Commit c7c2ff0c authored by Luiz Capitulino's avatar Luiz Capitulino Committed by Kevin Wolf
Browse files

block: extend BLOCK_IO_ERROR event with nospace indicator 



Management software, such as RHEV's vdsm, want to be able to allocate
disk space on demand. The basic use case is to start a VM with a small
disk and then the disk is enlarged when QEMU hits a ENOSPC condition.

To this end, the management software has to be notified when QEMU
encounters ENOSPC. The solution implemented by this commit is simple:
it extends the BLOCK_IO_ERROR with a 'nospace' key, which is true
when QEMU is stopped due to ENOSPC.

Note that support for querying this event is already present in
query-block by means of the 'io-status' key. Also, the new 'nospace'
BLOCK_IO_ERROR field shares the same semantics with 'io-status',
which basically means that werror= has to be set to either
'stop' or 'enospc' to enable 'nospace'.

Finally, this commit also updates the 'io-status' key doc in the
schema with a list of supported device models.

Signed-off-by: default avatarLuiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 10601bef

block.c

+14 −8
Original line number Diff line number Diff line
@@ -3639,6 +3639,18 @@ BlockErrorAction bdrv_get_error_action(BlockDriverState *bs, bool is_read, int e 
    }

}



static void send_qmp_error_event(BlockDriverState *bs,

                                 BlockErrorAction action,

                                 bool is_read, int error)

{

    BlockErrorAction ac;



    ac = is_read ? IO_OPERATION_TYPE_READ : IO_OPERATION_TYPE_WRITE;

    qapi_event_send_block_io_error(bdrv_get_device_name(bs), ac, action,

                                   bdrv_iostatus_is_enabled(bs),

                                   error == ENOSPC, &error_abort);

}



/* This is done by device models because, while the block layer knows

 * about the error, it does not know whether an operation comes from

 * the device or the block layer (from a job, for example).
@@ -3664,16 +3676,10 @@ void bdrv_error_action(BlockDriverState *bs, BlockErrorAction action, 
         * also ensures that the STOP/RESUME pair of events is emitted.

         */

        qemu_system_vmstop_request_prepare();

        qapi_event_send_block_io_error(bdrv_get_device_name(bs),

                                       is_read ? IO_OPERATION_TYPE_READ :

                                       IO_OPERATION_TYPE_WRITE,

                                       action, &error_abort);

        send_qmp_error_event(bs, action, is_read, error);

        qemu_system_vmstop_request(RUN_STATE_IO_ERROR);

    } else {

        qapi_event_send_block_io_error(bdrv_get_device_name(bs),

                                       is_read ? IO_OPERATION_TYPE_READ :

                                       IO_OPERATION_TYPE_WRITE,

                                       action, &error_abort);

        send_qmp_error_event(bs, action, is_read, error);

    }

}

qapi/block-core.json

+7 −1
Original line number Diff line number Diff line
@@ -336,6 +336,7 @@ 
#

# @io-status: #optional @BlockDeviceIoStatus. Only present if the device

#             supports it and the VM is configured to stop on errors

#             (supported device models: virtio-blk, ide, scsi-disk)

#

# @inserted: #optional @BlockDeviceInfo describing the device if media is

#            present
@@ -1587,6 +1588,11 @@ 
#

# @action: action that has been taken

#

# @nospace: #optional true if I/O error was caused due to a no-space

#           condition. This key is only present if query-block's

#           io-status is present, please see query-block documentation

#           for more information (since: 2.2)

#

# Note: If action is "stop", a STOP event will eventually follow the

# BLOCK_IO_ERROR event

#
@@ -1594,7 +1600,7 @@ 
##

{ 'event': 'BLOCK_IO_ERROR',

  'data': { 'device': 'str', 'operation': 'IoOperationType',

            'action': 'BlockErrorAction' } }

            'action': 'BlockErrorAction', '*nospace': 'bool' } }



##

# @BLOCK_JOB_COMPLETED