Re: [Libguestfs] Error ret=-1 with EINTR in nbd_connect_systemd_socket_activation()
I found that the latest version of libnbd already included the fix. Thank you!
https://github.com/libguestfs/libnbd/commit/b3440853cdeca0e44ad9c526e71fa...
Thanks,
Motohiro Kawahito
-----Original Message-----
From: Richard W.M. Jones <rjones(a)redhat.com>
Sent: Tuesday, July 12, 2022 9:51 PM
To: Motohiro Kawahito <JL25131(a)jp.ibm.com>
Cc: libguestfs(a)redhat.com; eblake(a)redhat.com
Subject: [EXTERNAL] Re: [Libguestfs] Error ret=-1 with EINTR in
nbd_connect_systemd_socket_activation()
On Tue, Jul 12, 2022 at 05:33:41AM +0000, Motohiro Kawahito wrote:
Hi, I’d like to connect to an encrypted QCOW2 file by
nbd_connect_systemd_socket_activation(), but I got ret=-1 with EINTR.
In our program, signals are frequently occurred, so I think this is
the background of the problem. Could you advise me what should I do
next? (such as open issue in https://gitlab.com/nbdkit/libnbd or something).
The arg parameter I used is
qemu-nbd --object secret,id=sec0,data=abc123 --image-opts driver=
qcow2,encrypt.format=luks,encrypt.key-secret=sec0,file.filename=/tmp/
empty.qcow2
The program worked OK for me. I cleaned up a few things. The attached program contains
my clean-ups.
$ ./nbd
Before nbd_create
Before nbd_connect_systemd_socket_activation
After nbd_connect_systemd_socket_activation
size=8539292672
kill end
However I'm using a slightly newer libnbd & qemu-nbd:
libnbd-1.12.0-1.fc37.x86_64
qemu-img-6.1.0-14.fc35.x86_64
One more problem is that this qemu-nbd process still remains when
error occurred.
qemu-nbd should be cleaned up if you call nbd_close, otherwise it won't be cleaned up
(eg. if you immediately exit on error). See:
https://gitlab.com/nbdkit/libnbd/-/blob/e714b9a7403311a1a173a31d86234324e...
nbdkit has a feature called --exit-on-error which means it will always be cleaned up when
the parent process goes away, but qemu-nbd does not have this feature as far as I know.
It would be a useful addition.
https://libguestfs.org/nbdkit-captive.1.html#EXIT-WITH-PARENT
I also attached a test program below. Is there any problem in my test
program?
The version of qemu-nbd is
$ qemu-nbd -V
qemu-nbd 4.2.1 (Debian 1:4.2-3ubuntu6.23)
I created this encrypted QCOW2 image by the following command.
qemu-img create --object secret,id=sec0,data=abc123 -f qcow2 -o
encrypt.format=
luks,encrypt.key-secret=sec0 /tmp/empty.qcow2 8539292672
Here is a test program I made. I found that this error occurred even
for a normal QCOW2 file (not encrypted one). If you need more
information, please let me know.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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