I could see this issue with,
1. replica 3 volume
2. arbiter volume
3. distribute volume

Looks like the issue is seen with libgfapi, and not on the volume type

Seeing the following bt. Backtrace of the thread ( that segfaults )doesn't have enough information


Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7f3c95fb6700 (LWP 3324)]
0x00007f3c963f26f3 in ?? ()
(gdb) bt
#0  0x00007f3c963f26f3 in ?? ()
#1  0x0000000000000000 in ?? ()
(gdb) thread apply all bt

Thread 11 (Thread 0x7f3ca2890700 (LWP 3317)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x00007f3ca5fd69d8 in syncenv_task (proc=proc@entry=0x7f3caeba4040) at syncop.c:603
#2  0x00007f3ca5fd7820 in syncenv_processor (thdata=0x7f3caeba4040) at syncop.c:695
#3  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3ca2890700) at pthread_create.c:308
#4  0x00007f3ca89eaced in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 10 (Thread 0x7f3ca208f700 (LWP 3318)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x00007f3ca5fd69d8 in syncenv_task (proc=proc@entry=0x7f3caeba4400) at syncop.c:603
#2  0x00007f3ca5fd7820 in syncenv_processor (thdata=0x7f3caeba4400) at syncop.c:695
#3  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3ca208f700) at pthread_create.c:308
#4  0x00007f3ca89eaced in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 9 (Thread 0x7f3c95fb6700 (LWP 3324)):
#0  0x00007f3c963f26f3 in ?? ()
#1  0x0000000000000000 in ?? ()

