From: Yongqiang Yang Subject: [PATCH 04/13] ext4: add a function which updates super block Date: Thu, 11 Aug 2011 11:28:19 +0800 Message-ID: <1313033308-882-5-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 S1753987Ab1HKDfe (ORCPT ); Wed, 10 Aug 2011 23:35:34 -0400 Received: by mail-pz0-f42.google.com with SMTP id 37so2947235pzk.1 for ; Wed, 10 Aug 2011 20:35:34 -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_update_super() which updates super block 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 | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 72 insertions(+), 0 deletions(-) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 6320baa..14be865 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -831,6 +831,78 @@ static int ext4_setup_new_desc(handle_t *handle, struct super_block *sb, return err; } +/* + * ext4_update_super() updates super so that new the added group can be seen + * by the filesystem. + * + * @sb: super block + */ +static void ext4_update_super(struct super_block *sb, + struct ext4_new_group_data *input) +{ + struct ext4_sb_info *sbi = EXT4_SB(sb); + struct ext4_super_block *es = sbi->s_es; + + /* + * Make the new blocks and inodes valid next. We do this before + * increasing the group count so that once the group is enabled, + * all of its blocks and inodes are already valid. + * + * We always allocate group-by-group, then block-by-block or + * inode-by-inode within a group, so enabling these + * blocks/inodes before the group is live won't actually let us + * allocate the new space yet. + */ + ext4_blocks_count_set(es, ext4_blocks_count(es) + + input->blocks_count); + le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb)); + + /* + * We need to protect s_groups_count against other CPUs seeing + * inconsistent state in the superblock. + * + * The precise rules we use are: + * + * * Writers must perform a smp_wmb() after updating all dependent + * data and before modifying the groups count + * + * * Readers must perform an smp_rmb() after reading the groups count + * and before reading any dependent data. + * + * NB. These rules can be relaxed when checking the group count + * while freeing data, as we can only allocate from a block + * group after serialising against the group count, and we can + * only then free after serialising in turn against that + * allocation. + */ + smp_wmb(); + + /* Update the global fs size fields */ + sbi->s_groups_count++; + + /* Update the reserved block counts only once the new group is + * active. */ + ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) + + input->reserved_blocks); + + /* Update the free space counts */ + percpu_counter_add(&sbi->s_freeblocks_counter, + input->free_blocks_count); + percpu_counter_add(&sbi->s_freeinodes_counter, + EXT4_INODES_PER_GROUP(sb)); + + if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG) && + sbi->s_log_groups_per_flex) { + ext4_group_t flex_group; + flex_group = ext4_flex_group(sbi, input->group); + atomic_add(input->free_blocks_count, + &sbi->s_flex_groups[flex_group].free_blocks); + atomic_add(EXT4_INODES_PER_GROUP(sb), + &sbi->s_flex_groups[flex_group].free_inodes); + } + +} + /* 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