linux-kernel - Re: [PATCH] f2fs: skip f2fs_preallocate

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YVNoHudG5c65X85G@google.com>
Date:   Tue, 28 Sep 2021 12:08:14 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

On 09/28, Chao Yu wrote:
> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
> check whethere it is overwrite case, for such case, we can skip
> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
> which may be blocked by checkpoint() potentially.
> 
> Signed-off-by: Chao Yu <chao@...nel.org>
> ---
>  fs/f2fs/file.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 13deae03df06..51fecb2f4db5 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  		preallocated = true;
>  		target_size = iocb->ki_pos + iov_iter_count(from);
>  
> +		if (f2fs_overwrite_io(inode, iocb->ki_pos,
> +						iov_iter_count(from)))
> +			goto write;

This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
case. Do we have other benefit?

> +
>  		err = f2fs_preallocate_blocks(iocb, from);
>  		if (err) {
>  out_err:
> -- 
> 2.32.0