Thread 8 (Thread 0x7f3c99765700 (LWP 3326)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x00007f3ca5fd69d8 in syncenv_task (proc=proc@entry=0x7f3cb0d24040) at syncop.c:603
#2  0x00007f3ca5fd7820 in syncenv_processor (thdata=0x7f3cb0d24040) at syncop.c:695
#3  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3c99765700) at pthread_create.c:308
#4  0x00007f3ca89eaced in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 7 (Thread 0x7f3c98560700 (LWP 3327)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x00007f3ca5fd69d8 in syncenv_task (proc=proc@entry=0x7f3cb0d24400) at syncop.c:603
#2  0x00007f3ca5fd7820 in syncenv_processor (thdata=0x7f3cb0d24400) at syncop.c:695
#3  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3c98560700) at pthread_create.c:308
#4  0x00007f3ca89eaced in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 6 (Thread 0x7f3c95eb5700 (LWP 3328)):
#0  0x00007f3ca8cc496d in nanosleep () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f3ca5fab816 in gf_timer_proc (data=0x7f3caea26640) at timer.c:176
#2  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3c95eb5700) at pthread_create.c:308
#3  0x00007f3ca89eaced in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 5 (Thread 0x7f3c97934700 (LWP 3329)):
#0  0x00007f3ca8cbeef7 in pthread_join (threadid=139898209384192, thread_return=thread_return@entry=0x0) at pthread_join.c:92
#1  0x00007f3ca5ff83b8 in event_dispatch_epoll (event_pool=0x7f3cb0d2e040) at event-epoll.c:758
#2  0x00007f3cab349c64 in glfs_poller (data=<optimized out>) at glfs.c:612
#3  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3c97934700) at pthread_create.c:308
#4  0x00007f3ca89eaced in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 4 (Thread 0x7f3c97133700 (LWP 3330)):
#0  0x00007f3ca89eb2c3 in epoll_wait () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f3ca5ff7e10 in event_dispatch_epoll_worker (data=0x7f3caea0ba20) at event-epoll.c:664
---Type <return> to continue, or q <return> to quit---
#2  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3c97133700) at pthread_create.c:308
#3  0x00007f3ca89eaced in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 3 (Thread 0x7f3c9442c700 (LWP 3331)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x00007f3c948686f3 in iot_worker (data=0x7f3cb0382200) at io-threads.c:176
#2  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3c9442c700) at pthread_create.c:308
#3  0x00007f3ca89eaced in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 2 (Thread 0x7f3c9432b700 (LWP 3332)):
#0  0x00007f3ca89eb2c3 in epoll_wait () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f3ca5ff7e10 in event_dispatch_epoll_worker (data=0x7f3cb0f363a0) at event-epoll.c:664
#2  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3c9432b700) at pthread_create.c:308
#3  0x00007f3ca89eaced in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 1 (Thread 0x7f3cac0058c0 (LWP 3316)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f3ca5fd866b in syncop_lookup (subvol=subvol@entry=0x7f3cb3404c40, loc=loc@entry=0x7f3caeb41a20, iatt=iatt@entry=0x7f3caeb41b50, parent=parent@entry=0x0, 
    xdata_in=xdata_in@entry=0x0, xdata_out=xdata_out@entry=0x0) at syncop.c:1223
#2  0x00007f3cab35b88f in glfs_resolve_base (fs=fs@entry=0x7f3caeb46000, subvol=subvol@entry=0x7f3cb3404c40, inode=inode@entry=0x7f3cb18ec05c, iatt=iatt@entry=0x7f3caeb41b50)
    at glfs-resolve.c:225
#3  0x00007f3cab35c09a in priv_glfs_resolve_at (fs=0x7f3caeb46000, subvol=0x7f3cb3404c40, at=at@entry=0x0, origpath=origpath@entry=0x7f3cab361c4e "/", loc=loc@entry=0x7f3caeb41ca0, 
    iatt=iatt@entry=0x7f3caeb41ce0, follow=follow@entry=1, reval=reval@entry=0) at glfs-resolve.c:404
#4  0x00007f3cab35d63c in glfs_resolve_path (fs=fs@entry=0x7f3caeb46000, subvol=subvol@entry=0x7f3cb3404c40, origpath=origpath@entry=0x7f3cab361c4e "/", loc=loc@entry=0x7f3caeb41ca0, 
    iatt=iatt@entry=0x7f3caeb41ce0, follow=follow@entry=1, reval=reval@entry=0) at glfs-resolve.c:530
#5  0x00007f3cab35d6d3 in priv_glfs_resolve (fs=fs@entry=0x7f3caeb46000, subvol=subvol@entry=0x7f3cb3404c40, origpath=origpath@entry=0x7f3cab361c4e "/", loc=loc@entry=0x7f3caeb41ca0, 
    iatt=iatt@entry=0x7f3caeb41ce0, reval=reval@entry=0) at glfs-resolve.c:557
#6  0x00007f3cab359df9 in pub_glfs_chdir (fs=fs@entry=0x7f3caeb46000, path=path@entry=0x7f3cab361c4e "/") at glfs-fops.c:3971
#7  0x00007f3cab34b144 in pub_glfs_init (fs=fs@entry=0x7f3caeb46000) at glfs.c:1003
#8  0x00007f3cac0477b3 in qemu_gluster_init (gconf=gconf@entry=0x7f3cae9fa2d0, filename=<optimized out>) at block/gluster.c:219
#9  0x00007f3cac047a03 in qemu_gluster_open (bs=<optimized out>, options=0x7f3cb0d29200, bdrv_flags=66, errp=<optimized out>) at block/gluster.c:341
#10 0x00007f3cac03d0b0 in bdrv_open_common (bs=bs@entry=0x7f3cb0406000, file=file@entry=0x0, options=options@entry=0x7f3cb0d29200, flags=flags@entry=2, 
    drv=drv@entry=0x7f3cac2dce80 <bdrv_gluster>, errp=0x7f3caeb41ea0) at block.c:836
#11 0x00007f3cac042194 in bdrv_file_open (pbs=pbs@entry=0x7f3caeb41f38, filename=filename@entry=0x7f3cae9fa030 "gluster://10.70.37.104/distvol/test3.img", options=0x7f3cb0d29200, 
    options@entry=0x0, flags=flags@entry=2, errp=errp@entry=0x7f3caeb41f40) at block.c:972
#12 0x00007f3cac057850 in qcow2_create2 (errp=0x7f3caeb41f30, version=3, prealloc=<optimized out>, cluster_size=65536, flags=0, backing_format=0x0, backing_file=0x0, 
    total_size=2097152, filename=0x7f3cae9fa030 "gluster://10.70.37.104/distvol/test3.img") at block/qcow2.c:1677
#13 qcow2_create (filename=0x7f3cae9fa030 "gluster://10.70.37.104/distvol/test3.img", options=<optimized out>, errp=0x7f3caeb41f90) at block/qcow2.c:1856
#14 0x00007f3cac03bbd9 in bdrv_create_co_entry (opaque=0x7fff3e460170) at block.c:393
#15 0x00007f3cac077a1a in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>) at coroutine-ucontext.c:118
#16 0x00007f3ca893b110 in ?? () from /lib64/libc.so.6
#17 0x00007fff3e45f9e0 in ?? ()
#18 0x0000000000000000 in ?? ()

To add to that information, this issue is not seen while creating raw image on gluster volume of any type

You mentioned a replica-3 volume; does this occur with a replica-2 volume?

