Re: [PATCH] btrfs: use ASSERT to report logical error in cow_file_range()

[Nikolay Borisov <nborisov@suse.com>]

On 15.02.2018 06:30, Anand Jain wrote:
> Use ASSERT to report logical error in cow_file_range(), also move
> it a bit closer to when the num_bytes is derived.
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  fs/btrfs/inode.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 4b156e191592..5648c4425f1e 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -976,6 +976,8 @@ static noinline int cow_file_range(struct inode *inode,
>  
>  	num_bytes = ALIGN(end - start + 1, blocksize);
>  	num_bytes = max(blocksize,  num_bytes);
> +	ASSERT(!(num_bytes >
> +		 btrfs_super_total_bytes(fs_info->super_copy)));

The gist of the assert is to see if the range we want to cow is not
larger than the actual filesystem size. So just write it like:

ASSERT(numbytes <= btrfs_super_total_bytes(fs_info->super_copy))

It's a lot easier to grok.

>  
>  	inode_should_defrag(BTRFS_I(inode), start, end, num_bytes, SZ_64K);
>  
> @@ -1006,9 +1008,6 @@ static noinline int cow_file_range(struct inode *inode,
>  		}
>  	}
>  
> -	BUG_ON(num_bytes >
> -	       btrfs_super_total_bytes(fs_info->super_copy));
> -
>  	alloc_hint = get_extent_allocation_hint(inode, start, num_bytes);
>  	btrfs_drop_extent_cache(BTRFS_I(inode), start,
>  			start + num_bytes - 1, 0);
>