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Date: Mon, 18 Jul 2011 11:46:25 +0800
From: Yongqiang Yang <xiaoqiangnk@...il.com>
To: Tao Ma <tm@....ma>
Cc: linux-ext4@...r.kernel.org
Subject: Re: [PATCH 09/12] ext4: simplify journal handling in ext4_setup_new_group_blocks
On Mon, Jul 18, 2011 at 11:40 AM, Tao Ma <tm@....ma> wrote:
> On 07/18/2011 11:21 AM, Yongqiang Yang wrote:
>> On Mon, Jul 18, 2011 at 11:09 AM, Tao Ma <tm@....ma> wrote:
>>> On 07/18/2011 10:52 AM, Yongqiang Yang wrote:
>>>> This patch simplifies journal handling in ext4_setup_new_group_blocks().
>>>>
>>>>
>>>> Signed-off-by: Yongqiang Yang <xiaoqiangnk@...il.com>
>>>> ---
>>>> fs/ext4/resize.c | 39 ++++++++++++++++++++-------------------
>>>> 1 files changed, 20 insertions(+), 19 deletions(-)
>>>>
>>>> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
>>>> index c91653c..ac5b63d 100644
>>>> --- a/fs/ext4/resize.c
>>>> +++ b/fs/ext4/resize.c
>>>> @@ -171,8 +171,7 @@ static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
>>>> * If that fails, restart the transaction & regain write access for the
>>>> * buffer head which is used for block_bitmap modifications.
>>>> */
>>>> -static int extend_or_restart_transaction(handle_t *handle, int thresh,
>>>> - struct buffer_head *bh)
>>>> +static int extend_or_restart_transaction(handle_t *handle, int thresh)
>>>> {
>>>> int err;
>>>>
>>>> @@ -183,9 +182,8 @@ static int extend_or_restart_transaction(handle_t *handle, int thresh,
>>>> if (err < 0)
>>>> return err;
>>>> if (err) {
>>>> - if ((err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
>>>> - return err;
>>>> - if ((err = ext4_journal_get_write_access(handle, bh)))
>>>> + err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA);
>>>> + if (err)
>>>> return err;
>>> you removed an ext4_journal_get_write_access here, and I didn't see you
>>> add it back anywhere.
>> This get_write_access() was used to guarantee modification on the
>> block bitmap is in the new handle in previous code. In previous code,
>> bitmap is modified everywhere in setup_group_blocks(), actually, this
>> makes things complicated, in this patch, the modifications on block
>> bitmap are batched and are done by ext4_set_bits() after
>> extend_or_restart_transaction(), so it is ok.
> oh, I see. You moved the initialization of bh after the extension of
> journal. OK, but please do describe all your changes in more detail in
> the commit log.
Yes, my carelessness.
Thank you for your review.
Yongqiang.
>
> Thanks
> Tao
>>
>> Thanks,
>> Yongqiang.
>>>
>>> Thanks
>>> Tao
>>>> }
>>>>
>>>> @@ -222,29 +220,24 @@ static int setup_new_group_blocks(struct super_block *sb,
>>>>
>>>> BUG_ON(input->group != sbi->s_groups_count);
>>>>
>>>> - if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
>>>> - err = PTR_ERR(bh);
>>>> - goto exit_journal;
>>>> - }
>>>> -
>>>> /* Copy all of the GDT blocks into the backup in this group */
>>>> for (i = 0, bit = 1, block = start + 1;
>>>> i < gdblocks; i++, block++, bit++) {
>>>> struct buffer_head *gdb;
>>>>
>>>> ext4_debug("update backup group %#04llx (+%d)\n", block, bit);
>>>> -
>>>> - if ((err = extend_or_restart_transaction(handle, 1, bh)))
>>>> - goto exit_bh;
>>>> + err = extend_or_restart_transaction(handle, 1);
>>>> + if (err)
>>>> + goto exit_journal;
>>>>
>>>> gdb = sb_getblk(sb, block);
>>>> if (!gdb) {
>>>> err = -EIO;
>>>> - goto exit_bh;
>>>> + goto exit_journal;
>>>> }
>>>> if ((err = ext4_journal_get_write_access(handle, gdb))) {
>>>> brelse(gdb);
>>>> - goto exit_bh;
>>>> + goto exit_journal;
>>>> }
>>>> lock_buffer(gdb);
>>>> memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, gdb->b_size);
>>>> @@ -253,7 +246,7 @@ static int setup_new_group_blocks(struct super_block *sb,
>>>> err = ext4_handle_dirty_metadata(handle, NULL, gdb);
>>>> if (unlikely(err)) {
>>>> brelse(gdb);
>>>> - goto exit_bh;
>>>> + goto exit_journal;
>>>> }
>>>> brelse(gdb);
>>>> }
>>>> @@ -264,7 +257,17 @@ static int setup_new_group_blocks(struct super_block *sb,
>>>> err = sb_issue_zeroout(sb, gdblocks + start + 1, reserved_gdb,
>>>> GFP_NOFS);
>>>> if (err)
>>>> - goto exit_bh;
>>>> + goto exit_journal;
>>>> +
>>>> + err = extend_or_restart_transaction(handle, 2);
>>>> + if (err)
>>>> + goto exit_journal;
>>>> +
>>>> + bh = bclean(handle, sb, input->block_bitmap);
>>>> + if (IS_ERR(bh)) {
>>>> + err = PTR_ERR(bh);
>>>> + goto exit_journal;
>>>> + }
>>>>
>>>> if (ext4_bg_has_super(sb, input->group)) {
>>>> ext4_debug("mark backup group tables %#04llx (+0)\n", start);
>>>> @@ -288,8 +291,6 @@ static int setup_new_group_blocks(struct super_block *sb,
>>>> ext4_set_bits(bh->b_data, input->inode_table - start,
>>>> sbi->s_itb_per_group);
>>>>
>>>> - if ((err = extend_or_restart_transaction(handle, 2, bh)))
>>>> - goto exit_bh;
>>>>
>>>> ext4_mark_bitmap_end(input->blocks_count, sb->s_blocksize * 8,
>>>> bh->b_data);
>>>
>>>
>>
>>
>>
>
>
--
Best Wishes
Yongqiang Yang
--
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