Re: [f2fs-dev] [PATCH] common/attr: _acl_get_max echo 532 for f2fs

[Chao Yu <chao@kernel.org>]

On 2022/2/2 1:53, Eric Biggers wrote:
> On Sun, Jan 30, 2022 at 11:07:17PM +0800, Chao Yu wrote:
>> On 2022/1/30 17:28, Sun Ke wrote:
>>> Run generic/026 on f2fs, the diff:
>>>
>>>       -chacl: cannot set access acl on "largeaclfile": Argument list too long
>>>       +Wrong ACL count - 532 != 531
>>>
>>> The ACL_MAX_ENTRIES depend on MAX_VALUE_LEN(inode), MAX_VALUE_LEN(inode) I got
>>> by printk is 4244, so I think the ACL_MAX_ENTRIES should be
>>> (4244 - 20) / 8 + 4 =532.
>>>
>>> Signed-off-by: Sun Ke <sunke32@huawei.com>
>>
>> FYI:
>>
>> https://patchwork.kernel.org/project/fstests/patch/20170428131307.3384-1-chao@kernel.org/
>>
>> I've update the patch based on Jaegeuk's comments, however, I forgot to send it to
>> mailing list, so could you please check revised one below?
>>
>>  From 68965c837fd04795064b352589e3f7005e6d75f5 Mon Sep 17 00:00:00 2001
>> From: Chao Yu <chao@kernel.org>
>> Date: Fri, 28 Apr 2017 20:51:11 +0800
>> Subject: [PATCH v2] attr: adbjust acl_max of f2fs
>>
>> f2fs has set inline_xattr as a default option, and introduced a new option
>> named 'noinline_xattr' for disabling default inline_xattr option. So in
>> _acl_get_max we need to check 'noinline_xattr' string in fs option,
>> otherwise we may select the wrong max acl number since we always found
>> the string 'inline_xattr' in fs option.
>>
>> Additionally, f2fs has changed disk layout of xattr block a bit, so will
>> contain one more entry in both inline and noinline xattr inode, this patch
>> will modify the max acl number to adjust it.
>>
>> Signed-off-by: Chao Yu <chao@kernel.org>
>> ---
>> v2:
>> - adjust the config for old kernel as well.
>>   common/attr | 11 ++++++++---
>>   1 file changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/common/attr b/common/attr
>> index 35682d7c..6377a936 100644
>> --- a/common/attr
>> +++ b/common/attr
>> @@ -26,11 +26,16 @@ _acl_get_max()
>>   		echo 8191
>>   		;;
>>   	f2fs)
>> -		_fs_options $TEST_DEV | grep "inline_xattr" >/dev/null 2>&1
>> +		_fs_options $TEST_DEV | grep "noinline_xattr" >/dev/null 2>&1
>>   		if [ $? -eq 0 ]; then
>> -			echo 531
>> +			echo 507
>>   		else
>> -			echo 506
>> +			_fs_options $TEST_DEV | grep "inline_xattr" >/dev/null 2>&1
>> +			if [ $? -eq 0 ]; then
>> +				echo 532
>> +			else
>> +				echo 507
>> +			fi
>>   		fi
>>   		;;
> 
> Can you add a comment that explains how these numbers were calculated?  They
> seem very random.

I guess Sun Ke has given a good example...

If inline_xattr is enabled, max xattr size should be:
(4096 - 24 + 200) - (24 + 4) = 4244
then ACL_MAX_ENTRIES should be:
(4244 - (4 + 4 * 4)) / 8 + 4 = 532

Otherwise, if noinline_xattr is enabled, max xattr size should be:
(4096 - 24) - (24 + 4) = 4044
then ACL_MAX_ENTRIES should be:
(4044 - (4 + 4 * 4)) / 8 + 4 = 507

+Cc f2fs mailing list.

Thanks,

> 
> - Eric


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