text: /*
   * QEMU Block backends
   *
   * Copyright (C) 2014-2016 Red Hat, Inc.
   *
   * Authors:
   *  Markus Armbruster <armbru@redhat.com>,
   *
   * This work is licensed under the terms of the GNU LGPL, version 2.1
   * or later.  See the COPYING.LIB file in the top-level directory.
   */
  
  #ifndef BLOCK_BACKEND_H
  #define BLOCK_BACKEND_H
  
  #include "qemu/iov.h"
  #include "block/throttle-groups.h"
  
  /*
   * TODO Have to include block/block.h for a bunch of block layer
   * types.  Unfortunately, this pulls in the whole BlockDriverState
   * API, which we don't want used by many BlockBackend users.  Some of
   * the types belong here, and the rest should be split into a common
   * header and one for the BlockDriverState API.
   */
  #include "block/block.h"
  
  /* Callbacks for block device models */
  typedef struct BlockDevOps {
      /*
       * Runs when virtual media changed (monitor commands eject, change)
       * Argument load is true on load and false on eject.
       * Beware: doesn't run when a host device's physical media
       * changes.  Sure would be useful if it did.
       * Device models with removable media must implement this callback.
       */
      void (*change_media_cb)(void *opaque, bool load, Error **errp);
      /*
       * Runs when an eject request is issued from the monitor, the tray
       * is closed, and the medium is locked.
       * Device models that do not implement is_medium_locked will not need
       * this callback.  Device models that can lock the medium or tray might
       * want to implement the callback and unlock the tray when "force" is
       * true, even if they do not support eject requests.
       */
      void (*eject_request_cb)(void *opaque, bool force);
      /*
       * Is the virtual tray open?
       * Device models implement this only when the device has a tray.
       */
      bool (*is_tray_open)(void *opaque);
      /*
       * Is the virtual medium locked into the device?
       * Device models implement this only when device has such a lock.
       */
      bool (*is_medium_locked)(void *opaque);
      /*
       * Runs when the size changed (e.g. monitor command block_resize)
       */
      void (*resize_cb)(void *opaque);
      /*
       * Runs when the backend receives a drain request.
       */
      void (*drained_begin)(void *opaque);
      /*
       * Runs when the backend's last drain request ends.
       */
      void (*drained_end)(void *opaque);
  } BlockDevOps;
  
  /* This struct is embedded in (the private) BlockBackend struct and contains
   * fields that must be public. This is in particular for QLIST_ENTRY() and
   * friends so that BlockBackends can be kept in lists outside block-backend.c */
  typedef struct BlockBackendPublic {
      /* I/O throttling has its own locking, but also some fields are
       * protected by the AioContext lock.
       */
  
      /* Protected by AioContext lock.  */
      CoQueue      throttled_reqs[2];
  
      /* Nonzero if the I/O limits are currently being ignored; generally
       * it is zero.  */
      unsigned int io_limits_disabled;
  
      /* The following fields are protected by the ThrottleGroup lock.
       * See the ThrottleGroup documentation for details.
       * throttle_state tells us if I/O limits are configured. */
      ThrottleState *throttle_state;
      ThrottleTimers throttle_timers;
      unsigned       pending_reqs[2];
      QLIST_ENTRY(BlockBackendPublic) round_robin;
  } BlockBackendPublic;
  
  BlockBackend *blk_new(uint64_t perm, uint64_t shared_perm);
  BlockBackend *blk_new_open(const char *filename, const char *reference,
                             QDict *options, int flags, Error **errp);
  int blk_get_refcnt(BlockBackend *blk);
  void blk_ref(BlockBackend *blk);
  void blk_unref(BlockBackend *blk);
  void blk_remove_all_bs(void);
  const char *blk_name(BlockBackend *blk);
  BlockBackend *blk_by_name(const char *name);
  BlockBackend *blk_next(BlockBackend *blk);
  bool monitor_add_blk(BlockBackend *blk, const char *name, Error **errp);
  void monitor_remove_blk(BlockBackend *blk);
  
  BlockBackendPublic *blk_get_public(BlockBackend *blk);
  BlockBackend *blk_by_public(BlockBackendPublic *public);
  
