block/reqlist.c

   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 #include "qemu/osdep.h"
  16 #include "qemu/range.h"
  17
  18 #include "block/reqlist.h"
  19
  20 void reqlist_init_req(BlockReqList *reqs, BlockReq *req, int64_t offset,
  21                       int64_t bytes)
  22 {
  23     assert(!reqlist_find_conflict(reqs, offset, bytes));
  24
  25     *req = (BlockReq) {
  26         .offset = offset,
  27         .bytes = bytes,
  28     };
  29     qemu_co_queue_init(&req->wait_queue);
  30     QLIST_INSERT_HEAD(reqs, req, list);
  31 }
  32
  33 BlockReq *reqlist_find_conflict(BlockReqList *reqs, int64_t offset,
  34                                 int64_t bytes)
  35 {
  36     BlockReq *r;
  37
  38     QLIST_FOREACH(r, reqs, list) {
  39         if (ranges_overlap(offset, bytes, r->offset, r->bytes)) {
  40             return r;
  41         }
  42     }
  43
  44     return NULL;
  45 }
  46
  47 bool coroutine_fn reqlist_wait_one(BlockReqList *reqs, int64_t offset,
  48                                    int64_t bytes, CoMutex *lock)
  49 {
  50     BlockReq *r = reqlist_find_conflict(reqs, offset, bytes);
  51
  52     if (!r) {
  53         return false;
  54     }
  55
  56     qemu_co_queue_wait(&r->wait_queue, lock);
  57
  58     return true;
  59 }
  60
  61 void coroutine_fn reqlist_wait_all(BlockReqList *reqs, int64_t offset,
  62                                    int64_t bytes, CoMutex *lock)
  63 {
  64     while (reqlist_wait_one(reqs, offset, bytes, lock)) {
  65         /* continue */
  66     }
  67 }
  68
  69 void coroutine_fn reqlist_shrink_req(BlockReq *req, int64_t new_bytes)
  70 {
  71     if (new_bytes == req->bytes) {
  72         return;
  73     }
  74
  75     assert(new_bytes > 0 && new_bytes < req->bytes);
  76
  77     req->bytes = new_bytes;
  78     qemu_co_queue_restart_all(&req->wait_queue);
  79 }
  80
  81 void coroutine_fn reqlist_remove_req(BlockReq *req)
  82 {
  83     QLIST_REMOVE(req, list);
  84     qemu_co_queue_restart_all(&req->wait_queue);
  85 }