linux-ext4 - Re: [PATCH v2] ext4: remove the entry from es tree when bigalloc is enabled

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Date:	Mon, 29 Jul 2013 23:07:10 +0800
From:	Zheng Liu <gnehzuil.liu@...il.com>
To:	linux-ext4@...r.kernel.org, tytso@....edu
Cc:	Jan Kara <jack@...e.cz>, Zheng Liu <wenqing.lz@...bao.com>
Subject: Re: [PATCH v2] ext4: remove the entry from es tree when bigalloc is
 enabled

On Fri, Jul 26, 2013 at 07:42:06AM +0800, Zheng Liu wrote:
> From: Jan Kara <jack@...e.cz>
> 
> Now in ext4_da_page_release_reservation() we remove the entry from es
> tree if to_release != 0.  But there are two issues.  One is that it is
> wrong when blocksize != pagesize, another is that we don't need to do
> this if ->s_cluster_ratio == 1 because we will remove the entry in
> ext4_truncate/ext4_punch_hole.  Here we need to do this just because
> when ->s_cluster_ratio > 1 we will determine whether we can release
> the reserved space according to ext4_find_delalloc_cluster().
> 
> This commit tries to fix these problems.  Now we remove the entry from
> es tree only if ->s_cluster_ratio > 1.
> 
> Signed-off-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Zheng Liu <wenqing.lz@...bao.com>

Any comment?

Thanks,
                                                - Zheng

> ---
> v2:
>  * fix a typo in comment.
> 
>  fs/ext4/inode.c |   10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index ba33c67..2cc97a4 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1387,7 +1387,15 @@ static void ext4_da_page_release_reservation(struct page *page,
>  		curr_off = next_off;
>  	} while ((bh = bh->b_this_page) != head);
>  
> -	if (to_release) {
> +	/*
> +	 * Here we need to remove the entry from es tree because when bigalloc
> +	 * is enabled we need to determine whether we can release the reserved
> +	 * space according to the result of ext4_find_delalloc_cluster().
> +	 *
> +	 * If bigalloc is disabled, we don't need to do this here because these
> +	 * entries in es tree will be removed in ext4_truncate/ext4_punch_hole.
> +	 */
> +	if (sbi->s_cluster_ratio > 1 && to_release) {
>  		lblk = page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
>  		ext4_es_remove_extent(inode, lblk, to_release);
>  	}
> -- 
> 1.7.9.7
> 
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