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vfs: new internal helper: mnt_has_parent(mnt)

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vfsmounts have ->mnt_parent pointing either to a different vfsmount
or to itself; it's never NULL and termination condition in loops
traversing the tree towards root is mnt == mnt->mnt_parent.  At least
one place (see the next patch) is confused about what's going on;
let's add an explicit helper checking it right way and use it in
all places where we need it.  Not that there had been too many,
but...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2011-11-23 19:26:23 -05:00
parent aa9c0e07bb
commit b2dba1af3c
5 changed files with 18 additions and 12 deletions
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6
fs/dcache.c
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@@ -38,6 +38,7 @@
#include <linux/prefetch.h>
#include <linux/ratelimit.h>
#include "internal.h"
#include "mount.h"
/*
* Usage:
@@ -2460,9 +2461,8 @@ static int prepend_path(const struct path *path,
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
/* Global root? */
if (vfsmnt->mnt_parent == vfsmnt) {
if (!mnt_has_parent(vfsmnt))
goto global_root;
}
dentry = vfsmnt->mnt_mountpoint;
vfsmnt = vfsmnt->mnt_parent;
continue;
@@ -2862,7 +2862,7 @@ int path_is_under(struct path *path1, struct path *path2)
br_read_lock(vfsmount_lock);
if (mnt != path2->mnt) {
for (;;) {
if (mnt->mnt_parent == mnt) {
if (!mnt_has_parent(mnt)) {
br_read_unlock(vfsmount_lock);
return 0;
}