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-rw-r--r--fs/dcache.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 4365998b8df..74da947b160 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2191,6 +2191,30 @@ int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
return result;
}
+int path_is_under(struct path *path1, struct path *path2)
+{
+ struct vfsmount *mnt = path1->mnt;
+ struct dentry *dentry = path1->dentry;
+ int res;
+ spin_lock(&vfsmount_lock);
+ if (mnt != path2->mnt) {
+ for (;;) {
+ if (mnt->mnt_parent == mnt) {
+ spin_unlock(&vfsmount_lock);
+ return 0;
+ }
+ if (mnt->mnt_parent == path2->mnt)
+ break;
+ mnt = mnt->mnt_parent;
+ }
+ dentry = mnt->mnt_mountpoint;
+ }
+ res = is_subdir(dentry, path2->dentry);
+ spin_unlock(&vfsmount_lock);
+ return res;
+}
+EXPORT_SYMBOL(path_is_under);
+
void d_genocide(struct dentry *root)
{
struct dentry *this_parent = root;