CIFS: Fix mkdir/rmdir bug for the non-POSIX case

Currently we do inc/drop_nlink for a parent directory for every
mkdir/rmdir calls. That's wrong when Unix extensions are disabled
because in this case a server doesn't follow the same semantic and
returns the old value on the next QueryInfo request. As the result,
we update our value with the server one and then decrement it on
every rmdir call - go to negative nlink values.

Fix this by removing inc/drop_nlink for the parent directory from
mkdir/rmdir, setting it for a revalidation and ignoring NumberOfLinks
for directories when Unix extensions are disabled.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Reviewed-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/inode.c

@@ -534,16 +534,21 @@ cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
 	if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
 		fattr->cf_mode = S_IFDIR | cifs_sb->mnt_dir_mode;
 		fattr->cf_dtype = DT_DIR;
+		/*
+		 * Server can return wrong NumberOfLinks value for directories
+		 * when Unix extensions are disabled - fake it.
+		 */
+		fattr->cf_nlink = 2;
 	} else {
 		fattr->cf_mode = S_IFREG | cifs_sb->mnt_file_mode;
 		fattr->cf_dtype = DT_REG;
 
 		/* clear write bits if ATTR_READONLY is set */
 		if (fattr->cf_cifsattrs & ATTR_READONLY)
 			fattr->cf_mode &= ~(S_IWUGO);
-	}
 
-	fattr->cf_nlink = le32_to_cpu(info->NumberOfLinks);
+		fattr->cf_nlink = le32_to_cpu(info->NumberOfLinks);
+	}
 
 	fattr->cf_uid = cifs_sb->mnt_uid;
 	fattr->cf_gid = cifs_sb->mnt_gid;
@@ -1322,7 +1327,6 @@ int cifs_mkdir(struct inode *inode, struct dentry *direntry, umode_t mode)
 			}
 /*BB check (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID ) to see if need
 	to set uid/gid */
-			inc_nlink(inode);
 
 			cifs_unix_basic_to_fattr(&fattr, pInfo, cifs_sb);
 			cifs_fill_uniqueid(inode->i_sb, &fattr);
@@ -1355,7 +1359,6 @@ int cifs_mkdir(struct inode *inode, struct dentry *direntry, umode_t mode)
 		d_drop(direntry);
 	} else {
 mkdir_get_info:
-		inc_nlink(inode);
 		if (pTcon->unix_ext)
 			rc = cifs_get_inode_info_unix(&newinode, full_path,
 						      inode->i_sb, xid);
@@ -1436,6 +1439,11 @@ int cifs_mkdir(struct inode *inode, struct dentry *direntry, umode_t mode)
 		}
 	}
 mkdir_out:
+	/*
+	 * Force revalidate to get parent dir info when needed since cached
+	 * attributes are invalid now.
+	 */
+	CIFS_I(inode)->time = 0;
 	kfree(full_path);
 	FreeXid(xid);
 	cifs_put_tlink(tlink);
@@ -1475,20 +1483,22 @@ int cifs_rmdir(struct inode *inode, struct dentry *direntry)
 	cifs_put_tlink(tlink);
 
 	if (!rc) {
-		drop_nlink(inode);
 		spin_lock(&direntry->d_inode->i_lock);
 		i_size_write(direntry->d_inode, 0);
 		clear_nlink(direntry->d_inode);
 		spin_unlock(&direntry->d_inode->i_lock);
 	}
 
 	cifsInode = CIFS_I(direntry->d_inode);
-	cifsInode->time = 0;	/* force revalidate to go get info when
-				   needed */
+	/* force revalidate to go get info when needed */
+	cifsInode->time = 0;
 
 	cifsInode = CIFS_I(inode);
-	cifsInode->time = 0;	/* force revalidate to get parent dir info
-				   since cached search results now invalid */
+	/*
+	 * Force revalidate to get parent dir info when needed since cached
+	 * attributes are invalid now.
+	 */
+	cifsInode->time = 0;
 
 	direntry->d_inode->i_ctime = inode->i_ctime = inode->i_mtime =
 		current_fs_time(inode->i_sb);