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

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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: Ian 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Ian Kent 2016-11-24 08:03:42 +11:00 committed by Al Viro
parent dd36a882e7
commit cfaf86ab6c
1 changed files with 7 additions and 7 deletions
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14
fs/autofs4/root.c
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@ -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;
}