[0/3] block: improve error reporting for unsupported O_DIRECT

Message

Daniel P. Berrangé July 1, 2020, 4:05 p.m. UTC

To repeat the commit message from patch 3...

Currently at startup if using cache=none on a filesystem lacking
O_DIRECT such as tmpfs, at startup QEMU prints

qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: file system may not support O_DIRECT
qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Could not open '/tmp/foo.img': Invalid argument

while at QMP level the hint is missing, so QEMU reports just

  "error": {
      "class": "GenericError",
      "desc": "Could not open '/tmp/foo.img': Invalid argument"
  }

which is close to useless for the end user trying to figure out what
they did wrong

With this change at startup QEMU prints

qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Unable to open '/tmp/foo.img' flags 0x4000: filesystem does not support O_DIRECT

while at the QMP level QEMU reports a massively more informative

  "error": {
     "class": "GenericError",
     "desc": "Unable to open '/tmp/foo.img' flags 0x4002: filesystem does not support O_DIRECT"
  }


qemu_open is used in many more places besides block layer, but
converting those to qemu_open_err is left as an exercise for
other maintainers.

Daniel P. Berrangé (3):
  util: validate whether O_DIRECT is supported after failure
  util: support detailed error reporting for qemu_open
  block: switch to use qemu_open_err for improved errors

 block/file-posix.c   | 10 +++----
 include/qemu/osdep.h |  1 +
 util/osdep.c         | 70 ++++++++++++++++++++++++++++++++++++++------
 3 files changed, 66 insertions(+), 15 deletions(-)

Comments

[e-mail] July 1, 2020, 4:58 p.m. UTC | #1

Patchew URL: https://patchew.org/QEMU/[e-mail]/



Hi,

This series failed the docker-quick@centos7 build test. Please find the testing commands and
their output below. If you have Docker installed, you can probably reproduce it
locally.

=== TEST SCRIPT BEGIN ===
#!/bin/bash
make docker-image-centos7 V=1 NETWORK=1
time make docker-test-quick@centos7 SHOW_ENV=1 J=14 NETWORK=1
=== TEST SCRIPT END ===

+++ /tmp/qemu-test/build/tests/qemu-iotests/226.out.bad 2020-07-01 16:58:11.321029717 +0000
@@ -6,7 +6,7 @@
 qemu-io: can't open: A regular file was expected by the 'file' driver, but something else was given
 qemu-io: warning: Opening a character device as a file using the 'file' driver is deprecated
 == Testing RW ==
-qemu-io: can't open: Could not open 'TEST_DIR/t.IMGFMT': Is a directory
+qemu-io: can't open: Unable to open 'TEST_DIR/t.IMGFMT' flags 0x2: Is a directory
 qemu-io: warning: Opening a character device as a file using the 'file' driver is deprecated
 
 === Testing with driver:host_device ===
@@ -14,13 +14,13 @@
---
Not run: 259
Failures: 061 069 111 226 244
Failed 5 of 119 iotests
make: *** [check-tests/check-block.sh] Error 1
Traceback (most recent call last):
  File "./tests/docker/docker.py", line 669, in <module>
    sys.exit(main())
---
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['sudo', '-n', 'docker', 'run', '--label', 'com.qemu.instance.uuid=67228a70e7844d70b07a864fef5c4569', '-u', '1003', '--security-opt', 'seccomp=unconfined', '--rm', '-e', 'TARGET_LIST=', '-e', 'EXTRA_CONFIGURE_OPTS=', '-e', 'V=', '-e', 'J=14', '-e', 'DEBUG=', '-e', 'SHOW_ENV=1', '-e', 'CCACHE_DIR=/var/tmp/ccache', '-v', '/home/patchew2/.cache/qemu-docker-ccache:/var/tmp/ccache:z', '-v', '/var/tmp/patchew-tester-tmp-y2quzqfb/src/docker-src.2020-07-01-12.41.12.23538:/var/tmp/qemu:z,ro', 'qemu:centos7', '/var/tmp/qemu/run', 'test-quick']' returned non-zero exit status 2.
filter=--filter=label=com.qemu.instance.uuid=67228a70e7844d70b07a864fef5c4569
make[1]: *** [docker-run] Error 1
make[1]: Leaving directory `/var/tmp/patchew-tester-tmp-y2quzqfb/src'
make: *** [docker-run-test-quick@centos7] Error 2

real    17m41.892s
user    0m5.790s


The full log is available at
http://patchew.org/logs/[e-mail]/testing.docker-quick@centos7/?type=message.
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