1 files changed, 20 insertions, 10 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 39085e7dd6d2..cee5a253a281 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1146,7 +1146,7 @@ static bool regular_request_wait(struct mddev *mddev, struct r10conf *conf,
 }
 
 static void raid10_read_request(struct mddev *mddev, struct bio *bio,
-				struct r10bio *r10_bio, bool io_accounting)
+				struct r10bio *r10_bio)
 {
 	struct r10conf *conf = mddev->private;
 	struct bio *read_bio;
@@ -1155,7 +1155,20 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
 	char b[BDEVNAME_SIZE];
 	int slot = r10_bio->read_slot;
 	struct md_rdev *err_rdev = NULL;
-	gfp_t gfp = GFP_NOIO;
+
+	/*
+	 * An md cloned bio indicates we are in the error path.
+	 * This is more reliable than checking slot, which might
+	 * be -1 even in the error path if a failed bio was split.
+	 */
+	bool err_path = md_cloned_bio(mddev, bio);
+
+	/*
+	 * If we are in the error path, we are blocking the raid10d
+	 * thread so there is a tiny risk of deadlock.  So ask for
+	 * emergency memory if needed.
+	 */
+	gfp_t gfp = err_path ? (GFP_NOIO | __GFP_HIGH) : GFP_NOIO;
 
 	if (slot >= 0 && r10_bio->devs[slot].rdev) {
 		/*
@@ -1166,11 +1179,6 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
 		 * we lose the device name in error messages.
 		 */
 		int disk;
-		/*
-		 * As we are blocking raid10, it is a little safer to
-		 * use __GFP_HIGH.
-		 */
-		gfp = GFP_NOIO | __GFP_HIGH;
 
 		disk = r10_bio->devs[slot].devnum;
 		err_rdev = conf->mirrors[disk].rdev;
@@ -1218,7 +1226,7 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
 	}
 	slot = r10_bio->read_slot;
 
-	if (io_accounting) {
+	if (likely(!md_cloned_bio(mddev, bio))) {
 		md_account_bio(mddev, &bio);
 		r10_bio->master_bio = bio;
 	}
@@ -1544,7 +1552,7 @@ static void __make_request(struct mddev *mddev, struct bio *bio, int sectors)
 			conf->geo.raid_disks);
 
 	if (bio_data_dir(bio) == READ)
-		raid10_read_request(mddev, bio, r10_bio, true);
+		raid10_read_request(mddev, bio, r10_bio);
 	else
 		raid10_write_request(mddev, bio, r10_bio);
 }
@@ -1727,6 +1735,7 @@ retry_discard:
 	r10_bio->mddev = mddev;
 	r10_bio->state = 0;
 	r10_bio->sectors = 0;
+	r10_bio->read_slot = -1;
 	memset(r10_bio->devs, 0, sizeof(r10_bio->devs[0]) * geo->raid_disks);
 	wait_blocked_dev(mddev, r10_bio);
 
@@ -2858,7 +2867,7 @@ static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
 
 	rdev_dec_pending(rdev, mddev);
 	r10_bio->state = 0;
-	raid10_read_request(mddev, r10_bio->master_bio, r10_bio, false);
+	raid10_read_request(mddev, r10_bio->master_bio, r10_bio);
 	/*
 	 * allow_barrier after re-submit to ensure no sync io
 	 * can be issued while regular io pending.
@@ -3941,6 +3950,7 @@ static int raid10_set_queue_limits(struct mddev *mddev)
 	lim.chunk_sectors = mddev->chunk_sectors;
 	lim.io_opt = lim.io_min * raid10_nr_stripes(conf);
 	lim.features |= BLK_FEAT_ATOMIC_WRITES;
+	lim.features |= BLK_FEAT_PCI_P2PDMA;
 	err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY);
 	if (err)
 		return err;