When we tested the VM migartion between different hosts with NBD
devices, we found if we sent a cancel command after the drive_mirror
was just started, a coroutine re-enter error would occur. The stack
was as follow:
(gdb) bt
00) 0x00007fdfc744d885 in raise () from /lib64/libc.so.6
01) 0x00007fdfc744ee61 in abort () from /lib64/libc.so.6
02) 0x00007fdfca467cc5 in qemu_coroutine_enter (co=0x7fdfcaedb400, opaque=0x0)
at qemu-coroutine.c:118
03) 0x00007fdfca467f6c in qemu_co_queue_run_restart (co=0x7fdfcaedb400) at
qemu-coroutine-lock.c:59
04) 0x00007fdfca467be5 in coroutine_swap (from=0x7fdfcaf3c4e8,
to=0x7fdfcaedb400) at qemu-coroutine.c:96
05) 0x00007fdfca467cea in qemu_coroutine_enter (co=0x7fdfcaedb400, opaque=0x0)
at qemu-coroutine.c:123
06) 0x00007fdfca467f6c in qemu_co_queue_run_restart (co=0x7fdfcaedbdc0) at
qemu-coroutine-lock.c:59
07) 0x00007fdfca467be5 in coroutine_swap (from=0x7fdfcaf3c4e8,
to=0x7fdfcaedbdc0) at qemu-coroutine.c:96
08) 0x00007fdfca467cea in qemu_coroutine_enter (co=0x7fdfcaedbdc0, opaque=0x0)
at qemu-coroutine.c:123
09) 0x00007fdfca4a1fa4 in nbd_recv_coroutines_enter_all (s=0x7fdfcaef7dd0) at
block/nbd-client.c:41
10) 0x00007fdfca4a1ff9 in nbd_teardown_connection (client=0x7fdfcaef7dd0) at
block/nbd-client.c:50
11) 0x00007fdfca4a20f0 in nbd_reply_ready (opaque=0x7fdfcaef7dd0) at
block/nbd-client.c:92
12) 0x00007fdfca45ed80 in aio_dispatch (ctx=0x7fdfcae15e90) at aio-posix.c:144
13) 0x00007fdfca45ef1b in aio_poll (ctx=0x7fdfcae15e90, blocking=false) at
aio-posix.c:222
14) 0x00007fdfca448c34 in aio_ctx_dispatch (source=0x7fdfcae15e90, callback=0x0,
user_data=0x0) at async.c:212
15) 0x00007fdfc8f2f69a in g_main_context_dispatch () from
/usr/lib64/libglib-2.0.so.0
16) 0x00007fdfca45c391 in glib_pollfds_poll () at main-loop.c:190
17) 0x00007fdfca45c489 in os_host_main_loop_wait (timeout=1483677098) at
main-loop.c:235
18) 0x00007fdfca45c57b in main_loop_wait (nonblocking=0) at main-loop.c:484
19) 0x00007fdfca25f403 in main_loop () at vl.c:2249
20) 0x00007fdfca266fc2 in main (argc=42, argv=0x7ffff517d638,
envp=0x7ffff517d790) at vl.c:4814
We find the nbd_recv_coroutines_enter_all function (triggered by a cancel
command or a network connection breaking down) will enter a coroutine which
is waiting for the sending lock. If the lock is still held by another coroutine,
the entering coroutine will be added into the co_queue again. Latter, when the
lock is released, a coroutine re-enter error will occur.
This bug can be fixed simply by delaying the setting of recv_coroutine as
suggested by paolo. After applying this patch, we have tested the cancel
operation in mirror phase looply for more than 5 hous and everything is fine.
Without this patch, a coroutine re-enter error will occur in 5 minutes.
Signed-off-by: Bn Wu <wu.wubin@huawei.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1423552846-3896-1-git-send-email-wu.wubin@huawei.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Before this patch, the "opaque" pointer in an NBD BDS points to a
BDRVNBDState, which contains an NbdClientSession object, which in turn
contains a pointer to the BDS. This pointer may become invalid due to
bdrv_swap(), so drop it, and instead pass the BDS directly to the
nbd-client.c functions which then retrieve the NbdClientSession object
from there.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1423256778-3340-2-git-send-email-mreitz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This patch makes use of the Error object for nbd_receive_negotiate() so
that errors during negotiation look nicer.
Furthermore, this patch adds an additional error message if the received
magic was wrong, but would be correct for the other protocol version,
respectively: So if an export name was specified, but the NBD server
magic corresponds to an old handshake, this condition is explicitly
signaled to the user, and vice versa.
As these messages are now part of the "Could not open image" error
message, additional filtering has to be employed in iotest 083, which
this patch does as well.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Drop the assumption that we're using the main AioContext. Convert
qemu_aio_set_fd_handler() calls to aio_set_fd_handler().
The .bdrv_detach/attach_aio_context() interfaces also need to be
implemented to move the socket fd handler from the old to the new
AioContext.
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
nbd_receive_reply() is called by the event loop whenever data is
available or the socket has been closed by the remote side.
This patch closes the socket when an error occurs to prevent the
nbd_receive_reply() handler from being called indefinitely after the
connection has failed.
Note that we were already correctly returning EIO for pending requests
but leaving the nbd_receive_reply() handler registered resulted in high
CPU consumption and a flood of error messages.
Reuse nbd_teardown_connection() to close the socket.
Reported-by: Zhifeng Cai <bluewindow@h3c.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Make sure all pending coroutines are finished when closing the session.
Signed-off-by: Marc-André Lureau <marcandre.lureau@gmail.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
There is no need to keep the export name around, and it seems a better
fit as an argument in the init() call.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
The caller might handle non-blocking using coroutine. Leave the choice
to the caller to use a blocking or non-blocking negotiate.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
