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vfs: bury ->get_sb()

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This is an ex-parrot.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2011-03-16 09:07:58 -04:00
parent 011949811b
commit 1a102ff925
5 changed files with 47 additions and 103 deletions
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6
Documentation/filesystems/Locking
View file

@ -166,13 +166,11 @@ prototypes:
void (*kill_sb) (struct super_block *);
locking rules:
may block
get_sb yes
mount yes
kill_sb yes
->get_sb() returns error or 0 with locked superblock attached to the vfsmount
(exclusive on ->s_umount).
->mount() returns ERR_PTR or the root dentry.
->mount() returns ERR_PTR or the root dentry; its superblock should be locked
on return.
->kill_sb() takes a write-locked superblock, does all shutdown work on it,
unlocks and drops the reference.

7
Documentation/filesystems/porting
View file

@ -394,3 +394,10 @@ file) you must return -EOPNOTSUPP if FALLOC_FL_PUNCH_HOLE is set in mode.
Currently you can only have FALLOC_FL_PUNCH_HOLE with FALLOC_FL_KEEP_SIZE set,
so the i_size should not change when hole punching, even when puching the end of
a file off.
--
[mandatory]
->get_sb() is gone. Switch to use of ->mount(). Typically it's just
a matter of switching from calling get_sb_... to mount_... and changing the
function type. If you were doing it manually, just switch from setting ->mnt_root
to some pointer to returning that pointer. On errors return ERR_PTR(...).

56
Documentation/filesystems/vfs.txt
View file

@ -95,10 +95,11 @@ functions:
extern int unregister_filesystem(struct file_system_type *);
The passed struct file_system_type describes your filesystem. When a
request is made to mount a device onto a directory in your filespace,
the VFS will call the appropriate get_sb() method for the specific
filesystem. The dentry for the mount point will then be updated to
point to the root inode for the new filesystem.
request is made to mount a filesystem onto a directory in your namespace,
the VFS will call the appropriate mount() method for the specific
filesystem. New vfsmount refering to the tree returned by ->mount()
will be attached to the mountpoint, so that when pathname resolution
reaches the mountpoint it will jump into the root of that vfsmount.
You can see all filesystems that are registered to the kernel in the
file /proc/filesystems.
@ -107,14 +108,14 @@ file /proc/filesystems.
struct file_system_type
-----------------------
This describes the filesystem. As of kernel 2.6.22, the following
This describes the filesystem. As of kernel 2.6.39, the following
members are defined:
struct file_system_type {
const char *name;
int fs_flags;
int (*get_sb) (struct file_system_type *, int,
const char *, void *, struct vfsmount *);
struct dentry (*mount) (struct file_system_type *, int,
const char *, void *);
void (*kill_sb) (struct super_block *);
struct module *owner;
struct file_system_type * next;
@ -128,11 +129,11 @@ struct file_system_type {
fs_flags: various flags (i.e. FS_REQUIRES_DEV, FS_NO_DCACHE, etc.)
get_sb: the method to call when a new instance of this
mount: the method to call when a new instance of this
filesystem should be mounted
kill_sb: the method to call when an instance of this filesystem
should be unmounted
should be shut down
owner: for internal VFS use: you should initialize this to THIS_MODULE in
most cases.
@ -141,7 +142,7 @@ struct file_system_type {
s_lock_key, s_umount_key: lockdep-specific
The get_sb() method has the following arguments:
The mount() method has the following arguments:
struct file_system_type *fs_type: describes the filesystem, partly initialized
by the specific filesystem code
@ -153,32 +154,39 @@ The get_sb() method has the following arguments:
void *data: arbitrary mount options, usually comes as an ASCII
string (see "Mount Options" section)
struct vfsmount *mnt: a vfs-internal representation of a mount point
The mount() method must return the root dentry of the tree requested by
caller. An active reference to its superblock must be grabbed and the
superblock must be locked. On failure it should return ERR_PTR(error).
The get_sb() method must determine if the block device specified
in the dev_name and fs_type contains a filesystem of the type the method
supports. If it succeeds in opening the named block device, it initializes a
struct super_block descriptor for the filesystem contained by the block device.
On failure it returns an error.
The arguments match those of mount(2) and their interpretation
depends on filesystem type. E.g. for block filesystems, dev_name is
interpreted as block device name, that device is opened and if it
contains a suitable filesystem image the method creates and initializes
struct super_block accordingly, returning its root dentry to caller.
->mount() may choose to return a subtree of existing filesystem - it
doesn't have to create a new one. The main result from the caller's
point of view is a reference to dentry at the root of (sub)tree to
be attached; creation of new superblock is a common side effect.
The most interesting member of the superblock structure that the
get_sb() method fills in is the "s_op" field. This is a pointer to
mount() method fills in is the "s_op" field. This is a pointer to
a "struct super_operations" which describes the next level of the
filesystem implementation.
Usually, a filesystem uses one of the generic get_sb() implementations
and provides a fill_super() method instead. The generic methods are:
Usually, a filesystem uses one of the generic mount() implementations
and provides a fill_super() callback instead. The generic variants are:
get_sb_bdev: mount a filesystem residing on a block device
mount_bdev: mount a filesystem residing on a block device
get_sb_nodev: mount a filesystem that is not backed by a device
mount_nodev: mount a filesystem that is not backed by a device
get_sb_single: mount a filesystem which shares the instance between
mount_single: mount a filesystem which shares the instance between
all mounts
A fill_super() method implementation has the following arguments:
A fill_super() callback implementation has the following arguments:
struct super_block *sb: the superblock structure. The method fill_super()
struct super_block *sb: the superblock structure. The callback
must initialize this properly.
void *data: arbitrary mount options, usually comes as an ASCII

