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Mon, 16 Sep 2024 18:22:12 -0600 (MDT) Received: by dev-ushankar.dev.purestorage.com (Postfix, from userid 1557716368) id 61923E40F10; Mon, 16 Sep 2024 18:22:12 -0600 (MDT) From: Uday Shankar To: Ming Lei , Jens Axboe Cc: Uday Shankar , linux-block@vger.kernel.org Subject: [PATCH v2 2/4] ublk: refactor recovery configuration flag helpers Date: Mon, 16 Sep 2024 18:21:53 -0600 Message-Id: <20240917002155.2044225-3-ushankar@purestorage.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240917002155.2044225-1-ushankar@purestorage.com> References: <20240917002155.2044225-1-ushankar@purestorage.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 ublk currently supports the following behaviors on ublk server exit: A: outstanding I/Os get errors, subsequently issued I/Os get errors B: outstanding I/Os get errors, subsequently issued I/Os queue C: outstanding I/Os get reissued, subsequently issued I/Os queue and the following behaviors for recovery of preexisting block devices by a future incarnation of the ublk server: 1: ublk devices stopped on ublk server exit (no recovery possible) 2: ublk devices are recoverable using start/end_recovery commands The userspace interface allows selection of combinations of these behaviors using flags specified at device creation time, namely: default behavior: A + 1 UBLK_F_USER_RECOVERY: B + 2 UBLK_F_USER_RECOVERY|UBLK_F_USER_RECOVERY_REISSUE: C + 2 We can't easily change the userspace interface to allow independent selection of one of {A, B, C} and one of {1, 2}, but we can refactor the internal helpers which test for the flags. Replace the existing helpers with the following set: ublk_nosrv_should_reissue_outstanding: tests for behavior C ublk_nosrv_[dev_]should_queue_io: tests for behavior B ublk_nosrv_should_stop_dev: tests for behavior 1 Signed-off-by: Uday Shankar --- Changes since v1 (https://lore.kernel.org/linux-block/20240617194451.435445-3-ushankar@purestorage.com/): - Make the fast-path test in ublk_queue_rq access the queue-local copy of the device flags. drivers/block/ublk_drv.c | 63 +++++++++++++++++++++++++++------------- 1 file changed, 43 insertions(+), 20 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 5e04a0fcd0b7..b069f4d2b9d2 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -675,22 +675,45 @@ static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id) PAGE_SIZE); } -static inline bool ublk_queue_can_use_recovery_reissue( - struct ublk_queue *ubq) +/* + * Should I/O outstanding to the ublk server when it exits be reissued? + * If not, outstanding I/O will get errors. + */ +static inline bool ublk_nosrv_should_reissue_outstanding(struct ublk_device *ub) { - return (ubq->flags & UBLK_F_USER_RECOVERY) && - (ubq->flags & UBLK_F_USER_RECOVERY_REISSUE); + return (ub->dev_info.flags & UBLK_F_USER_RECOVERY) && + (ub->dev_info.flags & UBLK_F_USER_RECOVERY_REISSUE); } -static inline bool ublk_queue_can_use_recovery( - struct ublk_queue *ubq) +/* + * Should I/O issued while there is no ublk server queue? If not, I/O + * issued while there is no ublk server will get errors. + */ +static inline bool ublk_nosrv_dev_should_queue_io(struct ublk_device *ub) +{ + return ub->dev_info.flags & UBLK_F_USER_RECOVERY; +} + +/* + * Same as ublk_nosrv_dev_should_queue_io, but uses a queue-local copy + * of the device flags for smaller cache footprint - better for fast + * paths. + */ +static inline bool ublk_nosrv_should_queue_io(struct ublk_queue *ubq) { return ubq->flags & UBLK_F_USER_RECOVERY; } -static inline bool ublk_can_use_recovery(struct ublk_device *ub) +/* + * Should ublk devices be stopped (i.e. no recovery possible) when the + * ublk server exits? If not, devices can be used again by a future + * incarnation of a ublk server via the start_recovery/end_recovery + * commands. + */ +static inline bool ublk_nosrv_should_stop_dev(struct ublk_device *ub) { - return ub->dev_info.flags & UBLK_F_USER_RECOVERY; + return (!(ub->dev_info.flags & UBLK_F_USER_RECOVERY)) && + (!(ub->dev_info.flags & UBLK_F_USER_RECOVERY_REISSUE)); } static void ublk_free_disk(struct gendisk *disk) @@ -1066,7 +1089,7 @@ static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io, { WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE); - if (ublk_queue_can_use_recovery_reissue(ubq)) + if (ublk_nosrv_should_reissue_outstanding(ubq->dev)) blk_mq_requeue_request(req, false); else ublk_put_req_ref(ubq, req); @@ -1094,7 +1117,7 @@ static inline void __ublk_abort_rq(struct ublk_queue *ubq, struct request *rq) { /* We cannot process this rq so just requeue it. */ - if (ublk_queue_can_use_recovery(ubq)) + if (ublk_nosrv_dev_should_queue_io(ubq->dev)) blk_mq_requeue_request(rq, false); else blk_mq_end_request(rq, BLK_STS_IOERR); @@ -1239,10 +1262,10 @@ static enum blk_eh_timer_return ublk_timeout(struct request *rq) struct ublk_device *ub = ubq->dev; if (ublk_abort_requests(ub, ubq)) { - if (ublk_can_use_recovery(ub)) - schedule_work(&ub->quiesce_work); - else + if (ublk_nosrv_should_stop_dev(ub)) schedule_work(&ub->stop_work); + else + schedule_work(&ub->quiesce_work); } return BLK_EH_DONE; } @@ -1271,7 +1294,7 @@ static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx, * Note: force_abort is guaranteed to be seen because it is set * before request queue is unqiuesced. */ - if (ublk_queue_can_use_recovery(ubq) && unlikely(ubq->force_abort)) + if (ublk_nosrv_should_queue_io(ubq) && unlikely(ubq->force_abort)) return BLK_STS_IOERR; if (unlikely(ubq->canceling)) { @@ -1492,10 +1515,10 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, ublk_cancel_cmd(ubq, io, issue_flags); if (need_schedule) { - if (ublk_can_use_recovery(ub)) - schedule_work(&ub->quiesce_work); - else + if (ublk_nosrv_should_stop_dev(ub)) schedule_work(&ub->stop_work); + else + schedule_work(&ub->quiesce_work); } } @@ -1600,7 +1623,7 @@ static void ublk_stop_dev(struct ublk_device *ub) mutex_lock(&ub->mutex); if (ub->dev_info.state == UBLK_S_DEV_DEAD) goto unlock; - if (ublk_can_use_recovery(ub)) { + if (ublk_nosrv_dev_should_queue_io(ub)) { if (ub->dev_info.state == UBLK_S_DEV_LIVE) __ublk_quiesce_dev(ub); ublk_unquiesce_dev(ub); @@ -2702,7 +2725,7 @@ static int ublk_ctrl_start_recovery(struct ublk_device *ub, int i; mutex_lock(&ub->mutex); - if (!ublk_can_use_recovery(ub)) + if (ublk_nosrv_should_stop_dev(ub)) goto out_unlock; if (!ub->nr_queues_ready) goto out_unlock; @@ -2755,7 +2778,7 @@ static int ublk_ctrl_end_recovery(struct ublk_device *ub, __func__, ub->dev_info.nr_hw_queues, header->dev_id); mutex_lock(&ub->mutex); - if (!ublk_can_use_recovery(ub)) + if (ublk_nosrv_should_stop_dev(ub)) goto out_unlock; if (ub->dev_info.state != UBLK_S_DEV_QUIESCED) {