linux-kernel - Re: [PATCH -next] ext4: Fix remount with 'abort' option isn't effective

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Date:   Tue, 21 Dec 2021 15:43:05 +0100
From:   Lukas Czerner <lczerner@...hat.com>
To:     Ye Bin <yebin10@...wei.com>
Cc:     tytso@....edu, adilger.kernel@...ger.ca,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        jack@...e.cz
Subject: Re: [PATCH -next] ext4: Fix remount with 'abort' option isn't
 effective

Hi,

nice catch. This is a bug indeed. However I am currently in a process of
changing the ctx_set/clear/test_ helpers because currently it generates
functions that are unused.

While I am at it I can just create a custom ctx_set_mount_flags()
helper that would behave as expected so that we won't have to specify
"1 < EXT4_MF_FS_ABORTED" which is not really obvious and hence error
prone.

My plan is to send my patch set including this one tomorrow, will that
be fine with you ?

-Lukas

On Tue, Dec 21, 2021 at 08:32:14PM +0800, Ye Bin wrote:
> We test remount with 'abort' option as follows:
> [root@...alhost home]# mount  /dev/sda test
> [root@...alhost home]# mount | grep test
> /dev/sda on /home/test type ext4 (rw,relatime)
> [root@...alhost home]# mount -o remount,abort test
> [root@...alhost home]# mount | grep test
> /dev/sda on /home/test type ext4 (rw,relatime)
> 
> Obviously, remount 'abort' option isn't effective.
> After 6e47a3cc68fc commit we process abort option with 'ctx_set_mount_flags':
> static inline void ctx_set_mount_flags(struct ext4_fs_context *ctx, int flag)
> {
> 	ctx->mask_s_mount_flags |= flag;
> 	ctx->vals_s_mount_flags |= flag;
> }
> 
> But we test 'abort' option with 'ext4_test_mount_flag':
> static inline int ext4_test_mount_flag(struct super_block *sb, int bit)
> {
>         return test_bit(bit, &EXT4_SB(sb)->s_mount_flags);
> }
> 
> To solve this issue, pass (1 <<  EXT4_MF_FS_ABORTED) to 'ctx_set_mount_flags'.
> 
> Fixes:6e47a3cc68fc("ext4: get rid of super block and sbi from handle_mount_ops()")
> Signed-off-by: Ye Bin <yebin10@...wei.com>
> ---
>  fs/ext4/super.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index b72d989b77fb..071b7b3c5678 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2236,7 +2236,7 @@ static int ext4_parse_param(struct fs_context *fc, struct fs_parameter *param)
>  			 param->key);
>  		return 0;
>  	case Opt_abort:
> -		ctx_set_mount_flags(ctx, EXT4_MF_FS_ABORTED);
> +		ctx_set_mount_flags(ctx, 1 << EXT4_MF_FS_ABORTED);
>  		return 0;
>  	case Opt_i_version:
>  		ctx_set_flags(ctx, SB_I_VERSION);
> -- 
> 2.31.1
>