bcache: Fix a sysfs splat on shutdown

commit c9502ea4424b31728703d113fc6b30bfead14633 upstream.

If we stopped a bcache device when we were already detaching (or
something like that), bcache_device_unlink() would try to remove a
symlink from sysfs that was already gone because the bcache dev kobject
had already been removed from sysfs.

So keep track of whether we've removed stuff from sysfs.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 11 insertions, 1 deletions

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index d3e15b42a4ab..c42b14b2304c 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -437,6 +437,7 @@ struct bcache_device {
 
         /* If nonzero, we're detaching/unregistering from cache set */
         atomic_t                detaching;
+        int                     flush_done;
 
         atomic_long_t           sectors_dirty;
         unsigned long           sectors_dirty_gc;
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 88113fe57fed..b4713cea1913 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -704,7 +704,8 @@ static void bcache_device_detach(struct bcache_device *d)
                 atomic_set(&d->detaching, 0);
         }
 
-        bcache_device_unlink(d);
+        if (!d->flush_done)
+                bcache_device_unlink(d);
 
         d->c->devices[d->id] = NULL;
         closure_put(&d->c->caching);
@@ -1016,6 +1017,14 @@ static void cached_dev_flush(struct closure *cl)
         struct cached_dev *dc = container_of(cl, struct cached_dev, disk.cl);
         struct bcache_device *d = &dc->disk;
 
+        mutex_lock(&bch_register_lock);
+        d->flush_done = 1;
+
+        if (d->c)
+                bcache_device_unlink(d);
+
+        mutex_unlock(&bch_register_lock);
+
         bch_cache_accounting_destroy(&dc->accounting);
         kobject_del(&d->kobj);