From patchwork Wed Sep 18 10:18:14 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dongsheng Yang X-Patchwork-Id: 13806766 Received: from out-177.mta1.migadu.com (out-177.mta1.migadu.com [95.215.58.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 57EF817C9E9 for ; Wed, 18 Sep 2024 10:18:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.177 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726654733; cv=none; b=WC0H+mq3WThe2nfnSps1Cg5iJIBMYvNCR0EVwEM+BOGLHaxaU+O803pRNB81P02YVL4dLh4iQJlVTXBY2IYZQDFlELPyeGRkgu/Gb8aa9WC4neMv8ODkuU0XPEtIasRskF9TQF2NMf6EOnRX4qSGO9g5jwff9OjYqggsoQ7TO54= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726654733; c=relaxed/simple; bh=cPNvongFuOAZs3svQNXpJ/mKG41uzjv2iOw2AIEwjAM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=AuUodZmLoaQW9UYWM0FaqROE8IfoMd475g2zbt4XS1kNVkmWdAtKsR2fb1jdY9fFQhjTNDb5oezSMA/zPt1sRMOYek7Qnr+n40+dohGNwXf79QybTwGpguhwqavvN0e2TxrZV1V/uCpW+BCu0smr2Xvfl3+746jZ/Em2LC4a2Fc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=qNrPAewg; arc=none smtp.client-ip=95.215.58.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="qNrPAewg" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1726654727; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=D9vMquosGNQahw5FgSUZEKnhEmjWaslUdu0G45Swvwc=; b=qNrPAewgqGx/23l5830GRIY2rcaypoKIKidPl98ZCfx3+0qFpFXEZoriqMQ+SZ1BiwI3Qh TVa1kA8glT3gYkQgwgX/gsUHBwC+89H7MEzvs7pAsLTsk+DtEkofUJQWQWHYIqAk/pwusS ZoaeBx+PL/NmrwPt/pj5MAkMwONH7Gw= From: Dongsheng Yang To: axboe@kernel.dk, dan.j.williams@intel.com, gregory.price@memverge.com, John@groves.net, Jonathan.Cameron@Huawei.com, bbhushan2@marvell.com, chaitanyak@nvidia.com, rdunlap@infradead.org Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, linux-bcache@vger.kernel.org, Dongsheng Yang Subject: [PATCH v2 1/8] cbd: introduce cbd_transport Date: Wed, 18 Sep 2024 10:18:14 +0000 Message-Id: <20240918101821.681118-2-dongsheng.yang@linux.dev> In-Reply-To: <20240918101821.681118-1-dongsheng.yang@linux.dev> References: <20240918101821.681118-1-dongsheng.yang@linux.dev> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT cbd_transport represents the layout of the entire shared memory, as shown below. +-------------------------------------------------------------------------------------------------------------------------------+ | cbd transport | +--------------------+-----------------------+-----------------------+----------------------+-----------------------------------+ | | hosts | backends | blkdevs | channels | | cbd transport info +----+----+----+--------+----+----+----+--------+----+----+----+-------+-------+-------+-------+-----------+ | | | | | ... | | | | ... | | | | ... | | | | ... | +--------------------+----+----+----+--------+----+----+----+--------+----+----+----+-------+---+---+---+---+-------+-----------+ | | | | | | | | +-------------------------------------------------------------------------------------+ | | | | | v | +-----------------------------------------------------------+ | | channel segment | | +--------------------+--------------------------------------+ | | channel meta | channel data | | +---------+----------+--------------------------------------+ | | | | | | | v | +----------------------------------------------------------+ | | channel meta | | +-----------+--------------+-------------------------------+ | | meta ctrl | comp ring | cmd ring | | +-----------+--------------+-------------------------------+ | | | | +--------------------------------------------------------------------------------------------+ | | | v +----------------------------------------------------------+ | cache segment | +-----------+----------------------------------------------+ | info | data | +-----------+----------------------------------------------+ The shared memory is divided into five regions: a) Transport_info: Information about the overall transport, including the layout of the transport. b) Hosts: Each host wishing to utilize this transport needs to register its own information within a host entry in this region. c) Backends: Starting a backend on a host requires filling in information in a backend entry within this region. d) Blkdevs: Once a backend is established, it can be mapped to CBD device on any associated host. The information about the blkdevs is then filled into the blkdevs region. e) Segments: This is the actual data communication area, where communication between blkdev and backend occurs. Each queue of a block device uses a channel, and each backend has a corresponding handler interacting with this queue. f) Channel segment: Channel is one type of segment, is further divided into meta and data regions. The meta region includes subm rings and comp rings. The blkdev converts upper-layer requests into cbd_se and fills them into the subm ring. The handler accepts the cbd_se from the subm ring and sends them to the local actual block device of the backend (e.g., sda). After completion, the results are formed into cbd_ce and filled into the comp ring. The blkdev then receives the cbd_ce and returns the results to the upper-layer IO sender. g) Cache segment: Cache segment is another type of segment, when cache enabled for a backend, transport will allocate cache segments to this backend. Signed-off-by: Dongsheng Yang --- drivers/block/cbd/cbd_internal.h | 1193 +++++++++++++++++++++++++++++ drivers/block/cbd/cbd_transport.c | 957 +++++++++++++++++++++++ 2 files changed, 2150 insertions(+) create mode 100644 drivers/block/cbd/cbd_internal.h create mode 100644 drivers/block/cbd/cbd_transport.c diff --git a/drivers/block/cbd/cbd_internal.h b/drivers/block/cbd/cbd_internal.h new file mode 100644 index 000000000000..236dbcb62906 --- /dev/null +++ b/drivers/block/cbd/cbd_internal.h @@ -0,0 +1,1193 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _CBD_INTERNAL_H +#define _CBD_INTERNAL_H + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * CBD (CXL Block Device) provides two usage scenarios: single-host and multi-hosts. + * + * (1) Single-host scenario, CBD can use a pmem device as a cache for block devices, + * providing a caching mechanism specifically designed for persistent memory. + * + * +-----------------------------------------------------------------+ + * | single-host | + * +-----------------------------------------------------------------+ + * | | + * | | + * | | + * | | + * | | + * | +-----------+ +------------+ | + * | | /dev/cbd0 | | /dev/cbd1 | | + * | | | | | | + * | +---------------------|-----------|-----|------------|-------+ | + * | | | | | | | | + * | | /dev/pmem0 | cbd0 cache| | cbd1 cache | | | + * | | | | | | | | + * | +---------------------|-----------|-----|------------|-------+ | + * | |+---------+| |+----------+| | + * | ||/dev/sda || || /dev/sdb || | + * | |+---------+| |+----------+| | + * | +-----------+ +------------+ | + * +-----------------------------------------------------------------+ + * + * (2) Multi-hosts scenario, CBD also provides a cache while taking advantage of + * shared memory features, allowing users to access block devices on other nodes across + * different hosts. + * + * As shared memory is supported in CXL3.0 spec, we can transfer data via CXL shared memory. + * CBD use CXL shared memory to transfer data between node-1 and node-2. + * + * +--------------------------------------------------------------------------------------------------------+ + * | multi-hosts | + * +--------------------------------------------------------------------------------------------------------+ + * | | + * | | + * | +-------------------------------+ +------------------------------------+ | + * | | node-1 | | node-2 | | + * | +-------------------------------+ +------------------------------------+ | + * | | | | | | + * | | +-------+ +---------+ | | + * | | | cbd0 | | backend0+------------------+ | | + * | | +-------+ +---------+ | | | + * | | | pmem0 | | pmem0 | v | | + * | | +-------+-------+ +---------+----+ +---------------+ | + * | | | cxl driver | | cxl driver | | /dev/sda | | + * | +---------------+--------+------+ +-----+--------+-----+---------------+ | + * | | | | + * | | | | + * | | CXL CXL | | + * | +----------------+ +-----------+ | + * | | | | + * | | | | + * | | | | + * | +-------------------------+---------------+--------------------------+ | + * | | +---------------+ | | + * | | shared memory device | cbd0 cache | | | + * | | +---------------+ | | + * | +--------------------------------------------------------------------+ | + * | | + * +--------------------------------------------------------------------------------------------------------+ + */ + +#define cbd_err(fmt, ...) \ + pr_err("cbd: %s:%u " fmt, __func__, __LINE__, ##__VA_ARGS__) +#define cbd_info(fmt, ...) \ + pr_info("cbd: %s:%u " fmt, __func__, __LINE__, ##__VA_ARGS__) +#define cbd_debug(fmt, ...) \ + pr_debug("cbd: %s:%u " fmt, __func__, __LINE__, ##__VA_ARGS__) + +#define cbdt_err(transport, fmt, ...) \ + cbd_err("cbd_transport%u: " fmt, \ + transport->id, ##__VA_ARGS__) +#define cbdt_info(transport, fmt, ...) \ + cbd_info("cbd_transport%u: " fmt, \ + transport->id, ##__VA_ARGS__) +#define cbdt_debug(transport, fmt, ...) \ + cbd_debug("cbd_transport%u: " fmt, \ + transport->id, ##__VA_ARGS__) + +#define cbdb_err(backend, fmt, ...) \ + cbdt_err(backend->cbdt, "backend%d: " fmt, \ + backend->backend_id, ##__VA_ARGS__) +#define cbdb_info(backend, fmt, ...) \ + cbdt_info(backend->cbdt, "backend%d: " fmt, \ + backend->backend_id, ##__VA_ARGS__) +#define cbdbdebug(backend, fmt, ...) \ + cbdt_debug(backend->cbdt, "backend%d: " fmt, \ + backend->backend_id, ##__VA_ARGS__) + +#define cbd_handler_err(handler, fmt, ...) \ + cbdb_err(handler->cbdb, "handler%d: " fmt, \ + handler->channel.seg_id, ##__VA_ARGS__) +#define cbd_handler_info(handler, fmt, ...) \ + cbdb_info(handler->cbdb, "handler%d: " fmt, \ + handler->channel.seg_id, ##__VA_ARGS__) +#define cbd_handler_debug(handler, fmt, ...) \ + cbdb_debug(handler->cbdb, "handler%d: " fmt, \ + handler->channel.seg_id, ##__VA_ARGS__) + +#define cbd_blk_err(dev, fmt, ...) \ + cbdt_err(dev->cbdt, "cbd%d: " fmt, \ + dev->mapped_id, ##__VA_ARGS__) +#define cbd_blk_info(dev, fmt, ...) \ + cbdt_info(dev->cbdt, "cbd%d: " fmt, \ + dev->mapped_id, ##__VA_ARGS__) +#define cbd_blk_debug(dev, fmt, ...) \ + cbdt_debug(dev->cbdt, "cbd%d: " fmt, \ + dev->mapped_id, ##__VA_ARGS__) + +#define cbd_queue_err(queue, fmt, ...) \ + cbd_blk_err(queue->cbd_blkdev, "queue%d: " fmt, \ + queue->channel.seg_id, ##__VA_ARGS__) +#define cbd_queue_info(queue, fmt, ...) \ + cbd_blk_info(queue->cbd_blkdev, "queue%d: " fmt, \ + queue->channel.seg_id, ##__VA_ARGS__) +#define cbd_queue_debug(queue, fmt, ...) \ + cbd_blk_debug(queue->cbd_blkdev, "queue%d: " fmt, \ + queue->channel.seg_id, ##__VA_ARGS__) + +#define cbd_channel_err(channel, fmt, ...) \ + cbdt_err(channel->cbdt, "channel%d: " fmt, \ + channel->seg_id, ##__VA_ARGS__) +#define cbd_channel_info(channel, fmt, ...) \ + cbdt_info(channel->cbdt, "channel%d: " fmt, \ + channel->seg_id, ##__VA_ARGS__) +#define cbd_channel_debug(channel, fmt, ...) \ + cbdt_debug(channel->cbdt, "channel%d: " fmt, \ + channel->seg_id, ##__VA_ARGS__) + +#define cbd_cache_err(cache, fmt, ...) \ + cbdt_err(cache->cbdt, "cache%d: " fmt, \ + cache->cache_id, ##__VA_ARGS__) +#define cbd_cache_info(cache, fmt, ...) \ + cbdt_info(cache->cbdt, "cache%d: " fmt, \ + cache->cache_id, ##__VA_ARGS__) +#define cbd_cache_debug(cache, fmt, ...) \ + cbdt_debug(cache->cbdt, "cache%d: " fmt, \ + cache->cache_id, ##__VA_ARGS__) + +#define CBD_KB (1024) +#define CBD_MB (CBD_KB * CBD_KB) + +#define CBD_TRANSPORT_MAX 1024 +#define CBD_PATH_LEN 512 +#define CBD_NAME_LEN 32 + +#define CBD_QUEUES_MAX 128 + +#define CBD_PART_SHIFT 4 +#define CBD_DRV_NAME "cbd" +#define CBD_DEV_NAME_LEN 32 + +#define CBD_HB_INTERVAL msecs_to_jiffies(5000) /* 5s */ +#define CBD_HB_TIMEOUT (30 * 1000) /* 30s */ + +/* + * CBD transport layout: + * + * +-------------------------------------------------------------------------------------------------------------------------------+ + * | cbd transport | + * +--------------------+-----------------------+-----------------------+----------------------+-----------------------------------+ + * | | hosts | backends | blkdevs | channels | + * | cbd transport info +----+----+----+--------+----+----+----+--------+----+----+----+-------+-------+-------+-------+-----------+ + * | | | | | ... | | | | ... | | | | ... | | | | ... | + * +--------------------+----+----+----+--------+----+----+----+--------+----+----+----+-------+---+---+---+---+-------+-----------+ + * | | + * | | + * | | + * | | + * +-------------------------------------------------------------------------------------+ | + * | | + * | | + * v | + * +-----------------------------------------------------------+ | + * | channel segment | | + * +--------------------+--------------------------------------+ | + * | channel meta | channel data | | + * +---------+----------+--------------------------------------+ | + * | | + * | | + * | | + * v | + * +----------------------------------------------------------+ | + * | channel meta | | + * +-----------+--------------+-------------------------------+ | + * | meta ctrl | comp ring | cmd ring | | + * +-----------+--------------+-------------------------------+ | + * | + * | + * | + * +--------------------------------------------------------------------------------------------+ + * | + * | + * | + * v + * +----------------------------------------------------------+ + * | cache segment | + * +-----------+----------------------------------------------+ + * | info | data | + * +-----------+----------------------------------------------+ + */ + +/* cbd segment */ +#define CBDT_SEG_SIZE (16 * 1024 * 1024) + +/* cbd channel seg */ +#define CBDC_META_SIZE (4 * 1024 * 1024) +#define CBDC_SUBMR_RESERVED sizeof(struct cbd_se) +#define CBDC_CMPR_RESERVED sizeof(struct cbd_ce) + +#define CBDC_DATA_ALIGH 4096 +#define CBDC_DATA_RESERVED CBDC_DATA_ALIGH + +#define CBDC_CTRL_OFF 0 +#define CBDC_CTRL_SIZE PAGE_SIZE +#define CBDC_COMPR_OFF (CBDC_CTRL_OFF + CBDC_CTRL_SIZE) +#define CBDC_COMPR_SIZE (sizeof(struct cbd_ce) * 1024) +#define CBDC_SUBMR_OFF (CBDC_COMPR_OFF + CBDC_COMPR_SIZE) +#define CBDC_SUBMR_SIZE (CBDC_META_SIZE - CBDC_SUBMR_OFF) + +#define CBDC_DATA_OFF CBDC_META_SIZE +#define CBDC_DATA_SIZE (CBDT_SEG_SIZE - CBDC_META_SIZE) + +#define CBDC_UPDATE_SUBMR_HEAD(head, used, size) (head = ((head % size) + used) % size) +#define CBDC_UPDATE_SUBMR_TAIL(tail, used, size) (tail = ((tail % size) + used) % size) + +#define CBDC_UPDATE_COMPR_HEAD(head, used, size) (head = ((head % size) + used) % size) +#define CBDC_UPDATE_COMPR_TAIL(tail, used, size) (tail = ((tail % size) + used) % size) + +/* cbd transport */ +#define CBD_TRANSPORT_MAGIC 0x65B05EFA96C596EFULL +#define CBD_TRANSPORT_VERSION 1 + +#define CBDT_INFO_OFF 0 +#define CBDT_INFO_SIZE PAGE_SIZE + +#define CBDT_HOST_INFO_SIZE round_up(sizeof(struct cbd_host_info), PAGE_SIZE) +#define CBDT_BACKEND_INFO_SIZE round_up(sizeof(struct cbd_backend_info), PAGE_SIZE) +#define CBDT_BLKDEV_INFO_SIZE round_up(sizeof(struct cbd_blkdev_info), PAGE_SIZE) + +#define CBD_TRASNPORT_SIZE_MIN (512 * 1024 * 1024) + +/* + * CBD structure diagram: + * + * +--------------+ + * | cbd_transport| +----------+ + * +--------------+ | cbd_host | + * | | +----------+ + * | host +---------------------------------------------->| | + * +--------------------+ backends | | hostname | + * | | devices +------------------------------------------+ | | + * | | | | +----------+ + * | +--------------+ | + * | | + * | | + * | | + * | | + * | | + * v v + * +------------+ +-----------+ +------+ +-----------+ +-----------+ +------+ + * | cbd_backend+---->|cbd_backend+---->| NULL | | cbd_blkdev+----->| cbd_blkdev+---->| NULL | + * +------------+ +-----------+ +------+ +-----------+ +-----------+ +------+ + * +------------+ cbd_cache | | handlers | +------+ queues | | queues | + * | | | +-----------+ | | | +-----------+ + * | +------+ handlers | | | | + * | | +------------+ | | cbd_cache +-------------------------------------+ + * | | | +-----------+ | + * | | | | + * | | +-------------+ +-------------+ +------+ | +-----------+ +-----------+ +------+ | + * | +----->| cbd_handler +------>| cbd_handler +---------->| NULL | +----->| cbd_queue +----->| cbd_queue +---->| NULL | | + * | +-------------+ +-------------+ +------+ +-----------+ +-----------+ +------+ | + * | +------+ channel | | channel | +------+ channel | | channel | | + * | | +-------------+ +-------------+ | +-----------+ +-----------+ | + * | | | | + * | | | | + * | | | | + * | | v | + * | | +-----------------------+ | + * | +------------------------------------------------------->| cbd_channel | | + * | +-----------------------+ | + * | | channel_id | | + * | | cmdr (cmd ring) | | + * | | compr (complete ring) | | + * | | data (data area) | | + * | | | | + * | +-----------------------+ | + * | | + * | +-----------------------------+ | + * +------------------------------------------------>| cbd_cache |<------------------------------------------------------------+ + * +-----------------------------+ + * | cache_wq | + * | cache_tree | + * | segments[] | + * +-----------------------------+ + */ + +#define CBD_DEVICE(OBJ) \ +struct cbd_## OBJ ##_device { \ + struct device dev; \ + struct cbd_transport *cbdt; \ + struct cbd_## OBJ ##_info *OBJ##_info; \ +}; \ + \ +struct cbd_## OBJ ##s_device { \ + struct device OBJ ##s_dev; \ + struct cbd_## OBJ ##_device OBJ ##_devs[]; \ +} + +/* cbd_worker_cfg*/ +struct cbd_worker_cfg { + u32 busy_retry_cur; + u32 busy_retry_count; + u32 busy_retry_max; + u32 busy_retry_min; + u64 busy_retry_interval; +}; + +static inline void cbdwc_init(struct cbd_worker_cfg *cfg) +{ + /* init cbd_worker_cfg with default values */ + cfg->busy_retry_cur = 0; + cfg->busy_retry_count = 100; + cfg->busy_retry_max = cfg->busy_retry_count * 2; + cfg->busy_retry_min = 0; + cfg->busy_retry_interval = 1; /* 1us */ +} + +/* reset retry_cur and increase busy_retry_count */ +static inline void cbdwc_hit(struct cbd_worker_cfg *cfg) +{ + u32 delta; + + cfg->busy_retry_cur = 0; + + if (cfg->busy_retry_count == cfg->busy_retry_max) + return; + + /* retry_count increase by 1/16 */ + delta = cfg->busy_retry_count >> 4; + if (!delta) + delta = (cfg->busy_retry_max + cfg->busy_retry_min) >> 1; + + cfg->busy_retry_count += delta; + + if (cfg->busy_retry_count > cfg->busy_retry_max) + cfg->busy_retry_count = cfg->busy_retry_max; +} + +/* reset retry_cur and decrease busy_retry_count */ +static inline void cbdwc_miss(struct cbd_worker_cfg *cfg) +{ + u32 delta; + + cfg->busy_retry_cur = 0; + + if (cfg->busy_retry_count == cfg->busy_retry_min) + return; + + /* retry_count decrease by 1/16 */ + delta = cfg->busy_retry_count >> 4; + if (!delta) + delta = cfg->busy_retry_count; + + cfg->busy_retry_count -= delta; +} + +static inline bool cbdwc_need_retry(struct cbd_worker_cfg *cfg) +{ + if (++cfg->busy_retry_cur < cfg->busy_retry_count) { + cpu_relax(); + fsleep(cfg->busy_retry_interval); + return true; + } + + return false; +} + +/* cbd_transport */ +#define CBDT_INFO_F_BIGENDIAN (1 << 0) +#define CBDT_INFO_F_CRC (1 << 1) + +#ifdef CONFIG_CBD_MULTIHOST +#define CBDT_HOSTS_MAX 16 +#else +#define CBDT_HOSTS_MAX 1 +#endif /*CONFIG_CBD_MULTIHOST*/ + +struct cbd_transport_info { + __le64 magic; + __le16 version; + __le16 flags; + + u32 hosts_registered; + + u64 host_area_off; + u32 host_info_size; + u32 host_num; + + u64 backend_area_off; + u32 backend_info_size; + u32 backend_num; + + u64 blkdev_area_off; + u32 blkdev_info_size; + u32 blkdev_num; + + u64 segment_area_off; + u32 segment_size; + u32 segment_num; +}; + +struct cbd_transport { + u16 id; + struct device device; + struct mutex lock; + struct mutex adm_lock; + + struct cbd_transport_info *transport_info; + + struct cbd_host *host; + struct list_head backends; + struct list_head devices; + + struct cbd_hosts_device *cbd_hosts_dev; + struct cbd_segments_device *cbd_segments_dev; + struct cbd_backends_device *cbd_backends_dev; + struct cbd_blkdevs_device *cbd_blkdevs_dev; + + struct dax_device *dax_dev; + struct file *bdev_file; +}; + +struct cbdt_register_options { + char hostname[CBD_NAME_LEN]; + char path[CBD_PATH_LEN]; + u16 format:1; + u16 force:1; + u16 unused:15; +}; + +struct cbd_blkdev; +struct cbd_backend; +struct cbd_backend_io; +struct cbd_cache; + +int cbdt_register(struct