block: Introduce get_current_ioprio()

Define get_current_ioprio() as an inline helper to obtain the caller
I/O priority from its task I/O context. Use this helper in
blk_init_request_from_bio() to set a request ioprio.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/ioprio.h b/include/linux/ioprio.h
index 9e30ed6443db..e9bfe6972aed 100644
--- a/include/linux/ioprio.h
+++ b/include/linux/ioprio.h
@@ -71,6 +71,19 @@ static inline int task_nice_ioclass(struct task_struct *task)
 }
 
 /*
+ * If the calling process has set an I/O priority, use that. Otherwise, return
+ * the default I/O priority.
+ */
+static inline int get_current_ioprio(void)
+{
+	struct io_context *ioc = current->io_context;
+
+	if (ioc)
+		return ioc->ioprio;
+	return IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
+}
+
+/*
  * For inheritance, return the highest of the two given priorities
  */
 extern int ioprio_best(unsigned short aprio, unsigned short bprio);