include/block/reqlist.h

   1 /*
   2  * reqlist API
   3  *
   4  * Copyright (C) 2013 Proxmox Server Solutions
   5  * Copyright (c) 2021 Virtuozzo International GmbH.
   6  *
   7  * Authors:
   8  *  Dietmar Maurer (dietmar@proxmox.com)
   9  *  Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  12  * See the COPYING file in the top-level directory.
  13  */
  14
  15 #ifndef REQLIST_H
  16 #define REQLIST_H
  17
  18 #include "qemu/coroutine.h"
  19
  20 /*
  21  * The API is not thread-safe and shouldn't be. The struct is public to be part
  22  * of other structures and protected by third-party locks, see
  23  * block/block-copy.c for example.
  24  */
  25
  26 typedef struct BlockReq {
  27     int64_t offset;
  28     int64_t bytes;
  29
  30     CoQueue wait_queue; /* coroutines blocked on this req */
  31     QLIST_ENTRY(BlockReq) list;
  32 } BlockReq;
  33
  34 typedef QLIST_HEAD(, BlockReq) BlockReqList;
  35
  36 /*
  37  * Initialize new request and add it to the list. Caller must be sure that
  38  * there are no conflicting requests in the list.
  39  */
  40 void reqlist_init_req(BlockReqList *reqs, BlockReq *req, int64_t offset,
  41                       int64_t bytes);
  42 /* Search for request in the list intersecting with @offset/@bytes area. */
  43 BlockReq *reqlist_find_conflict(BlockReqList *reqs, int64_t offset,
  44                                 int64_t bytes);
  45
  46 /*
  47  * If there are no intersecting requests return false. Otherwise, wait for the
  48  * first found intersecting request to finish and return true.
  49  *
  50  * @lock is passed to qemu_co_queue_wait()
  51  * False return value proves that lock was released at no point.
  52  */
  53 bool coroutine_fn reqlist_wait_one(BlockReqList *reqs, int64_t offset,
  54                                    int64_t bytes, CoMutex *lock);
  55
  56 /*
  57  * Wait for all intersecting requests. It just calls reqlist_wait_one() in a
  58  * loop, caller is responsible to stop producing new requests in this region
  59  * in parallel, otherwise reqlist_wait_all() may never return.
  60  */
  61 void coroutine_fn reqlist_wait_all(BlockReqList *reqs, int64_t offset,
  62                                    int64_t bytes, CoMutex *lock);
  63
  64 /*
  65  * Shrink request and wake all waiting coroutines (maybe some of them are not
  66  * intersecting with shrunk request).
  67  */
  68 void coroutine_fn reqlist_shrink_req(BlockReq *req, int64_t new_bytes);
  69
  70 /*
  71  * Remove request and wake all waiting coroutines. Do not release any memory.
  72  */
  73 void coroutine_fn reqlist_remove_req(BlockReq *req);
  74
  75 #endif /* REQLIST_H */