Commit Graph

91 Commits

Author SHA1 Message Date
Paolo Bonzini
ed76671888 9p: remove 'proxy' filesystem backend driver
It has been deprecated since 8.1; remove it and suggest using the 'local' file
system backend driver instead or virtiofsd.

Acked-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-10-03 19:33:25 +02:00
Stefan Weil
24c32ed374 docs: Fix some typos (found by typos) and grammar issues
Fix the misspellings of "overriden" also in code comments.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20240813125638.395461-1-sw@weilnetz.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240813202329.1237572-20-alex.bennee@linaro.org>
2024-08-16 14:12:59 +01:00
Anthony Harivel
84369d7621 tools: build qemu-vmsr-helper
Introduce a privileged helper to access RAPL MSR.

The privileged helper tool, qemu-vmsr-helper, is designed to provide
virtual machines with the ability to read specific RAPL (Running Average
Power Limit) MSRs without requiring CAP_SYS_RAWIO privileges or relying
on external, out-of-tree patches.

The helper tool leverages Unix permissions and SO_PEERCRED socket
options to enforce access control, ensuring that only processes
explicitly requesting read access via readmsr() from a valid Thread ID
can access these MSRs.

The list of RAPL MSRs that are allowed to be read by the helper tool is
defined in rapl-msr-index.h. This list corresponds to the RAPL MSRs that
will be supported in the next commit titled "Add support for RAPL MSRs
in KVM/QEMU."

The tool is intentionally designed to run on the Linux x86 platform.
This initial implementation is tailored for Intel CPUs but can be
extended to support AMD CPUs in the future.

Signed-off-by: Anthony Harivel <aharivel@redhat.com>
Link: https://lore.kernel.org/r/20240522153453.1230389-3-aharivel@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-07-22 13:50:21 +02:00
Samuel Tardieu
8a8be21dde docs/tools/qemu-img.rst: fix typo (sumarizes)
Signed-off-by: Samuel Tardieu <sam@rfc1149.net>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2023-12-23 19:35:47 +03:00
Andrey Drobyshev
26ea27898b qemu-img: add compression option to rebase subcommand
If we rebase an image whose backing file has compressed clusters, we
might end up wasting disk space since the copied clusters are now
uncompressed.  In order to have better control over this, let's add
"--compress" option to the "qemu-img rebase" command.

Note that this option affects only the clusters which are actually being
copied from the original backing file.  The clusters which were
uncompressed in the target image will remain so.

Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Message-ID: <20230919165804.439110-8-andrey.drobyshev@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-10-31 13:51:28 +01:00
Stefan Hajnoczi
78f8b6d9c8 Block layer patches
- Optimise reqs_lock to make multiqueue actually scale
 - virtio: Drop out of coroutine context in virtio_load()
 - iotests: Fix reference output for some tests after recent changes
 - vpc: Avoid dynamic stack allocation
 - Code cleanup, improved documentation
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Merge tag 'for-upstream' of https://repo.or.cz/qemu/kevin into staging

Block layer patches

- Optimise reqs_lock to make multiqueue actually scale
- virtio: Drop out of coroutine context in virtio_load()
- iotests: Fix reference output for some tests after recent changes
- vpc: Avoid dynamic stack allocation
- Code cleanup, improved documentation

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* tag 'for-upstream' of https://repo.or.cz/qemu/kevin:
  virtio: Drop out of coroutine context in virtio_load()
  vmstate: Mark VMStateInfo.get/put() coroutine_mixed_fn
  block: Make more BlockDriver definitions static
  block/meson.build: Restore alphabetical order of files
  block: Remove unnecessary variable in bdrv_block_device_info
  block: Remove bdrv_query_block_node_info
  vmdk: Clean up bdrv_open_child() return value check
  qemu-img: Update documentation for compressed images
  block: Be more verbose in create fallback
  block/iscsi: Document why we use raw malloc()
  qemu-img: omit errno value in error message
  block: change reqs_lock to QemuMutex
  block: minimize bs->reqs_lock section in tracked_request_end()
  iotests: adapt test output for new qemu_cleanup() behavior
  block/vpc: Avoid dynamic stack allocation

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2023-09-11 09:11:22 -04:00
Kevin Wolf
a675ca4c62 qemu-img: Update documentation for compressed images
Document the 'compression_type' option for qcow2, and mention that
streamOptimized vmdk supports compression, too.

Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230901102430.23856-1-kwolf@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-09-08 17:03:09 +02:00
Denis V. Lunev
35e087de08 qemu-nbd: document -v behavior in respect to --fork in man
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230906093210.339585-8-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: Wording improvement]
Signed-off-by: Eric Blake <eblake@redhat.com>
2023-09-08 07:21:43 -05:00
Christian Schoenebeck
71d72ececa 9pfs: deprecate 'proxy' backend
As recent CVE-2023-2861 (fixed by f6b0de53fb) once again showed, the 9p
'proxy' fs driver is in bad shape. Using the 'proxy' backend was already
discouraged for safety reasons before and we recommended to use the
'local' backend (preferably in conjunction with its 'mapped' security
model) instead, but now it is time to officially deprecate the 'proxy'
backend.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <E1qDkmw-0007M1-8f@lizzy.crudebyte.com>
2023-07-06 11:42:08 +02:00
Dr. David Alan Gilbert
e0dc2631ec virtiofsd: Remove source
Now remove all the source.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
2023-02-16 18:15:08 +00:00
Dr. David Alan Gilbert
8ab5e8a503 virtiofsd: Remove build and docs glue
Remove all the virtiofsd build and docs infrastructure.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
2023-02-16 18:15:08 +00:00
Alex Bennée
9d195efd65 docs: add hotlinks to about preface text
Make it easier to navigate the documentation.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230124180127.1881110-20-alex.bennee@linaro.org>
2023-02-02 10:44:23 +00:00
Stefan Weil
1e458f1127 Fix some typos in documentation and comments
Most of them were found and fixed using codespell.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20221030105944.311940-1-sw@weilnetz.de>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2022-11-05 20:35:45 +01:00
Markus Armbruster
7f118b433a qemu-img: Wean documentation and help output off '?' for help
'?' for help is deprecated since commit c8057f951d "Support 'help' as
a synonym for '?' in command line options", v1.2.0.  We neglected to
update output of qemu-img --help and the manual.  Do that now.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20220908130842.641410-1-armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-09-30 18:02:30 +02:00
Daniel P. Berrangé
7a21bee2aa misc: fix commonly doubled up words
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220707163720.1421716-5-berrange@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2022-08-01 11:58:02 +02:00
Thomas Huth
2d2e4843b6 Replace 'whitelist' with 'allow'
Let's use more inclusive language here and avoid terms
that are frowned upon nowadays.

Message-Id: <20220711095300.60462-1-thuth@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2022-07-18 20:24:36 +02:00
Xie Yongji
779d82e1d3 vduse-blk: Add name option
Currently we use 'id' option as the name of VDUSE device.
It's a bit confusing since we use one value for two different
purposes: the ID to identfy the export within QEMU (must be
distinct from any other exports in the same QEMU process, but
can overlap with names used by other processes), and the VDUSE
name to uniquely identify it on the host (must be distinct from
other VDUSE devices on the same host, but can overlap with other
export types like NBD in the same process). To make it clear,
this patch adds a separate 'name' option to specify the VDUSE
name for the vduse-blk export instead.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Message-Id: <20220614051532.92-7-xieyongji@bytedance.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-06-24 17:07:06 +02:00
Xie Yongji
0862a087fd vduse-blk: Add serial option
Add a 'serial' option to allow user to specify this value
explicitly. And the default value is changed to an empty
string as what we did in "hw/block/virtio-blk.c".

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Message-Id: <20220614051532.92-6-xieyongji@bytedance.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-06-24 17:07:06 +02:00
Stefan Hajnoczi
ca941c406c qsd: document vduse-blk exports
Document vduse-blk exports in qemu-storage-daemon --help and the
qemu-storage-daemon(1) man page.

