0c9b70d590
block-export-add type=fuse allows mounting block graph nodes via FUSE on some existing regular file. That file should then appears like a raw disk image, and accesses to it result in accesses to the exported BDS. Right now, we only implement the necessary block export functions to set it up and shut it down. We do not implement any access functions, so accessing the mount point only results in errors. This will be addressed by a followup patch. We keep a hash table of exported mount points, because we want to be able to detect when users try to use a mount point twice. This is because we invoke stat() to check whether the given mount point is a regular file, but if that file is served by ourselves (because it is already used as a mount point), then this stat() would have to be served by ourselves, too, which is impossible to do while we (as the caller) are waiting for it to settle. Therefore, keep track of mount point paths to at least catch the most obvious instances of that problem. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20201027190600.192171-3-mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
365 lines
10 KiB
Python
365 lines
10 KiB
Python
# -*- Mode: Python -*-
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# vim: filetype=python
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##
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# == Block device exports
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##
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{ 'include': 'sockets.json' }
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##
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# @NbdServerOptions:
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#
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# Keep this type consistent with the nbd-server-start arguments. The only
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# intended difference is using SocketAddress instead of SocketAddressLegacy.
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#
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# @addr: Address on which to listen.
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# @tls-creds: ID of the TLS credentials object (since 2.6).
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# @tls-authz: ID of the QAuthZ authorization object used to validate
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# the client's x509 distinguished name. This object is
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# is only resolved at time of use, so can be deleted and
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# recreated on the fly while the NBD server is active.
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# If missing, it will default to denying access (since 4.0).
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# @max-connections: The maximum number of connections to allow at the same
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# time, 0 for unlimited. (since 5.2; default: 0)
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#
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# Since: 4.2
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##
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{ 'struct': 'NbdServerOptions',
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'data': { 'addr': 'SocketAddress',
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'*tls-creds': 'str',
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'*tls-authz': 'str',
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'*max-connections': 'uint32' } }
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##
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# @nbd-server-start:
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#
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# Start an NBD server listening on the given host and port. Block
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# devices can then be exported using @nbd-server-add. The NBD
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# server will present them as named exports; for example, another
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# QEMU instance could refer to them as "nbd:HOST:PORT:exportname=NAME".
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#
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# Keep this type consistent with the NbdServerOptions type. The only intended
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# difference is using SocketAddressLegacy instead of SocketAddress.
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#
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# @addr: Address on which to listen.
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# @tls-creds: ID of the TLS credentials object (since 2.6).
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# @tls-authz: ID of the QAuthZ authorization object used to validate
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# the client's x509 distinguished name. This object is
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# is only resolved at time of use, so can be deleted and
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# recreated on the fly while the NBD server is active.
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# If missing, it will default to denying access (since 4.0).
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# @max-connections: The maximum number of connections to allow at the same
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# time, 0 for unlimited. (since 5.2; default: 0)
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#
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# Returns: error if the server is already running.
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#
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# Since: 1.3
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##
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{ 'command': 'nbd-server-start',
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'data': { 'addr': 'SocketAddressLegacy',
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'*tls-creds': 'str',
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'*tls-authz': 'str',
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'*max-connections': 'uint32' } }
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##
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# @BlockExportOptionsNbdBase:
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#
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# An NBD block export (common options shared between nbd-server-add and
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# the NBD branch of block-export-add).
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#
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# @name: Export name. If unspecified, the @device parameter is used as the
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# export name. (Since 2.12)
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#
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# @description: Free-form description of the export, up to 4096 bytes.
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# (Since 5.0)
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#
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# Since: 5.0
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##
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{ 'struct': 'BlockExportOptionsNbdBase',
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'data': { '*name': 'str', '*description': 'str' } }
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##
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# @BlockExportOptionsNbd:
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#
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# An NBD block export (distinct options used in the NBD branch of
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# block-export-add).
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#
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# @bitmaps: Also export each of the named dirty bitmaps reachable from
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# @device, so the NBD client can use NBD_OPT_SET_META_CONTEXT with
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# the metadata context name "qemu:dirty-bitmap:BITMAP" to inspect
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# each bitmap.
