Skip to content

Commit cde93be

Browse files
ebiedermAl Viro
authored and
Al Viro
committed
dcache: Handle escaped paths in prepend_path
A rename can result in a dentry that by walking up d_parent will never reach it's mnt_root. For lack of a better term I call this an escaped path. prepend_path is called by four different functions __d_path, d_absolute_path, d_path, and getcwd. __d_path only wants to see paths are connected to the root it passes in. So __d_path needs prepend_path to return an error. d_absolute_path similarly wants to see paths that are connected to some root. Escaped paths are not connected to any mnt_root so d_absolute_path needs prepend_path to return an error greater than 1. So escaped paths will be treated like paths on lazily unmounted mounts. getcwd needs to prepend "(unreachable)" so getcwd also needs prepend_path to return an error. d_path is the interesting hold out. d_path just wants to print something, and does not care about the weird cases. Which raises the question what should be printed? Given that <escaped_path>/<anything> should result in -ENOENT I believe it is desirable for escaped paths to be printed as empty paths. As there are not really any meaninful path components when considered from the perspective of a mount tree. So tweak prepend_path to return an empty path with an new error code of 3 when it encounters an escaped path. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1 parent 6f179af commit cde93be

File tree

1 file changed

+7
-0
lines changed

1 file changed

+7
-0
lines changed

Diff for: fs/dcache.c

+7
Original file line numberDiff line numberDiff line change
@@ -2926,6 +2926,13 @@ static int prepend_path(const struct path *path,
29262926

29272927
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
29282928
struct mount *parent = ACCESS_ONCE(mnt->mnt_parent);
2929+
/* Escaped? */
2930+
if (dentry != vfsmnt->mnt_root) {
2931+
bptr = *buffer;
2932+
blen = *buflen;
2933+
error = 3;
2934+
break;
2935+
}
29292936
/* Global root? */
29302937
if (mnt != parent) {
29312938
dentry = ACCESS_ONCE(mnt->mnt_mountpoint);

0 commit comments

Comments
 (0)