Commit Graph

91 Commits

Author SHA1 Message Date
Max Reitz 4c58e80acd qemu-nbd: Use BlockBackend where reasonable
Because qemu-nbd creates the BlockBackend by itself, it should create
the according BlockDriverState tree by itself as well; that means, it
has call bdrv_open() on its own. This is one of the places where
qemu-nbd still needs to use a BlockDriverState directly (the root BDS
below the BB); other places are the configuration of zero detection
(which may be lifted into the BB eventually, but is not yet) and
temporarily loading a snapshot.

Everywhere else, though, qemu-nbd can and thus should use BlockBackend.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1416309679-333-7-git-send-email-mreitz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-12-10 10:31:12 +01:00
Max Reitz e140177d9c nbd: Change external interface to BlockBackend
Substitute BlockDriverState by BlockBackend in every globally visible
function provided by nbd.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1416309679-333-5-git-send-email-mreitz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-12-10 10:31:12 +01:00
Markus Armbruster 9ba10c95a4 block: Make BlockBackend own its BlockDriverState
On BlockBackend destruction, unref its BlockDriverState.  Replaces the
callers' unrefs.

This turns the pointer from BlockBackend to BlockDriverState into a
strong reference, managed with bdrv_ref() / bdrv_unref().  The
back-pointer remains weak.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-10-20 13:41:26 +02:00
Markus Armbruster 7e7d56d9e0 block: Connect BlockBackend to BlockDriverState
Convenience function blk_new_with_bs() creates a BlockBackend with its
BlockDriverState.  Callers have to unref both.  The commit after next
will relieve them of the need to unref the BlockDriverState.

Complication: due to the silly way drive_del works, we need a way to
hide a BlockBackend, just like bdrv_make_anon().  To emphasize its
"special" status, give the function a suitably off-putting name:
blk_hide_on_behalf_of_do_drive_del().  Unfortunately, hiding turns the
BlockBackend's name into the empty string.  Can't avoid that without
breaking the blk->bs->device_name equals blk->name invariant.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-10-20 13:41:26 +02:00
Markus Armbruster 26f54e9a3c block: New BlockBackend
A block device consists of a frontend device model and a backend.

A block backend has a tree of block drivers doing the actual work.
The tree is managed by the block layer.

We currently use a single abstraction BlockDriverState both for tree
nodes and the backend as a whole.  Drawbacks:

* Its API includes both stuff that makes sense only at the block
  backend level (root of the tree) and stuff that's only for use
  within the block layer.  This makes the API bigger and more complex
  than necessary.  Moreover, it's not obvious which interfaces are
  meant for device models, and which really aren't.

* Since device models keep a reference to their backend, the backend
  object can't just be destroyed.  But for media change, we need to
  replace the tree.  Our solution is to make the BlockDriverState
  generic, with actual driver state in a separate object, pointed to
  by member opaque.  That lets us replace the tree by deinitializing
  and reinitializing its root.  This special need of the root makes
  the data structure awkward everywhere in the tree.

The general plan is to separate the APIs into "block backend", for use
by device models, monitor and whatever other code dealing with block
backends, and "block driver", for use by the block layer and whatever
other code (if any) dealing with trees and tree nodes.

Code dealing with block backends, device models in particular, should
become completely oblivious of BlockDriverState.  This should let us
clean up both APIs, and the tree data structures.

This commit is a first step.  It creates a minimal "block backend"
API: type BlockBackend and functions to create, destroy and find them.

BlockBackend objects are created and destroyed exactly when root
BlockDriverState objects are created and destroyed.  "Root" in the
sense of "in bdrv_states".  They're not yet used for anything; that'll
come shortly.

A root BlockDriverState is created with bdrv_new_root(), so where to
create a BlockBackend is obvious.  Where these roots get destroyed
isn't always as obvious.

It is obvious in qemu-img.c, qemu-io.c and qemu-nbd.c, and in error
paths of blockdev_init(), blk_connect().  That leaves destruction of
objects successfully created by blockdev_init() and blk_connect().

blockdev_init() is used only by drive_new() and qmp_blockdev_add().
Objects created by the latter are currently indestructible (see commit
48f364d "blockdev: Refuse to drive_del something added with
blockdev-add" and commit 2d246f0 "blockdev: Introduce
DriveInfo.enable_auto_del").  Objects created by the former get
destroyed by drive_del().

Objects created by blk_connect() get destroyed by blk_disconnect().

BlockBackend is reference-counted.  Its reference count never exceeds
one so far, but that's going to change.

