[CIFS] Support deep tree mounts (e.g. mounts to //server/share/path)

Samba bugzilla #4040

Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 914239d5..66b825a 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -46,7 +46,8 @@
 build_path_from_dentry(struct dentry *direntry)
 {
 	struct dentry *temp;
-	int namelen = 0;
+	int namelen;
+	int pplen;
 	char *full_path;
 	char dirsep;
 
@@ -56,7 +57,9 @@
 		when the server crashed */
 
 	dirsep = CIFS_DIR_SEP(CIFS_SB(direntry->d_sb));
+	pplen = CIFS_SB(direntry->d_sb)->prepathlen;
 cifs_bp_rename_retry:
+	namelen = pplen; 
 	for (temp = direntry; !IS_ROOT(temp);) {
 		namelen += (1 + temp->d_name.len);
 		temp = temp->d_parent;
@@ -70,7 +73,6 @@
 	if(full_path == NULL)
 		return full_path;
 	full_path[namelen] = 0;	/* trailing null */
-
 	for (temp = direntry; !IS_ROOT(temp);) {
 		namelen -= 1 + temp->d_name.len;
 		if (namelen < 0) {
@@ -79,7 +81,7 @@
 			full_path[namelen] = dirsep;
 			strncpy(full_path + namelen + 1, temp->d_name.name,
 				temp->d_name.len);
-			cFYI(0, (" name: %s ", full_path + namelen));
+			cFYI(0, ("name: %s", full_path + namelen));
 		}
 		temp = temp->d_parent;
 		if(temp == NULL) {
@@ -88,18 +90,23 @@
 			return NULL;
 		}
 	}
-	if (namelen != 0) {
+	if (namelen != pplen) {
 		cERROR(1,
-		       ("We did not end path lookup where we expected namelen is %d",
+		       ("did not end path lookup where expected namelen is %d",
 			namelen));
-		/* presumably this is only possible if we were racing with a rename 
+		/* presumably this is only possible if racing with a rename 
 		of one of the parent directories  (we can not lock the dentries
 		above us to prevent this, but retrying should be harmless) */
 		kfree(full_path);
-		namelen = 0;
 		goto cifs_bp_rename_retry;
 	}
-
+	/* DIR_SEP already set for byte  0 / vs \ but not for
+	   subsequent slashes in prepath which currently must
+	   be entered the right way - not sure if there is an alternative
+	   since the '\' is a valid posix character so we can not switch
+	   those safely to '/' if any are found in the middle of the prepath */
+	/* BB test paths to Windows with '/' in the midst of prepath */
+	strncpy(full_path,CIFS_SB(direntry->d_sb)->prepath,pplen);
 	return full_path;
 }