Re: [PATCH v2] f2fs: fix to preserve previous reserve_{blocks,node} value when remount

[Chao Yu <chao@kernel.org>]

On 3/5/26 11:22, Zhiguo Niu wrote:
> The following steps will change previous value of reserve_{blocks,node},
> this dones not match the original intention.
> 
> 1.mount -t f2fs -o reserve_root=8192 imgfile test_mount/
> F2FS-fs (loop56): Mounted with checkpoint version = 1b69f8c7
> mount info:
> /dev/block/loop56 on /data/test_mount type f2fs (xxx,reserve_root=8192,reserve_node=0,resuid=0,resgid=0,xxx)
> 
> 2.mount -t f2fs -o remount,reserve_root=4096 /data/test_mount
> F2FS-fs (loop56): Preserve previous reserve_root=8192
> check mount info: reserve_root change to 4096
> /dev/block/loop56 on /data/test_mount type f2fs (xxx,reserve_root=4096,reserve_node=0,resuid=0,resgid=0,xxx)
> 
> Prior to commit d18535132523 ("f2fs: separate the options parsing and options checking"),
> the value of reserve_{blocks,node} was only set during the first mount, along with
> the corresponding mount option F2FS_MOUNT_RESERVE_{ROOT,NODE} . If the mount option
> F2FS_MOUNT_RESERVE_{ROOT,NODE} was found to have been set during the mount/remount,
> the previously value of reserve_{blocks,node} would also be preserved, as shown in
> the code below.
>              if (test_opt(sbi, RESERVE_ROOT)) {
>                    f2fs_info(sbi, "Preserve previous reserve_root=%u",
>                           F2FS_OPTION(sbi).root_reserved_blocks);
>              } else {
>                    F2FS_OPTION(sbi).root_reserved_blocks = arg;
>                    set_opt(sbi, RESERVE_ROOT);
>              }
> But commit d18535132523 ("f2fs: separate the options parsing and options checking")
> only preserved the previous mount option; it did not preserve the previous value of
> reserve_{blocks,node}. Since value of reserve_{blocks,node} value is assigned
> or not depends on ctx->spec_mask, ctx->spec_mask should be alos handled in
> f2fs_check_opt_consistency.
> 
> This patch will clear the corresponding ctx->spec_mask bits in f2fs_check_opt_consistency
> to preserve the previously values of reserve_{blocks,node} if it already have a value.
> 
> Fixes: d18535132523 ("f2fs: separate the options parsing and options checking")
> Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
> ---
> v2: add more detail info in commit msg suggested by Chao

Thanks Zhiguo, the commit message makes sense to me, and it looks good now.

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,