cbdt_register_options *opts); +int cbdt_unregister(u32 transport_id); + +struct cbd_host_info *cbdt_get_host_info(struct cbd_transport *cbdt, u32 id); +struct cbd_backend_info *cbdt_get_backend_info(struct cbd_transport *cbdt, u32 id); +struct cbd_blkdev_info *cbdt_get_blkdev_info(struct cbd_transport *cbdt, u32 id); +struct cbd_segment_info *cbdt_get_segment_info(struct cbd_transport *cbdt, u32 id); +static inline struct cbd_channel_info *cbdt_get_channel_info(struct cbd_transport *cbdt, u32 id) +{ + return (struct cbd_channel_info *)cbdt_get_segment_info(cbdt, id); +} + +int cbdt_get_empty_host_id(struct cbd_transport *cbdt, u32 *id); +int cbdt_get_empty_backend_id(struct cbd_transport *cbdt, u32 *id); +int cbdt_get_empty_blkdev_id(struct cbd_transport *cbdt, u32 *id); +int cbdt_get_empty_segment_id(struct cbd_transport *cbdt, u32 *id); + +void cbdt_add_backend(struct cbd_transport *cbdt, struct cbd_backend *cbdb); +void cbdt_del_backend(struct cbd_transport *cbdt, struct cbd_backend *cbdb); +struct cbd_backend *cbdt_get_backend(struct cbd_transport *cbdt, u32 id); +void cbdt_add_blkdev(struct cbd_transport *cbdt, struct cbd_blkdev *blkdev); +void cbdt_del_blkdev(struct cbd_transport *cbdt, struct cbd_blkdev *blkdev); +struct cbd_blkdev *cbdt_get_blkdev(struct cbd_transport *cbdt, u32 id); + +struct page *cbdt_page(struct cbd_transport *cbdt, u64 transport_off, u32 *page_off); +void cbdt_zero_range(struct cbd_transport *cbdt, void *pos, u32 size); + +/* cbd_host */ +CBD_DEVICE(host); + +enum cbd_host_state { + cbd_host_state_none = 0, + cbd_host_state_running, + cbd_host_state_removing +}; + +struct cbd_host_info { + u8 state; + u64 alive_ts; + char hostname[CBD_NAME_LEN]; +}; + +struct cbd_host { + u32 host_id; + struct cbd_transport *cbdt; + + struct cbd_host_device *dev; + struct cbd_host_info *host_info; + struct delayed_work hb_work; /* heartbeat work */ +}; + +int cbd_host_register(struct cbd_transport *cbdt, char *hostname); +int cbd_host_unregister(struct cbd_transport *cbdt); +int cbd_host_clear(struct cbd_transport *cbdt, u32 host_id); +bool cbd_host_info_is_alive(struct cbd_host_info *info); + +/* cbd_segment */ +CBD_DEVICE(segment); + +enum cbd_segment_state { + cbd_segment_state_none = 0, + cbd_segment_state_running, + cbd_segment_state_removing +}; + +enum cbd_seg_type { + cbds_type_none = 0, + cbds_type_channel, + cbds_type_cache +}; + +static inline const char *cbds_type_str(enum cbd_seg_type type) +{ + if (type == cbds_type_channel) + return "channel"; + else if (type == cbds_type_cache) + return "cache"; + + return "Unknown"; +} + +struct cbd_segment_info { + u8 state; + u8 type; + u8 ref; + u32 next_seg; + u64 alive_ts; +}; + +struct cbd_seg_pos { + struct cbd_segment *segment; + u32 off; +}; + +struct cbd_seg_ops { + void (*sanitize_pos)(struct cbd_seg_pos *pos); +}; + +struct cbds_init_options { + u32 seg_id; + enum cbd_seg_type type; + u32 data_off; + struct cbd_seg_ops *seg_ops; + void *priv_data; +}; + +struct cbd_segment { + struct cbd_transport *cbdt; + struct cbd_segment *next; + + u32 seg_id; + struct cbd_segment_info *segment_info; + struct cbd_seg_ops *seg_ops; + + void *data; + u32 data_size; + + void *priv_data; + + struct delayed_work hb_work; /* heartbeat work */ +}; + +int cbd_segment_clear(struct cbd_transport *cbdt, u32 segment_id); +void cbd_segment_init(struct cbd_transport *cbdt, struct cbd_segment *segment, + struct cbds_init_options *options); +void cbd_segment_exit(struct cbd_segment *segment); +bool cbd_segment_info_is_alive(struct cbd_segment_info *info); +void cbds_copy_to_bio(struct cbd_segment *segment, + u32 data_off, u32 data_len, struct bio *bio, u32 bio_off); +void cbds_copy_from_bio(struct cbd_segment *segment, + u32 data_off, u32 data_len, struct bio *bio, u32 bio_off); +u32 cbd_seg_crc(struct cbd_segment *segment, u32 data_off, u32 data_len); +int cbds_map_pages(struct cbd_segment *segment, struct cbd_backend_io *io); +int cbds_pos_advance(struct cbd_seg_pos *seg_pos, u32 len); +void cbds_copy_data(struct cbd_seg_pos *dst_pos, + struct cbd_seg_pos *src_pos, u32 len); + +/* cbd_channel */ + +enum cbdc_blkdev_state { + cbdc_blkdev_state_none = 0, + cbdc_blkdev_state_running, + cbdc_blkdev_state_stopped, +}; + +enum cbdc_backend_state { + cbdc_backend_state_none = 0, + cbdc_backend_state_running, + cbdc_backend_state_stopped, +}; + +struct cbd_channel_info { + struct cbd_segment_info seg_info; /* must be the first member */ + u8 blkdev_state; + u32 blkdev_id; + + u8 backend_state; + u32 backend_id; + + u32 polling:1; + + u32 submr_head; + u32 submr_tail; + + u32 compr_head; + u32 compr_tail; +}; + +struct cbd_channel { + u32 seg_id; + struct cbd_segment segment; + + struct cbd_channel_info *channel_info; + + struct cbd_transport *cbdt; + + void *submr; + void *compr; + + u32 submr_size; + u32 compr_size; + + u32 data_size; + u32 data_head; + u32 data_tail; + + spinlock_t submr_lock; + spinlock_t compr_lock; +}; + +void cbd_channel_init(struct cbd_channel *channel, struct cbd_transport *cbdt, u32 seg_id); +void cbd_channel_exit(struct cbd_channel *channel); +void cbdc_copy_from_bio(struct cbd_channel *channel, + u32 data_off, u32 data_len, struct bio *bio, u32 bio_off); +void cbdc_copy_to_bio(struct cbd_channel *channel, + u32 data_off, u32 data_len, struct bio *bio, u32 bio_off); +u32 cbd_channel_crc(struct cbd_channel *channel, u32 data_off, u32 data_len); +int cbdc_map_pages(struct cbd_channel *channel, struct cbd_backend_io *io); +int cbd_get_empty_channel_id(struct cbd_transport *cbdt, u32 *id); +ssize_t cbd_channel_seg_detail_show(struct cbd_channel_info *channel_info, char *buf); + +/* cbd cache */ +struct cbd_cache_seg_info { + struct cbd_segment_info segment_info; /* first member */ + u32 flags; + u32 next_cache_seg_id; /* index in cache->segments */ + u64 gen; +}; + +#define CBD_CACHE_SEG_FLAGS_HAS_NEXT (1 << 0) +#define CBD_CACHE_SEG_FLAGS_WB_DONE (1 << 1) +#define CBD_CACHE_SEG_FLAGS_GC_DONE (1 << 2) + +enum cbd_cache_blkdev_state { + cbd_cache_blkdev_state_none = 0, + cbd_cache_blkdev_state_running, + cbd_cache_blkdev_state_removing +}; + +struct cbd_cache_segment { + struct cbd_cache *cache; + u32 cache_seg_id; /* index in cache->segments */ + u32 used; + spinlock_t gen_lock; + struct cbd_cache_seg_info *cache_seg_info; + struct cbd_segment segment; + atomic_t refs; +}; + +struct cbd_cache_pos { + struct cbd_cache_segment *cache_seg; + u32 seg_off; +}; + +struct cbd_cache_pos_onmedia { + u32 cache_seg_id; + u32 seg_off; +}; + +struct cbd_cache_info { + u8 blkdev_state; + u32 blkdev_id; + + u32 seg_id; + u32 n_segs; + + u32 used_segs; + u16 gc_percent; + + struct cbd_cache_pos_onmedia key_tail_pos; + struct cbd_cache_pos_onmedia dirty_tail_pos; +}; + +struct cbd_cache_tree { + struct rb_root root; + spinlock_t tree_lock; +}; + +struct