Based-on: <20220523084611.91-1-xieyongji@bytedance.com>
Cc: Xie Yongji <xieyongji@bytedance.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220525121947.859820-1-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-06-24 17:07:06 +02:00
Liu Yiding
29320530cf docs: Correct the default thread-pool-size
Refer to 26ec190964 virtiofsd: Do not use a thread pool by default

Signed-off-by: Liu Yiding <liuyd.fnst@fujitsu.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Message-id: 20220413042054.1484640-1-liuyd.fnst@fujitsu.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-05-25 11:01:38 +01:00
Eric Blake
58a6fdcc9e nbd/server: Allow MULTI_CONN for shared writable exports
According to the NBD spec, a server that advertises
NBD_FLAG_CAN_MULTI_CONN promises that multiple client connections will
not see any cache inconsistencies: when properly separated by a single
flush, actions performed by one client will be visible to another
client, regardless of which client did the flush.

We always satisfy these conditions in qemu - even when we support
multiple clients, ALL clients go through a single point of reference
into the block layer, with no local caching.  The effect of one client
is instantly visible to the next client.  Even if our backend were a
network device, we argue that any multi-path caching effects that
would cause inconsistencies in back-to-back actions not seeing the
effect of previous actions would be a bug in that backend, and not the
fault of caching in qemu.  As such, it is safe to unconditionally
advertise CAN_MULTI_CONN for any qemu NBD server situation that
supports parallel clients.

Note, however, that we don't want to advertise CAN_MULTI_CONN when we
know that a second client cannot connect (for historical reasons,
qemu-nbd defaults to a single connection while nbd-server-add and QMP
commands default to unlimited connections; but we already have
existing means to let either style of NBD server creation alter those
defaults).  This is visible by no longer advertising MULTI_CONN for
'qemu-nbd -r' without -e, as in the iotest nbd-qemu-allocation.

The harder part of this patch is setting up an iotest to demonstrate
behavior of multiple NBD clients to a single server.  It might be
possible with parallel qemu-io processes, but I found it easier to do
in python with the help of libnbd, and help from Nir and Vladimir in
writing the test.

Signed-off-by: Eric Blake <eblake@redhat.com>
Suggested-by: Nir Soffer <nsoffer@redhat.com>
Suggested-by: Vladimir Sementsov-Ogievskiy <v.sementsov-og@mail.ru>
Message-Id: <20220512004924.417153-3-eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-05-12 13:10:52 +02:00
Denis V. Lunev
8e28b65f52 qemu-img: properly list formats which have consistency check implemented
Simple grep for the .bdrv_co_check callback presence gives the following
list of block drivers
* QED
* VDI
* VHDX
* VMDK
* Parallels
which have this callback. The presense of the callback means that
consistency check is supported.

The patch updates documentation accordingly.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220407083932.531965-1-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-05-04 15:55:23 +02:00
Liu Yiding
d45c83328f virtiofsd: Add docs/helper for killpriv_v2/no_killpriv_v2 option
virtiofsd has introduced killpriv_v2/no_killpriv_v2 for a while. Add
description of it to docs/helper.

Signed-off-by: Liu Yiding <liuyd.fnst@fujitsu.com>
Message-Id: <20220421095151.2231099-1-liuyd.fnst@fujitsu.com>

[Small documentation fixes: s/as client supports/as the client supports/
and s/.  /. /.
--Stefan]

