Fix cifs_get_root()

Add missing ->i_mutex, convert to lookup_one_len() instead of
(broken) open-coded analog, cope with getting something like
a//b as relative pathname.  Simplify the hell out of it, while
we are there...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Jeff Layton <jlayton@redhat.com>

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 3e29899..bc4b12c 100644 (file)
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -35,6 +35,7 @@
 #include <linux/delay.h>
 #include <linux/kthread.h>
 #include <linux/freezer.h>
+#include <linux/namei.h>
 #include <net/ipv6.h>
 #include "cifsfs.h"
 #include "cifspdu.h"
@@ -542,14 +543,12 @@ static const struct super_operations cifs_super_ops = {
 static struct dentry *
 cifs_get_root(struct smb_vol *vol, struct super_block *sb)
 {
-       int xid, rc;
-       struct inode *inode;
-       struct qstr name;
-       struct dentry *dparent = NULL, *dchild = NULL, *alias;
+       struct dentry *dentry;
        struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
-       unsigned int i, full_len, len;
-       char *full_path = NULL, *pstart;
+       char *full_path = NULL;
+       char *s, *p;
        char sep;
+       int xid;
 
        full_path = cifs_build_path_to_root(vol, cifs_sb,
                                            cifs_sb_master_tcon(cifs_sb));
@@ -560,73 +559,32 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
 
        xid = GetXid();
        sep = CIFS_DIR_SEP(cifs_sb);
-       dparent = dget(sb->s_root);
-       full_len = strlen(full_path);
-       full_path[full_len] = sep;
-       pstart = full_path + 1;
-
-       for (i = 1, len = 0; i <= full_len; i++) {
-               if (full_path[i] != sep || !len) {
-                       len++;
-                       continue;
-               }
-
-               full_path[i] = 0;
-               cFYI(1, "get dentry for %s", pstart);
-
-               name.name = pstart;
-               name.len = len;
-               name.hash = full_name_hash(pstart, len);
-               dchild = d_lookup(dparent, &name);
-               if (dchild == NULL) {
-                       cFYI(1, "not exists");
-                       dchild = d_alloc(dparent, &name);
-                       if (dchild == NULL) {
-                               dput(dparent);
-                               dparent = ERR_PTR(-ENOMEM);
-                               goto out;
-                       }
-               }
-
-               cFYI(1, "get inode");
-               if (dchild->d_inode == NULL) {
-                       cFYI(1, "not exists");
-                       inode = NULL;
-                       if (cifs_sb_master_tcon(CIFS_SB(sb))->unix_ext)
-                               rc = cifs_get_inode_info_unix(&inode, full_path,
-                                                             sb, xid);
-                       else
-                               rc = cifs_get_inode_info(&inode, full_path,
-                                                        NULL, sb, xid, NULL);
-                       if (rc) {
-                               dput(dchild);
-                               dput(dparent);
-                               dparent = ERR_PTR(rc);
-                               goto out;
-                       }
-                       alias = d_materialise_unique(dchild, inode);
-                       if (alias != NULL) {
-                               dput(dchild);
-                               if (IS_ERR(alias)) {
-                                       dput(dparent);
-                                       dparent = ERR_PTR(-EINVAL); /* XXX */
-                                       goto out;
-                               }
-                               dchild = alias;
-                       }
-               }
-               cFYI(1, "parent %p, child %p", dparent, dchild);
-
-               dput(dparent);
-               dparent = dchild;
-               len = 0;
-               pstart = full_path + i + 1;
-               full_path[i] = sep;
-       }
-out:
+       dentry = dget(sb->s_root);
+       p = s = full_path;
+
+       do {
+               struct inode *dir = dentry->d_inode;
+               struct dentry *child;
+
+               /* skip separators */
+               while (*s == sep)
+                       s++;
+               if (!*s)
+                       break;
+               p = s++;
+               /* next separator */
+               while (*s && *s != sep)
+                       s++;
+
+               mutex_lock(&dir->i_mutex);
+               child = lookup_one_len(p, dentry, s - p);
+               mutex_unlock(&dir->i_mutex);
+               dput(dentry);
+               dentry = child;
+       } while (!IS_ERR(dentry));
        _FreeXid(xid);
        kfree(full_path);
-       return dparent;
+       return dentry;
 }
 
 static int cifs_set_super(struct super_block *sb, void *data)