Re: [PATCH] btrfs: add missing check for nocow and compression inode flags

Johannes Thumshirn
2020-07-10T10:17:59Z

On 10/07/2020 12:06, David Sterba wrote:
> +static int check_fsflags(unsigned int old_flags, unsigned int flags)
> {
> if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
> FS_NOATIME_FL | FS_NODUMP_FL | \
> @@ -174,9 +177,19 @@ static int check_fsflags(unsigned int flags)
> FS_NOCOW_FL))
> return -EOPNOTSUPP;
>
> + /* COMPR and NOCOMP on new/old are valid */
> if ((flags & FS_NOCOMP_FL) && (flags & FS_COMPR_FL))
> return -EINVAL;
>
> + if ((flags & FS_COMPR_FL) && (flags & FS_NOCOW_FL))
> + return -EINVAL;
> +
> + /* NOCOW and compression options are mutually exclusive */
> + if ((old_flags & FS_NOCOW_FL) && (flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
> + return -EINVAL;
> + if ((flags & FS_NOCOW_FL) && (old_flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
> + return -EINVAL;
> +

If we'd pass in fs_info to check_fsflags() we could also validate against mount options
which are incompatible with inode flags. Like -o nodatacow and FS_COMPR_FL or
-o auth_key and FS_NOCOW_FL.