[PATCH 3.18 26/28] rbd: use GFP_NOIO for parent stat and data requests

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ilya Dryomov <idryomov@gmail.com>

commit 1e37f2f84680fa7f8394fd444b6928e334495ccc upstream.

rbd_img_obj_exists_submit() and rbd_img_obj_parent_read_full() are on
the writeback path for cloned images -- we attempt a stat on the parent
object to see if it exists and potentially read it in to call copyup.
GFP_NOIO should be used instead of GFP_KERNEL here.

Link: http://tracker.ceph.com/issues/22014
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: David Disseldorp <ddiss@suse.de>
[idryomov@gmail.com: backport to < 4.9: context]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/block/rbd.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2700,7 +2700,7 @@ static int rbd_img_obj_parent_read_full(
 	 * from the parent.
 	 */
 	page_count = (u32)calc_pages_for(0, length);
-	pages = ceph_alloc_page_vector(page_count, GFP_KERNEL);
+	pages = ceph_alloc_page_vector(page_count, GFP_NOIO);
 	if (IS_ERR(pages)) {
 		result = PTR_ERR(pages);
 		pages = NULL;
@@ -2827,7 +2827,7 @@ static int rbd_img_obj_exists_submit(str
 	 */
 	size = sizeof (__le64) + sizeof (__le32) + sizeof (__le32);
 	page_count = (u32)calc_pages_for(0, size);
-	pages = ceph_alloc_page_vector(page_count, GFP_KERNEL);
+	pages = ceph_alloc_page_vector(page_count, GFP_NOIO);
 	if (IS_ERR(pages))
 		return PTR_ERR(pages);