block: reorganize request fetching functions

Impact: code reorganization

elv_next_request() and elv_dequeue_request() are public block layer
interface than actual elevator implementation.  They mostly deal with
how requests interact with block layer and low level drivers at the
beginning of rqeuest processing whereas __elv_next_request() is the
actual eleveator request fetching interface.

Move the two functions to blk-core.c.  This prepares for further
interface cleanup.

Signed-off-by: Tejun Heo <tj@kernel.org>

3 files changed, 132 insertions, 128 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 406a93e526b6..678ede23ed0a 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1712,6 +1712,101 @@ unsigned int blk_rq_cur_bytes(struct request *rq)
 }
 EXPORT_SYMBOL_GPL(blk_rq_cur_bytes);
 
+struct request *elv_next_request(struct request_queue *q)
+{
+        struct request *rq;
+        int ret;
+
+        while ((rq = __elv_next_request(q)) != NULL) {
+                if (!(rq->cmd_flags & REQ_STARTED)) {
+                        /*
+                         * This is the first time the device driver
+                         * sees this request (possibly after
+                         * requeueing).  Notify IO scheduler.
+                         */
+                        if (blk_sorted_rq(rq))
+                                elv_activate_rq(q, rq);
+
+                        /*
+                         * just mark as started even if we don't start
+                         * it, a request that has been delayed should
+                         * not be passed by new incoming requests
+                         */
+                        rq->cmd_flags |= REQ_STARTED;
+                        trace_block_rq_issue(q, rq);
+                }
+
+                if (!q->boundary_rq || q->boundary_rq == rq) {
+                        q->end_sector = rq_end_sector(rq);
+                        q->boundary_rq = NULL;
+                }
+
+                if (rq->cmd_flags & REQ_DONTPREP)
+                        break;
+
+                if (q->dma_drain_size && rq->data_len) {
+                        /*
+                         * make sure space for the drain appears we
+                         * know we can do this because max_hw_segments
+                         * has been adjusted to be one fewer than the
+                         * device can handle
+                         */
+                        rq->nr_phys_segments++;
+                }
+
+                if (!q->prep_rq_fn)
+                        break;
+
+                ret = q->prep_rq_fn(q, rq);
+                if (ret == BLKPREP_OK) {
+                        break;
+                } else if (ret == BLKPREP_DEFER) {
+                        /*
+                         * the request may have been (partially) prepped.
+                         * we need to keep this request in the front to
+                         * avoid resource deadlock.  REQ_STARTED will
+                         * prevent other fs requests from passing this one.
+                         */
+                        if (q->dma_drain_size && rq->data_len &&
+                            !(rq->cmd_flags & REQ_DONTPREP)) {
+                                /*
+                                 * remove the space for the drain we added
+                                 * so that we don't add it again
+                                 */
+                                --rq->nr_phys_segments;
+                        }
+
+                        rq = NULL;
+                        break;
+                } else if (ret == BLKPREP_KILL) {
+                        rq->cmd_flags |= REQ_QUIET;
+                        __blk_end_request(rq, -EIO, blk_rq_bytes(rq));
+                } else {
+                        printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
+                        break;
+                }
+        }
+
+        return rq;
+}
+EXPORT_SYMBOL(elv_next_request);
+
+void elv_dequeue_request(struct request_queue *q, struct request *rq)
+{
+        BUG_ON(list_empty(&rq->queuelist));
+        BUG_ON(ELV_ON_HASH(rq));
+
+        list_del_init(&rq->queuelist);
+
+        /*
+         * the time frame between a request being removed from the lists
+         * and to it is freed is accounted as io that is in progress at
+         * the driver side.
+         */
+        if (blk_account_rq(rq))
+                q->in_flight++;
+}
+
 /**
  * __end_that_request_first - end I/O on a request
  * @req:      the request being processed
diff --git a/block/blk.h b/block/blk.h
index 79c85f7c9ff5..9b2c324e4407 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -43,6 +43,43 @@ static inline void blk_clear_rq_complete(struct request *rq)
         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 }
 
+/*
+ * Internal elevator interface
+ */
+#define ELV_ON_HASH(rq)         (!hlist_unhashed(&(rq)->hash))
+
+static inline struct request *__elv_next_request(struct request_queue *q)
+{
+        struct request *rq;
+
+        while (1) {
+                while (!list_empty(&q->queue_head)) {
+                        rq = list_entry_rq(q->queue_head.next);
+                        if (blk_do_ordered(q, &rq))
+                                return rq;
+                }
+
+                if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
+                        return NULL;
+        }
+}
+
+static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
+{
+        struct elevator_queue *e = q->elevator;
+
+        if (e->ops->elevator_activate_req_fn)
+                e->ops->elevator_activate_req_fn(q, rq);
+}
+
+static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
+{
+        struct elevator_queue *e = q->elevator;
+
+        if (e->ops->elevator_deactivate_req_fn)
+                e->ops->elevator_deactivate_req_fn(q, rq);
+}
+
 #ifdef CONFIG_FAIL_IO_TIMEOUT
 int blk_should_fake_timeout(struct request_queue *);
 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
diff --git a/block/elevator.c b/block/elevator.c
index 2e0fb21485b7..b03b8752e18b 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -53,7 +53,6 @@ static const int elv_hash_shift = 6;
                 (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift))
 #define ELV_HASH_ENTRIES        (1 << elv_hash_shift)
 #define rq_hash_key(rq)         ((rq)->sector + (rq)->nr_sectors)
-#define ELV_ON_HASH(rq)         (!hlist_unhashed(&(rq)->hash))
 
