md/raid0: Ignore RAID0 layout if the second zone has only one device

stable inclusion
from stable-v5.10.122
commit 63bcb9da91eb0aba2e87022200f9b9aa45c4c111
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5W6OE

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=63bcb9da91eb0aba2e87022200f9b9aa45c4c111

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

commit ea23994e upstream.

The RAID0 layout is irrelevant if all members have the same size so the
array has only one zone. It is *also* irrelevant if the array has two
zones and the second zone has only one device, for example if the array
has two members of different sizes.

So in that case it makes sense to allow assembly even when the layout is
undefined, like what is done when the array has only one zone.
Reviewed-by: NNeilBrown <neilb@suse.de>
Signed-off-by: NPascal Hambourg <pascal@plouf.fr.eu.org>
Signed-off-by: NSong Liu <song@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

drivers/md/raid0.c

@@ -128,21 +128,6 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
 	pr_debug("md/raid0:%s: FINAL %d zones\n",
 		 mdname(mddev), conf->nr_strip_zones);
 
-	if (conf->nr_strip_zones == 1) {
-		conf->layout = RAID0_ORIG_LAYOUT;
-	} else if (mddev->layout == RAID0_ORIG_LAYOUT ||
-		   mddev->layout == RAID0_ALT_MULTIZONE_LAYOUT) {
-		conf->layout = mddev->layout;
-	} else if (default_layout == RAID0_ORIG_LAYOUT ||
-		   default_layout == RAID0_ALT_MULTIZONE_LAYOUT) {
-		conf->layout = default_layout;
-	} else {
-		pr_err("md/raid0:%s: cannot assemble multi-zone RAID0 with default_layout setting\n",
-		       mdname(mddev));
-		pr_err("md/raid0: please set raid0.default_layout to 1 or 2\n");
-		err = -ENOTSUPP;
-		goto abort;
-	}
 	/*
 	 * now since we have the hard sector sizes, we can make sure
 	 * chunk size is a multiple of that sector size
@@ -273,6 +258,22 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
 			 (unsigned long long)smallest->sectors);
 	}
 
+	if (conf->nr_strip_zones == 1 || conf->strip_zone[1].nb_dev == 1) {
+		conf->layout = RAID0_ORIG_LAYOUT;
+	} else if (mddev->layout == RAID0_ORIG_LAYOUT ||
+		   mddev->layout == RAID0_ALT_MULTIZONE_LAYOUT) {
+		conf->layout = mddev->layout;
+	} else if (default_layout == RAID0_ORIG_LAYOUT ||
+		   default_layout == RAID0_ALT_MULTIZONE_LAYOUT) {
+		conf->layout = default_layout;
+	} else {
+		pr_err("md/raid0:%s: cannot assemble multi-zone RAID0 with default_layout setting\n",
+		       mdname(mddev));
+		pr_err("md/raid0: please set raid0.default_layout to 1 or 2\n");
+		err = -EOPNOTSUPP;
+		goto abort;
+	}
+
 	pr_debug("md/raid0:%s: done.\n", mdname(mddev));
 	*private_conf = conf;