[PATCH v2 3/3] md: sync blockdev before stopping raid or setting readonly

[linan666]

From: Li Nan <linan122@xxxxxxxxxx>

Commit a05b7ea03d72 ("md: avoid crash when stopping md array races
with closing other open fds.") added sync_block before stopping raid and
setting readonly. Later in commit 260fa034ef7a ("md: avoid deadlock when
dirty buffers during md_stop.") it is moved to ioctl. array_state_store()
was ignored. Add sync blockdev to array_state_store() now.

Signed-off-by: Li Nan <linan122@xxxxxxxxxx>
---
 drivers/md/md.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 2c793992a604..aea39598457c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4477,6 +4477,7 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
 {
 	int err = 0;
 	enum array_state st = match_word(buf, array_states);
+	bool clear_md_closing = false;
 
 	/* No lock dependent actions */
 	switch (st) {
@@ -4511,6 +4512,16 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
 		spin_unlock(&mddev->lock);
 		return err ?: len;
 	}
+
+	/* we will call set readonly or stop raid, sync blockdev */
+	if (st == clear || (mddev->pers && (st == readonly ||
+	    st == inactive || (st == read_auto && md_is_rdwr(mddev))))) {
+		err = mddev_sync_blockdev(mddev);
+		if (err)
+			return err;
+		clear_md_closing = true;
+	}
+
 	err = mddev_lock(mddev);
 	if (err)
 		return err;
@@ -4523,6 +4534,8 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
 		break;
 	case clear:
 		err = do_md_stop(mddev, 0, NULL);
+		if (!err)
+			clear_md_closing = false;
 		break;
 	case readonly:
 		if (mddev->pers)
@@ -4585,6 +4598,8 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
 		sysfs_notify_dirent_safe(mddev->sysfs_state);
 	}
 	mddev_unlock(mddev);
+	if (clear_md_closing)
+		clear_bit(MD_CLOSING, &mddev->flags);
 	return err ?: len;
 }
 static struct md_sysfs_entry md_array_state =
-- 
2.39.2