loop: be paranoid on exit and prevent new additions / removals

Be pedantic on removal as well and hold the mutex.
This should prevent uses of addition while we exit.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 4acae24..a943207 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -2404,6 +2404,8 @@ static void __exit loop_exit(void)
 
        range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
 
+       mutex_lock(&loop_ctl_mutex);
+
        idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
        idr_destroy(&loop_index_idr);
 
@@ -2411,6 +2413,8 @@ static void __exit loop_exit(void)
        unregister_blkdev(LOOP_MAJOR, "loop");
 
        misc_deregister(&loop_misc);
+
+       mutex_unlock(&loop_ctl_mutex);
 }
 
 module_init(loop_init);