  BlockDriverState *blk_bs(BlockBackend *blk);
  BdrvChild *blk_child(BlockBackend *blk);
  void blk_remove_bs(BlockBackend *blk);
  int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp);
  bool bdrv_has_blk(BlockDriverState *bs);
  bool bdrv_is_root_node(BlockDriverState *bs);
  int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
                   Error **errp);
  void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm);
  
  void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow);
  void blk_iostatus_enable(BlockBackend *blk);
  bool blk_iostatus_is_enabled(const BlockBackend *blk);
  BlockDeviceIoStatus blk_iostatus(const BlockBackend *blk);
  void blk_iostatus_disable(BlockBackend *blk);
  void blk_iostatus_reset(BlockBackend *blk);
  void blk_iostatus_set_err(BlockBackend *blk, int error);
  int blk_attach_dev(BlockBackend *blk, DeviceState *dev);
  void blk_attach_dev_legacy(BlockBackend *blk, void *dev);
  void blk_detach_dev(BlockBackend *blk, void *dev);
  void *blk_get_attached_dev(BlockBackend *blk);
  BlockBackend *blk_by_dev(void *dev);
  BlockBackend *blk_by_qdev_id(const char *id, Error **errp);
  void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops, void *opaque);
  int blk_pread_unthrottled(BlockBackend *blk, int64_t offset, uint8_t *buf,
                            int count);
  int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
                                 unsigned int bytes, QEMUIOVector *qiov,
                                 BdrvRequestFlags flags);
  int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
                                 unsigned int bytes, QEMUIOVector *qiov,
                                 BdrvRequestFlags flags);
  int blk_pwrite_zeroes(BlockBackend *blk, int64_t offset,
                        int count, BdrvRequestFlags flags);
  BlockAIOCB *blk_aio_pwrite_zeroes(BlockBackend *blk, int64_t offset,
                                    int count, BdrvRequestFlags flags,
                                    BlockCompletionFunc *cb, void *opaque);
  int blk_make_zero(BlockBackend *blk, BdrvRequestFlags flags);
  int blk_pread(BlockBackend *blk, int64_t offset, void *buf, int count);
  int blk_pwrite(BlockBackend *blk, int64_t offset, const void *buf, int count,
                 BdrvRequestFlags flags);
  int64_t blk_getlength(BlockBackend *blk);
  void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr);
  int64_t blk_nb_sectors(BlockBackend *blk);
  BlockAIOCB *blk_aio_preadv(BlockBackend *blk, int64_t offset,
                             QEMUIOVector *qiov, BdrvRequestFlags flags,
                             BlockCompletionFunc *cb, void *opaque);
  BlockAIOCB *blk_aio_pwritev(BlockBackend *blk, int64_t offset,
                              QEMUIOVector *qiov, BdrvRequestFlags flags,
                              BlockCompletionFunc *cb, void *opaque);
  BlockAIOCB *blk_aio_flush(BlockBackend *blk,
                            BlockCompletionFunc *cb, void *opaque);
  BlockAIOCB *blk_aio_pdiscard(BlockBackend *blk, int64_t offset, int count,
                               BlockCompletionFunc *cb, void *opaque);
  void blk_aio_cancel(BlockAIOCB *acb);
  void blk_aio_cancel_async(BlockAIOCB *acb);
  int blk_co_ioctl(BlockBackend *blk, unsigned long int req, void *buf);
  int blk_ioctl(BlockBackend *blk, unsigned long int req, void *buf);
  BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
                            BlockCompletionFunc *cb, void *opaque);
  int blk_co_pdiscard(BlockBackend *blk, int64_t offset, int count);
  int blk_co_flush(BlockBackend *blk);
  int blk_flush(BlockBackend *blk);
  int blk_commit_all(void);
  void blk_drain(BlockBackend *blk);
  void blk_drain_all(void);
  void blk_set_on_error(BlockBackend *blk, BlockdevOnError on_read_error,
                        BlockdevOnError on_write_error);
  BlockdevOnError blk_get_on_error(BlockBackend *blk, bool is_read);
  BlockErrorAction blk_get_error_action(BlockBackend *blk, bool is_read,
                                        int error);
  void blk_error_action(BlockBackend *blk, BlockErrorAction action,
                        bool is_read, int error);
  int blk_is_read_only(BlockBackend *blk);
  int blk_is_sg(BlockBackend *blk);
  int blk_enable_write_cache(BlockBackend *blk);
  void blk_set_enable_write_cache(BlockBackend *blk, bool wce);
  void blk_invalidate_cache(BlockBackend *blk, Error **errp);
  bool blk_is_inserted(BlockBackend *blk);
  bool blk_is_available(BlockBackend *blk);
  void blk_lock_medium(BlockBackend *blk, bool locked);
  void blk_eject(BlockBackend *blk, bool eject_flag);
  int blk_get_flags(BlockBackend *blk);
  uint32_t blk_get_max_transfer(BlockBackend *blk);
  int blk_get_max_iov(BlockBackend *blk);
  void blk_set_guest_block_size(BlockBackend *blk, int align);
  void *blk_try_blockalign(BlockBackend *blk, size_t size);
  void *blk_blockalign(BlockBackend *blk, size_t size);
  bool blk_op_is_blocked(BlockBackend *blk, BlockOpType op, Error **errp);
  void blk_op_unblock(BlockBackend *blk, BlockOpType op, Error *reason);
  void blk_op_block_all(BlockBackend *blk, Error *reason);
  void blk_op_unblock_all(BlockBackend *blk, Error *reason);
  AioContext *blk_get_aio_context(BlockBackend *blk);
  void blk_set_aio_context(BlockBackend *blk, AioContext *new_context);
  void blk_add_aio_context_notifier(BlockBackend *blk,
          void (*attached_aio_context)(AioContext *new_context, void *opaque),
          void (*detach_aio_context)(void *opaque), void *opaque);
  void blk_remove_aio_context_notifier(BlockBackend *blk,
                                       void (*attached_aio_context)(AioContext *,
                                                                    void *),
                                       void (*detach_aio_context)(void *),
                                       void *opaque);
  void blk_add_remove_bs_notifier(BlockBackend *blk, Notifier *notify);
  void blk_add_insert_bs_notifier(BlockBackend *blk, Notifier *notify);
  void blk_io_plug(BlockBackend *blk);
  void blk_io_unplug(BlockBackend *blk);
  BlockAcctStats *blk_get_stats(BlockBackend *blk);
  BlockBackendRootState *blk_get_root_state(BlockBackend *blk);
  void blk_update_root_state(BlockBackend *blk);
  bool blk_get_detect_zeroes_from_root_state(BlockBackend *blk);
  int blk_get_open_flags_from_root_state(BlockBackend *blk);
  
