block: interface update for ioc/icq creation functions

Make the following interface updates to prepare for future ioc related
changes.

* create_io_context() returning ioc only works for %current because it
  doesn't increment ref on the ioc.  Drop @task parameter from it and
  always assume %current.

* Make create_io_context_slowpath() return 0 or -errno and rename it
  to create_task_io_context().

* Make ioc_create_icq() take @ioc as parameter instead of assuming
  that of %current.  The caller, get_request(), is updated to create
  ioc explicitly and then pass it into ioc_create_icq().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 10 insertions, 12 deletions

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 92bf55540d87..10928740b5da 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -212,15 +212,14 @@ void ioc_clear_queue(struct request_queue *q)
         }
 }
 
-void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags,
-                                int node)
+int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node)
 {
         struct io_context *ioc;
 
         ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO,
                                     node);
         if (unlikely(!ioc))
-                return;
+                return -ENOMEM;
 
         /* initialize */
         atomic_long_set(&ioc->refcount, 1);
@@ -244,6 +243,8 @@ void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags,
         else
                 kmem_cache_free(iocontext_cachep, ioc);
         task_unlock(task);
+
+        return 0;
 }
 
 /**
@@ -275,7 +276,7 @@ struct io_context *get_task_io_context(struct task_struct *task,
                         return ioc;
                 }
                 task_unlock(task);
-        } while (create_io_context(task, gfp_flags, node));
+        } while (!create_task_io_context(task, gfp_flags, node));
 
         return NULL;
 }
@@ -319,26 +320,23 @@ EXPORT_SYMBOL(ioc_lookup_icq);
 
 /**
  * ioc_create_icq - create and link io_cq
+ * @ioc: io_context of interest
  * @q: request_queue of interest
  * @gfp_mask: allocation mask
  *
- * Make sure io_cq linking %current->io_context and @q exists.  If either
- * io_context and/or icq don't exist, they will be created using @gfp_mask.
+ * Make sure io_cq linking @ioc and @q exists.  If icq doesn't exist, they
+ * will be created using @gfp_mask.
  *
  * The caller is responsible for ensuring @ioc won't go away and @q is
  * alive and will stay alive until this function returns.
  */
-struct io_cq *ioc_create_icq(struct request_queue *q, gfp_t gfp_mask)
+struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
+                             gfp_t gfp_mask)
 {
         struct elevator_type *et = q->elevator->type;
-        struct io_context *ioc;
         struct io_cq *icq;
 
         /* allocate stuff */
-        ioc = create_io_context(current, gfp_mask, q->node);
-        if (!ioc)
-                return NULL;
-
         icq = kmem_cache_alloc_node(et->icq_cache, gfp_mask | __GFP_ZERO,
                                     q->node);
         if (!icq)