[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,
>>> In which protocol are you seeing this issue? Fuse/NFS/SMB?
It is fuse, within mountpoint by “mount -t glusterfs  …“ command.

Thanks & Best Regards,
George

From: 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>
Cc: Zhou, Cynthia (NSB - CN/Hangzhou) <cynthia.zhou at nokia-sbell.com>; Zhong, Hua (NSB - CN/Hangzhou) <hua.zhong at nokia-sbell.com>; Li, Deqian (NSB - CN/Hangzhou) <deqian.li at nokia-sbell.com>; Gluster-devel at gluster.org; 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 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
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