In drive_del(), the BB's reference count is surely one now.  The BDS's
reference count is greater than one when something else is holding a
reference, such as a block job.  In this case, the BB is destroyed
right away, but the BDS lives on until all extra references get
dropped.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-10-20 13:41:26 +02:00
Markus Armbruster e4e9986b1c block: Split bdrv_new_root() off bdrv_new()
Creating an anonymous BDS can't fail.  Make that obvious.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Benoît Canet <benoit.canet@nodalink.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-10-20 13:41:26 +02:00
Markus Armbruster fbf28a4328 block: Drop superfluous conditionals around qemu_opts_del()
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1411999675-14533-1-git-send-email-armbru@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-10-03 10:30:33 +01:00
Markus Armbruster e5d7bbeb10 qemu-nbd: Destroy the BlockDriverState properly
Match the bdrv_new() with a bdrv_unref(), just to be tidy.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-09-25 15:24:14 +02:00
Chrysostomos Nanakos 2f78e491d7 async: aio_context_new(): Handle event_notifier_init failure
On a system with a low limit of open files the initialization
of the event notifier could fail and QEMU exits without printing any
error information to the user.

The problem can be easily reproduced by enforcing a low limit of open
files and start QEMU with enough I/O threads to hit this limit.

The same problem raises, without the creation of I/O threads, while
QEMU initializes the main event loop by enforcing an even lower limit of
open files.

This commit adds an error message on failure:

 # qemu [...] -object iothread,id=iothread0 -object iothread,id=iothread1
 qemu: Failed to initialize event notifier: Too many open files in system

Signed-off-by: Chrysostomos Nanakos <cnanakos@grnet.gr>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-09-22 11:39:48 +01:00
Peter Lieven 713cc671f1 qemu-nbd: fix indentation and coding style
Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Benoit Canet <benoit.canet@nodalink.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-09-08 11:12:43 +01:00
Peter Lieven b3838a4088 qemu-nbd: add option to set detect-zeroes mode
Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Benoit Canet <benoit.canet@nodalink.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-09-08 11:12:43 +01:00
Hani Benhabiles 27e5eae457 nbd: Shutdown socket before closing.
This forces finishing data sending to client before closing the socket like in
exports listing or replying with NBD_REP_ERR_UNSUP cases.

Signed-off-by: Hani Benhabiles <kroosec@gmail.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-06-30 12:50:12 +02:00
Markus Armbruster 3775ec6f5a qemu-nbd: Don't use qerror_report()
qerror_report() is a transitional interface to help with converting
existing HMP commands to QMP.  It should not be used elsewhere.
Replace by error_report().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-05-28 14:28:46 +02:00
Hani Benhabiles 5672ee54d5 nbd: Miscellaneous typo fixes.
Signed-off-by: Hani Benhabiles <hani@linux.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2014-05-24 00:07:29 +04:00
Hani Benhabiles 36af599417 nbd: Close socket on negotiation failure.
Otherwise, the nbd client may hang waiting for the server response.

Signed-off-by: Hani Benhabiles <hani@linux.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2014-05-24 00:07:29 +04:00
Kevin Wolf 98522f63f4 block: Add errp to bdrv_new()
This patch adds an errp parameter to bdrv_new() and updates all its
callers. The next patches will make use of this in order to check for
duplicate IDs. Most of the callers know that their ID is fine, so they
can simply assert that there is no error.

Behaviour doesn't change with this patch yet as bdrv_new() doesn't
actually assign errors to errp.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2014-04-22 12:00:20 +02:00
Paolo Bonzini 0c544d73bb qemu-nbd: Fix coverity issues
There are two issues in qemu-nbd: a missing return value check after
calling accept(), and file descriptor leaks in nbd_client_thread.

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-03-17 13:21:11 +01:00
Peter Maydell e7a1d6c52a Block patches
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Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block patches

# gpg: Signature made Fri 21 Feb 2014 21:42:24 GMT using RSA key ID C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"

