Merge remote-tracking branch 'remotes/kraxel/tags/audio-20210617-pull-request' into...
[qemu.git] / include / block / export.h
1 /*
2 * Declarations for block exports
3 *
4 * Copyright (c) 2012, 2020 Red Hat, Inc.
5 *
6 * Authors:
7 * Paolo Bonzini <pbonzini@redhat.com>
8 * Kevin Wolf <kwolf@redhat.com>
9 *
10 * This work is licensed under the terms of the GNU GPL, version 2 or
11 * later. See the COPYING file in the top-level directory.
12 */
13
14 #ifndef BLOCK_EXPORT_H
15 #define BLOCK_EXPORT_H
16
17 #include "qapi/qapi-types-block-export.h"
18 #include "qemu/queue.h"
19
20 typedef struct BlockExport BlockExport;
21
22 typedef struct BlockExportDriver {
23 /* The export type that this driver services */
24 BlockExportType type;
25
26 /*
27 * The size of the driver-specific state that contains BlockExport as its
28 * first field.
29 */
30 size_t instance_size;
31
32 /* Creates and starts a new block export */
33 int (*create)(BlockExport *, BlockExportOptions *, Error **);
34
35 /*
36 * Frees a removed block export. This function is only called after all
37 * references have been dropped.
38 */
39 void (*delete)(BlockExport *);
40
41 /*
42 * Start to disconnect all clients and drop other references held
43 * internally by the export driver. When the function returns, there may
44 * still be active references while the export is in the process of
45 * shutting down.
46 */
47 void (*request_shutdown)(BlockExport *);
48 } BlockExportDriver;
49
50 struct BlockExport {
51 const BlockExportDriver *drv;
52
53 /* Unique identifier for the export */
54 char *id;
55
56 /*
57 * Reference count for this block export. This includes strong references
58 * both from the owner (qemu-nbd or the monitor) and clients connected to
59 * the export.
60 */
61 int refcount;
62
63 /*
64 * True if one of the references in refcount belongs to the user. After the
65 * user has dropped their reference, they may not e.g. remove the same
66 * export a second time (which would decrease the refcount without having
67 * it incremented first).
68 */
69 bool user_owned;
70
71 /* The AioContext whose lock protects this BlockExport object. */
72 AioContext *ctx;
73
74 /* The block device to export */
75 BlockBackend *blk;
76
77 /* List entry for block_exports */
78 QLIST_ENTRY(BlockExport) next;
79 };
80
81 BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
82 BlockExport *blk_exp_find(const char *id);
83 void blk_exp_ref(BlockExport *exp);
84 void blk_exp_unref(BlockExport *exp);
85 void blk_exp_request_shutdown(BlockExport *exp);
86 void blk_exp_close_all(void);
87 void blk_exp_close_all_type(BlockExportType type);
88
89 #endif