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#
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# @allocation-depth: Also export the allocation depth map for @device, so
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# the NBD client can use NBD_OPT_SET_META_CONTEXT with
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# the metadata context name "qemu:allocation-depth" to
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# inspect allocation details. (since 5.2)
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#
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# Since: 5.2
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##
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{ 'struct': 'BlockExportOptionsNbd',
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'base': 'BlockExportOptionsNbdBase',
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'data': { '*bitmaps': ['str'], '*allocation-depth': 'bool' } }
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##
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# @BlockExportOptionsVhostUserBlk:
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#
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# A vhost-user-blk block export.
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#
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# @addr: The vhost-user socket on which to listen. Both 'unix' and 'fd'
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# SocketAddress types are supported. Passed fds must be UNIX domain
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# sockets.
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# @logical-block-size: Logical block size in bytes. Defaults to 512 bytes.
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# @num-queues: Number of request virtqueues. Must be greater than 0. Defaults
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# to 1.
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#
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# Since: 5.2
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##
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{ 'struct': 'BlockExportOptionsVhostUserBlk',
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'data': { 'addr': 'SocketAddress',
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'*logical-block-size': 'size',
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'*num-queues': 'uint16'} }
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##
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# @BlockExportOptionsFuse:
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#
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# Options for exporting a block graph node on some (file) mountpoint
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# as a raw image.
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#
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# @mountpoint: Path on which to export the block device via FUSE.
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# This must point to an existing regular file.
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#
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# Since: 6.0
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##
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{ 'struct': 'BlockExportOptionsFuse',
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'data': { 'mountpoint': 'str' },
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'if': 'defined(CONFIG_FUSE)' }
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##
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# @NbdServerAddOptions:
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#
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# An NBD block export, per legacy nbd-server-add command.
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#
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# @device: The device name or node name of the node to be exported
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#
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# @writable: Whether clients should be able to write to the device via the
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# NBD connection (default false).
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#
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# @bitmap: Also export a single dirty bitmap reachable from @device, so the
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# NBD client can use NBD_OPT_SET_META_CONTEXT with the metadata
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# context name "qemu:dirty-bitmap:BITMAP" to inspect the bitmap
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# (since 4.0).
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#
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# Since: 5.0
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##
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{ 'struct': 'NbdServerAddOptions',
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'base': 'BlockExportOptionsNbdBase',
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'data': { 'device': 'str',
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'*writable': 'bool', '*bitmap': 'str' } }
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##
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# @nbd-server-add:
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#
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# Export a block node to QEMU's embedded NBD server.
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#
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# The export name will be used as the id for the resulting block export.
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#
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# Features:
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# @deprecated: This command is deprecated. Use @block-export-add instead.
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#
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# Returns: error if the server is not running, or export with the same name
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# already exists.
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#
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# Since: 1.3
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##
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{ 'command': 'nbd-server-add',
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'data': 'NbdServerAddOptions', 'boxed': true, 'features': ['deprecated'] }
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##
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# @BlockExportRemoveMode:
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#
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# Mode for removing a block export.
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#
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# @safe: Remove export if there are no existing connections, fail otherwise.
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#
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# @hard: Drop all connections immediately and remove export.
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#
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# Potential additional modes to be added in the future:
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#
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# hide: Just hide export from new clients, leave existing connections as is.
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# Remove export after all clients are disconnected.
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#
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# soft: Hide export from new clients, answer with ESHUTDOWN for all further
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# requests from existing clients.
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#
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# Since: 2.12
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##
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{'enum': 'BlockExportRemoveMode', 'data': ['safe', 'hard']}
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##
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# @nbd-server-remove:
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#
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# Remove NBD export by name.
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#
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# @name: Block export id.
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#
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# @mode: Mode of command operation. See @BlockExportRemoveMode description.
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# Default is 'safe'.
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#
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# Features:
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# @deprecated: This command is deprecated. Use @block-export-del instead.
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#
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# Returns: error if
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# - the server is not running
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# - export is not found
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# - mode is 'safe' and there are existing connections
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#
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# Since: 2.12
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##
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{ 'command': 'nbd-server-remove',
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'data': {'name': 'str', '*mode': 'BlockExportRemoveMode'},
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'features': ['deprecated'] }
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##
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# @nbd-server-stop:
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#
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# Stop QEMU's embedded NBD server, and unregister all devices previously
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# added via @nbd-server-add.
