From patchwork Thu Jan 28 17:12:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergei Shtepa X-Patchwork-Id: 12054249 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 685CAC433E0 for ; Thu, 28 Jan 2021 17:27:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 250E464DED for ; Thu, 28 Jan 2021 17:27:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232746AbhA1R13 (ORCPT ); Thu, 28 Jan 2021 12:27:29 -0500 Received: from mx2.veeam.com ([64.129.123.6]:53906 "EHLO mx2.veeam.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233051AbhA1RYP (ORCPT ); Thu, 28 Jan 2021 12:24:15 -0500 X-Greylist: delayed 633 seconds by postgrey-1.27 at vger.kernel.org; Thu, 28 Jan 2021 12:24:12 EST Received: from mail.veeam.com (prgmbx01.amust.local [172.24.0.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx2.veeam.com (Postfix) with ESMTPS id 6056541278; Thu, 28 Jan 2021 12:12:52 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=veeam.com; s=mx2; t=1611853972; bh=9z5w/TK6NX92KWN8HScKS4YWvjDaJW4yPJChgQq87MA=; h=From:To:CC:Subject:Date:In-Reply-To:References:From; b=s6hNB4cOizoVyBGV/QGCMCChDyl4un0la43vmOupgunFcttRbDC2VuXevs5rAOdjW ht5So26q5Ss0B7W1ivEmXD4DGPU+5OL4V5U/8EtCMlyVUJvuR/SV8Lr2306DRwa9/z Nisc7QH1qpN9/LsJYZl5MGFO6PMoGV0y/J2dqRRE= Received: from prgdevlinuxpatch01.amust.local (172.24.14.5) by prgmbx01.amust.local (172.24.0.171) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.721.2; Thu, 28 Jan 2021 18:12:51 +0100 From: Sergei Shtepa To: , , , , , CC: , Subject: [PATCH 1/2] block: blk_interposer Date: Thu, 28 Jan 2021 20:12:34 +0300 Message-ID: <1611853955-32167-2-git-send-email-sergei.shtepa@veeam.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1611853955-32167-1-git-send-email-sergei.shtepa@veeam.com> References: <1611853955-32167-1-git-send-email-sergei.shtepa@veeam.com> MIME-Version: 1.0 X-Originating-IP: [172.24.14.5] X-ClientProxiedBy: prgmbx01.amust.local (172.24.0.171) To prgmbx01.amust.local (172.24.0.171) X-EsetResult: clean, is OK X-EsetId: 37303A29C604D265677D6B X-Veeam-MMEX: True Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org The block layer interposer allows to intercept bio requests. This allows to connect device mapper and other kernel modules to the block device stack on the fly. changes: * new BIO_INTERPOSED bio flag. * new function __submit_bio_interposed() implements the interposers logic. * new function blk_mq_is_queue_frozen() allow to assert that the queue is frozen. * functions blk_interposer_attach() and blk_interposer_detach() allow to attach and detach interposers. Signed-off-by: Sergei Shtepa --- block/bio.c | 2 + block/blk-core.c | 29 ++++++++++++++ block/blk-mq.c | 13 +++++++ block/genhd.c | 82 +++++++++++++++++++++++++++++++++++++++ include/linux/blk-mq.h | 1 + include/linux/blk_types.h | 6 ++- include/linux/genhd.h | 19 +++++++++ 7 files changed, 150 insertions(+), 2 deletions(-) diff --git a/block/bio.c b/block/bio.c index 1f2cc1fbe283..f6f135eb84b5 100644 --- a/block/bio.c +++ b/block/bio.c @@ -684,6 +684,8 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src) bio_set_flag(bio, BIO_CLONED); if (bio_flagged(bio_src, BIO_THROTTLED)) bio_set_flag(bio, BIO_THROTTLED); + if (bio_flagged(bio_src, BIO_INTERPOSED)) + bio_set_flag(bio, BIO_INTERPOSED); bio->bi_opf = bio_src->bi_opf; bio->bi_ioprio = bio_src->bi_ioprio; bio->bi_write_hint = bio_src->bi_write_hint; diff --git a/block/blk-core.c b/block/blk-core.c index 7663a9b94b80..07ec82d8fe57 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1032,6 +1032,32 @@ static blk_qc_t __submit_bio_noacct_mq(struct bio *bio) return ret; } +static blk_qc_t __submit_bio_interposed(struct bio *bio) +{ + struct bio_list bio_list[2] = { }; + blk_qc_t ret = BLK_QC_T_NONE; + + current->bio_list = bio_list; + if (likely(bio_queue_enter(bio) == 0)) { + struct gendisk *disk = bio->bi_disk; + + bio_set_flag(bio, BIO_INTERPOSED); + if (likely(blk_has_interposer(disk))) + disk->interposer->ip_submit_bio(bio); + else /* interposer was removed */ + bio_list_add(¤t->bio_list[0], bio); + + blk_queue_exit(disk->queue); + } + current->bio_list = NULL; + + /* Resubmit remaining bios */ + while ((bio = bio_list_pop(&bio_list[0]))) + ret = submit_bio_noacct(bio); + + return ret; +} + /** * submit_bio_noacct - re-submit a bio to the block device layer for I/O * @bio: The bio describing the location in memory and on the device. @@ -1057,6 +1083,9 @@ blk_qc_t submit_bio_noacct(struct bio *bio) return BLK_QC_T_NONE; } + if (blk_has_interposer(bio->bi_disk) && + !bio_flagged(bio, BIO_INTERPOSED)) + return __submit_bio_interposed(bio); if (!bio->bi_disk->fops->submit_bio) return __submit_bio_noacct_mq(bio); return __submit_bio_noacct(bio); diff --git a/block/blk-mq.c b/block/blk-mq.c index f285a9123a8b..924ec26fae5f 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -161,6 +161,19 @@ int blk_mq_freeze_queue_wait_timeout(struct request_queue *q, } EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout); + +bool blk_mq_is_queue_frozen(struct request_queue *q) +{ + bool ret; + + mutex_lock(&q->mq_freeze_lock); + ret = percpu_ref_is_dying(&q->q_usage_counter) && percpu_ref_is_zero(&q->q_usage_counter); + mutex_unlock(&q->mq_freeze_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(blk_mq_is_queue_frozen); + /* * Guarantee no request is in use, so we can change any data structure of * the queue afterward. diff --git a/block/genhd.c b/block/genhd.c index 419548e92d82..d3459582f56c 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -30,6 +30,7 @@ static struct kobject *block_depr; DECLARE_RWSEM(bdev_lookup_sem); +DEFINE_MUTEX(bdev_interposer_mutex); /* for extended dynamic devt allocation, currently only one major is used */ #define NR_EXT_DEVT (1 << MINORBITS) @@ -2148,3 +2149,84 @@ static void disk_release_events(struct gendisk *disk) WARN_ON_ONCE(disk->ev && disk->ev->block != 1); kfree(disk->ev); } + +/** + * blk_interposer_attach - Attach interposer to disk + * @disk: target disk + * @interposer: block device interposer + * @ip_submit_bio: hook for submit_bio() + * + * Returns: + * -EINVAL if @interposer is NULL. + * -EPERM if queue is not frozen. + * -EBUSY if the block device already has @interposer. + * -EALREADY if the block device already has @interposer with same callback. + * + * Disk must be frozen by blk_mq_freeze_queue(). + */ +int blk_interposer_attach(struct gendisk *disk, struct blk_interposer *interposer, + const ip_submit_bio_t ip_submit_bio) +{ + int ret = 0; + + if (!interposer) + return -EINVAL; + + if (!blk_mq_is_queue_frozen(disk->queue)) + return -EPERM; + + mutex_lock(&bdev_interposer_mutex); + if (blk_has_interposer(disk)) { + if (disk->interposer->ip_submit_bio == ip_submit_bio) + ret = -EALREADY; + else + ret = -EBUSY; + goto out; + } + + interposer->ip_submit_bio = ip_submit_bio; + interposer->disk = disk; + + disk->interposer = interposer; +out: + mutex_unlock(&bdev_interposer_mutex); + + return ret; +} +EXPORT_SYMBOL_GPL(blk_interposer_attach); + +/** + * blk_interposer_detach - Detach interposer from disk + * @interposer: block device interposer + * @ip_submit_bio: hook for submit_bio() + * + * Disk must be frozen by blk_mq_freeze_queue(). + */ +void blk_interposer_detach(struct blk_interposer *interposer, + const ip_submit_bio_t ip_submit_bio) +{ + struct gendisk *disk; + + if (WARN_ON(!interposer)) + return; + + mutex_lock(&bdev_interposer_mutex); + + /* Check if the interposer is still active. */ + disk = interposer->disk; + if (WARN_ON(!disk)) + goto out; + + if (WARN_ON(!blk_mq_is_queue_frozen(disk->queue))) + goto out; + + /* Check if it is really our interposer. */ + if (WARN_ON(disk->interposer->ip_submit_bio != ip_submit_bio)) + goto out; + + disk->interposer = NULL; + interposer->disk = NULL; +out: + mutex_unlock(&bdev_interposer_mutex); +} +EXPORT_SYMBOL_GPL(blk_interposer_detach); diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index d705b174d346..9d1e8c4e922e 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -525,6 +525,7 @@ void blk_freeze_queue_start(struct request_queue *q); void blk_mq_freeze_queue_wait(struct request_queue *q); int blk_mq_freeze_queue_wait_timeout(struct request_queue *q, unsigned long timeout); +bool blk_mq_is_queue_frozen(struct request_queue *q); int blk_mq_map_queues(struct blk_mq_queue_map *qmap); void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues); diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 866f74261b3b..6c1351d7b73f 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -227,7 +227,7 @@ struct bio { * top bits REQ_OP. Use * accessors. */ - unsigned short bi_flags; /* status, etc and bvec pool number */ + unsigned int bi_flags; /* status, etc and bvec pool number */ unsigned short bi_ioprio; unsigned short bi_write_hint; blk_status_t bi_status; @@ -304,6 +304,8 @@ enum { * of this bio. */ BIO_CGROUP_ACCT, /* has been accounted to a cgroup */ BIO_TRACKED, /* set if bio goes through the rq_qos path */ + BIO_INTERPOSED, /* bio has been interposed and can be moved to + * a different disk */ BIO_FLAG_LAST }; @@ -322,7 +324,7 @@ enum { * freed. */ #define BVEC_POOL_BITS (3) -#define BVEC_POOL_OFFSET (16 - BVEC_POOL_BITS) +#define BVEC_POOL_OFFSET (32 - BVEC_POOL_BITS) #define BVEC_POOL_IDX(bio) ((bio)->bi_flags >> BVEC_POOL_OFFSET) #if (1<< BVEC_POOL_BITS) < (BVEC_POOL_NR+1) # error "BVEC_POOL_BITS is too small" diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 809aaa32d53c..8094af3a3db9 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -134,6 +134,14 @@ struct blk_integrity { unsigned char tag_size; }; +struct blk_interposer; +typedef void (*ip_submit_bio_t) (struct bio *bio); + +struct blk_interposer { + ip_submit_bio_t ip_submit_bio; + struct gendisk *disk; +}; + struct gendisk { /* major, first_minor and minors are input parameters only, * don't use directly. Use disk_devt() and disk_max_parts(). @@ -158,6 +166,7 @@ struct gendisk { const struct block_device_operations *fops; struct request_queue *queue; + struct blk_interposer *interposer; void *private_data; int flags; @@ -346,4 +355,14 @@ static inline void printk_all_partitions(void) } #endif /* CONFIG_BLOCK */ +/* + * block layer interposer + */ +#define blk_has_interposer(d) ((d)->interposer != NULL) + +int blk_interposer_attach(struct gendisk *disk, struct blk_interposer *interposer, + const ip_submit_bio_t ip_submit_bio); +void blk_interposer_detach(struct blk_interposer *interposer, + const ip_submit_bio_t ip_submit_bio); + #endif /* _LINUX_GENHD_H */