linux-ext4 - Re: [PATCH] ext4: reject the 'commit' option on ext2 filesystems

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Date:   Wed, 11 May 2022 18:01:22 +0530
From:   Ritesh Harjani <ritesh.list@...il.com>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     linux-ext4@...r.kernel.org, fstests@...r.kernel.org,
        Lukas Czerner <lczerner@...hat.com>
Subject: Re: [PATCH] ext4: reject the 'commit' option on ext2 filesystems

On 22/05/10 11:32AM, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@...gle.com>
>
> The 'commit' option is only applicable for ext3 and ext4 filesystems,
> and has never been accepted by the ext2 filesystem driver, so the ext4
> driver shouldn't allow it on ext2 filesystems.

Yes indeed.

Although with -o commit=1 it doesn't mount due to extra checks when commit is not
equal to it's default value where it also checks if the fs has journal or not.

[19084.421413] EXT4-fs (loop2): mounting ext2 file system using the ext4 subsystem
[19084.422679] EXT4-fs (loop2): can't mount with commit=1, fs mounted w/o journal


But when mounted with -o commit=5, ext2 gets mounted w/o this patch ;)

[19146.337981] EXT4-fs (loop2): mounting ext2 file system using the ext4 subsystem
[19146.345082] EXT4-fs (loop2): mounted filesystem without journal. Quota mode: none.

Feel free to add -

Reviewed-by: Ritesh Harjani <ritesh.list@...il.com>

-ritesh

>
> This fixes a failure in xfstest ext4/053.
>
> Fixes: 8dc0aa8cf0f7 ("ext4: check incompatible mount options while mounting ext2/3")
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> ---
>  fs/ext4/super.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 1847b46af8083..69d67724df24f 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1913,6 +1913,7 @@ static const struct mount_opts {
>  	 MOPT_EXT4_ONLY | MOPT_CLEAR},
>  	{Opt_warn_on_error, EXT4_MOUNT_WARN_ON_ERROR, MOPT_SET},
>  	{Opt_nowarn_on_error, EXT4_MOUNT_WARN_ON_ERROR, MOPT_CLEAR},
> +	{Opt_commit, 0, MOPT_NO_EXT2},
>  	{Opt_nojournal_checksum, EXT4_MOUNT_JOURNAL_CHECKSUM,
>  	 MOPT_EXT4_ONLY | MOPT_CLEAR},
>  	{Opt_journal_checksum, EXT4_MOUNT_JOURNAL_CHECKSUM,
>
> base-commit: 23e3d7f7061f8682c751c46512718f47580ad8f0
> --
> 2.36.1
>