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Fri, 12 Mar 2021 10:45:22 -0500 X-MC-Unique: zk7LRHQiNE-YQRDp4Hngag-1 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 mx4.veeam.com (Postfix) with ESMTPS id 741A9874F3; Fri, 12 Mar 2021 18:45:19 +0300 (MSK) 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; Fri, 12 Mar 2021 16:45:17 +0100 From: Sergei Shtepa To: Christoph Hellwig , Mike Snitzer , Alasdair Kergon , Hannes Reinecke , Jens Axboe , , , , Date: Fri, 12 Mar 2021 18:44:54 +0300 Message-ID: <1615563895-28565-3-git-send-email-sergei.shtepa@veeam.com> In-Reply-To: <1615563895-28565-1-git-send-email-sergei.shtepa@veeam.com> References: <1615563895-28565-1-git-send-email-sergei.shtepa@veeam.com> MIME-Version: 1.0 X-Originating-IP: [172.24.14.5] X-ClientProxiedBy: prgmbx02.amust.local (172.24.0.172) To prgmbx01.amust.local (172.24.0.171) X-EsetResult: clean, is OK X-EsetId: 37303A29D2A50B58627366 X-Veeam-MMEX: True X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-loop: dm-devel@redhat.com Cc: pavel.tide@veeam.com, sergei.shtepa@veeam.com Subject: [dm-devel] [PATCH v7 2/3] block: add bdev_interposer X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com bdev_interposer allows to redirect bio requests to another devices. Signed-off-by: Sergei Shtepa --- block/bio.c | 2 ++ block/blk-core.c | 57 +++++++++++++++++++++++++++++++++++++++ block/genhd.c | 54 +++++++++++++++++++++++++++++++++++++ include/linux/blk_types.h | 3 +++ include/linux/blkdev.h | 9 +++++++ 5 files changed, 125 insertions(+) diff --git a/block/bio.c b/block/bio.c index a1c4d2900c7a..0bfbf06475ee 100644 --- a/block/bio.c +++ b/block/bio.c @@ -640,6 +640,8 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src) bio_set_flag(bio, BIO_THROTTLED); if (bio_flagged(bio_src, BIO_REMAPPED)) bio_set_flag(bio, BIO_REMAPPED); + 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 fc60ff208497..da1abc4c27a9 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1018,6 +1018,55 @@ static blk_qc_t __submit_bio_noacct_mq(struct bio *bio) return ret; } +static noinline blk_qc_t submit_bio_interposed(struct bio *bio) +{ + blk_qc_t ret = BLK_QC_T_NONE; + struct bio_list bio_list[2] = { }; + struct gendisk *orig_disk; + + if (current->bio_list) { + bio_list_add(¤t->bio_list[0], bio); + return BLK_QC_T_NONE; + } + + orig_disk = bio->bi_bdev->bd_disk; + if (unlikely(bio_queue_enter(bio))) + return BLK_QC_T_NONE; + + current->bio_list = bio_list; + + do { + struct block_device *interposer = bio->bi_bdev->bd_interposer; + + if (unlikely(!interposer)) { + /* interposer was removed */ + bio_list_add(¤t->bio_list[0], bio); + break; + } + /* assign bio to interposer device */ + bio_set_dev(bio, interposer); + bio_set_flag(bio, BIO_INTERPOSED); + + if (!submit_bio_checks(bio)) + break; + /* + * Because the current->bio_list is initialized, + * the submit_bio callback will always return BLK_QC_T_NONE. + */ + interposer->bd_disk->fops->submit_bio(bio); + } while (false); + + current->bio_list = NULL; + + blk_queue_exit(orig_disk->queue); + + /* 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. @@ -1029,6 +1078,14 @@ static blk_qc_t __submit_bio_noacct_mq(struct bio *bio) */ blk_qc_t submit_bio_noacct(struct bio *bio) { + /* + * Checking the BIO_INTERPOSED flag is necessary so that the bio + * created by the bdev_interposer do not get to it for processing. + */ + if (bdev_has_interposer(bio->bi_bdev) && + !bio_flagged(bio, BIO_INTERPOSED)) + return submit_bio_interposed(bio); + if (!submit_bio_checks(bio)) return BLK_QC_T_NONE; diff --git a/block/genhd.c b/block/genhd.c index c55e8f0fced1..c840ecffea68 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -30,6 +30,11 @@ static struct kobject *block_depr; DECLARE_RWSEM(bdev_lookup_sem); +/* + * Prevents different block-layer interposers from attaching or detaching + * to the block device at the same time. + */ +static DEFINE_MUTEX(bdev_interposer_attach_lock); /* for extended dynamic devt allocation, currently only one major is used */ #define NR_EXT_DEVT (1 << MINORBITS) @@ -1940,3 +1945,52 @@ static void disk_release_events(struct gendisk *disk) WARN_ON_ONCE(disk->ev && disk->ev->block != 1); kfree(disk->ev); } + +int bdev_interposer_attach(struct block_device *original, + struct block_device *interposer) +{ + int ret = 0; + + if (WARN_ON(((!original) || (!interposer)))) + return -EINVAL; + /* + * interposer should be simple, no a multi-queue device + */ + if (!interposer->bd_disk->fops->submit_bio) + return -EINVAL; + + if (WARN_ON(!blk_mq_is_queue_frozen(original->bd_disk->queue))) + return -EPERM; + + mutex_lock(&bdev_interposer_attach_lock); + + if (bdev_has_interposer(original)) + ret = -EBUSY; + else { + original->bd_interposer = bdgrab(interposer); + if (!original->bd_interposer) + ret = -ENODEV; + } + + mutex_unlock(&bdev_interposer_attach_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(bdev_interposer_attach); + +void bdev_interposer_detach(struct block_device *original) +{ + if (WARN_ON(!original)) + return; + + if (WARN_ON(!blk_mq_is_queue_frozen(original->bd_disk->queue))) + return; + + mutex_lock(&bdev_interposer_attach_lock); + if (bdev_has_interposer(original)) { + bdput(original->bd_interposer); + original->bd_interposer = NULL; + } + mutex_unlock(&bdev_interposer_attach_lock); +} +EXPORT_SYMBOL_GPL(bdev_interposer_detach); diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index db026b6ec15a..13bda4732cf5 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -19,6 +19,7 @@ struct io_context; struct cgroup_subsys_state; typedef void (bio_end_io_t) (struct bio *); struct bio_crypt_ctx; +struct bdev_interposer; struct block_device { sector_t bd_start_sect; @@ -46,6 +47,7 @@ struct block_device { spinlock_t bd_size_lock; /* for bd_inode->i_size updates */ struct gendisk * bd_disk; struct backing_dev_info *bd_bdi; + struct block_device *bd_interposer; /* The counter of freeze processes */ int bd_fsfreeze_count; @@ -304,6 +306,7 @@ enum { BIO_CGROUP_ACCT, /* has been accounted to a cgroup */ BIO_TRACKED, /* set if bio goes through the rq_qos path */ BIO_REMAPPED, + BIO_INTERPOSED, /* bio was reassigned to another block device */ BIO_FLAG_LAST }; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index bc6bc8383b43..90f62b4197da 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -2031,4 +2031,13 @@ int fsync_bdev(struct block_device *bdev); int freeze_bdev(struct block_device *bdev); int thaw_bdev(struct block_device *bdev); +static inline bool bdev_has_interposer(struct block_device *bdev) +{ + return (bdev->bd_interposer != NULL); +}; + +int bdev_interposer_attach(struct block_device *original, + struct block_device *interposer); +void bdev_interposer_detach(struct block_device *original); + #endif /* _LINUX_BLKDEV_H */