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-04-21 12:05:15 +02:00
Eric Blake
a2c2d44ae1 docs: Consistent typography for options of qemu-nbd
Prefer the :option:`--name` form when cross-referencing other options
from the qemu-nbd documentation.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20220314203818.3681277-2-eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2022-03-21 15:19:58 -05:00
Daniel P. Berrangé
003b2b2521 qemu-nbd: add --tls-hostname option for TLS certificate validation
When using the --list option, qemu-nbd acts as an NBD client rather
than a server. As such when using TLS, it has a need to validate
the server certificate. This adds a --tls-hostname option which can
be used to override the default hostname used for certificate
validation.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220304193610.3293146-5-berrange@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
2022-03-07 15:58:42 -06:00
Hanna Reitz
2525edd85f qsd: Add --daemonize
To implement this, we reuse the existing daemonizing functions from the
system emulator, which mainly do the following:
- Fork off a child process, and set up a pipe between parent and child
- The parent process waits until the child sends a status byte over the
  pipe (0 means that the child was set up successfully; anything else
  (including errors or EOF) means that the child was not set up
  successfully), and then exits with an appropriate exit status
- The child process enters a new session (forking off again), changes
  the umask, and will ignore terminal signals from then on
- Once set-up is complete, the child will chdir to /, redirect all
  standard I/O streams to /dev/null, and tell the parent that set-up has
  been completed successfully

In contrast to qemu-nbd's --fork implementation, during the set up
phase, error messages are not piped through the parent process.
qemu-nbd mainly does this to detect errors, though (while os_daemonize()
has the child explicitly signal success after set up); because we do not
redirect stderr after forking, error messages continue to appear on
whatever the parent's stderr was (until set up is complete).

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220303164814.284974-4-hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-03-04 18:14:40 +01:00
Vivek Goyal
963061dc11 virtiofsd: Add an option to enable/disable security label
Provide an option "-o security_label/no_security_label" to enable/disable
security label functionality. By default these are turned off.

If enabled, server will indicate to client that it is capable of handling
one security label during file creation. Typically this is expected to
be a SELinux label. File server will set this label on the file. It will
try to set it atomically wherever possible. But its not possible in
all the cases.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-11-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-02-17 17:22:26 +00:00
Hanna Reitz
111fbd74f6 qemu-img: Unify [-b [-F]] documentation
qemu-img convert documents the backing file and backing format options
as follows:
    [-B backing_file [-F backing_fmt]]
whereas qemu-img create has this:
    [-b backing_file] [-F backing_fmt]

That is, for convert, we document that -F cannot be given without -B,
while for create, way say that they are independent.

Indeed, it is technically possible to give -F without -b, because it is
left to the block driver to decide whether this is an error or not, so
sometimes it is:

$ qemu-img create -f qed -F qed test.qed 64M
Formatting 'test.qed', fmt=qed size=67108864 backing_fmt=qed [...]

And sometimes it is not:

$ qemu-img create -f qcow2 -F qcow2 test.qcow2 64M
Formatting 'test.qcow2', fmt=qcow2 cluster_size=65536 [...]
qemu-img: test.qcow2: Backing format cannot be used without backing file

Generally, it does not make much sense, though, and users should only
give -F with -b, so document it that way, as we have already done for
qemu-img convert (commit 1899bf4737).

Reported-by: Tingting Mao <timao@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220131135908.32393-1-hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-02-01 13:49:15 +01:00
Hanna Reitz
cb90ec3a36 qsd: Document fuse's allow-other option
We did not add documentation to the storage daemon's man page for fuse's
allow-other option when it was introduced, so do that now.

Fixes: 8fc54f9428 ("export/fuse: Add allow-other option")
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220131103124.20325-1-hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-02-01 13:49:15 +01:00
Philippe Mathieu-Daudé
9bd11f9638 docs: Correct 'vhost-user-blk' spelling
Reported-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220107105420.395011-2-f4bug@amsat.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-01-14 12:03:16 +01:00
Thomas Huth
057dc9a635 docs/tools/qemu-trace-stap.rst: Do not hard-code the QEMU binary name
In downstream, we want to use a different name for the QEMU binary,
and some people might also use the docs for non-x86 binaries, that's
why we already created the |qemu_system| placeholder in the past.
Use it now in the stap trace doc, too.

