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open-style analog of vfs_path_lookup()

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new function: file_open_root(dentry, mnt, name, flags) opens the file
vfs_path_lookup would arrive to.

Note that name can be empty; in that case the usual requirement that
dentry should be a directory is lifted.

open-coded equivalents switched to it, may_open() got down exactly
one caller and became static.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2011-03-11 12:08:24 -05:00
parent 5b6ca027d8
commit 73d049a40f
7 changed files with 77 additions and 84 deletions
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21
arch/um/drivers/mconsole_kern.c
View file

@ -124,35 +124,18 @@ void mconsole_log(struct mc_request *req)
#if 0
void mconsole_proc(struct mc_request *req)
{
struct nameidata nd;
struct vfsmount *mnt = current->nsproxy->pid_ns->proc_mnt;
struct file *file;
int n, err;
int n;
char *ptr = req->request.data, *buf;
mm_segment_t old_fs = get_fs();
ptr += strlen("proc");
ptr = skip_spaces(ptr);
err = vfs_path_lookup(mnt->mnt_root, mnt, ptr, LOOKUP_FOLLOW, &nd);
if (err) {
mconsole_reply(req, "Failed to look up file", 1, 0);
goto out;
}
err = may_open(&nd.path, MAY_READ, O_RDONLY);
if (result) {
mconsole_reply(req, "Failed to open file", 1, 0);
path_put(&nd.path);
goto out;
}
file = dentry_open(nd.path.dentry, nd.path.mnt, O_RDONLY,
current_cred());
err = PTR_ERR(file);
file = file_open_root(mnt->mnt_root, mnt, ptr, O_RDONLY);
if (IS_ERR(file)) {
mconsole_reply(req, "Failed to open file", 1, 0);
path_put(&nd.path);
goto out;
}

2
fs/internal.h
View file

@ -114,6 +114,8 @@ struct open_flags {
};
extern struct file *do_filp_open(int dfd, const char *pathname,
const struct open_flags *op, int lookup_flags);
extern struct file *do_file_open_root(struct dentry *, struct vfsmount *,
const char *, const struct open_flags *, int lookup_flags);
/*
* inode.c

70
fs/namei.c
View file

@ -1487,11 +1487,13 @@ static int path_init(int dfd, const char *name, unsigned int flags,
nd->depth = 0;
if (flags & LOOKUP_ROOT) {
struct inode *inode = nd->root.dentry->d_inode;
if (*name) {
if (!inode->i_op->lookup)
return -ENOTDIR;
retval = inode_permission(inode, MAY_EXEC);
if (retval)
return retval;
}
nd->path = nd->root;
nd->inode = inode;
if (flags & LOOKUP_RCU) {
@ -1937,7 +1939,7 @@ int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
return error;
}
int may_open(struct path *path, int acc_mode, int flag)
static int may_open(struct path *path, int acc_mode, int flag)
{
struct dentry *dentry = path->dentry;
struct inode *inode = dentry->d_inode;
@ -2250,11 +2252,10 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
}
static struct file *path_openat(int dfd, const char *pathname,
const struct open_flags *op, int flags)
struct nameidata *nd, const struct open_flags *op, int flags)
{
struct file *base = NULL;
struct file *filp;
struct nameidata nd;
struct path path;
int count = 0;
int error;
@ -2264,27 +2265,27 @@ static struct file *path_openat(int dfd, const char *pathname,
return ERR_PTR(-ENFILE);
filp->f_flags = op->open_flag;
nd.intent.open.file = filp;
nd.intent.open.flags = open_to_namei_flags(op->open_flag);
nd.intent.open.create_mode = op->mode;
nd->intent.open.file = filp;
nd->intent.open.flags = open_to_namei_flags(op->open_flag);
nd->intent.open.create_mode = op->mode;
error = path_init(dfd, pathname, flags | LOOKUP_PARENT, &nd, &base);
error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
if (unlikely(error))
goto out_filp;
current->total_link_count = 0;
error = link_path_walk(pathname, &nd);
error = link_path_walk(pathname, nd);
if (unlikely(error))
goto out_filp;
filp = do_last(&nd, &path, op, pathname);
filp = do_last(nd, &path, op, pathname);
while (unlikely(!filp)) { /* trailing symlink */
struct path link = path;
struct inode *linki = link.dentry->d_inode;
void *cookie;
if (!(nd.flags & LOOKUP_FOLLOW) || count++ == 32) {
path_put_conditional(&path, &nd);
path_put(&nd.path);
if (!(nd->flags & LOOKUP_FOLLOW) || count++ == 32) {
path_put_conditional(&path, nd);
path_put(&nd->path);
filp = ERR_PTR(-ELOOP);
break;
}
@ -2299,23 +2300,23 @@ static struct file *path_openat(int dfd, const char *pathname,
* have to putname() it when we are done. Procfs-like symlinks
* just set LAST_BIND.
*/
nd.flags |= LOOKUP_PARENT;
nd.flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
error = __do_follow_link(&link, &nd, &cookie);
nd->flags |= LOOKUP_PARENT;
nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
error = __do_follow_link(&link, nd, &cookie);
if (unlikely(error))
filp = ERR_PTR(error);
else
filp = do_last(&nd, &path, op, pathname);
filp = do_last(nd, &path, op, pathname);
if (!IS_ERR(cookie) && linki->i_op->put_link)
linki->i_op->put_link(link.dentry, &nd, cookie);
linki->i_op->put_link(link.dentry, nd, cookie);
path_put(&link);
}
out:
if (nd.root.mnt && !(nd.flags & LOOKUP_ROOT))
path_put(&nd.root);
if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))
path_put(&nd->root);
if (base)
fput(base);
release_open_intent(&nd);
release_open_intent(nd);
return filp;
out_filp:
@ -2326,16 +2327,39 @@ static struct file *path_openat(int dfd, const char *pathname,
struct file *do_filp_open(int dfd, const char *pathname,
const struct open_flags *op, int flags)
{
struct nameidata nd;
struct file *filp;
filp = path_openat(dfd, pathname, op, flags | LOOKUP_RCU);
filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
if (unlikely(filp == ERR_PTR(-ECHILD)))
filp = path_openat(dfd, pathname, op, flags);
filp = path_openat(dfd, pathname, &nd, op, flags);
if (unlikely(filp == ERR_PTR(-ESTALE)))
filp = path_openat(dfd, pathname, op, flags | LOOKUP_REVAL);
filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL);
return filp;
}
struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
const char *name, const struct open_flags *op, int flags)
{
struct nameidata nd;
struct file *file;
nd.root.mnt = mnt;
nd.root.dentry = dentry;
flags |= LOOKUP_ROOT;
if (dentry->d_inode->i_op->follow_link)
return ERR_PTR(-ELOOP);
file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU);
if (unlikely(file == ERR_PTR(-ECHILD)))
file = path_openat(-1, name, &nd, op, flags);
if (unlikely(file == ERR_PTR(-ESTALE)))
file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL);
return file;
}
/**
* lookup_create - lookup a dentry, creating it if it doesn't exist
* @nd: nameidata info

