2 files changed, 26 insertions, 31 deletions

diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index 5caebe2cf0a1..1197462bb6ba 100644
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -1876,7 +1876,7 @@ static struct request *get_request(request_queue_t *q, int rw, struct bio *bio,
 {
         struct request *rq = NULL;
         struct request_list *rl = &q->rq;
-        struct io_context *ioc = get_io_context(GFP_ATOMIC);
+        struct io_context *ioc = current_io_context(GFP_ATOMIC);
 
         if (unlikely(test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)))
                 goto out;
@@ -1959,7 +1959,6 @@ rq_starved:
         rq_init(q, rq);
         rq->rl = rl;
 out:
-        put_io_context(ioc);
         return rq;
 }
 
@@ -1997,9 +1996,8 @@ static struct request *get_request_wait(request_queue_t *q, int rw,
                          * up to a big batch of them for a small period time.
                          * See ioc_batching, ioc_set_batching
                          */
-                        ioc = get_io_context(GFP_NOIO);
+                        ioc = current_io_context(GFP_NOIO);
                         ioc_set_batching(q, ioc);
-                        put_io_context(ioc);
 
                         spin_lock_irq(q->queue_lock);
                 }
@@ -3282,24 +3280,20 @@ void exit_io_context(void)
 
 /*
  * If the current task has no IO context then create one and initialise it.
- * If it does have a context, take a ref on it.
+ * Otherwise, return its existing IO context.
  *
- * This is always called in the context of the task which submitted the I/O.
- * But weird things happen, so we disable local interrupts to ensure exclusive
- * access to *current.
+ * This returned IO context doesn't have a specifically elevated refcount,
+ * but since the current task itself holds a reference, the context can be
+ * used in general code, so long as it stays within `current` context.
  */
-struct io_context *get_io_context(int gfp_flags)
+struct io_context *current_io_context(int gfp_flags)
 {
         struct task_struct *tsk = current;
-        unsigned long flags;
         struct io_context *ret;
 
-        local_irq_save(flags);
         ret = tsk->io_context;
-        if (ret)
-                goto out;
-
-        local_irq_restore(flags);
+        if (likely(ret))
+                return ret;
 
         ret = kmem_cache_alloc(iocontext_cachep, gfp_flags);
         if (ret) {
@@ -3310,25 +3304,25 @@ struct io_context *get_io_context(int gfp_flags)
                 ret->nr_batch_requests = 0; /* because this is 0 */
                 ret->aic = NULL;
                 ret->cic = NULL;
+                tsk->io_context = ret;
+        }
 
-                local_irq_save(flags);
-
-                /*
-                 * very unlikely, someone raced with us in setting up the task
-                 * io context. free new context and just grab a reference.
-                 */
-                if (!tsk->io_context)
-                        tsk->io_context = ret;
-                else {
-                        kmem_cache_free(iocontext_cachep, ret);
-                        ret = tsk->io_context;
-                }
+        return ret;
+}
+EXPORT_SYMBOL(current_io_context);
 
-out:
+/*
+ * If the current task has no IO context then create one and initialise it.
+ * If it does have a context, take a ref on it.
+ *
+ * This is always called in the context of the task which submitted the I/O.
+ */
+struct io_context *get_io_context(int gfp_flags)
+{
+        struct io_context *ret;
+        ret = current_io_context(gfp_flags);
+        if (likely(ret))
                 atomic_inc(&ret->refcount);
-                local_irq_restore(flags);
-        }
-
         return ret;
 }
 EXPORT_SYMBOL(get_io_context);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 21a8674cd149..0881b5cdee3d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -96,6 +96,7 @@ struct io_context {
 
 void put_io_context(struct io_context *ioc);
 void exit_io_context(void);
+struct io_context *current_io_context(int gfp_flags);
 struct io_context *get_io_context(int gfp_flags);
 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
 void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);