  void *blk_aio_get(const AIOCBInfo *aiocb_info, BlockBackend *blk,
                    BlockCompletionFunc *cb, void *opaque);
  int coroutine_fn blk_co_pwrite_zeroes(BlockBackend *blk, int64_t offset,
                                        int count, BdrvRequestFlags flags);
  int blk_pwrite_compressed(BlockBackend *blk, int64_t offset, const void *buf,
                            int count);
  int blk_truncate(BlockBackend *blk, int64_t offset);
  int blk_pdiscard(BlockBackend *blk, int64_t offset, int count);
  int blk_save_vmstate(BlockBackend *blk, const uint8_t *buf,
                       int64_t pos, int size);
  int blk_load_vmstate(BlockBackend *blk, uint8_t *buf, int64_t pos, int size);
  int blk_probe_blocksizes(BlockBackend *blk, BlockSizes *bsz);
  int blk_probe_geometry(BlockBackend *blk, HDGeometry *geo);
  BlockAIOCB *blk_abort_aio_request(BlockBackend *blk,
                                    BlockCompletionFunc *cb,
                                    void *opaque, int ret);
  
  void blk_set_io_limits(BlockBackend *blk, ThrottleConfig *cfg);
  void blk_io_limits_disable(BlockBackend *blk);
  void blk_io_limits_enable(BlockBackend *blk, const char *group);
  void blk_io_limits_update_group(BlockBackend *blk, const char *group);
  
  #endif
  