From patchwork Tue Apr 4 14:08:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergei Shtepa X-Patchwork-Id: 13202178 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14A63C77B62 for ; Wed, 5 Apr 2023 16:16:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232695AbjDEQQQ (ORCPT ); Wed, 5 Apr 2023 12:16:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232896AbjDEQPw (ORCPT ); Wed, 5 Apr 2023 12:15:52 -0400 Received: from mx2.veeam.com (mx2.veeam.com [64.129.123.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B98727DAC; Wed, 5 Apr 2023 09:15:09 -0700 (PDT) Received: from mx1.veeam.com (mx1.veeam.com [172.18.34.147]) (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 601D440FFD; Wed, 5 Apr 2023 12:13:42 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=veeam.com; s=mx2-2022; t=1680711222; bh=3UR7des7d1SNvYKVMBIh+qNln+2BT+04uvAOd7yuI2M=; h=From:To:CC:Subject:Date:In-Reply-To:References:From; b=RIn3+U5jfhLQPg7zRfvsc7fK79NALYNvCq4O6/oPagmitiWZ7B2wDCCLFlXAP+LR+ z2uKPTyIUEEdZfx/9JeZlVdmA9RJVJhtO2IZ99bG8jQZSqa0ct/Mh1G8MUyfGEvPRk MKIRN+m7/95OUFkeL5gKOAubKH34DQHNY82brfnxaOToZO/FsHRll99hx7rW8WVCcl +FK7hNt54IxmfOxlZu2YPHPRd/zNxbrJ3Ka8miSsvrXjRQ0vPO5h0bv++yX97cnYqg PnYEiXSISZcIX8fSGK+KuaHxdbuT0QImTaOk0KbUvT7ngJCEE6qSuQU29LsNkOFPtk mr6GLnSZrsE/A== Received: from mx4.veeam.com (mx4.amust.local [172.31.224.40]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.veeam.com (Postfix) with ESMTPS id 5664A42411; Wed, 5 Apr 2023 06:09:16 -0400 (EDT) Received: from mail.veeam.com (prgmbx01.amust.local [172.24.128.102]) (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 65A047D65D; Tue, 4 Apr 2023 17:09:03 +0300 (MSK) Received: from ssh-deb10-ssd-vb.amust.local (172.24.10.107) by prgmbx01.amust.local (172.24.128.102) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.26; Tue, 4 Apr 2023 16:08:59 +0200 From: Sergei Shtepa To: , , , CC: , , , , , , , , , , , , Subject: [PATCH v3 02/11] block: Block Device Filtering Mechanism Date: Tue, 4 Apr 2023 16:08:26 +0200 Message-ID: <20230404140835.25166-3-sergei.shtepa@veeam.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20230404140835.25166-1-sergei.shtepa@veeam.com> References: <20230404140835.25166-1-sergei.shtepa@veeam.com> MIME-Version: 1.0 X-Originating-IP: [172.24.10.107] X-ClientProxiedBy: prgmbx02.amust.local (172.24.128.103) To prgmbx01.amust.local (172.24.128.102) X-EsetResult: clean, is OK X-EsetId: 37303A2924031554657367 X-Veeam-MMEX: True Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org The block device filtering mechanism is an API that allows to attach block device filters. Block device filters allow perform additional processing for I/O units. The idea of handling I/O units on block devices is not new. Back in the 2.6 kernel, there was an undocumented possibility of handling I/O units by substituting the make_request_fn() function, which belonged to the request_queue structure. But none of the in-tree kernel modules used this feature, and it was eliminated in the 5.10 kernel. The block device filtering mechanism returns the ability to handle I/O units. It is possible to safely attach filter to a block device "on the fly" without changing the structure of block devices stack. Co-developed-by: Christoph Hellwig Signed-off-by: Christoph Hellwig Signed-off-by: Sergei Shtepa --- MAINTAINERS | 3 + block/Makefile | 2 +- block/bdev.c | 1 + block/blk-core.c | 40 ++++++- block/blk-filter.c | 199 ++++++++++++++++++++++++++++++++ block/blk.h | 10 ++ block/genhd.c | 2 + block/ioctl.c | 7 ++ block/partitions/core.c | 2 + include/linux/blk-filter.h | 51 ++++++++ include/linux/blk_types.h | 2 + include/linux/blkdev.h | 1 + include/uapi/linux/blk-filter.h | 35 ++++++ include/uapi/linux/fs.h | 5 + 14 files changed, 