[PATCH v4 4/4] md: check mddev->pers before calling md_set_readonly()

[linan666]

From: Li Nan <linan122@xxxxxxxxxx>

If 'mddev->pers' is NULL, there is nothing to do in md_set_readonly().
To simplify the code, move the check of 'mddev->pers' to the caller of
md_set_readonly().

Signed-off-by: Li Nan <linan122@xxxxxxxxxx>
---
 drivers/md/md.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 24e33b65c6ff..ece6eddb2748 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6412,6 +6412,7 @@ void md_stop(struct mddev *mddev)
 
 EXPORT_SYMBOL_GPL(md_stop);
 
+/* ensure 'mddev->pers' exist before calling md_set_readonly() */
 static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
 {
 	int err = 0;
@@ -6432,28 +6433,25 @@ static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
 	mddev_lock_nointr(mddev);
 
 	mutex_lock(&mddev->open_mutex);
-	if ((mddev->pers && atomic_read(&mddev->openers) > !!bdev) ||
-	    mddev->sync_thread ||
+	if (atomic_read(&mddev->openers) > !!bdev || mddev->sync_thread ||
 	    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
 		pr_warn("md: %s still in use.\n",mdname(mddev));
 		err = -EBUSY;
 		goto out;
 	}
 
-	if (mddev->pers) {
-		__md_stop_writes(mddev);
-
-		if (mddev->ro == MD_RDONLY) {
-			err  = -ENXIO;
-			goto out;
-		}
+	__md_stop_writes(mddev);
 
-		mddev->ro = MD_RDONLY;
-		set_disk_ro(mddev->gendisk, 1);
+	if (mddev->ro == MD_RDONLY) {
+		err  = -ENXIO;
+		goto out;
 	}
 
+	mddev->ro = MD_RDONLY;
+	set_disk_ro(mddev->gendisk, 1);
+
 out:
-	if ((mddev->pers && !err) || did_freeze) {
+	if (!err || did_freeze) {
 		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 		md_wakeup_thread(mddev->thread);
@@ -7772,7 +7770,8 @@ static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
 		goto unlock;
 
 	case STOP_ARRAY_RO:
-		err = md_set_readonly(mddev, bdev);
+		if (mddev->pers)
+			err = md_set_readonly(mddev, bdev);
 		goto unlock;
 
 	case HOT_REMOVE_DISK:
-- 
2.39.2