block: ioc_task_link() can't fail

ioc_task_link() is used to share %current's ioc on clone.  If
%current->io_context is set, %current is guaranteed to have refcount
on the ioc and, thus, ioc_task_link() can't fail.

Replace error checking in ioc_task_link() with WARN_ON_ONCE() and make
it just increment refcount and nr_tasks.

-v2: Description typo fix (Vivek).

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, 5 insertions, 11 deletions

diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index 1a301806303..81a8870ac22 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -120,18 +120,12 @@ struct io_context {
         struct work_struct release_work;
 };
 
-static inline struct io_context *ioc_task_link(struct io_context *ioc)
+static inline void ioc_task_link(struct io_context *ioc)
 {
-        /*
-         * if ref count is zero, don't allow sharing (ioc is going away, it's
-         * a race).
-         */
-        if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
-                atomic_inc(&ioc->nr_tasks);
-                return ioc;
-        }
-
-        return NULL;
+        WARN_ON_ONCE(atomic_long_read(&ioc->refcount) <= 0);
+        WARN_ON_ONCE(atomic_read(&ioc->nr_tasks) <= 0);
+        atomic_long_inc(&ioc->refcount);
+        atomic_inc(&ioc->nr_tasks);
 }
 
 struct task_struct;