357 insertions(+), 3 deletions(-) create mode 100644 block/blk-filter.c create mode 100644 include/linux/blk-filter.h create mode 100644 include/uapi/linux/blk-filter.h diff --git a/MAINTAINERS b/MAINTAINERS index 2cbe4331ac97..fb6b7abe83e1 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3576,6 +3576,9 @@ M: Sergei Shtepa L: linux-block@vger.kernel.org S: Supported F: Documentation/block/blkfilter.rst +F: block/blk-filter.c +F: include/linux/blk-filter.h +F: include/uapi/linux/blk-filter.h BLOCK LAYER M: Jens Axboe diff --git a/block/Makefile b/block/Makefile index 4e01bb71ad6e..d4671c7e499c 100644 --- a/block/Makefile +++ b/block/Makefile @@ -9,7 +9,7 @@ obj-y := bdev.o fops.o bio.o elevator.o blk-core.o blk-sysfs.o \ blk-lib.o blk-mq.o blk-mq-tag.o blk-stat.o \ blk-mq-sysfs.o blk-mq-cpumap.o blk-mq-sched.o ioctl.o \ genhd.o ioprio.o badblocks.o partitions/ blk-rq-qos.o \ - disk-events.o blk-ia-ranges.o + disk-events.o blk-ia-ranges.o blk-filter.o obj-$(CONFIG_BOUNCE) += bounce.o obj-$(CONFIG_BLK_DEV_BSG_COMMON) += bsg.o diff --git a/block/bdev.c b/block/bdev.c index 1795c7d4b99e..e290020810dd 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -424,6 +424,7 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno) return NULL; } bdev->bd_disk = disk; + bdev->bd_filter = NULL; return bdev; } diff --git a/block/blk-core.c b/block/blk-core.c index 42926e6cb83c..179a1c9ecc90 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -591,10 +592,32 @@ static inline blk_status_t blk_check_zone_append(struct request_queue *q, return BLK_STS_OK; } +static bool submit_bio_filter(struct bio *bio) +{ + /* + * If this bio came from the filter driver, send it straight down to the + * actual device and clear the filtered flag, as the bio could be passed + * on to another device that might have a filter attached again. + */ + if (bio_flagged(bio, BIO_FILTERED)) { + bio_clear_flag(bio, BIO_FILTERED); + return false; + } + bio_set_flag(bio, BIO_FILTERED); + return bio->bi_bdev->bd_filter->ops->submit_bio(bio); +} + static void __submit_bio(struct bio *bio) { struct gendisk *disk = bio->bi_bdev->bd_disk; + /* + * If there is a filter driver attached, check if the BIO needs to go to + * the filter driver first, which can then pass on the bio or consume it. + */ + if (bio->bi_bdev->bd_filter && submit_bio_filter(bio)) + return; + if (unlikely(!blk_crypto_bio_prep(&bio))) return; @@ -682,6 +705,15 @@ static void __submit_bio_noacct_mq(struct bio *bio) current->bio_list = NULL; } +/** + * submit_bio_noacct_nocheck - re-submit a bio to the block device layer for I/O + * from block device filter. + * @bio: The bio describing the location in memory and on the device. + * + * This is a version of submit_bio() that shall only be used for I/O that is + * resubmitted to lower level by block device filters. All file systems and + * other upper level users of the block layer should use submit_bio() instead. + */ void submit_bio_noacct_nocheck(struct bio *bio) { blk_cgroup_bio_start(bio); @@ -702,13 +734,17 @@ void submit_bio_noacct_nocheck(struct bio *bio) * to collect a list of requests submited by a ->submit_bio method while * it is active, and then process them after it returned. */ - if (current->bio_list) + if (current->bio_list) { bio_list_add(¤t->bio_list[0], bio); - else if (!bio->bi_bdev->bd_disk->fops->submit_bio) + return; + } + + if (!bio->bi_bdev->bd_disk->fops->submit_bio) __submit_bio_noacct_mq(bio); else __submit_bio_noacct(bio); } +EXPORT_SYMBOL_GPL(submit_bio_noacct_nocheck); /** * submit_bio_noacct - re-submit a bio to the block device layer for I/O diff --git a/block/blk-filter.c b/block/blk-filter.c new file mode 100644 index 000000000000..5e9d884fad4d --- /dev/null +++ b/block/blk-filter.c @@ -0,0 +1,199 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (C) 2023 Veeam Software Group GmbH */ +#include +#include +#include + +#include "blk.h" + +static LIST_HEAD(blkfilters); +static DEFINE_SPINLOCK(blkfilters_lock); + +static inline struct blkfilter_operations *__blkfilter_find(const char *name) +{ + struct blkfilter_operations *ops; + + list_for_each_entry(ops, &blkfilters, link) + if (strncmp(ops->name, name, BLKFILTER_NAME_LENGTH) == 0) + return ops; + + return NULL; +} + +static inline struct blkfilter_operations *blkfilter_find_get(const char *name) +{ + struct blkfilter_operations *ops; + + spin_lock(&blkfilters_lock); + ops = __blkfilter_find(name); + if (ops && !try_module_get(ops->owner)) + ops = NULL; + spin_unlock(&blkfilters_lock); + + return ops; +} + +int blkfilter_ioctl_attach(struct block_device *bdev, + struct blkfilter_name __user *argp) +{ + struct blkfilter_name name; + struct blkfilter_operations *ops; + struct blkfilter *flt; + int ret; + + if (copy_from_user(&name, argp, sizeof(name))) + return -EFAULT; + + ops = blkfilter_find_get(name.name); + if (!ops) + return -ENOENT; + + ret = freeze_bdev(bdev); + if (ret) + goto out_put_module; + blk_mq_freeze_queue(bdev->bd_queue); + + if (bdev->bd_filter) { + if (bdev->bd_filter->ops == ops) + ret = -EALREADY; + else + ret = -EBUSY; + goto out_unfreeze; + } + + flt = ops->attach(bdev); + if (IS_ERR(flt)) { + ret = PTR_ERR(flt); + goto out_unfreeze; + } + + flt->ops = ops; + bdev->bd_filter = flt; + +out_unfreeze: + blk_mq_unfreeze_queue(bdev->bd_queue); + thaw_bdev(bdev); +out_put_module: + if (ret) + module_put(ops->owner); + return ret; +} + +static void __blkfilter_detach(struct block_device *bdev) +{ + struct blkfilter *flt = bdev->bd_filter; + const struct blkfilter_operations *ops = flt->ops; + + bdev->bd_filter = NULL; + ops->detach(flt); + module_put(ops->owner); +} + +void blkfilter_detach(struct block_device *bdev) +{ + if (bdev->bd_filter) { + blk_mq_freeze_queue(bdev->bd_queue); + __blkfilter_detach(bdev); + blk_mq_unfreeze_queue(bdev->bd_queue); + } +} + +int blkfilter_ioctl_detach(struct block_device *bdev, + struct blkfilter_name __user *argp) +{ + struct blkfilter_name name; + int error = 0; + + if (copy_from_user(&name, argp, sizeof(name))) + return -EFAULT; + + blk_mq_freeze_queue(bdev->bd_queue); + if (!bdev->bd_filter) { + error = -ENOENT; + goto out_unfreeze; + } + if (strncmp(bdev->bd_filter->ops->name, name.name, + BLKFILTER_NAME_LENGTH)) { + error = -EINVAL; + goto out_unfreeze; + } + + __blkfilter_detach(bdev); +out_unfreeze: + blk_mq_unfreeze_queue(bdev->bd_queue); + return error; +} + +int blkfilter_ioctl_ctl(struct block_device *bdev, + struct blkfilter_ctl __user *argp) +{ + struct blkfilter_ctl ctl; + struct blkfilter *flt; + int ret; + + if (copy_from_user(&ctl, argp, sizeof(ctl))) + return -EFAULT; + + ret = blk_queue_enter(bdev_get_queue(bdev), 0); + if (ret) + return ret; + + flt = bdev->bd_filter; + if (!flt || strncmp(flt->ops->name, ctl.name, BLKFILTER_NAME_LENGTH)) { + ret = -ENOENT; + goto out_queue_exit; + } + + if (!flt->ops->ctl) { + ret = -ENOTTY; + goto out_queue_exit; + } + + ret = flt->ops->ctl(flt, ctl.cmd, u64_to_user_ptr(ctl.opt), + &ctl.optlen); +out_queue_exit: + blk_queue_exit(bdev_get_queue(bdev)); + return ret; +} + +/** + * blkfilter_register() - Register block device filter operations + * @ops: The operations to register. + * + * Return: + * 0 if succeeded, + * -EBUSY if a block device filter with the same name is already + * registered. + */ +int blkfilter_register(struct blkfilter_operations *ops) +{ + struct blkfilter_operations *found; + int ret = 0; + + spin_lock(&blkfilters_lock); + found = __blkfilter_find(ops->name); + if (found) + ret = -EBUSY; + else + list_add_tail(&ops->link, &blkfilters); + spin_unlock(&blkfilters_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(blkfilter_register); + +/** + * blkfilter_unregister() - Unregister block device filter operations + * @ops: The operations to unregister. + * + * Important: before unloading, it is necessary to detach the filter from all + * block devices. + * + */ +void blkfilter_unregister(struct blkfilter_operations *ops) +{ + spin_lock(&blkfilters_lock); + list_del(&ops->link); + spin_unlock(&blkfilters_lock); +} +EXPORT_SYMBOL_GPL(blkfilter_unregister); diff --git a/block/blk.h b/block/blk.h index cc4e8873dfde..3500e46368e3 100644 --- a/block/blk.h +++ b/block/blk.h @@ -7,6 +7,8 @@ #include #include "blk-crypto-internal.h" +struct blkfilter_ctl; +struct blkfilter_name; struct elevator_type; /* Max future timer expiry for timeouts */ @@ -454,6 +456,14 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg); extern const struct address_space_operations def_blk_aops; +int blkfilter_ioctl_attach(struct block_device *bdev, + struct blkfilter_name __user *argp); +int blkfilter_ioctl_detach(struct block_device *bdev, + struct blkfilter_name __user *argp); +int blkfilter_ioctl_ctl(struct block_device *bdev, + struct blkfilter_ctl __user *argp); +void blkfilter_detach(struct block_device *bdev); + int disk_register_independent_access_ranges(struct gendisk *disk); void disk_unregister_independent_access_ranges(struct gendisk *disk); diff --git a/block/genhd.c b/block/genhd.c index 02d9cfb9e077..b23ceea895de 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -25,6 +25,7 @@ #include #include #include +#include #include "blk-throttle.h" #include "blk.h" @@ -625,6 +626,7 @@ void del_gendisk(struct gendisk *disk) fsync_bdev(disk->part0); __invalidate_device(disk->part0, true); + blkfilter_detach(disk->part0); /* * Fail any new I/O. diff --git a/block/ioctl.c b/block/ioctl.c index 9c5f637ff153..e840150e1aa8 100644 --- a/block/ioctl.c +++ b/block/ioctl.c @@ -2,6 +2,7 @@ #include #include #include +#include #include #include #include @@ -545,6 +546,12 @@ static int blkdev_common_ioctl(struct block_device *bdev, fmode_t mode, return blkdev_pr_preempt(bdev, argp, true); case IOC_PR_CLEAR: return blkdev_pr_clear(bdev, argp); + case BLKFILTER_ATTACH: + return blkfilter_ioctl_attach(bdev, argp); + case BLKFILTER_DETACH: + return blkfilter_ioctl_detach(bdev, argp); + case BLKFILTER_CTL: + return blkfilter_ioctl_ctl(bdev, argp); default: return -ENOIOCTLCMD; } diff --git a/block/partitions/core.c b/block/partitions/core.c index 7b8ef6296abd..0b5e3a3f7c31 100644 --- a/block/partitions/core.c +++ b/block/partitions/core.c @@ -10,6 +10,7 @@ #include #include #include +#include #include "check.h" static int (*check_part[])(struct parsed_partitions *) = { @@ -277,6 +278,7 @@ static void delete_partition(struct block_device *part) fsync_bdev(part); __invalidate_device(part, true); + blkfilter_detach(part); xa_erase(&part->bd_disk->part_tbl, part->bd_partno); kobject_put(part->bd_holder_dir); diff --git a/include/linux/blk-filter.h b/include/linux/blk-filter.h new file mode 100644 index 000000000000..0afdb40f3bab --- /dev/null +++ b/include/linux/blk-filter.h @@ -0,0 +1,51 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2023 Veeam Software Group GmbH */ +#ifndef _LINUX_BLK_FILTER_H +#define _LINUX_BLK_FILTER_H + +#include + +struct bio; +struct block_device; +struct blkfilter_operations; + +/** + * struct blkfilter - Block device filter. + * + * @ops: Block device filter operations. + * + * For each filtered block device, the filter creates a data structure + * associated with this device. The data in this structure is specific to the + * filter, but it must