| 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 */ |