fork: move copy_io to block/blk-ioc.c

Move the copying of the I/O context to the block layer as that is where
we can use the proper low-level interfaces.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-3-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-ioc.c

@@ -322,6 +322,33 @@ struct io_context *get_task_io_context(struct task_struct *task,
 	return NULL;
 }
 
+int __copy_io(unsigned long clone_flags, struct task_struct *tsk)
+{
+	struct io_context *ioc = current->io_context;
+	struct io_context *new_ioc;
+
+	/*
+	 * Share io context with parent, if CLONE_IO is set
+	 */
+	if (clone_flags & CLONE_IO) {
+		get_io_context_active(ioc);
+
+		WARN_ON_ONCE(atomic_read(&ioc->nr_tasks) <= 0);
+		atomic_inc(&ioc->nr_tasks);
+
+		tsk->io_context = ioc;
+	} else if (ioprio_valid(ioc->ioprio)) {
+		new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE);
+		if (unlikely(!new_ioc))
+			return -ENOMEM;
+
+		new_ioc->ioprio = ioc->ioprio;
+		put_io_context(new_ioc);
+	}
+
+	return 0;
+}
+
 /**
  * ioc_lookup_icq - lookup io_cq from ioc
  * @ioc: the associated io_context

include/linux/iocontext.h

@@ -129,14 +129,6 @@ static inline void get_io_context_active(struct io_context *ioc)
 	atomic_inc(&ioc->active_ref);
 }
 
-static inline void ioc_task_link(struct io_context *ioc)
-{
-	get_io_context_active(ioc);
-
-	WARN_ON_ONCE(atomic_read(&ioc->nr_tasks) <= 0);
-	atomic_inc(&ioc->nr_tasks);
-}
-
 struct task_struct;
 #ifdef CONFIG_BLOCK
 void put_io_context(struct io_context *ioc);
@@ -144,10 +136,21 @@ void put_io_context_active(struct io_context *ioc);
 void exit_io_context(struct task_struct *task);
 struct io_context *get_task_io_context(struct task_struct *task,
 				       gfp_t gfp_flags, int node);
+int __copy_io(unsigned long clone_flags, struct task_struct *tsk);
+static inline int copy_io(unsigned long clone_flags, struct task_struct *tsk)
+{
+	if (!current->io_context)
+		return 0;
+	return __copy_io(clone_flags, tsk);
+}
 #else
 struct io_context;
 static inline void put_io_context(struct io_context *ioc) { }
 static inline void exit_io_context(struct task_struct *task) { }
-#endif
+static inline int copy_io(unsigned long clone_flags, struct task_struct *tsk)
+{
+	return 0;
+}
+#endif /* CONFIG_BLOCK */
 
-#endif
+#endif /* IOCONTEXT_H */

kernel/fork.c

@@ -1556,32 +1556,6 @@ static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
 	return error;
 }
 
-static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
-{
-#ifdef CONFIG_BLOCK
-	struct io_context *ioc = current->io_context;
-	struct io_context *new_ioc;
-
-	if (!ioc)
-		return 0;
-	/*
-	 * Share io context with parent, if CLONE_IO is set
-	 */
-	if (clone_flags & CLONE_IO) {
-		ioc_task_link(ioc);
-		tsk->io_context = ioc;
-	} else if (ioprio_valid(ioc->ioprio)) {
-		new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE);
-		if (unlikely(!new_ioc))
-			return -ENOMEM;
-
-		new_ioc->ioprio = ioc->ioprio;
-		put_io_context(new_ioc);
-	}
-#endif
-	return 0;
-}
-
 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
 {
 	struct sighand_struct *sig;