I tried reproducing this with gluster 3.8.4, and a local build of qemu-img-1.5.3-105.el7, and I did not run into this issue.  However, my test gluster volume is as follows:

gluster volume info gv0
 
Volume Name: gv0
Type: Replicate
Volume ID: 6bcb7964-0594-4801-a60b-22dae7f871f6
Status: Started
Snapshot Count: 0
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Bricks:
Brick1: 192.168.15.180:/mnt/brick1/brick
Brick2: 192.168.15.180:/mnt/brick2/brick
Options Reconfigured:
performance.readdir-ahead: on

Status of volume: gv0
Gluster process                             TCP Port  RDMA Port  Online  Pid
------------------------------------------------------------------------------
Brick 192.168.15.180:/mnt/brick1/brick      49157     0          Y       7929 
Brick 192.168.15.180:/mnt/brick2/brick      49158     0          Y       7930 
NFS Server on localhost                     N/A       N/A        N       N/A  
Self-heal Daemon on localhost               N/A       N/A        Y       7916 
 
Task Status of Volume gv0
------------------------------------------------------------------------------
There are no active volume tasks



Creating the image:

qemu-img create -f qcow2 gluster://192.168.15.180/gv0/test-bz.qcow2 5G
Formatting 'gluster://192.168.15.180/gv0/test-bz.qcow2', fmt=qcow2 size=5368709120 encryption=off cluster_size=65536 lazy_refcounts=off 
[2016-09-28 03:29:42.693494] E [MSGID: 108006] [afr-common.c:4316:afr_notify] 0-gv0-replicate-0: All subvolumes are down. Going offline until atleast one of them comes back up.
[2016-09-28 03:29:43.812529] E [MSGID: 108006] [afr-common.c:4316:afr_notify] 0-gv0-replicate-0: All subvolumes are down. Going offline until atleast one of them comes back up.
[2016-09-28 03:29:44.706092] E [MSGID: 108006] [afr-common.c:4316:afr_notify] 0-gv0-replicate-0: All subvolumes are down. Going offline until atleast one of them comes back up


Verifying the image:
qemu-img info gluster://192.168.15.180/gv0/test-bz.qcow2
[2016-09-28 03:30:19.361722] E [MSGID: 108006] [afr-common.c:4316:afr_notify] 0-gv0-replicate-0: All subvolumes are down. Going offline until atleast one of them comes back up.
image: gluster://192.168.15.180/gv0/test-bz.qcow2
file format: qcow2
virtual size: 5.0G (5368709120 bytes)
disk size: 193K
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: false

(In reply to Jeff Cody from comment #7)
> You mentioned a replica-3 volume; does this occur with a replica-2 volume?
> 
> I tried reproducing this with gluster 3.8.4, and a local build of
> qemu-img-1.5.3-105.el7, and I did not run into this issue.  However, my test
> gluster volume is as follows:
> 
I tried with replica 2 volume as well.
I am hitting the same issue.

@Jeff, are you using the upstream gluster 3.8.4 ?
I am talking about the interim RHGS downstream build - glusterfs-3.8.4-1.el7rhgs on server, and glusterfs-3.8.4-1.el7 on client

(In reply to SATHEESARAN from comment #9)
> (In reply to Jeff Cody from comment #7)
> > You mentioned a replica-3 volume; does this occur with a replica-2 volume?
> > 
> > I tried reproducing this with gluster 3.8.4, and a local build of
> > qemu-img-1.5.3-105.el7, and I did not run into this issue.  However, my test
> > gluster volume is as follows:
> > 
> I tried with replica 2 volume as well.
> I am hitting the same issue.
> 
> @Jeff, are you using the upstream gluster 3.8.4 ?
> I am talking about the interim RHGS downstream build -
> glusterfs-3.8.4-1.el7rhgs on server, and glusterfs-3.8.4-1.el7 on client

Yes, I was using the upstream gluster 3.8.4.  I will retest with glusterfs-3.8.4-1.el7 and glusterfs-3.8.4-1.el7rhgs.

