Currently super_blocks are shut down using the ->kill_sb method, which
must call generic_shutdown_super, but allows the file system to
add extra work before or after the call to generic_shutdown_super.
File systems tend to get rather confused by this, so add an alternative
shutdown sequence where generic_shutdown_super is called by the core
code, and there are extra ->shutdown_sb and ->free_sb hooks before and
after it. To remove the amount of boilerplate code ->shutdown_sb is only
called if the super has finished initialization and ->d_root is set.
Signed-off-by: Christoph Hellwig <h...@lst.de>
---
Documentation/filesystems/locking.rst | 4 ++++
Documentation/filesystems/vfs.rst | 12 ++++++++++++
fs/super.c | 9 +++++++--
include/linux/fs.h | 2 ++
4 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/Documentation/filesystems/locking.rst
b/Documentation/filesystems/locking.rst
index 7be2900806c853..c33e2f03ed1f69 100644
--- a/Documentation/filesystems/locking.rst
+++ b/Documentation/filesystems/locking.rst
@@ -220,7 +220,9 @@ prototypes::
struct dentry *(*mount) (struct file_system_type *, int,
const char *, void *);
+ void (*shutdown_sb) (struct super_block *);
void (*kill_sb) (struct super_block *);
+ void (*free_sb) (struct super_block *);
locking rules:
@@ -228,7 +230,9 @@ locking rules:
ops may block
======= =========
mount yes
+shutdown_sb yes
kill_sb yes
+free_sb yes
======= =========
->mount() returns ERR_PTR or the root dentry; its superblock should be locked
diff --git a/Documentation/filesystems/vfs.rst
b/Documentation/filesystems/vfs.rst
index 99acc2e9867391..1a7c6926c31f34 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -119,7 +119,9 @@ members are defined:
const struct fs_parameter_spec *parameters;
struct dentry *(*mount) (struct file_system_type *, int,
const char *, void *);
+ void (*shutdown_sb) (struct super_block *);
void (*kill_sb) (struct super_block *);
+ void (*free_sb) (struct super_block *);
struct module *owner;
struct file_system_type * next;
struct hlist_head fs_supers;
@@ -155,10 +157,20 @@ members are defined:
the method to call when a new instance of this filesystem should
be mounted
+``shutdown_sb``
+ Cleanup after a super_block has reached a zero active count, and before
+ the VFS level cleanup happens. Typical picks all fs-specific objects
+ (if any) that need destruction out of superblock and releases them.
+ Note: dentries and inodes are normally taken care of and do not need
+ specific handling unless they are pinned by kernel users.
+
``kill_sb``
the method to call when an instance of this filesystem should be
shut down
+``free_sb``
+ Free file system specific resources like sb->s_fs_info that are
+ still needed while inodes are freed during umount.
``owner``
for internal VFS use: you should initialize this to THIS_MODULE
diff --git a/fs/super.c b/fs/super.c
index 5c685b4944c2d6..8e173eccc8c113 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -480,10 +480,15 @@ void deactivate_locked_super(struct super_block *s)
unregister_shrinker(&s->s_shrink);
- if (fs->kill_sb)
+ if (fs->kill_sb) {
fs->kill_sb(s);
- else
+ } else {
+ if (fs->shutdown_sb)
+ fs->shutdown_sb(s);
generic_shutdown_super(s);
+ if (fs->free_sb)
+ fs->free_sb(s);
+ }
kill_super_notify(s);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 31b6b235b36efa..12fff7df3cc46b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2341,6 +2341,8 @@ struct file_system_type {
struct dentry *(*mount) (struct file_system_type *, int,
const char *, void *);
void (*kill_sb) (struct super_block *);
+ void (*shutdown_sb)(struct super_block *sb);
+ void (*free_sb)(struct super_block *sb);
struct module *owner;
struct file_system_type * next;
struct hlist_head fs_supers;
--
2.39.2