cbd_cache_data_head { + spinlock_t data_head_lock; + struct cbd_cache_pos head_pos; +}; + +struct cbd_cache_key { + struct cbd_cache *cache; + struct cbd_cache_tree *cache_tree; + struct kref ref; + + struct rb_node rb_node; + struct list_head list_node; + + u64 off; + u32 len; + u64 flags; + + struct cbd_cache_pos cache_pos; + + u64 seg_gen; +#ifdef CONFIG_CBD_CRC + u32 data_crc; +#endif +}; + +#define CBD_CACHE_KEY_FLAGS_EMPTY (1 << 0) +#define CBD_CACHE_KEY_FLAGS_CLEAN (1 << 1) + +struct cbd_cache_key_onmedia { + u64 off; + u32 len; + + u32 flags; + + u32 cache_seg_id; + u32 cache_seg_off; + + u64 seg_gen; +#ifdef CONFIG_CBD_CRC + u32 data_crc; +#endif +}; + +struct cbd_cache_kset_onmedia { + u32 crc; + u64 magic; + u64 flags; + u32 key_num; + struct cbd_cache_key_onmedia data[]; +}; + +#define CBD_KSET_FLAGS_LAST (1 << 0) + +#define CBD_KSET_MAGIC 0x676894a64e164f1aULL + +struct cbd_cache_kset { + struct cbd_cache *cache; + spinlock_t kset_lock; + struct delayed_work flush_work; + struct cbd_cache_kset_onmedia kset_onmedia; +}; + +enum cbd_cache_state { + cbd_cache_state_none = 0, + cbd_cache_state_running, + cbd_cache_state_stopping +}; + +struct cbd_cache { + struct cbd_transport *cbdt; + struct cbd_cache_info *cache_info; + u32 cache_id; /* same with related backend->backend_id */ + + u32 n_heads; + struct cbd_cache_data_head *data_heads; + + spinlock_t key_head_lock; + struct cbd_cache_pos key_head; + u32 n_ksets; + struct cbd_cache_kset *ksets; + + struct cbd_cache_pos key_tail; + struct cbd_cache_pos dirty_tail; + + struct kmem_cache *key_cache; + u32 n_trees; + struct cbd_cache_tree *cache_trees; + struct work_struct clean_work; + + spinlock_t miss_read_reqs_lock; + struct list_head miss_read_reqs; + struct work_struct miss_read_end_work; + + struct workqueue_struct *cache_wq; + + struct file *bdev_file; + u64 dev_size; + struct delayed_work writeback_work; + struct delayed_work gc_work; + struct bio_set *bioset; + + struct kmem_cache *req_cache; + + u32 state:8; + u32 init_keys:1; + u32 start_writeback:1; + u32 start_gc:1; + + u32 n_segs; + unsigned long *seg_map; + u32 last_cache_seg; + spinlock_t seg_map_lock; + struct cbd_cache_segment segments[]; /* should be the last member */ +}; + +struct cbd_request; +struct cbd_cache_opts { + struct cbd_cache_info *cache_info; + bool alloc_segs; + bool start_writeback; + bool start_gc; + bool init_keys; + u64 dev_size; + u32 n_paral; + struct file *bdev_file; /* needed for start_writeback is true */ +}; + +struct cbd_cache *cbd_cache_alloc(struct cbd_transport *cbdt, + struct cbd_cache_opts *opts); +void cbd_cache_destroy(struct cbd_cache *cache); +int cbd_cache_handle_req(struct cbd_cache *cache, struct cbd_request *cbd_req); + +/* cbd_handler */ +struct cbd_handler { + struct cbd_backend *cbdb; + struct cbd_channel_info *channel_info; + + struct cbd_channel channel; + spinlock_t compr_lock; + + u32 se_to_handle; + u64 req_tid_expected; + + u32 polling:1; + + struct delayed_work handle_work; + struct cbd_worker_cfg handle_worker_cfg; + + struct hlist_node hash_node; + struct bio_set bioset; +}; + +void cbd_handler_destroy(struct cbd_handler *handler); +int cbd_handler_create(struct cbd_backend *cbdb, u32 seg_id); +void cbd_handler_notify(struct cbd_handler *handler); + +/* cbd_backend */ +CBD_DEVICE(backend); + +enum cbd_backend_state { + cbd_backend_state_none = 0, + cbd_backend_state_running, + cbd_backend_state_removing +}; + +#define CBDB_BLKDEV_COUNT_MAX 1 + +struct cbd_backend_info { + u8 state; + u32 host_id; + u32 blkdev_count; + u64 alive_ts; + u64 dev_size; /* nr_sectors */ + struct cbd_cache_info cache_info; + + char path[CBD_PATH_LEN]; +}; + +struct cbd_backend_io { + struct cbd_se *se; + u64 off; + u32 len; + struct bio *bio; + struct cbd_handler *handler; +}; + +#define CBD_BACKENDS_HANDLER_BITS 7 + +struct cbd_backend { + u32 backend_id; + char path[CBD_PATH_LEN]; + struct cbd_transport *cbdt; + struct cbd_backend_info *backend_info; + spinlock_t lock; + + struct block_device *bdev; + struct file *bdev_file; + + struct workqueue_struct *task_wq; + struct delayed_work state_work; + struct delayed_work hb_work; /* heartbeat work */ + + struct list_head node; /* cbd_transport->backends */ + DECLARE_HASHTABLE(handlers_hash, CBD_BACKENDS_HANDLER_BITS); + + struct cbd_backend_device *backend_device; + + struct kmem_cache *backend_io_cache; + + struct cbd_cache *cbd_cache; + struct device cache_dev; + bool cache_dev_registered; +}; + +int cbd_backend_start(struct cbd_transport *cbdt, char *path, u32 backend_id, u32 cache_segs); +int cbd_backend_stop(struct cbd_transport *cbdt, u32 backend_id); +int cbd_backend_clear(struct cbd_transport *cbdt, u32 backend_id); +int cbdb_add_handler(struct cbd_backend *cbdb, struct cbd_handler *handler); +void cbdb_del_handler(struct cbd_backend *cbdb, struct cbd_handler *handler); +bool cbd_backend_info_is_alive(struct cbd_backend_info *info); +bool cbd_backend_cache_on(struct cbd_backend_info *backend_info); +void cbd_backend_notify(struct cbd_backend *cbdb, u32 seg_id); + +/* cbd_queue */ +enum cbd_op { + CBD_OP_WRITE = 0, + CBD_OP_READ, + CBD_OP_FLUSH, +}; + +struct cbd_se { +#ifdef CONFIG_CBD_CRC + u32 se_crc; /* should be the first member */ + u32 data_crc; +#endif + u32 op; + u32 flags; + u64 req_tid; + + u64 offset; + u32 len; + + u32 data_off; + u32 data_len; +}; + +struct cbd_ce { +#ifdef CONFIG_CBD_CRC + u32 ce_crc; /* should be the first member */ + u32 data_crc; +#endif + u64 req_tid; + u32 result; + u32 flags; +}; + +#ifdef CONFIG_CBD_CRC +static inline u32 cbd_se_crc(struct cbd_se *se) +{ + return crc32(0, (void *)se + 4, sizeof(*se) - 4); +} + +static inline u32 cbd_ce_crc(struct cbd_ce *ce) +{ + return crc32(0, (void *)ce + 4, sizeof(*ce) - 4); +} +#endif + +struct cbd_request { + struct cbd_queue *cbdq; + + struct cbd_se *se; + struct cbd_ce *ce; + struct request *req; + + u64 off; + struct bio *bio; + u32 bio_off; + spinlock_t lock; /* race between cache and complete_work to access bio */ + + enum cbd_op op; + u64 req_tid; + struct list_head inflight_reqs_node; + + u32 data_off; + u32 data_len; + + struct work_struct work; + + struct kref ref; + int ret; + struct cbd_request *parent; + + void *priv_data; + void (*end_req)(struct cbd_request *cbd_req, void *priv_data); +}; + +struct cbd_cache_req { + struct cbd_cache *cache; + enum cbd_op op; + struct work_struct work; +}; + +#define CBD_SE_FLAGS_DONE 1 + +static inline bool cbd_se_flags_test(struct cbd_se *se, u32 bit) +{ + return (se->flags & bit); +} + +static inline void cbd_se_flags_set(struct cbd_se *se, u32 bit) +{ + se->flags |= bit; +} + +enum cbd_queue_state { + cbd_queue_state_none = 0, + cbd_queue_state_running, + cbd_queue_state_removing +}; + +struct cbd_queue { + struct cbd_blkdev *cbd_blkdev; + u32 index; + struct