Message-Id: <20220104103319.179870-1-thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2022-01-05 11:10:13 +01:00
Philippe Mathieu-Daudé
c5ba621954 docs: Render binary names as monospaced text
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211118192744.64325-1-philmd@redhat.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2021-11-22 15:02:38 +01:00
Rao, Lei
8f75cae2dd docs: Drop deprecated 'props' from object-add
In commit 5024340745 "qapi/qom: Drop deprecated 'props' from
object-add" (v6.0.0), we also should update documents.

Signed-off-by: Lei Rao <lei.rao@intel.com>
Message-Id: <1637567387-28250-1-git-send-email-lei.rao@intel.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2021-11-22 15:02:38 +01:00
Eric Blake
9a5d135267 qemu-img: Consistent docs for convert -F
Use consistent capitalization, and fix a missed line (we duplicate the
qemu-img synopses in too many places).

Fixes: 1899bf4737 (qemu-img: Add -F shorthand to convert)
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210921142812.2631605-1-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
2021-11-02 12:47:51 +01:00
Vivek Goyal
5afc8df46c virtiofsd: xattr mapping add a new type "unsupported"
Right now for xattr remapping, we support types of "prefix", "ok" or "bad".
Type "bad" returns -EPERM on setxattr and hides xattr in listxattr. For
getxattr, mapping code returns -EPERM but getxattr code converts it to -ENODATA.

I need a new semantics where if an xattr is unsupported, then
getxattr()/setxattr() return -ENOTSUP and listxattr() should hide the xattr.
This is needed to simulate that security.selinux is not supported by
virtiofs filesystem and in that case client falls back to some default
label specified by policy.

So add a new type "unsupported" which returns -ENOTSUP on getxattr() and
setxattr() and hides xattrs in listxattr().

For example, one can use following mapping rule to not support
security.selinux xattr and allow others.

"-o xattrmap=/unsupported/all/security.selinux/security.selinux//ok/all///"

Suggested-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <YUt9qbmgAfCFfg5t@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2021-10-25 18:48:23 +01:00
Nir Soffer
0961525705 qemu-nbd: Change default cache mode to writeback
Both qemu and qemu-img use writeback cache mode by default, which is
already documented in qemu(1). qemu-nbd uses writethrough cache mode by
default, and the default cache mode is not documented.

According to the qemu-nbd(8):

   --cache=CACHE
          The  cache  mode  to be used with the file.  See the
          documentation of the emulator's -drive cache=... option for
          allowed values.

qemu(1) says:

    The default mode is cache=writeback.

So users have no reason to assume that qemu-nbd is using writethough
cache mode. The only hint is the painfully slow writing when using the
defaults.

Looking in git history, it seems that qemu used writethrough in the past
to support broken guests that did not flush data properly, or could not
flush due to limitations in qemu. But qemu-nbd clients can use
NBD_CMD_FLUSH to flush data, so using writethrough does not help anyone.

Change the default cache mode to writback, and document the default and
available values properly in the online help and manual.

With this change converting image via qemu-nbd is 3.5 times faster.

    $ qemu-img create dst.img 50g
    $ qemu-nbd -t -f raw -k /tmp/nbd.sock dst.img

Before this change:

    $ hyperfine -r3 "./qemu-img convert -p -f raw -O raw -T none -W fedora34.img nbd+unix:///?socket=/tmp/nbd.sock"
    Benchmark #1: ./qemu-img convert -p -f raw -O raw -T none -W fedora34.img nbd+unix:///?socket=/tmp/nbd.sock
      Time (mean ± σ):     83.639 s ±  5.970 s    [User: 2.733 s, System: 6.112 s]
      Range (min … max):   76.749 s … 87.245 s    3 runs

After this change:

    $ hyperfine -r3 "./qemu-img convert -p -f raw -O raw -T none -W fedora34.img nbd+unix:///?socket=/tmp/nbd.sock"
    Benchmark #1: ./qemu-img convert -p -f raw -O raw -T none -W fedora34.img nbd+unix:///?socket=/tmp/nbd.sock
      Time (mean ± σ):     23.522 s ±  0.433 s    [User: 2.083 s, System: 5.475 s]
      Range (min … max):   23.234 s … 24.019 s    3 runs

Users can avoid the issue by using --cache=writeback[1] but the defaults
should give good performance for the common use case.

