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Message-Id: <1397669058-31720-1-git-send-email-nasa4836@gmail.com>
Date: Thu, 17 Apr 2014 01:24:18 +0800
From: Jianyu Zhan <nasa4836@...il.com>
To: gregkh@...uxfoundation.org, tj@...nel.org, lizefan@...wei.com,
nasa4836@...il.com
Cc: linux-kernel@...r.kernel.org,
containers@...ts.linux-foundation.org, cgroups@...r.kernel.org
Subject: Re: [PATCH] kernfs: move the last knowledge of sysfs out from kernfs
On Thu, Apr 17, 2014 at 12:46 AM, Tejun Heo <tj@...nel.org> wrote:
> Please put it before @new_sb_created.
Ok.
> Also, why isn't it unsigned long magic?
I just thought there may be more private data in the future, so I made
it a void pointer. But now I think this is overskill and meaningless.
Renewed patch here:
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@...il.com>
---
fs/kernfs/mount.c | 11 ++++++-----
fs/sysfs/mount.c | 4 +++-
include/linux/kernfs.h | 13 ++++++++-----
kernel/cgroup.c | 4 +++-
4 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 6a5f04a..95dcd1d 100644
--- 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;
@@ -70,7 +70,7 @@ static int kernfs_fill_super(struct super_block *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;
@@ -131,6 +131,7 @@ 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
*
@@ -142,8 +143,8 @@ 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;
@@ -166,7 +167,7 @@ struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
*new_sb_created = !sb->s_root;
if (!sb->s_root) {
- 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 a66ad61..024134e 100644
--- 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 b0122dc..5e363e1 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -280,8 +280,8 @@ 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);
@@ -374,7 +374,8 @@ 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) { }
@@ -432,9 +433,11 @@ 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 9fcdaa7..ab5a995 100644
--- 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;
--
1.9.0.GIT
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