list_head inflight_reqs; + spinlock_t inflight_reqs_lock; + u64 req_tid; + + u64 *released_extents; + + struct cbd_channel_info *channel_info; + struct cbd_channel channel; + + atomic_t state; + + struct delayed_work complete_work; + struct cbd_worker_cfg complete_worker_cfg; +}; + +int cbd_queue_start(struct cbd_queue *cbdq); +void cbd_queue_stop(struct cbd_queue *cbdq); +extern const struct blk_mq_ops cbd_mq_ops; +int cbd_queue_req_to_backend(struct cbd_request *cbd_req); +void cbd_req_get(struct cbd_request *cbd_req); +void cbd_req_put(struct cbd_request *cbd_req, int ret); +void cbd_queue_advance(struct cbd_queue *cbdq, struct cbd_request *cbd_req); + +/* cbd_blkdev */ +CBD_DEVICE(blkdev); + +enum cbd_blkdev_state { + cbd_blkdev_state_none = 0, + cbd_blkdev_state_running, + cbd_blkdev_state_removing +}; + +struct cbd_blkdev_info { + u8 state; + u64 alive_ts; + u32 backend_id; + u32 host_id; + u32 mapped_id; +}; + +struct cbd_blkdev { + u32 blkdev_id; /* index in transport blkdev area */ + u32 backend_id; + int mapped_id; /* id in block device such as: /dev/cbd0 */ + + struct cbd_backend *backend; /* reference to backend if blkdev and backend on the same host */ + + int major; /* blkdev assigned major */ + int minor; + struct gendisk *disk; /* blkdev's gendisk and rq */ + + struct mutex lock; + unsigned long open_count; /* protected by lock */ + + struct list_head node; + struct delayed_work hb_work; /* heartbeat work */ + + /* Block layer tags. */ + struct blk_mq_tag_set tag_set; + + uint32_t num_queues; + struct cbd_queue *queues; + + u64 dev_size; + + struct workqueue_struct *task_wq; + + struct cbd_blkdev_device *blkdev_dev; + struct cbd_blkdev_info *blkdev_info; + + struct cbd_transport *cbdt; + + struct cbd_cache *cbd_cache; +}; + +int cbd_blkdev_init(void); +void cbd_blkdev_exit(void); +int cbd_blkdev_start(struct cbd_transport *cbdt, u32 backend_id, u32 queues); +int cbd_blkdev_stop(struct cbd_transport *cbdt, u32 devid, bool force); +int cbd_blkdev_clear(struct cbd_transport *cbdt, u32 devid); +bool cbd_blkdev_info_is_alive(struct cbd_blkdev_info *info); + +extern struct workqueue_struct *cbd_wq; + +#define cbd_setup_device(DEV, PARENT, TYPE, fmt, ...) \ +do { \ + device_initialize(DEV); \ + device_set_pm_not_required(DEV); \ + dev_set_name(DEV, fmt, ##__VA_ARGS__); \ + DEV->parent = PARENT; \ + DEV->type = TYPE; \ + \ + ret = device_add(DEV); \ +} while (0) + +#define CBD_OBJ_HEARTBEAT(OBJ) \ +static void OBJ##_hb_workfn(struct work_struct *work) \ +{ \ + struct cbd_##OBJ *obj = container_of(work, struct cbd_##OBJ, hb_work.work); \ + struct cbd_##OBJ##_info *info = obj->OBJ##_info; \ + \ + info->alive_ts = ktime_get_real(); \ + \ + queue_delayed_work(cbd_wq, &obj->hb_work, CBD_HB_INTERVAL); \ +} \ + \ +bool cbd_##OBJ##_info_is_alive(struct cbd_##OBJ##_info *info) \ +{ \ + ktime_t oldest, ts; \ + \ + ts = info->alive_ts; \ + oldest = ktime_sub_ms(ktime_get_real(), CBD_HB_TIMEOUT); \ + \ + if (ktime_after(ts, oldest)) \ + return true; \ + \ + return false; \ +} \ + \ +static ssize_t cbd_##OBJ##_alive_show(struct device *dev, \ + struct device_attribute *attr, \ + char *buf) \ +{ \ + struct cbd_##OBJ##_device *_dev; \ + \ + _dev = container_of(dev, struct cbd_##OBJ##_device, dev); \ + \ + if (cbd_##OBJ##_info_is_alive(_dev->OBJ##_info)) \ + return sprintf(buf, "true\n"); \ + \ + return sprintf(buf, "false\n"); \ +} \ + \ +static DEVICE_ATTR(alive, 0400, cbd_##OBJ##_alive_show, NULL) + +#endif /* _CBD_INTERNAL_H */ diff --git a/drivers/block/cbd/cbd_transport.c b/drivers/block/cbd/cbd_transport.c new file mode 100644 index 000000000000..30dc4cd6c77a --- /dev/null +++ b/drivers/block/cbd/cbd_transport.c @@ -0,0 +1,957 @@ +#include +#include "cbd_internal.h" + +#define CBDT_OBJ(OBJ, OBJ_SIZE) \ +extern struct device_type cbd_##OBJ##_type; \ +extern struct device_type cbd_##OBJ##s_type; \ + \ +static int cbd_##OBJ##s_init(struct cbd_transport *cbdt) \ +{ \ + struct cbd_##OBJ##s_device *devs; \ + struct cbd_##OBJ##_device *cbd_dev; \ + struct device *dev; \ + int i; \ + int ret; \ + \ + u32 memsize = struct_size(devs, OBJ##_devs, \ + cbdt->transport_info->OBJ##_num); \ + devs = kzalloc(memsize, GFP_KERNEL); \ + if (!devs) { \ + return -ENOMEM; \ + } \ + \ + dev = &devs->OBJ##s_dev; \ + device_initialize(dev); \ + device_set_pm_not_required(dev); \ + dev_set_name(dev, "cbd_" #OBJ "s"); \ + dev->parent = &cbdt->device; \ + dev->type = &cbd_##OBJ##s_type; \ + ret = device_add(dev); \ + if (ret) { \ + goto devs_free; \ + } \ + \ + for (i = 0; i < cbdt->transport_info->OBJ##_num; i++) { \ + cbd_dev = &devs->OBJ##_devs[i]; \ + dev = &cbd_dev->dev; \ + \ + cbd_dev->cbdt = cbdt; \ + cbd_dev->OBJ##_info = cbdt_get_##OBJ##_info(cbdt, i); \ + device_initialize(dev); \ + device_set_pm_not_required(dev); \ + dev_set_name(dev, #OBJ "%u", i); \ + dev->parent = &devs->OBJ##s_dev; \ + dev->type = &cbd_##OBJ##_type; \ + \ + ret = device_add(dev); \ + if (ret) { \ + i--; \ + goto del_device; \ + } \ + } \ + cbdt->cbd_##OBJ##s_dev = devs; \ + \ + return 0; \ +del_device: \ + for (; i >= 0; i--) { \ + cbd_dev = &devs->OBJ##_devs[i]; \ + dev = &cbd_dev->dev; \ + device_del(dev); \ + } \ +devs_free: \ + kfree(devs); \ + return ret; \ +} \ + \ +static void cbd_##OBJ##s_exit(struct cbd_transport *cbdt) \ +{ \ + struct cbd_##OBJ##s_device *devs = cbdt->cbd_##OBJ##s_dev; \ + struct device *dev; \ + int i; \ + \ + if (!devs) \ + return; \ + \ + for (i = 0; i < cbdt->transport_info->OBJ##_num; i++) { \ + struct cbd_##OBJ##_device *cbd_dev = &devs->OBJ##_devs[i]; \ + dev = &cbd_dev->dev; \ + \ + device_del(dev); \ + } \ + \ + device_del(&devs->OBJ##s_dev); \ + \ + kfree(devs); \ + cbdt->cbd_##OBJ##s_dev = NULL; \ + \ + return; \ +} \ + \ +static inline struct cbd_##OBJ##_info \ +*__get_##OBJ##_info(struct cbd_transport *cbdt, u32 id) \ +{ \ + struct cbd_transport_info *info = cbdt->transport_info; \ + void *start = cbdt->transport_info; \ + \ + start += info->OBJ##_area_off; \ + \ + return start + ((u64)info->OBJ_SIZE * id); \ +} \ + \ +struct cbd_##OBJ##_info \ +*cbdt_get_##OBJ##_info(struct cbd_transport *cbdt, u32 id) \ +{ \ + struct cbd_##OBJ##_info *info; \ + \ + mutex_lock(&cbdt->lock); \ + info = __get_##OBJ##_info(cbdt, id); \ + mutex_unlock(&cbdt->lock); \ + \ + return info; \ +} \ + \ +int cbdt_get_empty_##OBJ##_id(struct cbd_transport *cbdt, u32 *id) \ +{ \ + struct cbd_transport_info *info = cbdt->transport_info; \ + struct cbd_##OBJ##_info *_info; \ + int ret = 0; \ + int i; \ + \ + mutex_lock(&cbdt->lock); \ + for (i = 0; i < info->OBJ##_num; i++) { \ + _info = __get_##OBJ##_info(cbdt, i); \ + if (_info->state == cbd_##OBJ##_state_none) { \ + cbdt_zero_range(cbdt, _info, info->OBJ_SIZE); \ + *id = i; \ + goto out; \ + } \ + } \ + \ + cbdt_err(cbdt, "No available " #OBJ "_id found."); \ + ret = -ENOENT; \ +out: \ + mutex_unlock(&cbdt->lock); \ + \ + return ret; \ +} + +CBDT_OBJ(host, host_info_size); +CBDT_OBJ(backend, backend_info_size); +CBDT_OBJ(blkdev, blkdev_info_size); +CBDT_OBJ(segment, segment_size); + +static struct cbd_transport *cbd_transports[CBD_TRANSPORT_MAX]; +static DEFINE_IDA(cbd_transport_id_ida); +static DEFINE_MUTEX(cbd_transport_mutex); + +extern struct bus_type cbd_bus_type; +extern struct device cbd_root_dev; + +static ssize_t cbd_myhost_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct cbd_transport *cbdt; + struct cbd_host *host; + + cbdt = container_of(dev, struct cbd_transport, device); + + host = cbdt->host; + if (!host) + return 0; + + return sprintf(buf, "%d\n", host->host_id); +} + +static DEVICE_ATTR(my_host_id, 0400, cbd_myhost_show, NULL); + +enum { + CBDT_ADM_OPT_ERR = 0, + CBDT_ADM_OPT_OP, + CBDT_ADM_OPT_FORCE, + CBDT_ADM_OPT_PATH, + CBDT_ADM_OPT_BID, + CBDT_ADM_OPT_DID, + CBDT_ADM_OPT_QUEUES, + CBDT_ADM_OPT_HID, + CBDT_ADM_OPT_SID, + CBDT_ADM_OPT_CACHE_SIZE, +}; + +enum { + CBDT_ADM_OP_B_START, + CBDT_ADM_OP_B_STOP, + CBDT_ADM_OP_B_CLEAR, + CBDT_ADM_OP_DEV_START, + CBDT_ADM_OP_DEV_STOP, + CBDT_ADM_OP_DEV_CLEAR, + CBDT_ADM_OP_H_CLEAR, + CBDT_ADM_OP_S_CLEAR, +}; + +static const char *const adm_op_names[] = { + [CBDT_ADM_OP_B_START] = "backend-start", + [CBDT_ADM_OP_B_STOP] = "backend-stop", + [CBDT_ADM_OP_B_CLEAR] = "backend-clear", + [CBDT_ADM_OP_DEV_START] = "dev-start", + [CBDT_ADM_OP_DEV_STOP] = "dev-stop", + [CBDT_ADM_OP_DEV_CLEAR] = "dev-clear", + [CBDT_ADM_OP_H_CLEAR] = "host-clear", + [CBDT_ADM_OP_S_CLEAR] = "segment-clear", +}; + +static const match_table_t adm_opt_tokens = { + { CBDT_ADM_OPT_OP, "op=%s" }, + { CBDT_ADM_OPT_FORCE, "force=%u" }, + { CBDT_ADM_OPT_PATH, "path=%s" }, + { CBDT_ADM_OPT_BID, "backend_id=%u" }, + { CBDT_ADM_OPT_DID, "dev_id=%u" }, + { CBDT_ADM_OPT_QUEUES, "queues=%u" }, + { CBDT_ADM_OPT_HID, "host_id=%u" }, + { CBDT_ADM_OPT_SID, "segment_id=%u" }, + { CBDT_ADM_OPT_CACHE_SIZE, "cache_size=%u" }, /* unit is MiB */ + { CBDT_ADM_OPT_ERR, NULL } +}; + + +struct cbd_adm_options { + u16 op; + u16 force:1; + u32 backend_id; + union { + struct host_options { + u32 hid; + } host; + struct backend_options { + char path[CBD_PATH_LEN]; + u64 cache_size_M; + } backend; + struct segment_options { + u32 sid; + } segment; + struct blkdev_options { + u32 devid; + u32 queues; + } blkdev; + }; +}; + +static int parse_adm_options(struct cbd_transport *cbdt, + char *buf, + struct cbd_adm_options *opts) +{ + substring_t args[MAX_OPT_ARGS]; + char *o, *p; + int token, ret = 0; + + o = buf; + + while ((p = strsep(&o, ",\n")) != NULL) { + if (!*p) + continue; + + token = match_token(p, adm_opt_tokens, args); + switch (token) { + case CBDT_ADM_OPT_OP: + ret = match_string(adm_op_names, ARRAY_SIZE(adm_op_names), args[0].from); + if (ret < 0) { + cbdt_err(cbdt, "unknown op: '%s'\n", args[0].from); + ret = -EINVAL; + break; + } + opts->op = ret; + break; + case CBDT_ADM_OPT_PATH: + if (match_strlcpy(opts->backend.path, &args[0], + CBD_PATH_LEN) == 0) { + ret = -EINVAL; + break; + } + break; + case CBDT_ADM_OPT_FORCE: + if (match_uint(args, &token) || token != 1) { + ret = -EINVAL; + goto out; + } + opts->force = 1; + break; + case CBDT_ADM_OPT_BID: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + opts->backend_id = token; + break; + case CBDT_ADM_OPT_DID: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + opts->blkdev.devid = token; + break; + case CBDT_ADM_OPT_QUEUES: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + opts->blkdev.queues = token; + break; + case CBDT_ADM_OPT_HID: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + opts->host.hid = token; + break; + case CBDT_ADM_OPT_SID: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + opts->segment.sid = token; + break; + case CBDT_ADM_OPT_CACHE_SIZE: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + opts->backend.cache_size_M = token; + break; + default: + cbdt_err(cbdt, "unknown parameter or missing value '%s'\n", p); + ret = -EINVAL; + goto out; + } + } + +out: + return ret; +} + +void cbdt_zero_range(struct cbd_transport *cbdt, void *pos, u32 size) +{ + memset(pos, 0, size); +} + +static void segments_format(struct cbd_transport *cbdt) +{ + u32 i; + struct cbd_segment_info *seg_info; + + for (i = 0; i < cbdt->transport_info->segment_num; i++) { + seg_info = cbdt_get_segment_info(cbdt, i); + cbdt_zero_range(cbdt, seg_info, sizeof(struct cbd_segment_info)); + } +} + +static int cbd_transport_format(struct cbd_transport *cbdt, bool force) +{ + struct cbd_transport_info *info = cbdt->transport_info; + u64 transport_dev_size; + u32 seg_size; + u32 nr_segs; + u64 magic; + u16 flags = 0; + + magic = le64_to_cpu(info->magic); + if (magic && !force) + return -EEXIST; + + transport_dev_size = bdev_nr_bytes(file_bdev(cbdt->bdev_file)); + if (transport_dev_size < CBD_TRASNPORT_SIZE_MIN) { + cbdt_err(cbdt, "dax device is too small, required at least %u", + CBD_TRASNPORT_SIZE_MIN); + return -ENOSPC; + } + + memset(info, 0, sizeof(*info)); + + info->magic = cpu_to_le64(CBD_TRANSPORT_MAGIC); + info->version = cpu_to_le16(CBD_TRANSPORT_VERSION); +#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN) + flags |= CBDT_INFO_F_BIGENDIAN; +#endif +#ifdef CONFIG_CBD_CRC + flags |= CBDT_INFO_F_CRC; +#endif + info->flags = cpu_to_le16(flags); + + info->hosts_registered = 0; + /* + * Try to fully utilize all available space, + * assuming host:blkdev:backend:segment = 1:1:1:1 + */ + seg_size = (CBDT_HOST_INFO_SIZE + CBDT_BACKEND_INFO_SIZE + + CBDT_BLKDEV_INFO_SIZE + CBDT_SEG_SIZE); + nr_segs = (transport_dev_size - CBDT_INFO_SIZE) / seg_size; + + info->host_area_off = CBDT_INFO_OFF + CBDT_INFO_SIZE; + info->host_info_size = CBDT_HOST_INFO_SIZE; + info->host_num = nr_segs; + + info->backend_area_off = info->host_area_off + (info->host_info_size * info->host_num); + info->backend_info_size = CBDT_BACKEND_INFO_SIZE; + info->backend_num = nr_segs; + + info->blkdev_area_off = info->backend_area_off + (info->backend_info_size * info->backend_num); + info->blkdev_info_size = CBDT_BLKDEV_INFO_SIZE; + info->blkdev_num = nr_segs; + + info->segment_area_off = info->blkdev_area_off + (info->blkdev_info_size * info->blkdev_num); + info->segment_size = CBDT_SEG_SIZE; + info->segment_num = nr_segs; + + cbdt_zero_range(cbdt, (void *)info + info->host_area_off, + info->segment_area_off - info->host_area_off); + + segments_format(cbdt); + + return 0; +} + +/* + * Any transport metadata allocation or reclaim should be in the + * control operation rutine + * + * All transport space allocation and deallocation should occur within the control flow, + * specifically within `adm_store()`, so that all transport space allocation + * and deallocation are managed within this function. This prevents other processes + * from