[PATCH 7/9] fs: add a method to shut down the file system

Christoph Hellwig
2023-05-05T17:53:19Z

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 <hch@lst.de>
---
fs/super.c | 21 +++++++++++++++++++--
include/linux/fs.h | 1 +
2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/fs/super.c b/fs/super.c
index 012ce140080375..f127589700ab25 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1206,6 +1206,22 @@ int get_tree_keyed(struct fs_context *fc,
EXPORT_SYMBOL(get_tree_keyed);

#ifdef CONFIG_BLOCK
+static void fs_mark_dead(struct block_device *bdev)
+{
+ struct super_block *sb;
+
+ sb = get_super(bdev);
+ if (!sb)
+ return;
+
+ if (sb->s_op->shutdown)
+ sb->s_op->shutdown(sb);
+ drop_super(sb);
+}
+
+static const struct blk_holder_ops fs_holder_ops = {
+ .mark_dead = fs_mark_dead,
+};

static int set_bdev_super(struct super_block *s, void *data)
{
@@ -1248,7 +1264,8 @@ int get_tree_bdev(struct fs_context *fc,
if (!fc->source)
return invalf(fc, "No source specified");

- bdev = blkdev_get_by_path(fc->source, mode, fc->fs_type, NULL);
+ bdev = blkdev_get_by_path(fc->source, mode, fc->fs_type,
+ &fs_holder_ops);
if (IS_ERR(bdev)) {
errorf(fc, "%s: Can't open blockdev", fc->source);
return PTR_ERR(bdev);
@@ -1333,7 +1350,7 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
if (!(flags & SB_RDONLY))
mode |= FMODE_WRITE;

- bdev = blkdev_get_by_path(dev_name, mode, fs_type, NULL);
+ bdev = blkdev_get_by_path(dev_name, mode, fs_type, &fs_holder_ops);
if (IS_ERR(bdev))
return ERR_CAST(bdev);

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 21a98168085641..cf3042641b9b30 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);
};

/*
--
2.39.2