Commit 161aff1d authored by Al Viro's avatar Al Viro
Browse files

LOOKUP_MOUNTPOINT: fold path_mountpointat() into path_lookupat() 



New LOOKUP flag, telling path_lookupat() to act as path_mountpointat().
IOW, traverse mounts at the final point and skip revalidation of the
location where it ends up.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent cbae4d12

fs/autofs/dev-ioctl.c

+3 −3
Original line number Diff line number Diff line
@@ -186,7 +186,7 @@ static int find_autofs_mount(const char *pathname, 
	struct path path;

	int err;



	err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);

	err = kern_path(pathname, LOOKUP_MOUNTPOINT, &path);

	if (err)

		return err;

	err = -ENOENT;
@@ -519,8 +519,8 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp, 


	if (!fp || param->ioctlfd == -1) {

		if (autofs_type_any(type))

			err = kern_path_mountpoint(AT_FDCWD,

						   name, &path, LOOKUP_FOLLOW);

			err = kern_path(name, LOOKUP_FOLLOW | LOOKUP_MOUNTPOINT,

					&path);

		else

			err = find_autofs_mount(name, &path,

						test_by_type, &type);

fs/internal.h

+0 −1
Original line number Diff line number Diff line
@@ -61,7 +61,6 @@ extern int finish_clean_context(struct fs_context *fc); 
 */

extern int filename_lookup(int dfd, struct filename *name, unsigned flags,

			   struct path *path, struct path *root);

extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);

extern int vfs_path_lookup(struct dentry *, struct vfsmount *,

			   const char *, unsigned int, struct path *);

long do_mknodat(int dfd, const char __user *filename, umode_t mode,

fs/namei.c

+6 −83
Original line number Diff line number Diff line
@@ -2382,6 +2382,10 @@ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path 
	if (!err && nd->flags & LOOKUP_DIRECTORY)

		if (!d_can_lookup(nd->path.dentry))

			err = -ENOTDIR;

	if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) {

		err = handle_lookup_down(nd);

		nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please...

	}

	if (!err) {

		*path = nd->path;

		nd->path.mnt = NULL;
@@ -2410,7 +2414,8 @@ int filename_lookup(int dfd, struct filename *name, unsigned flags, 
		retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path);



	if (likely(!retval))

		audit_inode(name, path->dentry, 0);

		audit_inode(name, path->dentry,

			    flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0);

	restore_nameidata();

	putname(name);

	return retval;
@@ -2688,88 +2693,6 @@ int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 
}

EXPORT_SYMBOL(user_path_at_empty);



/**

 * path_mountpoint - look up a path to be umounted

 * @nd:		lookup context

 * @flags:	lookup flags

 * @path:	pointer to container for result

 *

 * Look up the given name, but don't attempt to revalidate the last component.

 * Returns 0 and "path" will be valid on success; Returns error otherwise.

 */

static int

path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path)

{

	const char *s = path_init(nd, flags);

	int err;



	while (!(err = link_path_walk(s, nd)) &&

		(err = lookup_last(nd)) > 0) {

		s = trailing_symlink(nd);

	}

	if (!err && (nd->flags & LOOKUP_RCU))

		err = unlazy_walk(nd);

	if (!err)

		err = handle_lookup_down(nd);

	if (!err) {

		*path = nd->path;

		nd->path.mnt = NULL;

		nd->path.dentry = NULL;

	}

	terminate_walk(nd);

	return err;

}



static int

filename_mountpoint(int dfd, struct filename *name, struct path *path,

			unsigned int flags)

{

	struct nameidata nd;

	int error;

	if (IS_ERR(name))

		return PTR_ERR(name);

	set_nameidata(&nd, dfd, name);

	error = path_mountpoint(&nd, flags | LOOKUP_RCU, path);

	if (unlikely(error == -ECHILD))

		error = path_mountpoint(&nd, flags, path);

	if (unlikely(error == -ESTALE))

		error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path);

	if (likely(!error))

		audit_inode(name, path->dentry, AUDIT_INODE_NOEVAL);

	restore_nameidata();

	putname(name);

	return error;

}



/**

 * user_path_mountpoint_at - lookup a path from userland in order to umount it

 * @dfd:	directory file descriptor

 * @name:	pathname from userland

 * @flags:	lookup flags

 * @path:	pointer to container to hold result

 *

 * A umount is a special case for path walking. We're not actually interested

 * in the inode in this situation, and ESTALE errors can be a problem. We

 * simply want track down the dentry and vfsmount attached at the mountpoint

 * and avoid revalidating the last component.

 *

 * Returns 0 and populates "path" on success.

 */

int

user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags,

			struct path *path)

{

	return filename_mountpoint(dfd, getname(name), path, flags);

}



int

kern_path_mountpoint(int dfd, const char *name, struct path *path,

			unsigned int flags)

{

	return filename_mountpoint(dfd, getname_kernel(name), path, flags);

}

EXPORT_SYMBOL(kern_path_mountpoint);



int __check_sticky(struct inode *dir, struct inode *inode)

{

	kuid_t fsuid = current_fsuid();

fs/namespace.c

+2 −2
Original line number Diff line number Diff line
@@ -1669,7 +1669,7 @@ int ksys_umount(char __user *name, int flags) 
	struct path path;

	struct mount *mnt;

	int retval;

	int lookup_flags = 0;

	int lookup_flags = LOOKUP_MOUNTPOINT;



	if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))

		return -EINVAL;
@@ -1680,7 +1680,7 @@ int ksys_umount(char __user *name, int flags) 
	if (!(flags & UMOUNT_NOFOLLOW))

		lookup_flags |= LOOKUP_FOLLOW;



	retval = user_path_mountpoint_at(AT_FDCWD, name, lookup_flags, &path);

	retval = user_path_at(AT_FDCWD, name, lookup_flags, &path);

	if (retval)

		goto out;

	mnt = real_mount(path.mnt);

include/linux/namei.h

+1 −1
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; 
#define LOOKUP_AUTOMOUNT	0x0004  /* force terminal automount */

#define LOOKUP_EMPTY		0x4000	/* accept empty path [user_... only] */

#define LOOKUP_DOWN		0x8000	/* follow mounts in the starting point */

#define LOOKUP_MOUNTPOINT	0x0080	/* follow mounts in the end */



#define LOOKUP_REVAL		0x0020	/* tell ->d_revalidate() to trust no cache */

#define LOOKUP_RCU		0x0040	/* RCU pathwalk mode; semi-internal */
@@ -64,7 +65,6 @@ extern struct dentry *kern_path_create(int, const char *, struct path *, unsigne 
extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);

extern void done_path_create(struct path *, struct dentry *);

extern struct dentry *kern_path_locked(const char *, struct path *);

extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);



extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);

extern struct dentry *lookup_one_len(const char *, struct dentry *, int);