block: open code create_task_io_context in set_task_ioprio

The flow in set_task_ioprio can be simplified by simply open coding
create_task_io_context, which removes a refcount roundtrip on the I/O
context.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 1ba7cfe..cff0e3b 100644 (file)
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -291,12 +291,18 @@ int set_task_ioprio(struct task_struct *task, int ioprio)
                struct io_context *ioc;
 
                task_unlock(task);
-               ioc = create_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
-               if (ioc) {
-                       ioc->ioprio = ioprio;
-                       put_io_context(ioc);
+
+               ioc = alloc_io_context(GFP_ATOMIC, NUMA_NO_NODE);
+               if (!ioc)
+                       return -ENOMEM;
+
+               task_lock(task);
+               if (task->io_context || (task->flags & PF_EXITING)) {
+                       kmem_cache_free(iocontext_cachep, ioc);
+                       ioc = task->io_context;
+               } else {
+                       task->io_context = ioc;
                }
-               return 0;
        }
        task->io_context->ioprio = ioprio;
        task_unlock(task);