Bug 1635820

+++ This bug was initially created as a clone of Bug #1635136 +++

Description of problem:
--------------------------
when we issue a volume info from a node in the cluster, which doesnt host any of the bricks of that volume, we see ambiguous data as below
However the same is not seen when issued from a node which is hosting one of the bricks(in below case either from dhcp35-140/38/184)
This is reproducible always
Also, this is seen when the volume is created only
Once started, you don't see this



vol info from node which doesnt host brick
==========================================
Volume Name: rep3-8
Type: Replicate
Volume ID: ecff9a6e-0c14-4124-acfb-e41aff40debf
Status: Created
Snapshot Count: 0
Xlator 1: BD
Capability 1: thin
Capability 2: offload_copy
Capability 3: offload_snapshot
Number of Bricks: 1 x 3 = 3
Transport-type: tcp
Bricks:
Brick1: dhcp35-140.lab.eng.blr.redhat.com:/gluster/brick8/rep3-8
Brick1 VG: 
Brick2: dhcp35-38.lab.eng.blr.redhat.com:/gluster/brick8/rep3-8
Brick2 VG: 
Brick3: dhcp35-184.lab.eng.blr.redhat.com:/gluster/brick8/rep3-8
Brick3 VG: 
Options Reconfigured:
transport.address-family: inet
nfs.disable: on
performance.client-io-threads: off


volinfo from node which hosts brick
=====================================
 
Volume Name: rep3-8
Type: Replicate
Volume ID: ecff9a6e-0c14-4124-acfb-e41aff40debf
Status: Created
Snapshot Count: 0
Number of Bricks: 1 x 3 = 3
Transport-type: tcp
Bricks:
Brick1: dhcp35-140.lab.eng.blr.redhat.com:/gluster/brick8/rep3-8
Brick2: dhcp35-38.lab.eng.blr.redhat.com:/gluster/brick8/rep3-8
Brick3: dhcp35-184.lab.eng.blr.redhat.com:/gluster/brick8/rep3-8
Options Reconfigured:
transport.address-family: inet
nfs.disable: on
performance.client-io-threads: off



I did go through some volfiles and found a descrepency here


[root@dhcp35-140 bricks]# cat dhcp35-140.lab.eng.blr.redhat.com\:-gluster-brick8-rep3-8 
uuid=c63a0191-c6b0-4073-a0b0-f5ca0cf3f128
hostname=dhcp35-140.lab.eng.blr.redhat.com
path=/gluster/brick8/rep3-8
real_path=/gluster/brick8/rep3-8
listen-port=0
rdma.listen-port=0
decommissioned=0
brick-id=rep3-8-client-0
mount_dir=/rep3-8
snap-status=0
brick-fsid=64810
[root@dhcp35-140 bricks]# 



[root@dhcp35-140 bricks]# cat /var/lib/glusterd/vols/rep3-8/bricks/dhcp35-140.lab.eng.blr.redhat.com\:-gluster-brick8-rep3-8 
uuid=c63a0191-c6b0-4073-a0b0-f5ca0cf3f128
hostname=dhcp35-140.lab.eng.blr.redhat.com
path=/gluster/brick8/rep3-8
real_path=/gluster/brick8/rep3-8
listen-port=0
rdma.listen-port=0
decommissioned=0
brick-id=rep3-8-client-0
mount_dir=/rep3-8
snap-status=0
brick-fsid=64810  ------------------>From node which hosts volume
[root@dhcp35-140 bricks]# 



[root@dhcp35-218 bricks]# cat /var/lib/glusterd/vols/rep3-8/bricks/dhcp35-140.lab.eng.blr.redhat.com:-gluster-brick8-rep3-8
uuid=c63a0191-c6b0-4073-a0b0-f5ca0cf3f128
hostname=dhcp35-140.lab.eng.blr.redhat.com
path=/gluster/brick8/rep3-8
real_path=/gluster/brick8/rep3-8
listen-port=0
rdma.listen-port=0
decommissioned=0
brick-id=rep3-8-client-0
mount_dir=/rep3-8
snap-status=0
brick-fsid=0            ------------------>From node which doesnt host volume
[root@dhcp35-218 bricks]# 




Version-Release number of selected component (if applicable):
------------------------------
3.12.2-18

How reproducible:
=================
always

Steps to Reproduce:
1.have a 6 node cluster
2.create a 1x3 or arbiter volume with bricks from only 3 of the 6 nodes
3.issue volume info from any node which hosts the brick of the volume
4. issue vol info from any node which *doesnt* host brick of the volume

You can notice the discrepancy.
 

--- Additional comment from Atin Mukherjee on 2018-10-02 19:24:50 IST ---

Sanju has started working on this. Moving the state to Assigned.

