linux-kernel - Re: [PATCH v2 4/6] ext4: correct the reserved credits for extent conversion

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Message-ID: <df82bd94-3fe8-41ab-9a3b-b3fe75bdc0c4@huawei.com>
Date: Mon, 23 Jun 2025 16:12:06 +0800
From: Baokun Li <libaokun1@...wei.com>
To: Zhang Yi <yi.zhang@...weicloud.com>, <linux-ext4@...r.kernel.org>
CC: <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<tytso@....edu>, <adilger.kernel@...ger.ca>, <jack@...e.cz>,
	<ojaswin@...ux.ibm.com>, <yi.zhang@...wei.com>, <yukuai3@...wei.com>,
	<yangerkun@...wei.com>, Baokun Li <libaokun1@...wei.com>
Subject: Re: [PATCH v2 4/6] ext4: correct the reserved credits for extent
 conversion

On 2025/6/11 19:16, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@...wei.com>
>
> Now, we reserve journal credits for converting extents in only one page
> to written state when the I/O operation is complete. This is
> insufficient when large folio is enabled.
>
> Fix this by reserving credits for converting up to one extent per block in
> the largest 2MB folio, this calculation should only involve extents index
> and leaf blocks, so it should not estimate too many credits.
>
> Fixes: 7ac67301e82f ("ext4: enable large folio for regular file")
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
> Reviewed-by: Jan Kara <jack@...e.cz>

Looks good to me. Feel free to add:

Reviewed-by: Baokun Li <libaokun1@...wei.com>

> ---
>   fs/ext4/inode.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index b51de58518b2..67e37dd546eb 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2848,12 +2848,12 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
>   	mpd->journalled_more_data = 0;
>   
>   	if (ext4_should_dioread_nolock(inode)) {
> +		int bpf = ext4_journal_blocks_per_folio(inode);
>   		/*
>   		 * We may need to convert up to one extent per block in
> -		 * the page and we may dirty the inode.
> +		 * the folio and we may dirty the inode.
>   		 */
> -		rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,
> -						PAGE_SIZE >> inode->i_blkbits);
> +		rsv_blocks = 1 + ext4_ext_index_trans_blocks(inode, bpf);
>   	}
>   
>   	if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)