md/bitmap: protect clearing of ->bitmap by mddev->lock

This makes it safe to inspect the struct while holding only
the spinlock.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 1695ee5f3ffc30b883c83c1926745ba22e48a7e1..3424b1915fc4a49098526670b792d0b39c8192ed 100644 (file)
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1619,7 +1619,9 @@ void bitmap_destroy(struct mddev *mddev)
                return;
 
        mutex_lock(&mddev->bitmap_info.mutex);
+       spin_lock(&mddev->lock);
        mddev->bitmap = NULL; /* disconnect from the md device */
+       spin_unlock(&mddev->lock);
        mutex_unlock(&mddev->bitmap_info.mutex);
        if (mddev->thread)
                mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;

diff --git a/drivers/md/md.h b/drivers/md/md.h
index e41559dccdc9a5f84adb3dc4ae6979b761ac6463..8770308a8052c4bcbae08adb89954372a4409864 100644 (file)
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -392,6 +392,7 @@ struct mddev {
         *   clearing MD_CHANGE_*
         *   in_sync - and related safemode and MD_CHANGE changes
         *   pers (also protected by reconfig_mutex and pending IO).
+        *   clearing ->bitmap
         */
        spinlock_t                      lock;
        wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */