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 */ 76