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kernfs: move the last knowledge of sysfs out from kernfs
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There is still one residue of sysfs remaining: the sb_magic
SYSFS_MAGIC. However this should be kernfs user specific,
so this patch moves it out. Kerrnfs user should specify their
magic number while mouting.

Signed-off-by: Jianyu Zhan <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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JianyuZhan authored and gregkh committed May 27, 2014
1 parent 9f70a40 commit 26fc9cd
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Showing 4 changed files with 20 additions and 12 deletions.
11 changes: 6 additions & 5 deletions fs/kernfs/mount.c
Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,7 @@ struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
return NULL;
}

static int kernfs_fill_super(struct super_block *sb)
static int kernfs_fill_super(struct super_block *sb, unsigned long magic)
{
struct kernfs_super_info *info = kernfs_info(sb);
struct inode *inode;
Expand All @@ -71,7 +71,7 @@ static int kernfs_fill_super(struct super_block *sb)
info->sb = sb;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = SYSFS_MAGIC;
sb->s_magic = magic;
sb->s_op = &kernfs_sops;
sb->s_time_gran = 1;

Expand Down Expand Up @@ -132,6 +132,7 @@ const void *kernfs_super_ns(struct super_block *sb)
* @fs_type: file_system_type of the fs being mounted
* @flags: mount flags specified for the mount
* @root: kernfs_root of the hierarchy being mounted
* @magic: file system specific magic number
* @new_sb_created: tell the caller if we allocated a new superblock
* @ns: optional namespace tag of the mount
*
Expand All @@ -143,8 +144,8 @@ const void *kernfs_super_ns(struct super_block *sb)
* The return value can be passed to the vfs layer verbatim.
*/
struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
struct kernfs_root *root, bool *new_sb_created,
const void *ns)
struct kernfs_root *root, unsigned long magic,
bool *new_sb_created, const void *ns)
{
struct super_block *sb;
struct kernfs_super_info *info;
Expand All @@ -169,7 +170,7 @@ struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
if (!sb->s_root) {
struct kernfs_super_info *info = kernfs_info(sb);

error = kernfs_fill_super(sb);
error = kernfs_fill_super(sb, magic);
if (error) {
deactivate_locked_super(sb);
return ERR_PTR(error);
Expand Down
4 changes: 3 additions & 1 deletion fs/sysfs/mount.c
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
#define DEBUG

#include <linux/fs.h>
#include <linux/magic.h>
#include <linux/mount.h>
#include <linux/init.h>
#include <linux/user_namespace.h>
Expand All @@ -38,7 +39,8 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
}

ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
root = kernfs_mount_ns(fs_type, flags, sysfs_root, &new_sb, ns);
root = kernfs_mount_ns(fs_type, flags, sysfs_root,
SYSFS_MAGIC, &new_sb, ns);
if (IS_ERR(root) || !new_sb)
kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
return root;
Expand Down
13 changes: 8 additions & 5 deletions include/linux/kernfs.h
Original file line number Diff line number Diff line change
Expand Up @@ -301,8 +301,8 @@ void kernfs_notify(struct kernfs_node *kn);

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, bool *new_sb_created,
const void *ns);
struct kernfs_root *root, unsigned long magic,
bool *new_sb_created, const void *ns);
void kernfs_kill_sb(struct super_block *sb);

void kernfs_init(void);
Expand Down Expand Up @@ -395,7 +395,8 @@ static inline const void *kernfs_super_ns(struct super_block *sb)

static inline struct dentry *
kernfs_mount_ns(struct file_system_type *fs_type, int flags,
struct kernfs_root *root, bool *new_sb_created, const void *ns)
struct kernfs_root *root, unsigned long magic,
bool *new_sb_created, const void *ns)
{ return ERR_PTR(-ENOSYS); }

static inline void kernfs_kill_sb(struct super_block *sb) { }
Expand Down Expand Up @@ -453,9 +454,11 @@ static inline int kernfs_rename(struct kernfs_node *kn,

static inline struct dentry *
kernfs_mount(struct file_system_type *fs_type, int flags,
struct kernfs_root *root, bool *new_sb_created)
struct kernfs_root *root, unsigned long magic,
bool *new_sb_created)
{
return kernfs_mount_ns(fs_type, flags, root, new_sb_created, NULL);
return kernfs_mount_ns(fs_type, flags, root,
magic, new_sb_created, NULL);
}

#endif /* __LINUX_KERNFS_H */
4 changes: 3 additions & 1 deletion kernel/cgroup.c
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@
#include <linux/init_task.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/magic.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/mount.h>
Expand Down Expand Up @@ -1604,7 +1605,8 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
if (ret)
return ERR_PTR(ret);

dentry = kernfs_mount(fs_type, flags, root->kf_root, &new_sb);
dentry = kernfs_mount(fs_type, flags, root->kf_root,
CGROUP_SUPER_MAGIC, &new_sb);
if (IS_ERR(dentry) || !new_sb)
cgroup_put(&root->cgrp);
return dentry;
Expand Down

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