[SRU][Zesty][PATCH 1/1] md: MD_CLOSING needs to be cleared after called md_set_readonly or do_md_stop

[Joseph Salisbury]

From: NeilBrown <neilb at suse.com>

BugLink: http://bugs.launchpad.net/bugs/1706243

if called md_set_readonly and set MD_CLOSING bit, the mddev cannot
be opened any more due to the MD_CLOING bit wasn't cleared. Thus it
needs to be cleared in md_ioctl after any call to md_set_readonly()
or do_md_stop().

Signed-off-by: NeilBrown <neilb at suse.com>
Fixes: af8d8e6f0315 ("md: changes for MD_STILL_CLOSED flag")
Cc: stable at vger.kernel.org (v4.9+)
Signed-off-by: Zhilong Liu <zlliu at suse.com>
Signed-off-by: Shaohua Li <shli at fb.com>
(cherry picked from commit 065e519e71b2c1f41936cce75b46b5ab34adb588)
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
---
 drivers/md/md.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 01175da..643920c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6787,6 +6787,7 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
 	void __user *argp = (void __user *)arg;
 	struct mddev *mddev = NULL;
 	int ro;
+	bool did_set_md_closing = false;
 
 	if (!md_ioctl_valid(cmd))
 		return -ENOTTY;
@@ -6876,7 +6877,9 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
 			err = -EBUSY;
 			goto out;
 		}
+		WARN_ON_ONCE(test_bit(MD_CLOSING, &mddev->flags));
 		set_bit(MD_CLOSING, &mddev->flags);
+		did_set_md_closing = true;
 		mutex_unlock(&mddev->open_mutex);
 		sync_blockdev(bdev);
 	}
@@ -7069,6 +7072,8 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
 		mddev->hold_active = 0;
 	mddev_unlock(mddev);
 out:
+	if(did_set_md_closing)
+		clear_bit(MD_CLOSING, &mddev->flags);
 	return err;
 }
 #ifdef CONFIG_COMPAT
-- 
2.7.4