On Fri, Oct 11, 2019 at 17:07:09PM +0000, Bruce Fields wrote:
>On Tue, Oct 08, 2019 at 10:23:56PM +0200, Thomas Deutschmann wrote:
>> Hi,
>>
>> we have some user reporting that NFS v3 mounts are broken
>> when using glibc-2.29 and linux-4.9.x (4.9.128) because
>> statx() with mask=STATX_BASIC_STATS returns EINVAL.
>>
>> Looks like this isn't happening with <nfs-utils-2.4.1 or
>> newer kernels.
>>
>> The following workaround was confirmed to be working:
>>
>> --- a/support/misc/xstat.c 2019-06-24 21:31:55.260371592 +0200
>> +++ b/support/misc/xstat.c 2019-06-24 21:32:29.098777436 +0200
>> @@ -47,6 +47,8 @@
>> statx_copy(statbuf, &stxbuf);
>> return 0;
>> }
>> + if (errno == EINVAL)
>> + errno = ENOSYS;
>> if (errno == ENOSYS)
>> statx_supported = 0;
>> } else
>>
>>
>> Bug: https://bugs.gentoo.org/688644
>>
>> At the moment I have no clue whether this is kernel/glibc or
>> nfs-utils related; if the patch is safe to apply...
>
>Well, sounds like nfs-utils started using statx in 2.4.1. And just the
>fact that varying the kernel version makes it sound like there was a
>kernel bug causing an EINVAL return in this case, and that bug got
>fixed.
>
>One way to confirm might be running mount under strace and looking for
>that EINVAL return.
Just to provide an update on this issue, it was tracked down to glibc's
statx emulation not supporting AT_STATX_DONT_SYNC and returning EINVAL.
So on a kernel without statx support, but a new glibc with statx
support, nfs-utils will always fail to stat any paths.
Either this or a similar fix is required to support older kernels.
Doug
