fs: add a method to shut down the file system

Add a new ->shutdown super operation that can be used to tell the file
system to shut down, and call it from newly created holder ops when the
block device under a file system shuts down.

This only covers the main block device for "simple" file systems using
get_tree_bdev / mount_bdev.  File systems their own get_tree method
or opening additional devices will need to set up their own
blk_holder_ops.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Christian Brauner <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Acked-by: Dave Chinner <[email protected]>
Reviewed-by: Dave Chinner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 08ba2ae1d3ce..7b2053649820 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1932,6 +1932,7 @@ struct super_operations {
 				  struct shrink_control *);
 	long (*free_cached_objects)(struct super_block *,
 				    struct shrink_control *);
+	void (*shutdown)(struct super_block *sb);
 };
 
 /*