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: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/autofs/dev-ioctl.c b/fs/autofs/dev-ioctl.c
index a3cdb00..f3a0f41 100644 (file)
--- a/fs/autofs/dev-ioctl.c
+++ b/fs/autofs/dev-ioctl.c
@@ -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);

diff --git a/fs/internal.h b/fs/internal.h
index f3f280b..b108a8e 100644 (file)
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -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,

diff --git a/fs/namei.c b/fs/namei.c
index 8a673f4..0fcd738 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -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();

diff --git a/fs/namespace.c b/fs/namespace.c
index 7439803..a28e4db 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -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);

diff --git a/include/linux/namei.h b/include/linux/namei.h
index 0dd980d..d9576a0 100644 (file)
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -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);