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  • Anton Anton anjo
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  1. Apr 24, 2017
  3. Apr 11, 2017
  5. Apr 07, 2017
  7. Apr 03, 2017
    • Markus Armbruster's avatar
      block: Document -drive problematic code and bugs · 129c7d1c
      Markus Armbruster authored 
      
-blockdev and blockdev_add convert their arguments via QObject to
BlockdevOptions for qmp_blockdev_add(), which converts them back to
QObject, then to a flattened QDict.  The QDict's members are typed
according to the QAPI schema.

-drive converts its argument via QemuOpts to a (flat) QDict.  This
QDict's members are all QString.

Thus, the QType of a flat QDict member depends on whether it comes
from -drive or -blockdev/blockdev_add, except when the QAPI type maps
to QString, which is the case for 'str' and enumeration types.

The block layer core extracts generic configuration from the flat
QDict, and the block driver extracts driver-specific configuration.

Both commonly do so by converting (parts of) the flat QDict to
QemuOpts, which turns all values into strings.  Not exactly elegant,
but correct.

However, A few places access the flat QDict directly:

* Most of them access members that are always QString.  Correct.

* bdrv_open_inherit() accesses a boolean, carefully.  Correct.

* nfs_config() uses a QObject input visitor.  Correct only because the
  visited type contains nothing but QStrings.

* nbd_config() and ssh_config() use a QObject input visitor, and the
  visited types contain non-QStrings: InetSocketAddress members
  @numeric, @to, @ipv4, @ipv6.  -drive works as long as you don't try
  to use them (they're all optional).  @to is ignored anyway.

  Reproducer:
  -drive driver=ssh,server.host=h,server.port=22,server.ipv4,path=p
  -drive driver=nbd,server.type=inet,server.data.host=h,server.data.port=22,server.data.ipv4
  both fail with "Invalid parameter type for 'data.ipv4', expected: boolean"

Add suitable comments to all these places.  Mark the buggy ones FIXME.

"Fortunately", -drive's driver-specific options are entirely
undocumented.

Signed-off-by: default avatarMarkus Armbruster <armbru@redhat.com>
Message-id: 1490895797-29094-5-git-send-email-armbru@redhat.com
[mreitz: Fixed two typos]
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
      129c7d1c
  9. Mar 17, 2017
    • Paolo Bonzini's avatar
      block: quiesce AioContext when detaching from it · c2b6428d
      Paolo Bonzini authored 
      
While it is true that bdrv_set_aio_context only works on a single
BlockDriverState subtree (see commit message for 53ec73e2, "block: Use
bdrv_drain to replace uncessary bdrv_drain_all", 2015-07-07), it works
at the AioContext level rather than the BlockDriverState level.

Therefore, it is also necessary to trigger pending bottom halves too,
even if no requests are pending.

For NBD this ensures that the aio_co_schedule of a previous call to
nbd_attach_aio_context is completed before detaching from the old
AioContext; it fixes qemu-iotest 094.  Another similar bug happens
when the VM is stopped and the virtio-blk dataplane irqfd is torn down.
In this case it's possible that guest I/O gets stuck if notify_guest_bh
was scheduled but doesn't run.

Calling aio_poll from another AioContext is safe if non-blocking; races
such as the one mentioned in the commit message for c9d1a561 ("block:
only call aio_poll on the current thread's AioContext", 2016-10-28)
are a concern for blocking calls.

I considered other options, including:

- moving the bs->wakeup mechanism to AioContext, and letting the caller
check.  This might work for virtio which has a clear place to wakeup
(notify_place_bh) and check the condition (virtio_blk_data_plane_stop).
For aio_co_schedule I couldn't find a clear place to check the condition.

- adding a dummy oneshot bottom half and waiting for it to trigger.
This has the complication that bottom half list is LIFO for historical
reasons.  There were performance issues caused by bottom half ordering
in the past, so I decided against it for 2.9.

Fixes: 99723548
Reported-by: default avatarMax Reitz <mreitz@redhat.com>
Reported-by: default avatarHalil Pasic <pasic@linux.vnet.ibm.com>
Tested-by: default avatarHalil Pasic <pasic@linux.vnet.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-id: 20170314111157.14464-2-pbonzini@redhat.com
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
      c2b6428d
    • Fam Zheng's avatar
      block: Propagate error in bdrv_open_backing_file · 8cd1a3e4
      Fam Zheng authored 
      
Signed-off-by: default avatarFam Zheng <famz@redhat.com>
Reviewed-by: default avatarAlberto Garcia <berto@igalia.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
      8cd1a3e4
    • Fam Zheng's avatar
      block: Always call bdrv_child_check_perm first · c1cef672
      Fam Zheng authored 
      
bdrv_child_set_perm alone is not very usable because the caller must
call bdrv_child_check_perm first. This is already encapsulated
conveniently in bdrv_child_try_set_perm, so remove the other prototypes
from the header and fix the one wrong caller, block/mirror.c.

Signed-off-by: default avatarFam Zheng <famz@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
      c1cef672
  11. Mar 13, 2017
  13. Mar 07, 2017
  15. Feb 28, 2017