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#
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# Since: 1.3
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##
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{ 'command': 'nbd-server-stop' }
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##
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# @BlockExportType:
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#
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# An enumeration of block export types
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#
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# @nbd: NBD export
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# @vhost-user-blk: vhost-user-blk export (since 5.2)
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# @fuse: FUSE export (since: 6.0)
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#
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# Since: 4.2
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##
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{ 'enum': 'BlockExportType',
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'data': [ 'nbd', 'vhost-user-blk',
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{ 'name': 'fuse', 'if': 'defined(CONFIG_FUSE)' } ] }
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##
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# @BlockExportOptions:
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#
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# Describes a block export, i.e. how single node should be exported on an
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# external interface.
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#
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# @id: A unique identifier for the block export (across all export types)
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#
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# @node-name: The node name of the block node to be exported (since: 5.2)
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#
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# @writable: True if clients should be able to write to the export
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# (default false)
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#
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# @writethrough: If true, caches are flushed after every write request to the
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# export before completion is signalled. (since: 5.2;
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# default: false)
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#
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# @iothread: The name of the iothread object where the export will run. The
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# default is to use the thread currently associated with the
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# block node. (since: 5.2)
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#
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# @fixed-iothread: True prevents the block node from being moved to another
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# thread while the export is active. If true and @iothread is
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# given, export creation fails if the block node cannot be
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# moved to the iothread. The default is false. (since: 5.2)
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#
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# Since: 4.2
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##
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{ 'union': 'BlockExportOptions',
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'base': { 'type': 'BlockExportType',
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'id': 'str',
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'*fixed-iothread': 'bool',
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'*iothread': 'str',
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'node-name': 'str',
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'*writable': 'bool',
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'*writethrough': 'bool' },
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'discriminator': 'type',
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'data': {
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'nbd': 'BlockExportOptionsNbd',
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'vhost-user-blk': 'BlockExportOptionsVhostUserBlk',
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'fuse': { 'type': 'BlockExportOptionsFuse',
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'if': 'defined(CONFIG_FUSE)' }
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} }
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##
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# @block-export-add:
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#
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# Creates a new block export.
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#
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# Since: 5.2
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##
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{ 'command': 'block-export-add',
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'data': 'BlockExportOptions', 'boxed': true }
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##
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# @block-export-del:
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#
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# Request to remove a block export. This drops the user's reference to the
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# export, but the export may still stay around after this command returns until
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# the shutdown of the export has completed.
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#
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# @id: Block export id.
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#
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# @mode: Mode of command operation. See @BlockExportRemoveMode description.
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# Default is 'safe'.
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#
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# Returns: Error if the export is not found or @mode is 'safe' and the export
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# is still in use (e.g. by existing client connections)
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#
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# Since: 5.2
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##
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{ 'command': 'block-export-del',
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'data': { 'id': 'str', '*mode': 'BlockExportRemoveMode' } }
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##
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# @BLOCK_EXPORT_DELETED:
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#
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# Emitted when a block export is removed and its id can be reused.
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#
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# @id: Block export id.
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#
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# Since: 5.2
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##
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{ 'event': 'BLOCK_EXPORT_DELETED',
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'data': { 'id': 'str' } }
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##
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# @BlockExportInfo:
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#
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# Information about a single block export.
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#
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# @id: The unique identifier for the block export
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#
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# @type: The block export type
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#
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# @node-name: The node name of the block node that is exported
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#
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# @shutting-down: True if the export is shutting down (e.g. after a
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# block-export-del command, but before the shutdown has
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# completed)
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#
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# Since: 5.2
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##
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{ 'struct': 'BlockExportInfo',
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'data': { 'id': 'str',
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'type': 'BlockExportType',
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'node-name': 'str',
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'shutting-down': 'bool' } }
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##
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# @query-block-exports:
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#
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# Returns: A list of BlockExportInfo describing all block exports
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#
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# Since: 5.2
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##
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{ 'command': 'query-block-exports', 'returns': ['BlockExportInfo'] }
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