[libvirt] [RFC: PATCHv4 00/15] outgoing migration via fd: rather than exec:

[Wen Congyang]

At 03/10/2011 01:24 PM, Laine Stump Write:
> On 03/09/2011 08:45 PM, Eric Blake wrote:
>> Needs more testing - especially on root-squash NFS
> 
> Starting up a domain with backing store on root-squash NFS works fine.
> 
> When I try to save the domain to a directory on a root-squash NFS,
> though, the save hangs forever with a zombified child process with a
> WCHAN of "exit", and the parent process is sitting on recvmsg():

I save the domain to a directory on a root-squash NFS, and it works
fine.

Restoring the domain works fine too.

> 
> Thread 4 (Thread 0x7f6045f55700 (LWP 3754)):
> #0  0x000000332840e9cd in recvmsg () from /lib64/libpthread.so.0
> #1  0x00007f604ea7ddc9 in virFileOpenAs (
>     path=0x7f6038009e90 "/remote/vhost-libvirt/qemu/RHEL6.save",
>     openflags=577, mode=432, uid=107, gid=107, flags=1) at util/util.c:1513
> #2  0x00000000004416b0 in qemudDomainSaveFlag (driver=0xbb96f0,
>     dom=0x7f60380095a0, vm=0xd219c0,
>     path=0x7f6038009e90 "/remote/vhost-libvirt/qemu/RHEL6.save",
>     compressed=<value optimized out>) at qemu/qemu_driver.c:1924
> #3  0x0000000000441a12 in qemudDomainSave (dom=0x7f60380095a0,
>     path=0x7f6038009e90 "/remote/vhost-libvirt/qemu/RHEL6.save")
>     at qemu/qemu_driver.c:2143
> #4  0x00007f604eadeae6 in virDomainSave (domain=0x7f60380095a0,
>     to=0x7f6038009e90 "/remote/vhost-libvirt/qemu/RHEL6.save")
>     at libvirt.c:2280
> 
> I get a similar hang when I try to restore from an image saved on
> root-squash NFS.
> 
> (if it makes any difference, this is on F13, with qemu-kvm-0.13.0-1)
> 
> Do you want me to try bisecting it? Access to the machine?
> 
>> Eric Blake (15):
>>    qemu: use lighter-weight fd:n on incoming tunneled migration
>>    qemu: consolidate duplicated monitor migration code
>>    qemu: improve efficiency of dd during snapshots
>>    qemu: support migration to fd
>>    util: use SCM_RIGHTS in virFileOperation when needed
>>    qemu: allow simple domain save to use fd: protocol
>>    qemu: simplify domain save fd handling
>>    storage: simplify fd handling
>>    util: rename virFileOperation to virFileOpenAs
>>    util: adjust indentation in previous patch
>>    qemu, storage: improve type safety
>>    qemu: use common API for reading difficult files
>>    qemu: consolidate migration to file code
>>    qemu: skip granting access during fd migration
>>    qemu: support fd: migration with compression
>>
>>   src/libvirt_private.syms      |    2 +-
>>   src/qemu/qemu_driver.c        |  626
>> ++++++++++++++++-------------------------
>>   src/qemu/qemu_migration.c     |   45 +--
>>   src/qemu/qemu_monitor.c       |  124 ++++++++-
>>   src/qemu/qemu_monitor.h       |    4 +
>>   src/qemu/qemu_monitor_json.c  |  125 +--------
>>   src/qemu/qemu_monitor_json.h  |   23 +--
>>   src/qemu/qemu_monitor_text.c  |  123 +--------
>>   src/qemu/qemu_monitor_text.h  |   23 +--
>>   src/storage/storage_backend.c |   80 +++---
>>   src/util/util.c               |  161 ++++++++----
>>   src/util/util.h               |   15 +-
>>   12 files changed, 544 insertions(+), 807 deletions(-)
>>
> 
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