From: Yongqiang Yang Subject: [PATCH 02/13] ext4: add a function which adds a new desc to a fs Date: Thu, 11 Aug 2011 11:28:17 +0800 Message-ID: <1313033308-882-3-git-send-email-xiaoqiangnk@gmail.com> References: <1313033308-882-1-git-send-email-xiaoqiangnk@gmail.com> Cc: aedilger@gmail.com, tytso@mit.edu, Yongqiang Yang To: linux-ext4@vger.kernel.org Return-path: Received: from mail-pz0-f42.google.com ([209.85.210.42]:48649 "EHLO mail-pz0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753987Ab1HKDfa (ORCPT ); Wed, 10 Aug 2011 23:35:30 -0400 Received: by mail-pz0-f42.google.com with SMTP id 37so2947235pzk.1 for ; Wed, 10 Aug 2011 20:35:30 -0700 (PDT) In-Reply-To: <1313033308-882-1-git-send-email-xiaoqiangnk@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: This patch adds a function named ext4_add_new_desc() which adds a new desc to a fs and whose code is copied from ext4_group_add(). The function will be used by new resize implementation. Signed-off-by: Yongqiang Yang --- fs/ext4/resize.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 42 insertions(+), 0 deletions(-) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 6ffbdb6..4fcd515 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -735,6 +735,48 @@ exit_err: } } +/* + * ext4_add_new_desc() adds group descriptor of group @group + * + * @handle: journal handle + * @sb; super block + * @group: the group no. of the first group desc to be added + * @resize_inode: the resize inode + */ +static int ext4_add_new_desc(handle_t *handle, struct super_block *sb, + ext4_group_t group, struct inode *resize_inode) +{ + struct ext4_sb_info *sbi = EXT4_SB(sb); + struct ext4_super_block *es = sbi->s_es; + struct buffer_head *gdb_bh; + int gdb_off, gdb_num, err = 0; + int reserved_gdb = ext4_bg_has_super(sb, group) ? + le16_to_cpu(es->s_reserved_gdt_blocks) : 0; + + gdb_off = group % EXT4_DESC_PER_BLOCK(sb); + gdb_num = group / EXT4_DESC_PER_BLOCK(sb); + + /* + * We will only either add reserved group blocks to a backup group + * or remove reserved blocks for the first group in a new group block. + * Doing both would be mean more complex code, and sane people don't + * use non-sparse filesystems anymore. This is already checked above. + */ + if (gdb_off) { + gdb_bh = sbi->s_group_desc[gdb_num]; + err = ext4_journal_get_write_access(handle, gdb_bh); + if (err) + goto out; + + if (reserved_gdb && ext4_bg_num_gdb(sb, group)) + err = reserve_backup_gdb(handle, resize_inode, group); + } else + err = add_new_gdb(handle, resize_inode, group); + +out: + return err; +} + /* Add group descriptor data to an existing or new group descriptor block. * Ensure we handle all possible error conditions _before_ we start modifying * the filesystem, because we cannot abort the transaction and not have it -- 1.7.5.1