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DIR:OUT; SFP:1102; SCL:1; SRVR:AM0PR08MB2977; H:AM0PR08MB4292.eurprd08.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; A:1; MX:1; received-spf: None (protection.outlook.com: virtuozzo.com does not designate permitted sender hosts) authentication-results: spf=none (sender IP is ) smtp.mailfrom=anton.nefedov@virtuozzo.com; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: EoO7tTv/YbAWP6AOYvwjPEGuTigKaoNlN15tH2/6SCURr47XZqzXWR6+GkaEdxip/j82i+CaPvCk/8MkM+7ikg+PCAv1/Z1/eGwJBV3SRoYMHU984jlKc802/6s49L9WZMMVp5neIvJ4pFlE9dkdHauwC3M3fdJh7YQOa8Uja8sxiAvekQR1QrT9x44wwICmFvwiM4a5x9+iIxQ52QX8xbeyEFFQ0Dn/BxqtAzNyn4mvwUEgNjKvfMMRUDr8Jh4LKe3nj6n1V/W5UxEnrFuvKg9cWsFrJOBoEIHe6DqkpoLPPgVRrnEBjD4Go6XVvef/Ab8XUwkkYsdK3DsJAEWM2MAoer+cih1klQlC1Rwbs4RMSf3dhFcjIBtiIUVwXJKnZA9DKXruBTHEXazRZ6TuTERs60y4SsxXm3pqKvU+V0o= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM MIME-Version: 1.0 X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-Network-Message-Id: e03ed20e-f717-45d4-6715-08d67a120127 X-MS-Exchange-CrossTenant-originalarrivaltime: 14 Jan 2019 11:18:26.1029 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 0bc7f26d-0264-416e-a6fc-8352af79c58f X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM0PR08MB2977 X-detected-operating-system: by eggs.gnu.org: Windows 7 or 8 [fuzzy] X-Received-From: 40.107.13.115 Subject: [Qemu-devel] [PATCH v12 05/10] block: treat BDRV_REQ_ALLOCATE as serialising X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "kwolf@redhat.com" , Vladimir Sementsov-Ogievskiy , "berto@igalia.com" , Denis Lunev , "qemu-block@nongnu.org" , "mreitz@redhat.com" , Anton Nefedov Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP The idea is that ALLOCATE requests may overlap with other requests. Reuse the existing block layer infrastructure for serialising requests. Use the following approach: - mark ALLOCATE also SERIALISING, so subsequent requests to the area wait - ALLOCATE request itself must never wait if another request is in flight already. Return EAGAIN, let the caller reconsider. Signed-off-by: Anton Nefedov Reviewed-by: Alberto Garcia --- include/block/block.h | 3 +++ block/io.c | 31 ++++++++++++++++++++++++------- 2 files changed, 27 insertions(+), 7 deletions(-) diff --git a/include/block/block.h b/include/block/block.h index 643d32f4b8..dfc0fc1b8f 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -88,6 +88,9 @@ typedef enum { * efficiently allocate the space so it reads as zeroes, or return an error. * If this flag is set then BDRV_REQ_ZERO_WRITE must also be set. * This flag cannot be set together with BDRV_REQ_MAY_UNMAP. + * This flag implicitly sets BDRV_REQ_SERIALISING meaning it is protected + * from conflicts with overlapping requests. If such conflict is detected, + * -EAGAIN is returned. */ BDRV_REQ_ALLOCATE = 0x100, diff --git a/block/io.c b/block/io.c index 66006a089d..4451714a60 100644 --- a/block/io.c +++ b/block/io.c @@ -720,12 +720,13 @@ void bdrv_dec_in_flight(BlockDriverState *bs) bdrv_wakeup(bs); } -static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self) +static bool coroutine_fn find_or_wait_serialising_requests( + BdrvTrackedRequest *self, bool wait) { BlockDriverState *bs = self->bs; BdrvTrackedRequest *req; bool retry; - bool waited = false; + bool found = false; if (!atomic_read(&bs->serialising_in_flight)) { return false; @@ -751,11 +752,14 @@ static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self) * will wait for us as soon as it wakes up, then just go on * (instead of producing a deadlock in the former case). */ if (!req->waiting_for) { + found = true; + if (!wait) { + break; + } self->waiting_for = req; qemu_co_queue_wait(&req->wait_queue, &bs->reqs_lock); self->waiting_for = NULL; retry = true; - waited = true; break; } } @@ -763,7 +767,12 @@ static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self) qemu_co_mutex_unlock(&bs->reqs_lock); } while (retry); - return waited; + return found; +} + +static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self) +{ + return find_or_wait_serialising_requests(self, true); } static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset, @@ -1585,7 +1594,7 @@ bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, uint64_t bytes, BdrvTrackedRequest *req, int flags) { BlockDriverState *bs = child->bs; - bool waited; + bool found; int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE); if (bs->read_only) { @@ -1602,9 +1611,13 @@ bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, uint64_t bytes, mark_request_serialising(req, bdrv_get_cluster_size(bs)); } - waited = wait_serialising_requests(req); + found = find_or_wait_serialising_requests(req, + !(flags & BDRV_REQ_ALLOCATE)); + if (found && (flags & BDRV_REQ_ALLOCATE)) { + return -EAGAIN; + } - assert(!waited || !req->serialising || + assert(!found || !req->serialising || is_request_serialising_and_aligned(req)); assert(req->overlap_offset <= offset); assert(offset + bytes <= req->overlap_offset + req->overlap_bytes); @@ -1864,6 +1877,10 @@ int coroutine_fn bdrv_co_pwritev(BdrvChild *child, assert(!((flags & BDRV_REQ_ALLOCATE) && (flags & BDRV_REQ_MAY_UNMAP))); assert(!((flags & BDRV_REQ_ALLOCATE) && !(flags & BDRV_REQ_ZERO_WRITE))); + if (flags & BDRV_REQ_ALLOCATE) { + flags |= BDRV_REQ_SERIALISING; + } + trace_bdrv_co_pwritev(child->bs, offset, bytes, flags); if (!bs->drv) {