Re: [PATCH v2] ltp/fsx: avoid infinite loop while finding offset2 in clone/dedupe/copy range ops

[Eryu Guan <eguan@linux.alibaba.com>]

On Sat, Aug 24, 2019 at 10:41:07PM +0800, Eryu Guan wrote:
> From: Eryu Guan <eguan@linux.alibaba.com>
> 
> In CLONE/DEDUPE/COPY RANGE operations, we pick a "offset" and "size"
> first, then find a suitable "offset2" by looping if there's overlap
> (|offset2-offset| < size) or final file size is greater than max
> file size (offset2 + size > maxfilelen).
> 
> But it's possible that there's no such suitable offset2 and we loop
> forever. e.g. block_size = 4096, offset = 0, size = 4096 and
> maxfilelen is a value smaller than 8212 (which could be set via '-l'
> option).
> 
> Fix it by making sure maxfilelen/file_size is big enough to hold
> 'size' bytes from 'offset2', and just skip this operation if not.
> 
> Signed-off-by: Eryu Guan <eguan@linux.alibaba.com>

Ping on this patch.

Eryu

> ---
> v2:
> - don't use macro with ugly hacks, use an inline function instead
> 
>  ltp/fsx.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/ltp/fsx.c b/ltp/fsx.c
> index 06d08e4e93f3..890666ab6140 100644
> --- a/ltp/fsx.c
> +++ b/ltp/fsx.c
> @@ -1911,6 +1911,15 @@ fail:
>  	return 0;
>  }
>  
> +/* Check if range operations are possible to find a suitable offset */
> +static inline bool check_range(unsigned long op, unsigned long off,
> +			       unsigned long len, unsigned long size)
> +{
> +	bool ret = ((off + len * 2) <= size);
> +	if (!ret)
> +		log5(op, off, len, -1, FL_SKIPPED);
> +	return ret;
> +}
>  
>  int
>  test(void)
> @@ -1989,6 +1998,8 @@ test(void)
>  		TRIM_OFF_LEN(offset, size, file_size);
>  		offset = offset & ~(block_size - 1);
>  		size = size & ~(block_size - 1);
> +		if (!check_range(op, offset, size, maxfilelen))
> +			goto out;
>  		do {
>  			offset2 = random();
>  			TRIM_OFF(offset2, maxfilelen);
> @@ -2003,6 +2014,8 @@ test(void)
>  			TRIM_OFF_LEN(offset, size, file_size);
>  			offset = offset & ~(block_size - 1);
>  			size = size & ~(block_size - 1);
> +			if (!check_range(op, offset, size, file_size))
> +				goto out;
>  			do {
>  				if (tries++ >= 30) {
>  					size = 0;
> @@ -2020,6 +2033,8 @@ test(void)
>  		offset -= offset % readbdy;
>  		if (o_direct)
>  			size -= size % readbdy;
> +		if (!check_range(op, offset, size, maxfilelen))
> +			goto out;
>  		do {
>  			offset2 = random();
>  			TRIM_OFF(offset2, maxfilelen);
> -- 
> 2.21.0