[PATCH v4 1/4] md: Don't clear MD_CLOSING when the raid is about to stop

[linan666]

From: Li Nan <linan122@xxxxxxxxxx>

The raid should not be opened anymore when it is about to be stopped.
However, other processes can open it again if the flag MD_CLOSING is
cleared before exiting. From now on, this flag will not be cleared when
the raid will be stopped.

Fixes: 065e519e71b2 ("md: MD_CLOSING needs to be cleared after called md_set_readonly or do_md_stop")
Signed-off-by: Li Nan <linan122@xxxxxxxxxx>
Acked-by: Mariusz Tkaczyk <mariusz.tkaczyk@xxxxxxxxxxxxxxx>
---
 drivers/md/md.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9bdd57324c37..06550fe34aa1 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6254,7 +6254,15 @@ static void md_clean(struct mddev *mddev)
 	mddev->persistent = 0;
 	mddev->level = LEVEL_NONE;
 	mddev->clevel[0] = 0;
-	mddev->flags = 0;
+	/*
+	 * Don't clear MD_CLOSING, or mddev can be opened again.
+	 * 'hold_active != 0' means mddev is still in the creation
+	 * process and will be used later.
+	 */
+	if (mddev->hold_active)
+		mddev->flags = 0;
+	else
+		mddev->flags &= BIT_ULL_MASK(MD_CLOSING);
 	mddev->sb_flags = 0;
 	mddev->ro = MD_RDWR;
 	mddev->metadata_type[0] = 0;
@@ -7600,7 +7608,7 @@ static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
 	int err = 0;
 	void __user *argp = (void __user *)arg;
 	struct mddev *mddev = NULL;
-	bool did_set_md_closing = false;
+	bool clear_md_closing = false;
 
 	if (!md_ioctl_valid(cmd))
 		return -ENOTTY;
@@ -7684,7 +7692,7 @@ static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
 			err = -EBUSY;
 			goto out;
 		}
-		did_set_md_closing = true;
+		clear_md_closing = true;
 		mutex_unlock(&mddev->open_mutex);
 		sync_blockdev(bdev);
 	}
@@ -7728,6 +7736,12 @@ static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
 
 	case STOP_ARRAY:
 		err = do_md_stop(mddev, 0, bdev);
+		if (!err)
+			/*
+			 * mddev has been stopped, keep the flag
+			 * MD_CLOSING to prevent reuse.
+			 */
+			clear_md_closing = false;
 		goto unlock;
 
 	case STOP_ARRAY_RO:
@@ -7826,7 +7840,7 @@ static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
 				     mddev_unlock(mddev);
 
 out:
-	if(did_set_md_closing)
+	if (clear_md_closing)
 		clear_bit(MD_CLOSING, &mddev->flags);
 	return err;
 }
-- 
2.39.2