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sysfs, kernfs: prepare mount path for kernfs

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We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges mount path so that the kernfs and sysfs parts are separate.

* As sysfs_super_info won't be visible outside kernfs proper,
  kernfs_super_ns() is added to allow kernfs users to access a
  super_block's namespace tag.

* Generic mount operation is separated out into kernfs_mount_ns().
  sysfs_mount() now just performs sysfs-specific permission check,
  acquires namespace tag, and invokes kernfs_mount_ns().

* Generic superblock release is separated out into kernfs_kill_sb()
  which can be used directly as file_system_type->kill_sb().  As sysfs
  needs to put the namespace tag, sysfs_kill_sb() wraps
  kernfs_kill_sb() with ns tag put.

* sysfs_dir_cachep init and sysfs_inode_init() are separated out into
  kernfs_init().  kernfs_init() uses only small amount of memory and
  trying to handle and propagate kernfs_init() failure doesn't make
  much sense.  Use SLAB_PANIC for sysfs_dir_cachep and make
  sysfs_inode_init() panic on failure.

  After this change, kernfs_init() should be called before
  sysfs_init(), fs/namespace.c::mnt_init() modified accordingly.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo 2013-11-28 14:54:43 -05:00 • committed by Greg Kroah-Hartman
parent df394fb56c
commit 4b93dc9b1c
5 changed files with 107 additions and 36 deletions
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28
include/linux/kernfs.h
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@ -18,6 +18,8 @@ struct file;
struct iattr;
struct seq_file;
struct vm_area_struct;
struct super_block;
struct file_system_type;
struct sysfs_dirent;
@ -109,6 +111,13 @@ void kernfs_enable_ns(struct sysfs_dirent *sd);
int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
void kernfs_notify(struct sysfs_dirent *sd);
const void *kernfs_super_ns(struct super_block *sb);
struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
struct kernfs_root *root, const void *ns);
void kernfs_kill_sb(struct super_block *sb);
void kernfs_init(void);
#else /* CONFIG_SYSFS */
static inline struct sysfs_dirent *
@ -160,6 +169,18 @@ static inline int kernfs_setattr(struct sysfs_dirent *sd,
static inline void kernfs_notify(struct sysfs_dirent *sd) { }
static inline const void *kernfs_super_ns(struct super_block *sb)
{ return NULL; }
static inline struct dentry *
kernfs_mount_ns(struct file_system_type *fs_type, int flags,
struct kernfs_root *root, const void *ns)
{ return ERR_PTR(-ENOSYS); }
static inline void kernfs_kill_sb(struct super_block *sb) { }
static inline void kernfs_init(void) { }
#endif /* CONFIG_SYSFS */
static inline struct sysfs_dirent *
@ -201,4 +222,11 @@ static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
return kernfs_remove_by_name_ns(parent, name, NULL);
}
static inline struct dentry *
kernfs_mount(struct file_system_type *fs_type, int flags,
struct kernfs_root *root)
{
return kernfs_mount_ns(fs_type, flags, root, NULL);
}
#endif /* __LINUX_KERNFS_H */