[PATCH 27/42] block: prepare request creation/destruction code to use REQ_OPs

mchristi
2016-04-15T10:41:10Z

This patch prepares *_get_request/*_put_request and freed_request,
to use separate variables for the operation and flags. In the
next patches the struct request users will be converted like
was done for bios. request->op will be used for the REQ_OP and
request->cmd_flags for the rq_flag_bits.

There is some temporary compat code in __get_request to
allow users to read the operation from the cmd_flags. This will
be deleted in one of the last patches when all drivers have
been converted.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
---
block/blk-core.c | 56 +++++++++++++++++++++++++++++++-------------------------
1 file changed, 31 insertions(+), 25 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 94736c3..3168962 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -959,10 +959,10 @@ static void __freed_request(struct request_list *rl, int sync)
* A request has just been released. Account for it, update the full and
* congestion status, wake up any waiters. Called under q->queue_lock.
*/
-static void freed_request(struct request_list *rl, unsigned int flags)
+static void freed_request(struct request_list *rl, int op, unsigned int flags)
{
struct request_queue *q = rl->q;
- int sync = rw_is_sync(flags);
+ int sync = rw_is_sync(op | flags);

q->nr_rqs[sync]--;
rl->count[sync]--;
@@ -1054,7 +1054,8 @@ static struct io_context *rq_ioc(struct bio *bio)
/**
* __get_request - get a free request
* @rl: request list to allocate from
- * @rw_flags: RW and SYNC flags
+ * @op: REQ_OP_READ/REQ_OP_WRITE
+ * @op_flags: rq_flag_bits
* @bio: bio to allocate request for (can be %NULL)
* @gfp_mask: allocation mask
*
@@ -1065,21 +1066,22 @@ static struct io_context *rq_ioc(struct bio *bio)
* Returns ERR_PTR on failure, with @q->queue_lock held.
* Returns request pointer on success, with @q->queue_lock *not held*.
*/
-static struct request *__get_request(struct request_list *rl, int rw_flags,
- struct bio *bio, gfp_t gfp_mask)
+static struct request *__get_request(struct request_list *rl, int op,
+ int op_flags, struct bio *bio,
+ gfp_t gfp_mask)
{
struct request_queue *q = rl->q;
struct request *rq;
struct elevator_type *et = q->elevator->type;
struct io_context *ioc = rq_ioc(bio);
struct io_cq *icq = NULL;
- const bool is_sync = rw_is_sync(rw_flags) != 0;
+ const bool is_sync = rw_is_sync(op | op_flags) != 0;
int may_queue;

if (unlikely(blk_queue_dying(q)))
return ERR_PTR(-ENODEV);

- may_queue = elv_may_queue(q, rw_flags);
+ may_queue = elv_may_queue(q, op | op_flags);
if (may_queue == ELV_MQUEUE_NO)
goto rq_starved;

@@ -1123,7 +1125,7 @@ static struct request *__get_request(struct request_list *rl, int rw_flags,

/*
* Decide whether the new request will be managed by elevator. If
- * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will
+ * so, mark @op_flags and increment elvpriv. Non-zero elvpriv will
* prevent the current elevator from being destroyed until the new
* request is freed. This guarantees icq's won't be destroyed and
* makes creating new ones safe.
@@ -1132,14 +1134,14 @@ static struct request *__get_request(struct request_list *rl, int rw_flags,
* it will be created after releasing queue_lock.
*/
if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
- rw_flags |= REQ_ELVPRIV;
+ op_flags |= REQ_ELVPRIV;
q->nr_rqs_elvpriv++;
if (et->icq_cache && ioc)
icq = ioc_lookup_icq(ioc, q);
}

if (blk_queue_io_stat(q))
- rw_flags |= REQ_IO_STAT;
+ op_flags |= REQ_IO_STAT;
spin_unlock_irq(q->queue_lock);

/* allocate and init request */
@@ -1149,10 +1151,12 @@ static struct request *__get_request(struct request_list *rl, int rw_flags,

blk_rq_init(q, rq);
blk_rq_set_rl(rq, rl);
- rq->cmd_flags = rw_flags | REQ_ALLOCED;
+ /* tmp compat - allow users to check either one for the op */
+ rq->cmd_flags = op | op_flags | REQ_ALLOCED;
+ rq->op = op;