* remotes/kevin/tags/for-upstream: (54 commits)
  iotests: Mixed quorum child device specifications
  quorum: Simplify quorum_open()
  quorum: Add unit test.
  quorum: Add quorum_open() and quorum_close().
  quorum: Implement recursive .bdrv_recurse_is_first_non_filter in quorum.
  quorum: Add quorum_co_flush().
  quorum: Add quorum_invalidate_cache().
  quorum: Add quorum_getlength().
  quorum: Add quorum mechanism.
  quorum: Add quorum_aio_readv.
  blkverify: Extract qemu_iovec_clone() and qemu_iovec_compare() from blkverify.
  quorum: Add quorum_aio_writev and its dependencies.
  quorum: Create BDRVQuorumState and BlkDriver and do init.
  quorum: Create quorum.c, add QuorumChildRequest and QuorumAIOCB.
  check-qdict: Test termination of qdict_array_split()
  check-qdict: Adjust test for qdict_array_split()
  qdict: Extract non-QDicts in qdict_array_split()
  qemu-config: Sections must consist of keys
  qemu-iotests: Check qemu-img command line parsing
  qemu-img: Allow -o help with incomplete argument list
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-02-25 10:50:11 +00:00
Paolo Bonzini 537b41f501 nbd: move socket wrappers to qemu-nbd
qemu-nbd is one of the few valid users of qerror_report_err.  Move
the error-reporting socket wrappers there.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21 21:02:23 +01:00
Max Reitz ddf5636dc9 block: Add reference parameter to bdrv_open()
Allow bdrv_open() to handle references to existing block devices just as
bdrv_file_open() is already capable of.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21 21:02:22 +01:00
Max Reitz f67503e5bd block: Change BDS parameter of bdrv_open() to **
Make bdrv_open() take a pointer to a BDS pointer, similarly to
bdrv_file_open(). If a pointer to a NULL pointer is given, bdrv_open()
will create a new BDS with an empty name; if the BDS pointer is not
NULL, that existing BDS will be reused (in the same way as bdrv_open()
already did).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21 21:02:21 +01:00
Fam Zheng 10f5bff622 util: Split out exec_dir from os_find_datadir
With this change, main() calls qemu_init_exec_dir and uses argv[0] to
init exec_dir. The saved value can be retrieved with
qemu_get_exec_dir later. It will be reused by module loading.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-02-20 13:12:54 +01:00
Wenchao Xia 4323fdcf94 qemu-nbd: add doc for option -f
Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-04 15:19:00 +01:00
Wenchao Xia 8c116b0e41 qemu-nbd: support internal snapshot export
Now it is possible to directly export an internal snapshot, which
can be used to probe the snapshot's contents without qemu-img
convert.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-04 15:19:00 +01:00
Max Reitz 34b5d2c68e block: Error parameter for open functions
Add an Error ** parameter to bdrv_open, bdrv_file_open and associated
functions to allow more specific error messages.

Signed-off-by: Max Reitz <mreitz@redhat.com>
2013-09-12 10:12:48 +02:00
Alex Bligh 6a1751b7aa aio / timers: Untangle include files
include/qemu/timer.h has no need to include main-loop.h and
doing so causes an issue for the next patch. Unfortunately
various files assume including timers.h will pull in main-loop.h.
Untangle this mess.

Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-08-22 19:10:27 +02:00
Daniel P. Berrange e6b636779b Add -f FMT / --format FMT arg to qemu-nbd
Currently the qemu-nbd program will auto-detect the format of
any disk it is given. This behaviour is known to be insecure.
For example, if qemu-nbd initially exposes a 'raw' file to an
unprivileged app, and that app runs

   'qemu-img create -f qcow2 -o backing_file=/etc/shadow /dev/nbd0'

then the next time the app is started, the qemu-nbd will now
detect it as a 'qcow2' file and expose /etc/shadow to the
unprivileged app.

The only way to avoid this is to explicitly tell qemu-nbd what
disk format to use on the command line, completely disabling
auto-detection. This patch adds a '-f' / '--format' arg for
this purpose, mirroring what is already available via qemu-img
and qemu commands.

  qemu-nbd --format raw -p 9000 evil.img

will now always use raw, regardless of what format 'evil.img'
looks like it contains

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
[Use errx, not err. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2013-04-15 14:29:20 -05:00
Kevin Wolf de9c0cec6c block: Add options QDict to bdrv_open() prototype
It doesn't do anything yet except storing the options QDict in the
BlockDriverState.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-03-15 16:07:49 +01:00
Paolo Bonzini ded9d2d5e2 qemu-nbd: add --discard option
Similar to --cache and --aio, this option mimics the discard suboption
of "-drive".

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-02-22 21:29:43 +01:00
Paolo Bonzini 737e150e89 block: move include files to include/block/
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-19 08:31:31 +01:00
Paolo Bonzini 7e7f4a0efc qemu-nbd: initialize main loop before block layer
qemu-nbd was broken because they initialized the block layer while
qemu_aio_context was still NULL.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-11-12 11:33:29 +01:00
Paolo Bonzini 7860a380ac qemu-nbd: rewrite termination conditions to use a state machine
Use a simple state machine with the following states:

- RUNNING     => accepting connections
- TERMINATE   => main loop must call nbd_export_close/put, and not accept
  connections anymore
- TERMINATING => waiting for pending requests to finish
- TERMINATED  => the NBDExport has been closed

