From: Andreas Dilger Subject: Re: [PATCH 02/13] ext4: add a function which adds a new desc to a fs Date: Wed, 10 Aug 2011 23:49:29 -0600 Message-ID: <883C890C-4FAB-4517-BB5C-47FB96AB4811@dilger.ca> References: <1313033308-882-1-git-send-email-xiaoqiangnk@gmail.com> <1313033308-882-3-git-send-email-xiaoqiangnk@gmail.com> Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: linux-ext4 List , Theodore Ts'o To: Yongqiang Yang Return-path: Received: from idcmail-mo2no.shaw.ca ([64.59.134.9]:59322 "EHLO idcmail-mo2no.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753210Ab1HKFta convert rfc822-to-8bit (ORCPT ); Thu, 11 Aug 2011 01:49:30 -0400 In-Reply-To: <1313033308-882-3-git-send-email-xiaoqiangnk@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2011-08-10, at 9:28 PM, Yongqiang Yang wrote: > 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. Similarly, this is duplicating a hunk of code from the middle of ext4_group_add(), and instead of just adding a second copy of that code, ext4_group_add() should be changed to call this new function to avoid the code duplication. > 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 > Cheers, Andreas