linux-kernel - Re: [RFC PATCH 0/7] Enable exfat_get_block to support obtaining multiple clusters

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Message-ID: <CAKYAXd962j=77AQSk2dVmBeQak3yWhGP5B1TptLfSjzNX23CSg@mail.gmail.com>
Date: Fri, 21 Nov 2025 10:17:33 +0900
From: Namjae Jeon <linkinjeon@...nel.org>
To: Chi Zhiling <chizhiling@....com>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
	Matthew Wilcox <willy@...radead.org>, Sungjong Seo <sj1557.seo@...sung.com>, 
	Yuezhang Mo <yuezhang.mo@...y.com>, Chi Zhiling <chizhiling@...inos.cn>
Subject: Re: [RFC PATCH 0/7] Enable exfat_get_block to support obtaining
 multiple clusters

On Tue, Nov 18, 2025 at 5:26 PM Chi Zhiling <chizhiling@....com> wrote:
>
> From: Chi Zhiling <chizhiling@...inos.cn>
Hi Chi,
>
> The purpose of this patchset is to prepare for adapting exfat to iomap
> in the future. Currently, the main issue preventing exfat from supporting
> iomap is its inability to fetch multiple contiguous clusters.
Do you have a plan to work iomap support for exfat ?
>
> However, this patchset does not directly modify exfat_map_cluster and
> exfat_get_cluster to support multi-clusters. Instead, after obtaining
> the first cluster, it uses exfat_count_contig_clusters to retrieve the
> subsequent contiguous clusters.
>
> This approach is the one with the fewest changes among all the solutions
> I have attempted, making the modifications easier to review.
>
> This patchset includes two main changes: one reduces the number of sb_bread
> calls when accessing adjacent clusters to save time, and the other enables
> fetching multiple contiguous entries in exfat_get_blocks.
Are there any performance improvement measurements when applying this patch-set?

Thanks.
>
> Chi Zhiling (7):
>   exfat: add cache option for __exfat_ent_get
>   exfat: support reuse buffer head for exfat_ent_get
>   exfat: reuse cache to improve exfat_get_cluster
>   exfat: improve exfat_count_num_clusters
>   exfat: improve exfat_find_last_cluster
>   exfat: introduce exfat_count_contig_clusters
>   exfat: get mutil-clusters in exfat_get_block
>
>  fs/exfat/cache.c    | 11 ++++--
>  fs/exfat/exfat_fs.h |  6 ++-
>  fs/exfat/fatent.c   | 90 ++++++++++++++++++++++++++++++++++++---------
>  fs/exfat/inode.c    | 14 ++++++-
>  4 files changed, 97 insertions(+), 24 deletions(-)
>
> --
> 2.43.0
>