Description of problem:

While we have fixed similar problems in the past (BZ 1551486, BZ 1603104), we have not addressed the root problem yet, which is that qemu should generally ignore file locking errors when loosening restrictions, because they are not fatal.  Certainly that should not lead to crashes.


Version-Release number of selected component (if applicable):

qemu-kvm-rhev-2.12.0-32.el7


How reproducible:

Always


Steps to Reproduce:
1. qemu-img create -f qcow2 foo.qcow2 64M
Formatting 'foo.qcow2', fmt=qcow2 size=67108864 cluster_size=65536 lazy_refcounts=off refcount_bits=16
2. qemu-system-x86_64 -hda foo.qcow2 &
[1] 11659
3. rm foo.qcow2
4. kill %1
qemu-system-x86_64: terminating on signal 15 from pid 4518 (zsh)
Unexpected error in raw_reconfigure_getfd() at block/file-posix.c:903:
qemu-system-x86_64: Could not reopen file: No such file or directory
5. [1]  + 11659 abort (core dumped)  qemu-system-x86_64 -hda foo.qcow2

Actual results:

qemu aborts, as shown above.


Expected results:

qemu should not abort.


Additional info:

If “qemu crashes when it should exit” does not sound bad, the above experiment works just as well with eject:

$ qemu-img create -f qcow2 foo.qcow2 1440K
Formatting 'foo.qcow2', fmt=qcow2 size=1474560 cluster_size=65536 lazy_refcounts=off refcount_bits=16
$ (sleep 2; echo 'eject floppy0') | \
    qemu-system-x86_64 -fda foo.qcow2 -monitor stdio &; \
    sleep 1; rm foo.qcow2; wait %1             
[1] 15970 15971
QEMU 2.12.0 monitor - type 'help' for more information
(qemu) eject floppy0
Unexpected error in raw_reconfigure_getfd() at block/file-posix.c:903:
Could not reopen file: No such file or directory
[1]  + 15970 done                 ( sleep 2; echo 'eject floppy0'; ) | 
       15971 abort (core dumped)  qemu-system-x86_64 -fda foo.qcow2 -monitor stdio

Or with USB devices:

$ qemu-img create -f qcow2 foo.qcow2 64M
Formatting 'foo.qcow2', fmt=qcow2 size=67108864 cluster_size=65536 lazy_refcounts=off refcount_bits=16
$ (sleep 2; echo 'device_del usb0') | \
    qemu-system-x86_64 -drive if=none,id=drv0,file=foo.qcow2 \
                       -device qemu-xhci \
                       -device usb-storage,id=usb0,drive=drv0 \
                       -monitor stdio &; \
    sleep 1; rm foo.qcow2; wait %1
[1] 16672 16673
QEMU 2.12.0 monitor - type 'help' for more information
(qemu) device_del usb0
Unexpected error in raw_reconfigure_getfd() at block/file-posix.c:903:
Could not reopen file: No such file or directory
[1]  + 16672 done                 ( sleep 2; echo 'device_del usb0'; ) | 
       16673 abort (core dumped)  qemu-system-x86_64 -drive if=none,id=drv0,file=foo.qcow2


The RHEL 8 BZs are BZ 1709791 and BZ 1703793.