Re: [PATCH] fsx: add more check for copy_file_range

[Su Yanjun <suyj.fnst@cn.fujitsu.com>]

在 2019/9/25 21:08, Eryu Guan 写道:
> On Wed, Sep 25, 2019 at 03:16:55PM +0800, Su Yanjun wrote:
>> On some linux distros(RHEL7, centos 7) copy_file_range uses
>> general implementation (splice interface). splice interace
>> uses pipe_to_file. pipe_to_file only work for different page.
>> The userspace cant's be  aware of such error because copy_file_range
>> returns ok too.
> This looks like a kernel bug to me.
Yes, it's RHEL kernel 3.10's bug. The new kernel is ok.
>> So for such case when copy_file_range return we read back data
>> then check it.
> Yeah, I think we should make sure the data copied is correct.
>
>> Signed-off-by: Su Yanjun <suyj.fnst@cn.fujitsu.com>
>> ---
>>   ltp/fsx.c | 32 ++++++++++++++++++++++++++++++++
>>   1 file changed, 32 insertions(+)
>>
>> diff --git a/ltp/fsx.c b/ltp/fsx.c
>> index 06d08e4..0439430 100644
>> --- a/ltp/fsx.c
>> +++ b/ltp/fsx.c
>> @@ -1602,6 +1602,7 @@ do_copy_range(unsigned offset, unsigned length, unsigned dest)
>>   	size_t olen;
>>   	ssize_t nr;
>>   	int tries = 0;
>> +	int ret = 0;
>>   
>>   	if (length == 0) {
>>   		if (!quiet && testcalls > simulatedopcount)
>> @@ -1665,6 +1666,37 @@ do_copy_range(unsigned offset, unsigned length, unsigned dest)
>>   		memset(good_buf + file_size, '\0', dest - file_size);
>>   	if (dest + length > file_size)
>>   		file_size = dest + length;
>> +	/*
>> +	 * Although copy_file_range returns ok
>> +	 * for some linux distros that use general implementation
>> +	 * (splice interface) such as RHEL 7, centos 7 that use
>> +	 * pipe_to_file will cause test fail.
>> +	 *
>> +	 * Here we add a little more check here for copy_file_range
>> +	 * We read copied data then check it. If check fail here
>> +	 * then report it.
>> +	 */
> Above comments seem like not necessary, the content check is inspired by
> Rthis HEL7 issue, but not the main purpose.
>
>> +	ret = lseek(fd, (off_t)dest, SEEK_SET);
>> +	if (ret == (off_t)-1) {
>> +		prterr("doread: lseek");
>                          ^^^^^^^ not doread
>
>> +		report_failure(140);
> Use a different failure number than that in doread, i.e. don't copy the
> code from doread.
>
>> +	}
>> +	ret = fsxread(fd, temp_buf, length, dest);
>> +	if (ret != length) {
>> +		if (ret == -1)
>> +				prterr("doread: read");
>> +		else
>> +				prt("short read: 0x%x bytes instead of 0x%x\n",
>> +					ret, length);
> Same here, not doread, and weired indention above.
>
>> +		report_failure(141);
>> +	}
>> +	if (memcmp(good_buf+dest, temp_buf, length) != 0) {
>> +		prt("copy range: 0x%x to 0x%x at 0x%x\n", offset,
>> +				offset + length, dest);
>> +		prterr("do_copy_range:");
>> +		report_failure(161);
> I think we could take use of check_buffers().
>
> And similar check could be added to do_clone_range as well, I think.

Ok, i'll send patch v2 later.

Thanks

>
> Thanks,
> Eryu
>
>> +
>> +	}
>>   }
>>   
>>   #else
>> -- 
>> 2.7.4
>>
>>
>>
>