Commit cfaf86ab authored by Ian Kent's avatar Ian Kent Committed by Al Viro
Browse files

autofs: use path_is_mountpoint() to fix unreliable d_mountpoint() checks 

If an automount mount is clone(2)ed into a file system that is propagation
private, when it later expires in the originating namespace, subsequent
calls to autofs ->d_automount() for that dentry in the original namespace
will return ELOOP until the mount is umounted in the cloned namespace.

Now that a struct path is available where needed use path_is_mountpoint()
instead of d_mountpoint() so we don't get false positives when checking if
a dentry is a mount point in the current namespace.

Link: http://lkml.kernel.org/r/20161011053418.27645.15241.stgit@pluto.themaw.net


Signed-off-by: default avatarIan Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Omar Sandoval <osandov@osandov.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent dd36a882

fs/autofs4/root.c

+7 −7
Original line number Diff line number Diff line
@@ -123,7 +123,7 @@ static int autofs4_dir_open(struct inode *inode, struct file *file) 
	 * it.

	 */

	spin_lock(&sbi->lookup_lock);

	if (!d_mountpoint(dentry) && simple_empty(dentry)) {

	if (!path_is_mountpoint(&file->f_path) && simple_empty(dentry)) {

		spin_unlock(&sbi->lookup_lock);

		return -ENOENT;

	}
@@ -372,15 +372,15 @@ static struct vfsmount *autofs4_d_automount(struct path *path) 


	/*

	 * If the dentry is a symlink it's equivalent to a directory

	 * having d_mountpoint() true, so there's no need to call back

	 * to the daemon.

	 * having path_is_mountpoint() true, so there's no need to call

	 * back to the daemon.

	 */

	if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {

		spin_unlock(&sbi->fs_lock);

		goto done;

	}



	if (!d_mountpoint(dentry)) {

	if (!path_is_mountpoint(path)) {

		/*

		 * It's possible that user space hasn't removed directories

		 * after umounting a rootless multi-mount, although it
@@ -434,7 +434,7 @@ static int autofs4_d_manage(const struct path *path, bool rcu_walk) 


	/* The daemon never waits. */

	if (autofs4_oz_mode(sbi)) {

		if (!d_mountpoint(dentry))

		if (!path_is_mountpoint(path))

			return -EISDIR;

		return 0;

	}
@@ -463,7 +463,7 @@ static int autofs4_d_manage(const struct path *path, bool rcu_walk) 


		if (ino->flags & AUTOFS_INF_WANT_EXPIRE)

			return 0;

		if (d_mountpoint(dentry))

		if (path_is_mountpoint(path))

			return 0;

		inode = d_inode_rcu(dentry);

		if (inode && S_ISLNK(inode->i_mode))
@@ -490,7 +490,7 @@ static int autofs4_d_manage(const struct path *path, bool rcu_walk) 
		 * we can avoid needless calls ->d_automount() and avoid

		 * an incorrect ELOOP error return.

		 */

		if ((!d_mountpoint(dentry) && !simple_empty(dentry)) ||

		if ((!path_is_mountpoint(path) && !simple_empty(dentry)) ||

		    (d_really_is_positive(dentry) && d_is_symlink(dentry)))

			status = -EISDIR;

	}

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