| 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 | /* True if the export type supports running on an inactive node */ |
| 33 | bool supports_inactive; |
| 34 | |
| 35 | /* |
| 36 | * Creates and starts a new block export. |
| 37 | * |
| 38 | * If the user passed a set of I/O threads for multi-threading, @multithread |
| 39 | * is a list of the @multithread_count corresponding contexts (freed by the |
| 40 | * caller). Note that @exp->ctx has no relation to that list. |
| 41 | */ |
| 42 | int (*create)(BlockExport *exp, BlockExportOptions *opts, |
| 43 | AioContext *const *multithread, size_t multithread_count, |
| 44 | Error **errp); |
| 45 | |
| 46 | /* |
| 47 | * Frees a removed block export. This function is only called after all |
| 48 | * references have been dropped. |
| 49 | */ |
| 50 | void (*delete)(BlockExport *); |
| 51 | |
| 52 | /* |
| 53 | * Start to disconnect all clients and drop other references held |
| 54 | * internally by the export driver. When the function returns, there may |
| 55 | * still be active references while the export is in the process of |
| 56 | * shutting down. |
| 57 | */ |
| 58 | void (*request_shutdown)(BlockExport *); |
| 59 | } BlockExportDriver; |
| 60 | |
| 61 | struct BlockExport { |
| 62 | const BlockExportDriver *drv; |
| 63 | |
| 64 | /* Unique identifier for the export */ |
| 65 | char *id; |
| 66 | |
| 67 | /* |
| 68 | * Reference count for this block export. This includes strong references |
| 69 | * both from the owner (qemu-nbd or the monitor) and clients connected to |
| 70 | * the export. |
| 71 | * |
| 72 | * Use atomics to access this field. |
| 73 | */ |
| 74 | int refcount; |
| 75 | |
| 76 | /* |
| 77 | * True if one of the references in refcount belongs to the user. After the |
| 78 | * user has dropped their reference, they may not e.g. remove the same |
| 79 | * export a second time (which would decrease the refcount without having |
| 80 | * it incremented first). |
| 81 | */ |
| 82 | bool user_owned; |
| 83 | |
| 84 | /* The AioContext whose lock protects this BlockExport object. */ |
| 85 | AioContext *ctx; |
| 86 | |
| 87 | /* The block device to export */ |
| 88 | BlockBackend *blk; |
| 89 | |
| 90 | /* List entry for block_exports */ |
| 91 | QLIST_ENTRY(BlockExport) next; |
| 92 | }; |
| 93 | |
| 94 | BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp); |
| 95 | BlockExport *blk_exp_find(const char *id); |
| 96 | void blk_exp_ref(BlockExport *exp); |
| 97 | void blk_exp_unref(BlockExport *exp); |
| 98 | void blk_exp_request_shutdown(BlockExport *exp); |
| 99 | void blk_exp_close_all(void); |
| 100 | void blk_exp_close_all_type(BlockExportType type); |
| 101 | |
| 102 | #endif |