include/sysemu/block-backend-common.h

   1 /*
   2  * QEMU Block backends
   3  *
   4  * Copyright (C) 2014-2016 Red Hat, Inc.
   5  *
   6  * Authors:
   7  *  Markus Armbruster <armbru@redhat.com>,
   8  *
   9  * This work is licensed under the terms of the GNU LGPL, version 2.1
  10  * or later.  See the COPYING.LIB file in the top-level directory.
  11  */
  12
  13 #ifndef BLOCK_BACKEND_COMMON_H
  14 #define BLOCK_BACKEND_COMMON_H
  15
  16 #include "qemu/iov.h"
  17 #include "block/throttle-groups.h"
  18
  19 /*
  20  * TODO Have to include block/block.h for a bunch of block layer
  21  * types.  Unfortunately, this pulls in the whole BlockDriverState
  22  * API, which we don't want used by many BlockBackend users.  Some of
  23  * the types belong here, and the rest should be split into a common
  24  * header and one for the BlockDriverState API.
  25  */
  26 #include "block/block.h"
  27
  28 /* Callbacks for block device models */
  29 typedef struct BlockDevOps {
  30
  31     /*
  32      * Global state (GS) API. These functions run under the BQL.
  33      *
  34      * See include/block/block-global-state.h for more information about
  35      * the GS API.
  36      */
  37
  38     /*
  39      * Runs when virtual media changed (monitor commands eject, change)
  40      * Argument load is true on load and false on eject.
  41      * Beware: doesn't run when a host device's physical media
  42      * changes.  Sure would be useful if it did.
  43      * Device models with removable media must implement this callback.
  44      */
  45     void (*change_media_cb)(void *opaque, bool load, Error **errp);
  46     /*
  47      * Runs when an eject request is issued from the monitor, the tray
  48      * is closed, and the medium is locked.
  49      * Device models that do not implement is_medium_locked will not need
  50      * this callback.  Device models that can lock the medium or tray might
  51      * want to implement the callback and unlock the tray when "force" is
  52      * true, even if they do not support eject requests.
  53      */
  54     void (*eject_request_cb)(void *opaque, bool force);
  55
  56     /*
  57      * Is the virtual medium locked into the device?
  58      * Device models implement this only when device has such a lock.
  59      */
  60     bool (*is_medium_locked)(void *opaque);
  61
  62     /*
  63      * I/O API functions. These functions are thread-safe.
  64      *
  65      * See include/block/block-io.h for more information about
  66      * the I/O API.
  67      */
  68
  69     /*
  70      * Is the virtual tray open?
  71      * Device models implement this only when the device has a tray.
  72      */
  73     bool (*is_tray_open)(void *opaque);
  74
  75     /*
  76      * Runs when the size changed (e.g. monitor command block_resize)
  77      */
  78     void (*resize_cb)(void *opaque);
  79     /*
  80      * Runs when the backend receives a drain request.
  81      */
  82     void (*drained_begin)(void *opaque);
  83     /*
  84      * Runs when the backend's last drain request ends.
  85      */
  86     void (*drained_end)(void *opaque);
  87     /*
  88      * Is the device still busy?
  89      */
  90     bool (*drained_poll)(void *opaque);
  91 } BlockDevOps;
  92
  93 /*
  94  * This struct is embedded in (the private) BlockBackend struct and contains
  95  * fields that must be public. This is in particular for QLIST_ENTRY() and
  96  * friends so that BlockBackends can be kept in lists outside block-backend.c
  97  */
  98 typedef struct BlockBackendPublic {
  99     ThrottleGroupMember throttle_group_member;
 100 } BlockBackendPublic;
 101
 102 #endif /* BLOCK_BACKEND_COMMON_H */