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-09-19 15:26:29 +02:00
Paolo Bonzini 0ddf08db22 nbd: add notification for closing an NBDExport
In order to exit cleanly from qemu-nbd, add a callback that triggers
when an NBDExport is closed.  In the case of qemu-nbd it will exit the
main loop.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-09-19 15:26:29 +02:00
Paolo Bonzini 2c8d9f0655 nbd: add reference counting to NBDExport
We will use a similar two-phase destruction for NBDExport, so we need
each NBDClient to add a reference to NBDExport.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-09-19 15:26:28 +02:00
Paolo Bonzini a4aab7b4cb nbd: do not close BlockDriverState in nbd_export_close
This is not desirable when embedding the NBD server inside QEMU.
Move the bdrv_close to qemu-nbd.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-09-19 15:26:15 +02:00
Paolo Bonzini 39a5235cd7 qemu-nbd: add --cache and --aio options
Add two options to tune the I/O implementation of qemu-nbd, matching
the possibilities given by the QEMU -drive option.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-07-24 09:31:53 +02:00
Paolo Bonzini b033cd8640 qemu-nbd: reorganize help message
This patch separates qemu-nbd's options in logical groups, thus making
the help message easier to read.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-07-24 09:31:53 +02:00
Paolo Bonzini 38ceff0412 nbd: do not include block_int.h
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-04-19 17:19:37 +02:00
Paolo Bonzini 185b43386a nbd: consistently return negative errno values
In the next patch we need to look at the return code of nbd_wr_sync.
To avoid percolating the socket_error() ugliness all around, let's
handle errors by returning negative errno values.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-04-19 16:36:43 +02:00
Paolo Bonzini fc19f8a02e nbd: consistently check for <0 or >=0
This prepares for the following patch, which changes -1 return values
to negative errno.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-04-19 16:36:43 +02:00
Paolo Bonzini a6ac2313a8 open /dev/nbd in nbd_client_thread
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-02-17 12:41:59 +01:00
Michael Tokarev 9faf31b68f do not chdir(/) in qemu-nbd before opening all files
When qemu-nbd becomes a daemon it calls daemon(3) with
nochdir=0, so daemon(3) changes current directory to /.
But at this time, qemu-nbd did not open any user-specified
files yet, so by changing current directory, all non-absolute
paths becomes wrong.  The solution is to pass nochdir=1 to
daemon(3) function, and to chdir("/") after all init has
been performed, before entering the main loop, -- just like
a good daemon should do.

This patch is applicable for -stable.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-02-17 12:41:48 +01:00
Stefan Hajnoczi dc10e8b3c5 qemu-nbd: drop loop which can never loop
For some reason nbd_client_thread() has a do..while loop which can never
loop, the condition is bogus because we would take a goto instead.  Drop
the loop.

Reported-by: Dr David Alan Gilbert <davidagilbert@uk.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2012-01-06 15:09:53 +00:00
Paolo Bonzini 1743b51586 qemu-nbd: move client handling to nbd.c
This patch sets up the fd handler in nbd.c instead of qemu-nbd.c.  It
introduces NBDClient, which wraps the arguments to nbd_trip in a single
structure, so that we can add a notifier to it.  This way, qemu-nbd can
know about disconnections.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2011-12-22 11:53:59 +01:00
Paolo Bonzini a61c67828d qemu-nbd: use common main loop
Using a single main loop for sockets will help yielding from the socket
coroutine back to the main loop, and later reentering it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2011-12-22 11:53:59 +01:00
Paolo Bonzini af49bbbe78 qemu-nbd: introduce NBDExport
Wrap the common parameters of nbd_trip and nbd_negotiate in a
single opaque struct.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2011-12-22 11:53:58 +01:00
Paolo Bonzini 3777b09fd7 qemu-nbd: remove data_size argument to nbd_trip
The size of the buffer is in practice part of the protocol.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2011-12-22 11:53:58 +01:00
Paolo Bonzini 94607e7a77 qemu-nbd: remove offset argument to nbd_trip
The argument is write-only.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2011-12-22 11:53:58 +01:00
Paolo Bonzini 802ddc375a qemu-nbd: open the block device after starting the client thread
This is cleaner, because we do not need to close the block device when
there is an error opening /dev/nbdX.  It was done this way only to
print errors before daemonizing.

At the same time, use atexit to ensure that the block device is closed
whenever we exit.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-11-11 14:02:58 +01:00
Paolo Bonzini f1ef5555c2 qemu-nbd: fix socket creation race
Now that the client and server are in the same process, there is
no need to race on the creation of the socket.  We can open the
listening socket before starting the client thread.

This avoids that "qemu-nbd -v -c" prints this once before connecting
successfully to the socket:

    connect(unix:/var/lock/qemu-nbd-nbd0): No such file or directory

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-11-11 14:02:58 +01:00