kernfs: move the last knowledge of sysfs out from kernfs

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 <nasa4836@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index f25a7c0..d171b98 100644 (file)
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -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;
@@ -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;
 
@@ -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
  *
@@ -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;
@@ -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);

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 8794423..8a49486 100644 (file)
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -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>
@@ -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;

diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index c841688..17aa1cc 100644 (file)
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -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);
@@ -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) { }
@@ -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 */

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3f1ca93..ceee0c5 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -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>
@@ -1604,7 +1605,8 @@ out_unlock:
        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;