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vfs: add helpers to get root and pwd

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Add three helpers that retrieve a refcounted copy of the root and cwd
from the supplied fs_struct.

 get_fs_root()
 get_fs_pwd()
 get_fs_root_and_pwd()

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Miklos Szeredi 2010-08-10 11:41:36 +02:00 committed by Al Viro
parent 542ce7a9bc
commit f7ad3c6be9
8 changed files with 49 additions and 62 deletions
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14
fs/cachefiles/daemon.c
View File

@ -552,7 +552,6 @@ static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
*/
static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
{
struct fs_struct *fs;
struct path path;
const struct cred *saved_cred;
int ret;
@ -573,11 +572,7 @@ static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
}
/* extract the directory dentry from the cwd */
fs = current->fs;
read_lock(&fs->lock);
path = fs->pwd;
path_get(&path);
read_unlock(&fs->lock);
get_fs_pwd(current->fs, &path);
if (!S_ISDIR(path.dentry->d_inode->i_mode))
goto notdir;
@ -629,7 +624,6 @@ static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
*/
static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
{
struct fs_struct *fs;
struct path path;
const struct cred *saved_cred;
int ret;
@ -650,11 +644,7 @@ static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
}
/* extract the directory dentry from the cwd */
fs = current->fs;
read_lock(&fs->lock);
path = fs->pwd;
path_get(&path);
read_unlock(&fs->lock);
get_fs_pwd(current->fs, &path);
if (!S_ISDIR(path.dentry->d_inode->i_mode))
goto notdir;

12
fs/dcache.c
View File

@ -2014,10 +2014,7 @@ char *d_path(const struct path *path, char *buf, int buflen)
if (path->dentry->d_op && path->dentry->d_op->d_dname)
return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
read_lock(&current->fs->lock);
root = current->fs->root;
path_get(&root);
read_unlock(&current->fs->lock);
get_fs_root(current->fs, &root);
spin_lock(&dcache_lock);
tmp = root;
res = __d_path(path, &tmp, buf, buflen);
@ -2129,12 +2126,7 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
if (!page)
return -ENOMEM;
read_lock(&current->fs->lock);
pwd = current->fs->pwd;
path_get(&pwd);
root = current->fs->root;
path_get(&root);
read_unlock(&current->fs->lock);
get_fs_root_and_pwd(current->fs, &root, &pwd);
error = -ENOENT;
spin_lock(&dcache_lock);

7
fs/fs_struct.c
View File

@ -106,12 +106,7 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old)
fs->in_exec = 0;
rwlock_init(&fs->lock);
fs->umask = old->umask;
read_lock(&old->lock);
fs->root = old->root;
path_get(&old->root);
fs->pwd = old->pwd;
path_get(&old->pwd);
read_unlock(&old->lock);
get_fs_root_and_pwd(old, &fs->root, &fs->pwd);
}
return fs;
}

15
fs/namei.c
View File

@ -483,13 +483,8 @@ static int exec_permission(struct inode *inode)
static __always_inline void set_root(struct nameidata *nd)
{
if (!nd->root.mnt) {
struct fs_struct *fs = current->fs;
read_lock(&fs->lock);
nd->root = fs->root;
path_get(&nd->root);
read_unlock(&fs->lock);
}
if (!nd->root.mnt)
get_fs_root(current->fs, &nd->root);
}
static int link_path_walk(const char *, struct nameidata *);
@ -1015,11 +1010,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, struct namei
nd->path = nd->root;
path_get(&nd->root);
} else if (dfd == AT_FDCWD) {
struct fs_struct *fs = current->fs;
read_lock(&fs->lock);
nd->path = fs->pwd;
path_get(&fs->pwd);
read_unlock(&fs->lock);
get_fs_pwd(current->fs, &nd->path);
} else {
struct dentry *dentry;

5
fs/namespace.c
View File

@ -2213,10 +2213,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
goto out1;
}
read_lock(&current->fs->lock);
root = current->fs->root;
path_get(&current->fs->root);
read_unlock(&current->fs->lock);
get_fs_root(current->fs, &root);
down_write(&namespace_sem);
mutex_lock(&old.dentry->d_inode->i_mutex);
error = -EINVAL;

22
fs/proc/base.c
View File

@ -149,18 +149,13 @@ static unsigned int pid_entry_count_dirs(const struct pid_entry *entries,
return count;
}
static int get_fs_path(struct task_struct *task, struct path *path, bool root)
static int get_task_root(struct task_struct *task, struct path *root)
{
struct fs_struct *fs;
int result = -ENOENT;
task_lock(task);
fs = task->fs;
if (fs) {
read_lock(&fs->lock);
*path = root ? fs->root : fs->pwd;
path_get(path);
read_unlock(&fs->lock);
if (task->fs) {
get_fs_root(task->fs, root);
result = 0;
}
task_unlock(task);
@ -173,7 +168,12 @@ static int proc_cwd_link(struct inode *inode, struct path *path)
int result = -ENOENT;
if (task) {
result = get_fs_path(task, path, 0);
task_lock(task);
if (task->fs) {
get_fs_pwd(task->fs, path);
result = 0;
}
task_unlock(task);
put_task_struct(task);
}
return result;
@ -185,7 +185,7 @@ static int proc_root_link(struct inode *inode, struct path *path)
int result = -ENOENT;
if (task) {
result = get_fs_path(task, path, 1);
result = get_task_root(task, path);
put_task_struct(task);
}
return result;
@ -597,7 +597,7 @@ static int mounts_open_common(struct inode *inode, struct file *file,
get_mnt_ns(ns);
}
rcu_read_unlock();
if (ns && get_fs_path(task, &root, 1) == 0)
if (ns && get_task_root(task, &root) == 0)
ret = 0;
put_task_struct(task);
}

27
include/linux/fs_struct.h
View File

@ -21,4 +21,31 @@ extern void free_fs_struct(struct fs_struct *);
extern void daemonize_fs_struct(void);
extern int unshare_fs_struct(void);
static inline void get_fs_root(struct fs_struct *fs, struct path *root)
{
read_lock(&fs->lock);
*root = fs->root;
path_get(root);
read_unlock(&fs->lock);
}
static inline void get_fs_pwd(struct fs_struct *fs, struct path *pwd)
{
read_lock(&fs->lock);
*pwd = fs->pwd;
path_get(pwd);
read_unlock(&fs->lock);
}
static inline void get_fs_root_and_pwd(struct fs_struct *fs, struct path *root,
struct path *pwd)
{
read_lock(&fs->lock);
*root = fs->root;
path_get(root);
*pwd = fs->pwd;
path_get(pwd);
read_unlock(&fs->lock);
}
#endif /* _LINUX_FS_STRUCT_H */

9
kernel/auditsc.c
View File

@ -1835,13 +1835,8 @@ void __audit_getname(const char *name)
context->names[context->name_count].ino = (unsigned long)-1;
context->names[context->name_count].osid = 0;
++context->name_count;
if (!context->pwd.dentry) {
read_lock(&current->fs->lock);
context->pwd = current->fs->pwd;
path_get(&current->fs->pwd);
read_unlock(&current->fs->lock);
}
if (!context->pwd.dentry)
get_fs_pwd(current->fs, &context->pwd);
}
/* audit_putname - intercept a putname request