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Message-Id: <200710181722.37629.jara@sin.cvut.cz>
Date: Thu, 18 Oct 2007 17:22:37 +0200
From: Jaroslav Sykora <jara@....cvut.cz>
To: linux-kernel@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org
Subject: [RFC PATCH 1/5] Shadow directories: headers
Header file changes for shadow directories.
Adds pointers to shadows dirs to the struct file and struct fs_struct.
Defines internal lookup flags and syscall flags.
Signed-off-by: Jaroslav Sykora <jaroslav.sykora@...il.com>
include/linux/file.h | 2 ++
include/linux/fs.h | 18 ++++++++++++++++++
include/linux/fs_struct.h | 25 +++++++++++++++++++++++++
include/linux/namei.h | 16 ++++++++++++++++
4 files changed, 61 insertions(+)
--- orig/include/linux/fs.h 2007-10-07 19:00:24.000000000 +0200
+++ new/include/linux/fs.h 2007-10-07 13:39:08.000000000 +0200
@@ -266,6 +266,14 @@ extern int dir_notify_enable;
#define SYNC_FILE_RANGE_WRITE 2
#define SYNC_FILE_RANGE_WAIT_AFTER 4
+/* sys_setshdwinfo(), sys_getshdwinfo(): */
+#define FSI_SHDW_ENABLE 1 /* enable shadow directories */
+#define FSI_SHDW_ESC_EN 2 /* enable use of escape character */
+#define FSI_SHDW_ESC_CHAR 3 /* specify escape character */
+/* sys_setshdwpath */
+#define SHDW_FD_ROOT -1 /* pseudo FD for root shadow dir */
+#define SHDW_FD_PWD -2 /* pseudo FD for pwd shadow dir */
+
#ifdef __KERNEL__
#include <linux/linkage.h>
@@ -752,6 +760,16 @@ struct file {
spinlock_t f_ep_lock;
#endif /* #ifdef CONFIG_EPOLL */
struct address_space *f_mapping;
+
+ /* the following fields are protected by f_owner.lock */
+ /* | f_shdw | f_shdwmnt | result
+ +----------+-------------+------------
+ | NULL | NULL | delayed
+ | NULL | !NULL | invalid
+ | !NULL | NULL | BUG
+ | !NULL | !NULL | valid */
+ struct dentry *f_shdw;
+ struct vfsmount *f_shdwmnt;
};
extern spinlock_t files_lock;
#define file_list_lock() spin_lock(&files_lock);
--- orig/include/linux/fs_struct.h 2007-07-09 01:32:17.000000000 +0200
+++ new/include/linux/fs_struct.h 2007-10-07 13:39:08.000000000 +0200
@@ -10,8 +10,31 @@ struct fs_struct {
int umask;
struct dentry * root, * pwd, * altroot;
struct vfsmount * rootmnt, * pwdmnt, * altrootmnt;
+
+ int flags;
+ /* shadow dirs: root and pwd */
+ /* | shdwroot | shdwrootmnt | result
+ +----------+-------------+------------
+ | NULL | NULL | BUG_ON(flags&SHDW_ENABLED)
+ | !NULL | !NULL | ok
+ +==========+=============+============
+ | shdwpwd | shdwpwdmnt | result
+ +----------+-------------+------------
+ | NULL | NULL | delayed
+ | NULL | !NULL | invalid
+ | !NULL | NULL | BUG
+ | !NULL | !NULL | valid */
+ struct dentry *shdwroot, *shdwpwd;
+ struct vfsmount *shdwrootmnt, *shdwpwdmnt;
+ /* shadow dirs: escape character */
+ unsigned char shdw_escch;
};
+/* bitflags for fs_struct.flags */
+#define SHDW_ENABLED 1 /* are shadow dirs enabled? */
+#define SHDW_USE_ESC 2 /* use escape char in shadow dirs? */
+
+
#define INIT_FS { \
.count = ATOMIC_INIT(1), \
.lock = RW_LOCK_UNLOCKED, \
@@ -24,6 +47,8 @@ extern void exit_fs(struct task_struct *
extern void set_fs_altroot(void);
extern void set_fs_root(struct fs_struct *, struct vfsmount *, struct dentry *);
extern void set_fs_pwd(struct fs_struct *, struct vfsmount *, struct dentry *);
+extern void set_fs_shdwpwd(struct fs_struct *fs,
+ struct vfsmount *mnt, struct dentry *dentry);
extern struct fs_struct *copy_fs_struct(struct fs_struct *);
extern void put_fs_struct(struct fs_struct *);
--- orig/include/linux/namei.h 2007-10-07 19:00:25.000000000 +0200
+++ new/include/linux/namei.h 2007-10-07 20:03:11.000000000 +0200
@@ -22,6 +22,7 @@ struct nameidata {
int last_type;
unsigned depth;
char *saved_names[MAX_NESTED_LINKS + 1];
+ unsigned char find_char;
/* Intent data */
union {
@@ -54,6 +55,16 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LA
#define LOOKUP_PARENT 16
#define LOOKUP_NOALT 32
#define LOOKUP_REVAL 64
+
+/* don't fallback to lookup in shadow directory */
+#define LOOKUP_NOSHDW 128
+/* try to find nameidata.find_char in pathname,
+ * set LOOKUP_CHARFOUND in nameidata.flags if found */
+#define LOOKUP_FINDCHAR (1<<16)
+#define LOOKUP_CHARFOUND (1<<17)
+/* (dentry,mnt) was found in shadow dir */
+#define LOOKUP_INSHDW (1<<18)
+
/*
* Intent data
*/
@@ -68,6 +79,8 @@ extern int FASTCALL(__user_walk_fd(int d
__user_walk_fd(AT_FDCWD, name, LOOKUP_FOLLOW, nd)
#define user_path_walk_link(name,nd) \
__user_walk_fd(AT_FDCWD, name, 0, nd)
+extern int FASTCALL(path_lookup_shdw(int dfd, const char *name,
+ unsigned int flags, struct nameidata *nd));
extern int FASTCALL(path_lookup(const char *, unsigned, struct nameidata *));
extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
const char *, unsigned int, struct nameidata *);
@@ -90,6 +103,9 @@ extern int follow_up(struct vfsmount **,
extern struct dentry *lock_rename(struct dentry *, struct dentry *);
extern void unlock_rename(struct dentry *, struct dentry *);
+extern int get_file_shdwdir(struct file *file, struct dentry **dentry,
+ struct vfsmount **mnt);
+
static inline void nd_set_link(struct nameidata *nd, char *path)
{
nd->saved_names[nd->depth] = path;
--- orig/include/linux/file.h 2007-10-07 19:00:24.000000000 +0200
+++ new/include/linux/file.h 2007-10-16 21:06:51.000000000 +0200
@@ -68,6 +68,8 @@ static inline void fput_light(struct fil
fput(file);
}
+extern struct file *FASTCALL(__fget(struct files_struct *files,
+ unsigned int fd));
extern struct file * FASTCALL(fget(unsigned int fd));
extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed));
extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag));
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
-
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