[PATCH] fs: btrfs: limit the mapped length to the original length

[Andreas Schwab]

On Feb 13 2023, Qu Wenruo wrote:

> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 4aaaeab663f5..7d4095d9ca88 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -956,6 +956,7 @@ int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
>  	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
>  	struct cache_extent *ce;
>  	struct map_lookup *map;
> +	u64 orig_len = *length;
>  	u64 offset;
>  	u64 stripe_offset;
>  	u64 *raid_map = NULL;
> @@ -1047,6 +1048,7 @@ again:
>  	} else {
>  		*length = ce->size - offset;
>  	}
> +	*length = min_t(u64, *length, orig_len);
>  
>  	if (!multi_ret)
>  		goto out;

I can confirm that this fixes the issue.

-- 
Andreas Schwab, schwab at linux-m68k.org
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