 DEFINE_TRACE(block_rq_insert);
 DEFINE_TRACE(block_rq_issue);
@@ -310,22 +309,6 @@ void elevator_exit(struct elevator_queue *e)
 }
 EXPORT_SYMBOL(elevator_exit);
 
-static void elv_activate_rq(struct request_queue *q, struct request *rq)
-{
-        struct elevator_queue *e = q->elevator;
-
-        if (e->ops->elevator_activate_req_fn)
-                e->ops->elevator_activate_req_fn(q, rq);
-}
-
-static void elv_deactivate_rq(struct request_queue *q, struct request *rq)
-{
-        struct elevator_queue *e = q->elevator;
-
-        if (e->ops->elevator_deactivate_req_fn)
-                e->ops->elevator_deactivate_req_fn(q, rq);
-}
-
 static inline void __elv_rqhash_del(struct request *rq)
 {
         hlist_del_init(&rq->hash);
@@ -758,117 +741,6 @@ void elv_add_request(struct request_queue *q, struct request *rq, int where,
 }
 EXPORT_SYMBOL(elv_add_request);
 
-static inline struct request *__elv_next_request(struct request_queue *q)
-{
-        struct request *rq;
-
-        while (1) {
-                while (!list_empty(&q->queue_head)) {
-                        rq = list_entry_rq(q->queue_head.next);
-                        if (blk_do_ordered(q, &rq))
-                                return rq;
-                }
-
-                if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
-                        return NULL;
-        }
-}
-
-struct request *elv_next_request(struct request_queue *q)
-{
-        struct request *rq;
-        int ret;
-
-        while ((rq = __elv_next_request(q)) != NULL) {
-                if (!(rq->cmd_flags & REQ_STARTED)) {
-                        /*
-                         * This is the first time the device driver
-                         * sees this request (possibly after
-                         * requeueing).  Notify IO scheduler.
-                         */
-                        if (blk_sorted_rq(rq))
-                                elv_activate_rq(q, rq);
-
-                        /*
-                         * just mark as started even if we don't start
-                         * it, a request that has been delayed should
-                         * not be passed by new incoming requests
-                         */
-                        rq->cmd_flags |= REQ_STARTED;
-                        trace_block_rq_issue(q, rq);
-                }
-
-                if (!q->boundary_rq || q->boundary_rq == rq) {
-                        q->end_sector = rq_end_sector(rq);
-                        q->boundary_rq = NULL;
-                }
-
-                if (rq->cmd_flags & REQ_DONTPREP)
-                        break;
-
-                if (q->dma_drain_size && rq->data_len) {
-                        /*
-                         * make sure space for the drain appears we
-                         * know we can do this because max_hw_segments
-                         * has been adjusted to be one fewer than the
-                         * device can handle
-                         */
-                        rq->nr_phys_segments++;
-                }
-
-                if (!q->prep_rq_fn)
-                        break;
-
-                ret = q->prep_rq_fn(q, rq);
-                if (ret == BLKPREP_OK) {
-                        break;
-                } else if (ret == BLKPREP_DEFER) {
-                        /*
-                         * the request may have been (partially) prepped.
-                         * we need to keep this request in the front to
-                         * avoid resource deadlock.  REQ_STARTED will
-                         * prevent other fs requests from passing this one.
-                         */
-                        if (q->dma_drain_size && rq->data_len &&
-                            !(rq->cmd_flags & REQ_DONTPREP)) {
-                                /*
-                                 * remove the space for the drain we added
-                                 * so that we don't add it again
-                                 */
-                                --rq->nr_phys_segments;
-                        }
-
-                        rq = NULL;
-                        break;
-                } else if (ret == BLKPREP_KILL) {
-                        rq->cmd_flags |= REQ_QUIET;
-                        __blk_end_request(rq, -EIO, blk_rq_bytes(rq));
-                } else {
-                        printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
-                        break;
-                }
-        }
-
-        return rq;
-}
-EXPORT_SYMBOL(elv_next_request);
-
-void elv_dequeue_request(struct request_queue *q, struct request *rq)
-{
-        BUG_ON(list_empty(&rq->queuelist));
-        BUG_ON(ELV_ON_HASH(rq));
-
-        list_del_init(&rq->queuelist);
-
-        /*
-         * the time frame between a request being removed from the lists
-         * and to it is freed is accounted as io that is in progress at
-         * the driver side.
-         */
-        if (blk_account_rq(rq))
-                q->in_flight++;
-}
-
 int elv_queue_empty(struct request_queue *q)
 {
         struct elevator_queue *e = q->elevator;