Re: [PATCH v2 10/12] btrfs-progs: check btrfs_super_used in lowmem check

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2021/8/19 上午5:33, Josef Bacik wrote:
> We can already fix this problem with the block accounting code, we just
> need to keep track of how much we should have used on the file system,
> and then check it against the bytes_super.  The repair just piggy backs
> on the block group used repair.
>
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>

Reviewed-by: Qu Wenruo <wqu@suse.com>

One unrelated concern inlined below.

> ---
>   check/mode-lowmem.c | 13 ++++++++++++-
>   check/mode-lowmem.h |  1 +
>   2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
> index 14815519..dacc5445 100644
> --- a/check/mode-lowmem.c
> +++ b/check/mode-lowmem.c
> @@ -28,6 +28,7 @@
>   #include "check/mode-lowmem.h"
>
>   static u64 last_allocated_chunk;
> +static u64 total_used = 0;
>
>   static int calc_extent_flag(struct btrfs_root *root, struct extent_buffer *eb,
>   			    u64 *flags_ret)
> @@ -3654,6 +3655,8 @@ next:
>   out:
>   	btrfs_release_path(&path);
>
> +	total_used += used;
> +
>   	if (total != used) {
>   		error(
>   		"block group[%llu %llu] used %llu but extent items used %llu",
> @@ -5556,6 +5559,14 @@ next:
>   	}
>   out:
>
> +	if (total_used != btrfs_super_bytes_used(gfs_info->super_copy)) {
> +		fprintf(stderr,
> +			"super bytes used %llu mismatches actual used %llu\n",
> +			btrfs_super_bytes_used(gfs_info->super_copy),
> +			total_used);
> +		err |= SUPER_BYTES_USED_ERROR;
> +	}
> +
>   	if (repair) {
>   		ret = end_avoid_extents_overwrite();
>   		if (ret < 0)
> @@ -5568,7 +5579,7 @@ out:
>   		if (ret)
>   			err |= ret;
>   		else
> -			err &= ~BG_ACCOUNTING_ERROR;
> +			err &= ~(BG_ACCOUNTING_ERROR|SUPER_BYTES_USED_ERROR);
>   	}
>
>   	btrfs_release_path(&path);
> diff --git a/check/mode-lowmem.h b/check/mode-lowmem.h
> index da9f8600..0bcc338b 100644
> --- a/check/mode-lowmem.h
> +++ b/check/mode-lowmem.h
> @@ -48,6 +48,7 @@
>   #define DIR_ITEM_HASH_MISMATCH	(1<<24) /* Dir item hash mismatch */
>   #define INODE_MODE_ERROR	(1<<25) /* Bad inode mode */
>   #define INVALID_GENERATION	(1<<26)	/* Generation is too new */
> +#define SUPER_BYTES_USED_ERROR	(1<<27)	/* Super bytes_used is invalid */

We're reaching U32 limit now...

Thanks,
Qu
>
>   /*
>    * Error bit for low memory mode check.
>