[1] https://bugzilla.redhat.com/1990656

Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Message-Id: <20210813205519.50518-1-nsoffer@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
2021-09-29 13:46:31 -05:00
Eric Blake
1899bf4737 qemu-img: Add -F shorthand to convert
Although we have long supported 'qemu-img convert -o
backing_file=foo,backing_fmt=bar', the fact that we have a shortcut -B
for backing_file but none for backing_fmt has made it more likely that
users accidentally run into:

qemu-img: warning: Deprecated use of backing file without explicit backing format

when using -B instead of -o.  For similarity with other qemu-img
commands, such as create and compare, add '-F $fmt' as the shorthand
for '-o backing_fmt=$fmt'.  Update iotest 122 for coverage of both
spellings.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210913131735.1948339-1-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
2021-09-15 18:42:38 +02:00
Paolo Bonzini
06905f6402 docs: standardize directory index to --- with overline
Use a standard heading format for the index.rst file in a directory.
Using overlines makes it clear that individual documents can use e.g.
=== for chapter titles and --- for section titles, as suggested in the
Linux kernel guidelines[1].  They could do it anyway, because documents
included in a toctree are parsed separately and therefore are not tied
to the same conventions for headings.  However, keeping some consistency is
useful since sometimes files are included from multiple places.

[1] https://www.kernel.org/doc/html/latest/doc-guide/sphinx.html

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-13 13:56:26 +02:00
Paolo Bonzini
8a1f7d299c docs: standardize book titles to === with overline
Documents within a Sphinx manual are separate files and therefore can use
different conventions for headings.  However, keeping some consistency is
useful so that included files are easy to get right.

This patch uses a standard heading format for book titles, so that it is
obvious when a file sits at the top level toctree of a book or man page.
The heading is irrelevant for man pages, but keep it consistent as well.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-13 13:56:26 +02:00
Peter Maydell
4d6646c7de docs/tools/virtiofsd.rst: Delete stray backtick
The documentation of the posix_acl option has a stray backtick
at the end of the text (which is rendered literally into the HTML).
Delete it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-id: 20210726142338.31872-11-peter.maydell@linaro.org
2021-08-02 12:55:51 +01:00
Eric Blake
955171e441 qemu-img: Add --skip-broken-bitmaps for 'convert --bitmaps'
The point of 'qemu-img convert --bitmaps' is to be a convenience for
actions that are already possible through a string of smaller
'qemu-img bitmap' sub-commands.  One situation not accounted for
already is that if a source image contains an inconsistent bitmap (for
example, because a qemu process died abruptly before flushing bitmap
state), the user MUST delete those inconsistent bitmaps before
anything else useful can be done with the image.

We don't want to delete inconsistent bitmaps by default: although a
corrupt bitmap is only a loss of optimization rather than a corruption
of user-visible data, it is still nice to require the user to opt in
to the fact that they are aware of the loss of the bitmap.  Still,
requiring the user to check 'qemu-img info' to see whether bitmaps are
consistent, then use 'qemu-img bitmap --remove' to remove offenders,
all before using 'qemu-img convert', is a lot more work than just
adding a knob 'qemu-img convert --bitmaps --skip-broken-bitmaps' which
opts in to skipping the broken bitmaps.