21
fs/nfsctl.c
View file

@ -22,30 +22,17 @@
static struct file *do_open(char *name, int flags)
{
struct nameidata nd;
struct vfsmount *mnt;
int error;
struct file *file;
mnt = do_kern_mount("nfsd", 0, "nfsd", NULL);
if (IS_ERR(mnt))
return (struct file *)mnt;
error = vfs_path_lookup(mnt->mnt_root, mnt, name, 0, &nd);
file = file_open_root(mnt->mnt_root, mnt, name, flags);
mntput(mnt); /* drop do_kern_mount reference */
if (error)
return ERR_PTR(error);
if (flags == O_RDWR)
error = may_open(&nd.path, MAY_READ|MAY_WRITE, flags);
else
error = may_open(&nd.path, MAY_WRITE, flags);
if (!error)
return dentry_open(nd.path.dentry, nd.path.mnt, flags,
current_cred());
path_put(&nd.path);
return ERR_PTR(error);
return file;
}
static struct {

14
fs/open.c
View file

@ -959,6 +959,20 @@ struct file *filp_open(const char *filename, int flags, int mode)
}
EXPORT_SYMBOL(filp_open);
struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
const char *filename, int flags)
{
struct open_flags op;
int lookup = build_open_flags(flags, 0, &op);
if (flags & O_CREAT)
return ERR_PTR(-EINVAL);
if (!filename && (flags & O_DIRECTORY))
if (!dentry->d_inode->i_op->lookup)
return ERR_PTR(-ENOTDIR);
return do_file_open_root(dentry, mnt, filename, &op, lookup);
}
EXPORT_SYMBOL(file_open_root);
long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
{
struct open_flags op;

4
include/linux/fs.h
View file

@ -1990,6 +1990,8 @@ extern int do_fallocate(struct file *file, int mode, loff_t offset,
extern long do_sys_open(int dfd, const char __user *filename, int flags,
int mode);
extern struct file *filp_open(const char *, int, int);
extern struct file *file_open_root(struct dentry *, struct vfsmount *,
const char *, int);
extern struct file * dentry_open(struct dentry *, struct vfsmount *, int,
const struct cred *);
extern int filp_close(struct file *, fl_owner_t id);
@ -2205,8 +2207,6 @@ extern struct file *create_read_pipe(struct file *f, int flags);
extern struct file *create_write_pipe(int flags);
extern void free_write_pipe(struct file *);
extern int may_open(struct path *, int, int);
extern int kernel_read(struct file *, loff_t, char *, unsigned long);
extern struct file * open_exec(const char *);

19
kernel/sysctl_binary.c
View file

@ -1321,13 +1321,11 @@ static ssize_t binary_sysctl(const int *name, int nlen,
void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
{
const struct bin_table *table = NULL;
struct nameidata nd;
struct vfsmount *mnt;
struct file *file;
ssize_t result;
char *pathname;
int flags;
int acc_mode;
pathname = sysctl_getname(name, nlen, &table);
result = PTR_ERR(pathname);
@ -1337,28 +1335,17 @@ static ssize_t binary_sysctl(const int *name, int nlen,
/* How should the sysctl be accessed? */
if (oldval && oldlen && newval && newlen) {
flags = O_RDWR;
acc_mode = MAY_READ | MAY_WRITE;
} else if (newval && newlen) {
flags = O_WRONLY;
acc_mode = MAY_WRITE;
} else if (oldval && oldlen) {
flags = O_RDONLY;
acc_mode = MAY_READ;
} else {
result = 0;
goto out_putname;
}
mnt = current->nsproxy->pid_ns->proc_mnt;
result = vfs_path_lookup(mnt->mnt_root, mnt, pathname, 0, &nd);
if (result)
goto out_putname;
result = may_open(&nd.path, acc_mode, flags);
if (result)
goto out_putpath;
file = dentry_open(nd.path.dentry, nd.path.mnt, flags, current_cred());
file = file_open_root(mnt->mnt_root, mnt, pathname, flags);
result = PTR_ERR(file);
if (IS_ERR(file))
goto out_putname;
@ -1370,10 +1357,6 @@ static ssize_t binary_sysctl(const int *name, int nlen,
putname(pathname);
out:
return result;
out_putpath:
path_put(&nd.path);
goto out_putname;
}