block, cfq: replace current_io_context() with create_io_context()

[linux-flexiantxendom0-3.2.10.git] / block / blk-core.c

diff --git a/block/blk-core.c b/block/blk-core.c
index fd47493..6804fdf 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -771,9 +771,12 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 {
        struct request *rq = NULL;
        struct request_list *rl = &q->rq;
-       struct io_context *ioc = NULL;
+       struct io_context *ioc;
        const bool is_sync = rw_is_sync(rw_flags) != 0;
+       bool retried = false;
        int may_queue;
+retry:
+       ioc = current->io_context;
 
        if (unlikely(blk_queue_dead(q)))
                return NULL;
@@ -784,7 +787,20 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 
        if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
                if (rl->count[is_sync]+1 >= q->nr_requests) {
-                       ioc = current_io_context(GFP_ATOMIC, q->node);
+                       /*
+                        * We want ioc to record batching state.  If it's
+                        * not already there, creating a new one requires
+                        * dropping queue_lock, which in turn requires
+                        * retesting conditions to avoid queue hang.
+                        */
+                       if (!ioc && !retried) {
+                               spin_unlock_irq(q->queue_lock);
+                               create_io_context(current, gfp_mask, q->node);
+                               spin_lock_irq(q->queue_lock);
+                               retried = true;
+                               goto retry;
+                       }
+
                        /*
                         * The queue will fill after this allocation, so set
                         * it as full, and mark this process as "batching".
@@ -892,7 +908,6 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
        rq = get_request(q, rw_flags, bio, GFP_NOIO);
        while (!rq) {
                DEFINE_WAIT(wait);
-               struct io_context *ioc;
                struct request_list *rl = &q->rq;
 
                if (unlikely(blk_queue_dead(q)))
@@ -912,8 +927,8 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
                 * up to a big batch of them for a small period time.
                 * See ioc_batching, ioc_set_batching
                 */
-               ioc = current_io_context(GFP_NOIO, q->node);
-               ioc_set_batching(q, ioc);
+               create_io_context(current, GFP_NOIO, q->node);
+               ioc_set_batching(q, current->io_context);
 
                spin_lock_irq(q->queue_lock);
                finish_wait(&rl->wait[is_sync], &wait);