After testing the new option, also demonstrate the way to manually fix
things (either deleting bad bitmaps, or re-creating them as empty) so
that it is possible to convert without the option.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1946084
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210709153951.2801666-4-eblake@redhat.com>
[eblake: warning message tweak, test enhancements]
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2021-07-21 14:14:41 -05:00
Peter Maydell
21b6c26d63 docs: Remove "Contents:" lines from top-level subsections
Since the top-level subsections aren't self-contained manuals
any more, the "Contents:" lines at the top of each of their
index pages look a bit odd; remove them.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20210705095547.15790-4-peter.maydell@linaro.org
2021-07-18 10:59:46 +01:00
Peter Maydell
b4634487c4 docs: Stop calling the top level subsections of our manual 'manuals'
We merged our previous multiple-manual setup into a single Sphinx
manual, but we left some text in the various index.rst lines that
still calls the top level subsections separate 'manuals'.  Update
them to talk about "this section of the manual" instead, and remove
now-obsolete comments about how the index.rst files are the "top
level page for the 'foo' manual".

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20210705095547.15790-3-peter.maydell@linaro.org
2021-07-18 10:59:46 +01:00
Eric Blake
a275b452c6 qemu-img: Reword 'qemu-img map --output=json' docs
Reword the paragraphs to list the JSON key first, rather than in the
middle of prose.

Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210707184125.2551140-1-eblake@redhat.com>
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2021-07-12 11:11:48 -05:00
Eric Blake
8417e1378c qemu-img: Make unallocated part of backing chain obvious in map
The recently-added NBD context qemu:allocation-depth is able to
distinguish between locally-present data (even when that data is
sparse) [shown as depth 1 over NBD], and data that could not be found
anywhere in the backing chain [shown as depth 0]; and the libnbd
project was recently patched to give the human-readable name "absent"
to an allocation-depth of 0.  But qemu-img map --output=json predates
that addition, and has the unfortunate behavior that all portions of
the backing chain that resolve without finding a hit in any backing
layer report the same depth as the final backing layer.  This makes it
harder to reconstruct a qcow2 backing chain using just 'qemu-img map'
output, especially when using "backing":null to artificially limit a
backing chain, because it is impossible to distinguish between a
QCOW2_CLUSTER_UNALLOCATED (which defers to a [missing] backing file)
and a QCOW2_CLUSTER_ZERO_PLAIN cluster (which would override any
backing file), since both types of clusters otherwise show as
"data":false,"zero":true" (but note that we can distinguish a
QCOW2_CLUSTER_ZERO_ALLOCATED, which would also have an "offset":
listing).

The task of reconstructing a qcow2 chain was made harder in commit
0da9856851 (nbd: server: Report holes for raw images), because prior
to that point, it was possible to abuse NBD's block status command to
see which portions of a qcow2 file resulted in BDRV_BLOCK_ALLOCATED
(showing up as NBD_STATE_ZERO in isolation) vs. missing from the chain
(showing up as NBD_STATE_ZERO|NBD_STATE_HOLE); but now qemu reports
more accurate sparseness information over NBD.

An obvious solution is to make 'qemu-img map --output=json' add an
additional "present":false designation to any cluster lacking an
allocation anywhere in the chain, without any change to the "depth"
parameter to avoid breaking existing clients.  The iotests have
several examples where this distinction demonstrates the additional
accuracy.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210701190655.2131223-3-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[eblake: fix more iotest fallout]
Signed-off-by: Eric Blake <eblake@redhat.com>
2021-07-12 11:10:53 -05:00
Vivek Goyal
65a820d292 virtiofsd: Add an option to enable/disable posix acls
fuse has an option FUSE_POSIX_ACL which needs to be opted in by fuse
server to enable posix acls. As of now we are not opting in for this,
so posix acls are disabled on virtiofs by default.

Add virtiofsd option "-o posix_acl/no_posix_acl" to let users enable/disable
posix acl support. By default it is disabled as of now due to performance
concerns with cache=none.

Currently even if file server has not opted in for FUSE_POSIX_ACL, user can
still query acl and set acl, and system.posix_acl_access and
system.posix_acl_default xattrs show up listxattr response.

Miklos said this is confusing. So he said lets block and filter
system.posix_acl_access and system.posix_acl_default xattrs in
getxattr/setxattr/listxattr if user has explicitly disabled
posix acls using -o no_posix_acl.

