[Qemu-commits] [qemu/qemu] 8cfd33: tools/virtiofsd: Add fstatfs64 syscall to the secc...

[Peter Maydell]

  Branch: refs/heads/staging
  Home:   https://github.com/qemu/qemu
  Commit: 8cfd339b3d402f913fe520a4f35f30152fb4fb80
      
https://github.com/qemu/qemu/commit/8cfd339b3d402f913fe520a4f35f30152fb4fb80
  Author: Thomas Huth <thuth@redhat.com>
  Date:   2021-09-16 (Thu, 16 Sep 2021)

  Changed paths:
    M tools/virtiofsd/passthrough_seccomp.c

  Log Message:
  -----------
  tools/virtiofsd: Add fstatfs64 syscall to the seccomp allowlist

The virtiofsd currently crashes on s390x when doing something like
this in the guest:

 mkdir -p /mnt/myfs
 mount -t virtiofs myfs /mnt/myfs
 touch /mnt/myfs/foo.txt
 stat -f /mnt/myfs/foo.txt

The problem is that the fstatfs64 syscall is called in this case
from the virtiofsd. We have to put it on the seccomp allowlist to
avoid that the daemon gets killed in this case.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001728
Suggested-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210914123214.181885-1-thuth@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Sergio Lopez <slp@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>


  Commit: 046d91c83caac29e2ba26c63fd7d685a57463f6d
      
https://github.com/qemu/qemu/commit/046d91c83caac29e2ba26c63fd7d685a57463f6d
  Author: Sergio Lopez <slp@redhat.com>
  Date:   2021-09-16 (Thu, 16 Sep 2021)

  Changed paths:
    M tools/virtiofsd/fuse_virtio.c

  Log Message:
  -----------
  virtiofsd: Reverse req_list before processing it

With the thread pool disabled, we add the requests in the queue to a
GList, processing by iterating over there afterwards.

For adding them, we're using "g_list_prepend()", which is more
efficient but causes the requests to be processed in reverse order,
breaking the read-ahead and request-merging optimizations in the host
for sequential operations.

According to the documentation, if you need to process the request
in-order, using "g_list_prepend()" and then reversing the list with
"g_list_reverse()" is more efficient than using "g_list_append()", so
let's do it that way.

Testing on a spinning disk (to boost the increase of read-ahead and
request-merging) shows a 4x improvement on sequential write fio test:

Test:
fio --directory=/mnt/virtio-fs --filename=fio-file1 --runtime=20
--iodepth=16 --size=4G --direct=1 --blocksize=4K --ioengine libaio
--rw write --name seqwrite-libaio

Without "g_list_reverse()":
...
Jobs: 1 (f=1): [W(1)][100.0%][w=22.4MiB/s][w=5735 IOPS][eta 00m:00s]
seqwrite-libaio: (groupid=0, jobs=1): err= 0: pid=710: Tue Aug 24 12:58:16 2021
  write: IOPS=5709, BW=22.3MiB/s (23.4MB/s)(446MiB/20002msec); 0 zone resets
...

With "g_list_reverse()":
...
Jobs: 1 (f=1): [W(1)][100.0%][w=84.0MiB/s][w=21.5k IOPS][eta 00m:00s]
seqwrite-libaio: (groupid=0, jobs=1): err= 0: pid=716: Tue Aug 24 13:00:15 2021
  write: IOPS=21.3k, BW=83.1MiB/s (87.2MB/s)(1663MiB/20001msec); 0 zone resets
...

Signed-off-by: Sergio Lopez <slp@redhat.com>
Message-Id: <20210824131158.39970-1-slp@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>


  Commit: 7adb961995a3744f51396502b33ad04a56a317c3
      
https://github.com/qemu/qemu/commit/7adb961995a3744f51396502b33ad04a56a317c3
  Author: Peter Maydell <peter.maydell@linaro.org>
  Date:   2021-09-19 (Sun, 19 Sep 2021)

  Changed paths:
    M tools/virtiofsd/fuse_virtio.c
    M tools/virtiofsd/passthrough_seccomp.c

  Log Message:
  -----------
  Merge remote-tracking branch 
'remotes/dgilbert-gitlab/tags/pull-virtiofs-20210916' into staging

virtiofsd pull 2021-08-16

Two minor fixes; one for performance, the other seccomp
on s390x.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

# gpg: Signature made Thu 16 Sep 2021 14:51:38 BST
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" 
[full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert-gitlab/tags/pull-virtiofs-20210916:
  virtiofsd: Reverse req_list before processing it
  tools/virtiofsd: Add fstatfs64 syscall to the seccomp allowlist

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>


Compare: https://github.com/qemu/qemu/compare/62e76dc7dab1...7adb961995a3