md: Wait for md_check_recovery before attempting device removal.

When a device has failed, it needs to be removed from the personality
module before it can be removed from the array as a whole.
The first step is performed by md_check_recovery() which is called
from the raid management thread.

So when a HOT_REMOVE ioctl arrives, wait briefly for md_check_recovery
to have run.  This increases the chance that the ioctl will succeed.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Neil Brown <nfbrown@suse.de>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9b82377a833bd6572b628c79426ca153781fd712..3b25b72ef0b6b594a954c73d04ea46ff9631183b 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6405,6 +6405,12 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
                /* need to ensure md_delayed_delete() has completed */
                flush_workqueue(md_misc_wq);
 
+       if (cmd == HOT_REMOVE_DISK)
+               /* need to ensure recovery thread has run */
+               wait_event_interruptible_timeout(mddev->sb_wait,
+                                                !test_bit(MD_RECOVERY_NEEDED,
+                                                          &mddev->flags),
+                                                msecs_to_jiffies(5000));
        err = mddev_lock(mddev);
        if (err) {
                printk(KERN_INFO 
@@ -7892,6 +7898,8 @@ void md_check_recovery(struct mddev *mddev)
                        md_new_event(mddev);
                }
        unlock:
+               wake_up(&mddev->sb_wait);
+
                if (!mddev->sync_thread) {
                        clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
                        if (test_and_clear_bit(MD_RECOVERY_RECOVER,