As of now continuing to keeping the existing behavior if user did not
specify any option to disable acl support due to concerns about backward
compatibility.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210622150852.1507204-8-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2021-07-05 10:51:26 +01:00
Daniel P. Berrangé
3399bca451 docs: describe the security considerations with virtiofsd xattr mapping
Different guest xattr prefixes have distinct access control rules applied
by the guest. When remapping a guest xattr care must be taken that the
remapping does not allow the a guest user to bypass guest kernel access
control rules.

For example if 'trusted.*' which requires CAP_SYS_ADMIN is remapped
to 'user.virtiofs.trusted.*', an unprivileged guest user which can
write to 'user.*' can bypass the CAP_SYS_ADMIN control. Thus the
target of any remapping must be explicitly blocked from read/writes
by the guest, to prevent access control bypass.

The examples shown in the virtiofsd man page already do the right
thing and ensure safety, but the security implications of getting
this wrong were not made explicit. This could lead to host admins
and apps unwittingly creating insecure configurations.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210611120427.49736-1-berrange@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2021-07-05 10:51:26 +01:00
Thomas Huth
af94f14046 docs/tools/virtiofsd: Fix bad rst syntax
For literal blocks, there has to be an empty line after the two colons,
and the block itself should be indented.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210607180015.924571-1-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2021-06-21 05:43:11 +02:00
Thomas Huth
771f3be1b5 docs/tools/virtiofsd.rst: Do not hard-code the QEMU binary name
In downstream, we want to use a different name for the QEMU binary,
and some people might also use the docs for non-x86 binaries, that's
why we already created the |qemu_system| placeholder in the past.
Use it now in the virtiofsd doc, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210607174250.920226-1-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2021-06-21 05:43:11 +02:00
Peter Maydell
32de74a1ac Block patches:
- drop block/io write notifiers
 - qemu-iotests enhancements to make debugging easier
 - rbd parsing fix
 - HMP qemu-io fix (for iothreads)
 - mirror job cancel relaxation (do not cancel in-flight requests when a
   READY mirror job is canceled with force=false)
 - document qcow2's data_file and data_file_raw features
 - fix iotest 297 for pylint 2.8
 - block/copy-on-read refactoring
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Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2021-05-14' into staging

Block patches:
- drop block/io write notifiers
- qemu-iotests enhancements to make debugging easier
- rbd parsing fix
- HMP qemu-io fix (for iothreads)
- mirror job cancel relaxation (do not cancel in-flight requests when a
  READY mirror job is canceled with force=false)
- document qcow2's data_file and data_file_raw features
- fix iotest 297 for pylint 2.8
- block/copy-on-read refactoring

# gpg: Signature made Fri 14 May 2021 17:43:40 BST
# gpg:                using RSA key 91BEB60A30DB3E8857D11829F407DB0061D5CF40
# gpg:                issuer "mreitz@redhat.com"
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>" [full]
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40

* remotes/maxreitz/tags/pull-block-2021-05-14:
  write-threshold: deal with includes
  test-write-threshold: drop extra TestStruct structure
  test-write-threshold: drop extra tests
  block/write-threshold: drop extra APIs
  test-write-threshold: rewrite test_threshold_(not_)trigger tests
  block: drop write notifiers
  block/write-threshold: don't use write notifiers
  qemu-iotests: fix pylint 2.8 consider-using-with error
  block/copy-on-read: use bdrv_drop_filter() and drop s->active
  Document qemu-img options data_file and data_file_raw
  qemu-iotests: fix case of SOCK_DIR already in the environment
  qemu-iotests: let "check" spawn an arbitrary test command
  qemu-iotests: move command line and environment handling from TestRunner to TestEnv
  qemu-iotests: allow passing unittest.main arguments to the test scripts
  qemu-iotests: do not buffer the test output
  mirror: stop cancelling in-flight requests on non-force cancel in READY
  monitor: hmp_qemu_io: acquire aio contex, fix crash
  block/rbd: Add an escape-aware strchr helper
  iotests/231: Update expected deprecation message

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2021-05-17 11:29:59 +01:00