[Gluster-devel] a link issue maybe introduced in a bug fix " Don't let NFS cache stat after writes"

[Lian, George (NSB - CN/Hangzhou)]

Hi,

Please see detail test step on https://bugzilla.redhat.com/show_bug.cgi?id=1531457

How reproducible:


Steps to Reproduce:
1.create a volume name "test" with replicated
2.set volume option cluster.consistent-metadata with on:
  gluster v set test cluster.consistent-metadata on
3. mount volume test on client on /mnt/test
4. create a file aaa size more than 1 byte
   echo "1234567890" >/mnt/test/aaa
5. shutdown a replicat node, let's say sn-1, only let sn-0 worked
6. cp /mnt/test/aaa /mnt/test/bbb; link /mnt/test/bbb /mnt/test/ccc


BRs
George

From: gluster-devel-bounces at gluster.org [mailto:gluster-devel-bounces at gluster.org] On Behalf Of Pranith Kumar Karampuri
Sent: Thursday, January 11, 2018 12:39 PM
To: Lian, George (NSB - CN/Hangzhou) <george.lian at nokia-sbell.com>
Cc: Zhou, Cynthia (NSB - CN/Hangzhou) <cynthia.zhou at nokia-sbell.com>; Gluster-devel at gluster.org; Li, Deqian (NSB - CN/Hangzhou) <deqian.li at nokia-sbell.com>; Sun, Ping (NSB - CN/Hangzhou) <ping.sun at nokia-sbell.com>
Subject: Re: [Gluster-devel] a link issue maybe introduced in a bug fix " Don't let NFS cache stat after writes"



On Thu, Jan 11, 2018 at 6:35 AM, Lian, George (NSB - CN/Hangzhou) <george.lian at nokia-sbell.com<mailto:george.lian at nokia-sbell.com>> wrote:
Hi,
>>> In which protocol are you seeing this issue? Fuse/NFS/SMB?
It is fuse, within mountpoint by “mount -t glusterfs  …“ command.

Could you let me know the test you did so that I can try to re-create and see what exactly is going on?
Configuration of the volume and the steps to re-create the issue you are seeing would be helpful in debugging the issue further.


Thanks & Best Regards,
George

From: gluster-devel-bounces at gluster.org<mailto:gluster-devel-bounces at gluster.org> [mailto:gluster-devel-bounces at gluster.org<mailto:gluster-devel-bounces at gluster.org>] On Behalf Of Pranith Kumar Karampuri
Sent: Wednesday, January 10, 2018 8:08 PM
To: Lian, George (NSB - CN/Hangzhou) <george.lian at nokia-sbell.com<mailto:george.lian at nokia-sbell.com>>
Cc: Zhou, Cynthia (NSB - CN/Hangzhou) <cynthia.zhou at nokia-sbell.com<mailto:cynthia.zhou at nokia-sbell.com>>; Zhong, Hua (NSB - CN/Hangzhou) <hua.zhong at nokia-sbell.com<mailto:hua.zhong at nokia-sbell.com>>; Li, Deqian (NSB - CN/Hangzhou) <deqian.li at nokia-sbell.com<mailto:deqian.li at nokia-sbell.com>>; Gluster-devel at gluster.org<mailto:Gluster-devel at gluster.org>; Sun, Ping (NSB - CN/Hangzhou) <ping.sun at nokia-sbell.com<mailto:ping.sun at nokia-sbell.com>>
Subject: Re: [Gluster-devel] a link issue maybe introduced in a bug fix " Don't let NFS cache stat after writes"



On Wed, Jan 10, 2018 at 11:09 AM, Lian, George (NSB - CN/Hangzhou) <george.lian at nokia-sbell.com<mailto:george.lian at nokia-sbell.com>> wrote:
Hi, Pranith Kumar,

I has create a bug on Bugzilla https://bugzilla.redhat.com/show_bug.cgi?id=1531457
After my investigation for this link issue, I suppose your changes on afr-dir-write.c with issue " Don't let NFS cache stat after writes" , your fix is like:
--------------------------------------
       if (afr_txn_nothing_failed (frame, this)) {
                        /*if it did pre-op, it will do post-op changing ctime*/
                        if (priv->consistent_metadata &&
                            afr_needs_changelog_update (local))
                                afr_zero_fill_stat (local);
                        local->transaction.unwind (frame, this);
                }
In the above fix, it set the ia_nlink to ‘0’ if option consistent-metadata is set to “on”.
And hard link a file with which just created will lead to an error, and the error is caused in kernel function “vfs_link”:
if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE))
             error =  -ENOENT;

could you please have a check and give some comments here?

When stat is "zero filled", understanding is that the higher layer protocol doesn't send stat value to the kernel and a separate lookup is sent by the kernel to get the latest stat value. In which protocol are you seeing this issue? Fuse/NFS/SMB?


Thanks & Best Regards,
George



--
Pranith



--
Pranith
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