On Fri, May 25, 2018 at 12:43:25PM +0800, Qu Wenruo wrote:
> Reported-by: Ken Swenson <flat@xxxxxxxxxxx>
> Reported-by: Ben Parsons <9parsonsb@xxxxxxxxx>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> fs/btrfs/disk-io.c | 43 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index b981ecc4b6f9..d6c0cee627d9 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2610,6 +2610,41 @@ static int btrfs_validate_mount_super(struct btrfs_fs_info *fs_info)
> return __validate_super(fs_info, fs_info->super_copy, 0);
> }
>
> +/*
> + * Check the validation of super block at write time.
> + * Some checks like bytenr check will be skipped as their values will be
> + * overwritten soon.
> + * Extra checks like csum type and incompact flags will be executed here.
> + */
> +static int btrfs_validate_write_super(struct btrfs_fs_info *fs_info,
> + struct btrfs_super_block *sb)
> +{
> + int ret;
> +
> + ret = __validate_super(fs_info, sb, -1);
Please note that the patches have been slightly updated in the committed
version. Updates to patches that come that late after the initial
iterations are more convenient as incremental updates.
> + if (ret < 0)
> + goto out;
> + if (btrfs_super_csum_type(sb) != BTRFS_CSUM_TYPE_CRC32) {
> + ret = -EUCLEAN;
> + btrfs_err(fs_info, "invalid csum type, has %u want %u",
> + btrfs_super_csum_type(sb), BTRFS_CSUM_TYPE_CRC32);
> + goto out;
> + }
> + if (btrfs_super_incompat_flags(sb) & ~BTRFS_FEATURE_INCOMPAT_SUPP) {
> + ret = -EUCLEAN;
> + btrfs_err(fs_info,
> + "invalid incompact flags, has 0x%llu valid mask 0x%llu",
> + btrfs_super_incompat_flags(sb),
> + BTRFS_FEATURE_INCOMPAT_SUPP);
> + goto out;
> + }
> +out:
> + if (ret < 0)
> + btrfs_err(fs_info,
> + "super block corruption detected before writing it to disk");
> + return ret;
> +}
> +
> int open_ctree(struct super_block *sb,
> struct btrfs_fs_devices *fs_devices,
> char *options)
> @@ -3770,6 +3805,14 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
> flags = btrfs_super_flags(sb);
> btrfs_set_super_flags(sb, flags | BTRFS_HEADER_FLAG_WRITTEN);
>
> + ret = btrfs_validate_write_super(fs_info, sb);
> + if (ret < 0) {
> + mutex_unlock(&fs_info->fs_devices->device_list_mutex);
> + btrfs_handle_fs_error(fs_info, -EUCLEAN,
> + "unexpected superblock corruption detected");
> + return -EUCLEAN;
The shortcut from here makes sense but we still have to wait for any
previous superblock writes that could have happened (write_dev_supers).
The sequence would be:
at device 1
check sb
write
at device 2
check sb
failed write
now the bh from device 1 write would have one more reference.
As the change is only in the 3rd patch, please send only that one and
based on the patch in misc-next. Thanks.
> + }
> +
> ret = write_dev_supers(dev, sb, max_mirrors);
(Here the reference gets incremented.)
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