This reminds me of bug 1350789, which should have been fixed with glusterfs-3.8.1 (and hence in the RHGS-3.2 packages). I am not aware of any backports that could have re-introduced this though.

The easiest might be to reproduce the problem on a volume that consists out of a single brick. If someone has a system available where this happens, please let us know here so that we can debug it a little quicker (make sure that all needed -debuginfo RPMs are installed too).

Possibly also reported on the gluster-devel mailinglist, with suggestion of the backported patch that causes the problem:
 - http://www.gluster.org/pipermail/gluster-devel/2016-October/051234.html

I am not sure if http://review.gluster.org/15585 (in upstream glusterfs-3.8.5) was backported to glusterfs-3.8.4 in RHGS-3.2.

This looks like an issue with client-io-threads enabled (bug1381830). I see iot_worker threads -

Thread 3 (Thread 0x7f3c9442c700 (LWP 3331)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x00007f3c948686f3 in iot_worker (data=0x7f3cb0382200) at io-threads.c:176
#2  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3c9442c700) at pthread_create.c:308
#3  0x00007f3ca89eaced in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113


Its being discussed in gluster ML as well. I think you need to retest with client-io-threads disabled once.

(In reply to Soumya Koduri from comment #14)
> This looks like an issue with client-io-threads enabled (bug1381830). I see
> iot_worker threads -
> 
> Thread 3 (Thread 0x7f3c9442c700 (LWP 3331)):
> #0  pthread_cond_timedwait@@GLIBC_2.3.2 () at
> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
> #1  0x00007f3c948686f3 in iot_worker (data=0x7f3cb0382200) at
> io-threads.c:176
> #2  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3c9442c700) at
> pthread_create.c:308
> #3  0x00007f3ca89eaced in clone () at
> ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
> 
> 
> Its being discussed in gluster ML as well. I think you need to retest with
> client-io-threads disabled once.

Sas - given this crash is been already addressed and fixed with latest build (glusterfs-3.8.4-3) can we retest this behaviour (with out disabling client.io-threads of course) and close the bug if the issue doesn't persist?

(In reply to Atin Mukherjee from comment #15)
> (In reply to Soumya Koduri from comment #14)
> > This looks like an issue with client-io-threads enabled (bug1381830). I see
> > iot_worker threads -
> > 
> > Thread 3 (Thread 0x7f3c9442c700 (LWP 3331)):
> > #0  pthread_cond_timedwait@@GLIBC_2.3.2 () at
> > ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
> > #1  0x00007f3c948686f3 in iot_worker (data=0x7f3cb0382200) at
> > io-threads.c:176
> > #2  0x00007f3ca8cbddc5 in start_thread (arg=0x7f3c9442c700) at
> > pthread_create.c:308
> > #3  0x00007f3ca89eaced in clone () at
> > ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
> > 
> > 
> > Its being discussed in gluster ML as well. I think you need to retest with
> > client-io-threads disabled once.
> 
> Sas - given this crash is been already addressed and fixed with latest build
> (glusterfs-3.8.4-3) can we retest this behaviour (with out disabling
> client.io-threads of course) and close the bug if the issue doesn't persist?

Atin,

client-io-threads is enabled by default.
I have tested with and without client-io-threads, and I still see the same issue.

I have tested with the latest glusterfs downstream interim build - glusterfs-3.8.4-3.el7rhgs and I still see the same issue

All,

I tested with the latest downstream RHGS 3.2.0 interim build - glusterfs-3.8.4-5.el7rhgs.
I am no longer seeing this issue. 

Please provide the patch URL for the fix and move this bug to ON_QA with the proper fixed-in-version

Fix for BZ1391093 also fixes this issue. Following is the corresponding downstream patch:
https://code.engineering.redhat.com/gerrit/#/c/89229/

Therefore moving the bug to ON_QA.

Tested with RHGS 3.2.0 interim build ( glusterfs-3.8.4-5.el7rhgs )

1. Created qcow2 image on the replica 3 gluster volume

# qemu-img create gluster://<server>/<vol-name>/vm.img 10G

I could successfully create qcow2 images
# qemu-img check testvm.img 
No errors were found on the image.
Image end offset: 262144

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2017-0486.html