/* init elvpriv */
- if (rw_flags & REQ_ELVPRIV) {
+ if (op_flags & REQ_ELVPRIV) {
if (unlikely(et->icq_cache && !icq)) {
if (ioc)
icq = ioc_create_icq(ioc, q, gfp_mask);
@@ -1178,7 +1182,7 @@ out:
if (ioc_batching(q, ioc))
ioc->nr_batch_requests--;

- trace_block_getrq(q, bio, rw_flags & 1);
+ trace_block_getrq(q, bio, op);
return rq;

fail_elvpriv:
@@ -1208,7 +1212,7 @@ fail_alloc:
* queue, but this is pretty rare.
*/
spin_lock_irq(q->queue_lock);
- freed_request(rl, rw_flags);
+ freed_request(rl, op, op_flags);

/*
* in the very unlikely event that allocation failed and no
@@ -1226,7 +1230,8 @@ rq_starved:
/**
* get_request - get a free request
* @q: request_queue to allocate request from
- * @rw_flags: RW and SYNC flags
+ * @op: REQ_OP_READ/REQ_OP_WRITE
+ * @op_flags: rq_flag_bits
* @bio: bio to allocate request for (can be %NULL)
* @gfp_mask: allocation mask
*
@@ -1237,17 +1242,18 @@ rq_starved:
* Returns ERR_PTR on failure, with @q->queue_lock held.
* Returns request pointer on success, with @q->queue_lock *not held*.
*/
-static struct request *get_request(struct request_queue *q, int rw_flags,
- struct bio *bio, gfp_t gfp_mask)
+static struct request *get_request(struct request_queue *q, int op,
+ int op_flags, struct bio *bio,
+ gfp_t gfp_mask)
{
- const bool is_sync = rw_is_sync(rw_flags) != 0;
+ const bool is_sync = rw_is_sync(op | op_flags) != 0;
DEFINE_WAIT(wait);
struct request_list *rl;
struct request *rq;

rl = blk_get_rl(q, bio); /* transferred to @rq on success */
retry:
- rq = __get_request(rl, rw_flags, bio, gfp_mask);
+ rq = __get_request(rl, op, op_flags, bio, gfp_mask);
if (!IS_ERR(rq))
return rq;

@@ -1260,7 +1266,7 @@ retry:
prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
TASK_UNINTERRUPTIBLE);

- trace_block_sleeprq(q, bio, rw_flags & 1);
+ trace_block_sleeprq(q, bio, op);

spin_unlock_irq(q->queue_lock);
io_schedule();
@@ -1289,7 +1295,7 @@ static struct request *blk_old_get_request(struct request_queue *q, int rw,
create_io_context(gfp_mask, q->node);

spin_lock_irq(q->queue_lock);
- rq = get_request(q, rw, NULL, gfp_mask);
+ rq = get_request(q, rw, 0, NULL, gfp_mask);
if (IS_ERR(rq))
spin_unlock_irq(q->queue_lock);
/* q->queue_lock is unlocked at this point */
@@ -1491,13 +1497,14 @@ void __blk_put_request(struct request_queue *q, struct request *req)
*/
if (req->cmd_flags & REQ_ALLOCED) {
unsigned int flags = req->cmd_flags;
+ int op = req->op;
struct request_list *rl = blk_rq_rl(req);

BUG_ON(!list_empty(&req->queuelist));
BUG_ON(ELV_ON_HASH(req));

blk_free_request(rl, req);
- freed_request(rl, flags);
+ freed_request(rl, op, flags);
blk_put_rl(rl);
}
}
@@ -1713,7 +1720,7 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
{
const bool sync = !!(bio->bi_rw & REQ_SYNC);
struct blk_plug *plug;
- int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
+ int el_ret, rw_flags = 0, where = ELEVATOR_INSERT_SORT;
struct request *req;
unsigned int request_count = 0;

@@ -1773,7 +1780,6 @@ get_rq:
* but we need to set it earlier to expose the sync flag to the
* rq allocator and io schedulers.
*/
- rw_flags = bio_data_dir(bio);
if (sync)
rw_flags |= REQ_SYNC;

@@ -1781,7 +1787,7 @@ get_rq:
* Grab a free request. This is might sleep but can not fail.
* Returns with the queue unlocked.
*/
- req = get_request(q, rw_flags, bio, GFP_NOIO);
+ req = get_request(q, bio_data_dir(bio), rw_flags, bio, GFP_NOIO);
if (IS_ERR(req)) {
bio->bi_error = PTR_ERR(req);
bio_endio(bio);