contain a pointer to the block device filter account. + */ +struct blkfilter { + const struct blkfilter_operations *ops; +}; + +/** + * struct blkfilter_operations - Block device filter operations. + * + * @link: Entry in the global list of filter drivers + * (must not be accessed by the driver). + * @owner: Module implementing the filter driver. + * @name: Name of the filter driver. + * @attach: Attach the filter driver to the block device. + * @detach: Detach the filter driver from the block device. + * @ctl: Send a control command to the filter driver. + * @submit_bio: Handle bio submissions to the filter driver. + */ +struct blkfilter_operations { + struct list_head link; + struct module *owner; + const char *name; + struct blkfilter *(*attach)(struct block_device *bdev); + void (*detach)(struct blkfilter *flt); + int (*ctl)(struct blkfilter *flt, const unsigned int cmd, + __u8 __user *buf, __u32 *plen); + bool (*submit_bio)(struct bio *bio); +}; + +int blkfilter_register(struct blkfilter_operations *ops); +void blkfilter_unregister(struct blkfilter_operations *ops); + +#endif /* _UAPI_LINUX_BLK_FILTER_H */ diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 99be590f952f..b140ddd9b7ab 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -68,6 +68,7 @@ struct block_device { #ifdef CONFIG_FAIL_MAKE_REQUEST bool bd_make_it_fail; #endif + struct blkfilter *bd_filter; } __randomize_layout; #define bdev_whole(_bdev) \ @@ -333,6 +334,7 @@ enum { BIO_QOS_MERGED, /* but went through rq_qos merge path */ BIO_REMAPPED, BIO_ZONE_WRITE_LOCKED, /* Owns a zoned device zone write lock */ + BIO_FILTERED, /* bio has already been filtered */ BIO_FLAG_LAST }; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 941304f17492..25ebbf296f35 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -854,6 +854,7 @@ void blk_request_module(dev_t devt); extern int blk_register_queue(struct gendisk *disk); extern void blk_unregister_queue(struct gendisk *disk); +void submit_bio_noacct_nocheck(struct bio *bio); void submit_bio_noacct(struct bio *bio); struct bio *bio_split_to_limits(struct bio *bio); diff --git a/include/uapi/linux/blk-filter.h b/include/uapi/linux/blk-filter.h new file mode 100644 index 000000000000..18885dc1b717 --- /dev/null +++ b/include/uapi/linux/blk-filter.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* Copyright (C) 2023 Veeam Software Group GmbH */ +#ifndef _UAPI_LINUX_BLK_FILTER_H +#define _UAPI_LINUX_BLK_FILTER_H + +#include + +#define BLKFILTER_NAME_LENGTH 32 + +/** + * struct blkfilter_name - parameter for BLKFILTER_ATTACH and BLKFILTER_DETACH + * ioctl. + * + * @name: Name of block device filter. + */ +struct blkfilter_name { + __u8 name[BLKFILTER_NAME_LENGTH]; +}; + +/** + * struct blkfilter_ctl - parameter for BLKFILTER_CTL ioctl + * + * @name: Name of block device filter. + * @cmd: The filter-specific operation code of the command. + * @optlen: Size of data at @opt. + * @opt: Userspace buffer with options. + */ +struct blkfilter_ctl { + __u8 name[BLKFILTER_NAME_LENGTH]; + __u32 cmd; + __u32 optlen; + __u64 opt; +}; + +#endif /* _UAPI_LINUX_BLK_FILTER_H */ diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index b7b56871029c..1848d62979a4 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -185,6 +185,11 @@ struct fsxattr { #define BLKROTATIONAL _IO(0x12,126) #define BLKZEROOUT _IO(0x12,127) #define BLKGETDISKSEQ _IOR(0x12,128,__u64) +/* 13* is defined in linux/blkzoned.h */ +#define BLKFILTER_ATTACH _IOWR(0x12, 140, struct blkfilter_name) +#define BLKFILTER_DETACH _IOWR(0x12, 141, struct blkfilter_name) +#define BLKFILTER_CTL _IOWR(0x12, 142, struct blkfilter_ctl) + /* * A jump here: 130-136 are reserved for zoned block devices * (see uapi/linux/blkzoned.h)