67
fs/super.c
View file

@ -843,23 +843,6 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
}
EXPORT_SYMBOL(mount_bdev);
int get_sb_bdev(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data,
int (*fill_super)(struct super_block *, void *, int),
struct vfsmount *mnt)
{
struct dentry *root;
root = mount_bdev(fs_type, flags, dev_name, data, fill_super);
if (IS_ERR(root))
return PTR_ERR(root);
mnt->mnt_root = root;
mnt->mnt_sb = root->d_sb;
return 0;
}
EXPORT_SYMBOL(get_sb_bdev);
void kill_block_super(struct super_block *sb)
{
struct block_device *bdev = sb->s_bdev;
@ -897,22 +880,6 @@ struct dentry *mount_nodev(struct file_system_type *fs_type,
}
EXPORT_SYMBOL(mount_nodev);
int get_sb_nodev(struct file_system_type *fs_type,
int flags, void *data,
int (*fill_super)(struct super_block *, void *, int),
struct vfsmount *mnt)
{
struct dentry *root;
root = mount_nodev(fs_type, flags, data, fill_super);
if (IS_ERR(root))
return PTR_ERR(root);
mnt->mnt_root = root;
mnt->mnt_sb = root->d_sb;
return 0;
}
EXPORT_SYMBOL(get_sb_nodev);
static int compare_single(struct super_block *s, void *p)
{
return 1;
@ -943,22 +910,6 @@ struct dentry *mount_single(struct file_system_type *fs_type,
}
EXPORT_SYMBOL(mount_single);
int get_sb_single(struct file_system_type *fs_type,
int flags, void *data,
int (*fill_super)(struct super_block *, void *, int),
struct vfsmount *mnt)
{
struct dentry *root;
root = mount_single(fs_type, flags, data, fill_super);
if (IS_ERR(root))
return PTR_ERR(root);
mnt->mnt_root = root;
mnt->mnt_sb = root->d_sb;
return 0;
}
EXPORT_SYMBOL(get_sb_single);
struct vfsmount *
vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
{
@ -988,19 +939,13 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
goto out_free_secdata;
}
if (type->mount) {
root = type->mount(type, flags, name, data);
if (IS_ERR(root)) {
error = PTR_ERR(root);
goto out_free_secdata;
}
mnt->mnt_root = root;
mnt->mnt_sb = root->d_sb;
} else {
error = type->get_sb(type, flags, name, data, mnt);
if (error < 0)
goto out_free_secdata;
root = type->mount(type, flags, name, data);
if (IS_ERR(root)) {
error = PTR_ERR(root);
goto out_free_secdata;
}
mnt->mnt_root = root;
mnt->mnt_sb = root->d_sb;
BUG_ON(!mnt->mnt_sb);
WARN_ON(!mnt->mnt_sb->s_bdi);
mnt->mnt_sb->s_flags |= MS_BORN;

14
include/linux/fs.h
View file

@ -1797,8 +1797,6 @@ int sync_inode_metadata(struct inode *inode, int wait);
struct file_system_type {
const char *name;
int fs_flags;
int (*get_sb) (struct file_system_type *, int,
const char *, void *, struct vfsmount *);
struct dentry *(*mount) (struct file_system_type *, int,
const char *, void *);
void (*kill_sb) (struct super_block *);
@ -1821,24 +1819,12 @@ extern struct dentry *mount_ns(struct file_system_type *fs_type, int flags,
extern struct dentry *mount_bdev(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data,
int (*fill_super)(struct super_block *, void *, int));
extern int get_sb_bdev(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data,
int (*fill_super)(struct super_block *, void *, int),
struct vfsmount *mnt);
extern struct dentry *mount_single(struct file_system_type *fs_type,
int flags, void *data,
int (*fill_super)(struct super_block *, void *, int));
extern int get_sb_single(struct file_system_type *fs_type,
int flags, void *data,
int (*fill_super)(struct super_block *, void *, int),
struct vfsmount *mnt);
extern struct dentry *mount_nodev(struct file_system_type *fs_type,
int flags, void *data,
int (*fill_super)(struct super_block *, void *, int));
extern int get_sb_nodev(struct file_system_type *fs_type,
int flags, void *data,
int (*fill_super)(struct super_block *, void *, int),
struct vfsmount *mnt);
void generic_shutdown_super(struct super_block *sb);
void kill_block_super(struct super_block *sb);
void kill_anon_super(struct super_block *sb);