--- Additional comment from Sanju on 2018-10-03 23:09:11 IST ---

RCA:
When "gluster v info" command is issued, glusterd_add_volume_detail_to_dict() will add all the data related to the respective volume into a dictionary.

a snippet from glusterd_add_volume_detail_to_dict() which adds BD xlator related information to the dict is:

#ifdef HAVE_BD_XLATOR
        if (volinfo->caps) {
                caps = 0;
                snprintf (key, 256, "volume%d.xlator0", count);
                buf = GF_MALLOC (256, gf_common_mt_char);
                if (!buf) {
                        ret = ENOMEM;
                        goto out;
                }
                if (volinfo->caps & CAPS_BD)
                        snprintf (buf, 256, "BD");
                ret = dict_set_dynstr (volumes, key, buf);
                if (ret) {
                        GF_FREE (buf);
                        goto out;
                }

                if (volinfo->caps & CAPS_THIN) {
                        snprintf (key, 256, "volume%d.xlator0.caps%d", count,
                                  caps++);
                        buf = GF_MALLOC (256, gf_common_mt_char);
                        if (!buf) {
                                ret = ENOMEM;
                                goto out;
                        }
                        snprintf (buf, 256, "thin");
                        ret = dict_set_dynstr (volumes, key, buf);
                        if (ret) {
                                GF_FREE (buf);
                                goto out;
                        }
                }

                if (volinfo->caps & CAPS_OFFLOAD_COPY) {
                        snprintf (key, 256, "volume%d.xlator0.caps%d", count,
                                  caps++);
                        buf = GF_MALLOC (256, gf_common_mt_char);
                        if (!buf) {
                                ret = ENOMEM;
                                goto out;
                        }
                        snprintf (buf, 256, "offload_copy");
                        ret = dict_set_dynstr (volumes, key, buf);
                        if (ret) {
                                GF_FREE (buf);
                                goto out;
                        }
                }

                if (volinfo->caps & CAPS_OFFLOAD_SNAPSHOT) {
                        snprintf (key, 256, "volume%d.xlator0.caps%d", count,
                                  caps++);
                        buf = GF_MALLOC (256, gf_common_mt_char);
                        if (!buf) {
                                ret = ENOMEM;
                                goto out;
                        }
                        snprintf (buf, 256, "offload_snapshot");
                        ret = dict_set_dynstr (volumes, key, buf);
                        if (ret)  {
                                GF_FREE (buf);
                                goto out;
                        }
                }

                if (volinfo->caps & CAPS_OFFLOAD_ZERO) {
                        snprintf (key, 256, "volume%d.xlator0.caps%d", count,
                                  caps++);
                        buf = GF_MALLOC (256, gf_common_mt_char);
                        if (!buf) {
                                ret = ENOMEM;
                                goto out;
                        }
                        snprintf (buf, 256, "offload_zerofill");
                        ret = dict_set_dynstr (volumes, key, buf);
                        if (ret)  {
                                GF_FREE (buf);
                                goto out;
                        }
                }

        }
#endif

A point to be noted here is, we disable BD xlator at the time of source compilation, only when RHEL version < 6.

So, the above block of code will be executed if volinfo->caps has a non-zero value (for RHEL>=6).

We set volinfo->caps during the volume creation in glusterd_op_create_volume(). caps value is set to 
caps = CAPS_BD | CAPS_THIN | CAPS_OFFLOAD_COPY | CAPS_OFFLOAD_SNAPSHOT in the beginning.

                if (!gf_uuid_compare (brickinfo->uuid, MY_UUID)) {
                        ret = sys_statvfs (brickinfo->path, &brickstat);
                        if (ret) {
                                gf_log ("brick-op", GF_LOG_ERROR, "Failed to fetch disk"
                                        " utilization from the brick (%s:%s). Please "
                                        "check health of the brick. Error code was %s",
                                        brickinfo->hostname, brickinfo->path,
                                        strerror (errno));
                                goto out;
                        }
                        brickinfo->statfs_fsid = brickstat.f_fsid;

#ifdef HAVE_BD_XLATOR
                        if (brickinfo->vg[0]) {
                                ret = glusterd_is_valid_vg (brickinfo, 0, msg);
                                if (ret) {
                                        gf_msg (this->name, GF_LOG_ERROR, 0,
                                                GD_MSG_INVALID_VG, "%s", msg);
                                        goto out;
                                }

                                /* if anyone of the brick does not have thin
                                   support, disable it for entire volume */
                                caps &= brickinfo->caps;
                        } else {
                                caps = 0;
                        }
#endif
                }

caps value will reset in the above code block. If brick doesn't belong to the same node, the caps value should be set to 0. In earlier versions of RHGS, we used to set caps to 0, if the brick doesn't belong to the same node or brickinfo->vg[0] is null. With the commit febf5ed4848, we are assigning caps to 0, only when brick belongs to the same node but brickinfo->vg[0] is null. We need to also set caps to 0, if the brick doesn't belong to the same node. 

Value of caps will be assigned to volinfo->caps, and glusterd_add_volume_detail_to_dict() uses volinfo->caps to add details into the dictionary. So, setting up correct value for volinfo->caps fixes the issue.

Thanks,
Sanju