block: move set_task_ioprio to blk-ioc.c

Keep set_task_ioprio with the other low-level code that accesses the
io_context structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 32 insertions, 2 deletions

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index f98a29ee8f36..c25ce2f3eb19 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -8,6 +8,7 @@
 #include <linux/bio.h>
 #include <linux/blkdev.h>
 #include <linux/slab.h>
+#include <linux/security.h>
 #include <linux/sched/task.h>
 
 #include "blk.h"
@@ -280,8 +281,8 @@ static struct io_context *create_task_io_context(struct task_struct *task,
  * This function always goes through task_lock() and it's better to use
  * %current->io_context + get_io_context() for %current.
  */
-struct io_context *get_task_io_context(struct task_struct *task,
-				       gfp_t gfp_flags, int node)
+static struct io_context *get_task_io_context(struct task_struct *task,
+		gfp_t gfp_flags, int node)
 {
 	struct io_context *ioc;
 
@@ -298,6 +299,35 @@ struct io_context *get_task_io_context(struct task_struct *task,
 	return ioc;
 }
 
+int set_task_ioprio(struct task_struct *task, int ioprio)
+{
+	int err;
+	struct io_context *ioc;
+	const struct cred *cred = current_cred(), *tcred;
+
+	rcu_read_lock();
+	tcred = __task_cred(task);
+	if (!uid_eq(tcred->uid, cred->euid) &&
+	    !uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) {
+		rcu_read_unlock();
+		return -EPERM;
+	}
+	rcu_read_unlock();
+
+	err = security_task_setioprio(task, ioprio);
+	if (err)
+		return err;
+
+	ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
+	if (ioc) {
+		ioc->ioprio = ioprio;
+		put_io_context(ioc);
+	}
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(set_task_ioprio);
+
 int __copy_io(unsigned long clone_flags, struct task_struct *tsk)
 {
 	struct io_context *ioc = current->io_context;