Re: [PATCH 2/2] f2fs: fix to allow removing qf_name

[Hongbo Li <lihongbo22@huawei.com>]

Hi Chao,

On 2025/8/18 10:09, Chao Yu wrote:
> The mount behavior changed after commit d18535132523 ("f2fs: separate the
> options parsing and options checking"), let's fix it.
> 
> [Scripts]
> mkfs.f2fs -f /dev/vdb
> mount -t f2fs -o usrquota /dev/vdb /mnt/f2fs
> quotacheck -uc /mnt/f2fs
> umount /mnt/f2fs
> mount -t f2fs -o usrjquota=aquota.user,jqfmt=vfsold /dev/vdb /mnt/f2fs
> mount|grep f2fs
> mount -t f2fs -o remount,usrjquota=,jqfmt=vfsold /dev/vdb /mnt/f2fs
> mount|grep f2fs
> dmesg
> 
> [Before commit]
> mount#1: ...,quota,jqfmt=vfsold,usrjquota=aquota.user,...
> mount#2: ...,quota,jqfmt=vfsold,...
> kmsg: no output
> 
> [After commit]
> mount#1: ...,quota,jqfmt=vfsold,usrjquota=aquota.user,...
> mount#2: ...,quota,jqfmt=vfsold,usrjquota=aquota.user,...
> kmsg: "user quota file already specified"
> 
> [After patch]
> mount#1: ...,quota,jqfmt=vfsold,usrjquota=aquota.user,...
> mount#2: ...,quota,jqfmt=vfsold,...
> kmsg: "remove qf_name aquota.user"
> 
> Fixes: d18535132523 ("f2fs: separate the options parsing and options checking")
> Cc: Hongbo Li <lihongbo22@huawei.com>
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
>   fs/f2fs/super.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 465604fdc5dd..07f6c8cac07a 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1219,8 +1219,11 @@ static int f2fs_check_quota_consistency(struct fs_context *fc,
>   				goto err_jquota_change;
>   
>   			if (old_qname) {
> -				if (new_qname &&
> -					strcmp(old_qname, new_qname) == 0) {
> +				if (!new_qname) {

Thanks for catching this. Do we also need the patch 1/2 ? It seems this 
patch also solve the syzbot problems.

Thanks,
Hongbo

> +					f2fs_info(sbi, "remove qf_name %s",
> +								old_qname);
> +					continue;
> +				} else if (strcmp(old_qname, new_qname) == 0) {
>   					ctx->qname_mask &= ~(1 << i);
>   					continue;
>   				}