
}

30
block/blk-merge.c
View File

@ -275,14 +275,8 @@ no_merge:
int ll_back_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio)
{
unsigned short max_sectors;
if (unlikely(req->cmd_type == REQ_TYPE_BLOCK_PC))
max_sectors = queue_max_hw_sectors(q);
else
max_sectors = queue_max_sectors(q);
if (blk_rq_sectors(req) + bio_sectors(bio) > max_sectors) {
if (blk_rq_sectors(req) + bio_sectors(bio) >
blk_rq_get_max_sectors(req)) {
req->cmd_flags |= REQ_NOMERGE;
if (req == q->last_merge)
q->last_merge = NULL;
@ -299,15 +293,8 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req,
int ll_front_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio)
{
unsigned short max_sectors;
if (unlikely(req->cmd_type == REQ_TYPE_BLOCK_PC))
max_sectors = queue_max_hw_sectors(q);
else
max_sectors = queue_max_sectors(q);
if (blk_rq_sectors(req) + bio_sectors(bio) > max_sectors) {
if (blk_rq_sectors(req) + bio_sectors(bio) >
blk_rq_get_max_sectors(req)) {
req->cmd_flags |= REQ_NOMERGE;
if (req == q->last_merge)
q->last_merge = NULL;
@ -338,7 +325,8 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
/*
* Will it become too large?
*/
if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > queue_max_sectors(q))
if ((blk_rq_sectors(req) + blk_rq_sectors(next)) >
blk_rq_get_max_sectors(req))
return 0;
total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
@ -417,6 +405,9 @@ static int attempt_merge(struct request_queue *q, struct request *req,
if (!rq_mergeable(req) || !rq_mergeable(next))
return 0;
if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags))
return 0;
/*
* not contiguous
*/
@ -512,6 +503,9 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
if (!rq_mergeable(rq) || !bio_mergeable(bio))
return false;
if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw))
return false;
/* different data direction or already started, don't merge */
if (bio_data_dir(bio) != rq_data_dir(rq))
return false;

31
include/linux/blkdev.h
View File

@ -605,6 +605,18 @@ static inline bool rq_mergeable(struct request *rq)
return true;
}
static inline bool blk_check_merge_flags(unsigned int flags1,
unsigned int flags2)
{
if ((flags1 & REQ_DISCARD) != (flags2 & REQ_DISCARD))
return false;
if ((flags1 & REQ_SECURE) != (flags2 & REQ_SECURE))
return false;
return true;
}
/*
* q->prep_rq_fn return values
*/
@ -800,6 +812,25 @@ static inline unsigned int blk_rq_cur_sectors(const struct request *rq)
return blk_rq_cur_bytes(rq) >> 9;
}
static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
unsigned int cmd_flags)
{
if (unlikely(cmd_flags & REQ_DISCARD))
return q->limits.max_discard_sectors;
return q->limits.max_sectors;
}
static inline unsigned int blk_rq_get_max_sectors(struct request *rq)
{
struct request_queue *q = rq->q;
if (unlikely(rq->cmd_type == REQ_TYPE_BLOCK_PC))
return q->limits.max_hw_sectors;
return blk_queue_get_max_sectors(q, rq->cmd_flags);
}
/*
* Request issue related functions.
*/