involving transport space allocation and deallocation. By making `adm_store` + * exclusive, we can manage space effectively. For a single-host scenario, `adm_lock` + * can ensure mutual exclusion of `adm_store`. However, in a multi-host scenario, + * we need a distributed lock to guarantee that all `adm_store` calls are mutually exclusive. + * + * TODO: Is there a way to lock the CXL shared memory device? + */ +static ssize_t adm_store(struct device *dev, + struct device_attribute *attr, + const char *ubuf, + size_t size) +{ + int ret; + char *buf; + struct cbd_adm_options opts = { 0 }; + struct cbd_transport *cbdt; + + opts.backend_id = U32_MAX; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + cbdt = container_of(dev, struct cbd_transport, device); + + buf = kmemdup(ubuf, size + 1, GFP_KERNEL); + if (IS_ERR(buf)) { + cbdt_err(cbdt, "failed to dup buf for adm option: %d", (int)PTR_ERR(buf)); + return PTR_ERR(buf); + } + buf[size] = '\0'; + ret = parse_adm_options(cbdt, buf, &opts); + if (ret < 0) { + kfree(buf); + return ret; + } + kfree(buf); + + mutex_lock(&cbdt->adm_lock); + switch (opts.op) { + case CBDT_ADM_OP_B_START: + u32 cache_segs = 0; + + if (opts.backend.cache_size_M > 0) + cache_segs = DIV_ROUND_UP(opts.backend.cache_size_M, + cbdt->transport_info->segment_size / CBD_MB); + + ret = cbd_backend_start(cbdt, opts.backend.path, opts.backend_id, cache_segs); + break; + case CBDT_ADM_OP_B_STOP: + ret = cbd_backend_stop(cbdt, opts.backend_id); + break; + case CBDT_ADM_OP_B_CLEAR: + ret = cbd_backend_clear(cbdt, opts.backend_id); + break; + case CBDT_ADM_OP_DEV_START: + if (opts.blkdev.queues > CBD_QUEUES_MAX) { + mutex_unlock(&cbdt->adm_lock); + cbdt_err(cbdt, "invalid queues = %u, larger than max %u\n", + opts.blkdev.queues, CBD_QUEUES_MAX); + return -EINVAL; + } + ret = cbd_blkdev_start(cbdt, opts.backend_id, opts.blkdev.queues); + break; + case CBDT_ADM_OP_DEV_STOP: + ret = cbd_blkdev_stop(cbdt, opts.blkdev.devid, opts.force); + break; + case CBDT_ADM_OP_DEV_CLEAR: + ret = cbd_blkdev_clear(cbdt, opts.blkdev.devid); + break; + case CBDT_ADM_OP_H_CLEAR: + ret = cbd_host_clear(cbdt, opts.host.hid); + break; + case CBDT_ADM_OP_S_CLEAR: + ret = cbd_segment_clear(cbdt, opts.segment.sid); + break; + default: + mutex_unlock(&cbdt->adm_lock); + cbdt_err(cbdt, "invalid op: %d\n", opts.op); + return -EINVAL; + } + mutex_unlock(&cbdt->adm_lock); + + if (ret < 0) + return ret; + + return size; +} + +static DEVICE_ATTR_WO(adm); + +static ssize_t cbd_transport_info(struct cbd_transport *cbdt, char *buf) +{ + struct cbd_transport_info *info = cbdt->transport_info; + ssize_t ret; + + mutex_lock(&cbdt->lock); + info = cbdt->transport_info; + mutex_unlock(&cbdt->lock); + + ret = sprintf(buf, "magic: 0x%llx\n" + "version: %u\n" + "flags: %x\n\n" + "hosts_registered: %u\n" + "host_area_off: %llu\n" + "bytes_per_host_info: %u\n" + "host_num: %u\n\n" + "backend_area_off: %llu\n" + "bytes_per_backend_info: %u\n" + "backend_num: %u\n\n" + "blkdev_area_off: %llu\n" + "bytes_per_blkdev_info: %u\n" + "blkdev_num: %u\n\n" + "segment_area_off: %llu\n" + "bytes_per_segment: %u\n" + "segment_num: %u\n", + le64_to_cpu(info->magic), + le16_to_cpu(info->version), + le16_to_cpu(info->flags), + info->hosts_registered, + info->host_area_off, + info->host_info_size, + info->host_num, + info->backend_area_off, + info->backend_info_size, + info->backend_num, + info->blkdev_area_off, + info->blkdev_info_size, + info->blkdev_num, + info->segment_area_off, + info->segment_size, + info->segment_num); + + return ret; +} + +static ssize_t cbd_info_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct cbd_transport *cbdt; + + cbdt = container_of(dev, struct cbd_transport, device); + + return cbd_transport_info(cbdt, buf); +} +static DEVICE_ATTR(info, 0400, cbd_info_show, NULL); + +static struct attribute *cbd_transport_attrs[] = { + &dev_attr_adm.attr, + &dev_attr_info.attr, + &dev_attr_my_host_id.attr, + NULL +}; + +static struct attribute_group cbd_transport_attr_group = { + .attrs = cbd_transport_attrs, +}; + +static const struct attribute_group *cbd_transport_attr_groups[] = { + &cbd_transport_attr_group, + NULL +}; + +static void cbd_transport_release(struct device *dev) +{ +} + +const struct device_type cbd_transport_type = { + .name = "cbd_transport", + .groups = cbd_transport_attr_groups, + .release = cbd_transport_release, +}; + +static int +cbd_dax_notify_failure( + struct dax_device *dax_devp, + u64 offset, + u64 len, + int mf_flags) +{ + + pr_err("%s: dax_devp %llx offset %llx len %lld mf_flags %x\n", + __func__, (u64)dax_devp, (u64)offset, (u64)len, mf_flags); + return -EOPNOTSUPP; +} + +const struct dax_holder_operations cbd_dax_holder_ops = { + .notify_failure = cbd_dax_notify_failure, +}; + +static struct cbd_transport *cbdt_alloc(void) +{ + struct cbd_transport *cbdt; + int ret; + + cbdt = kzalloc(sizeof(struct cbd_transport), GFP_KERNEL); + if (!cbdt) + return NULL; + + mutex_init(&cbdt->lock); + mutex_init(&cbdt->adm_lock); + INIT_LIST_HEAD(&cbdt->backends); + INIT_LIST_HEAD(&cbdt->devices); + + ret = ida_simple_get(&cbd_transport_id_ida, 0, CBD_TRANSPORT_MAX, + GFP_KERNEL); + if (ret < 0) + goto cbdt_free; + + cbdt->id = ret; + cbd_transports[cbdt->id] = cbdt; + + return cbdt; + +cbdt_free: + kfree(cbdt); + return NULL; +} + +static void cbdt_destroy(struct cbd_transport *cbdt) +{ + cbd_transports[cbdt->id] = NULL; + ida_simple_remove(&cbd_transport_id_ida, cbdt->id); + kfree(cbdt); +} + +static int cbdt_dax_init(struct cbd_transport *cbdt, char *path) +{ + struct dax_device *dax_dev = NULL; + struct file *bdev_file = NULL; + long access_size; + void *kaddr; + u64 start_off = 0; + int ret; + int id; + + bdev_file = bdev_file_open_by_path(path, BLK_OPEN_READ | BLK_OPEN_WRITE, cbdt, NULL); + if (IS_ERR(bdev_file)) { + cbdt_err(cbdt, "%s: failed blkdev_get_by_path(%s)\n", __func__, path); + ret = PTR_ERR(bdev_file); + goto err; + } + + dax_dev = fs_dax_get_by_bdev(file_bdev(bdev_file), &start_off, + cbdt, + &cbd_dax_holder_ops); + if (IS_ERR(dax_dev)) { + cbdt_err(cbdt, "%s: unable to get daxdev from bdev_file\n", __func__); + ret = -ENODEV; + goto fput; + } + + id = dax_read_lock(); + access_size = dax_direct_access(dax_dev, 0, 1, DAX_ACCESS, &kaddr, NULL); + if (access_size != 1) { + dax_read_unlock(id); + ret = -EINVAL; + goto dax_put; + } + + cbdt->bdev_file = bdev_file; + cbdt->dax_dev = dax_dev; + cbdt->transport_info = (struct cbd_transport_info *)kaddr; + dax_read_unlock(id); + + return 0; + +dax_put: + fs_put_dax(dax_dev, cbdt); +fput: + fput(bdev_file); +err: + return ret; +} + +static void cbdt_dax_release(struct cbd_transport *cbdt) +{ + if (cbdt->dax_dev) + fs_put_dax(cbdt->dax_dev, cbdt); + + if (cbdt->bdev_file) + fput(cbdt->bdev_file); +} + +static int cbd_transport_init(struct cbd_transport *cbdt) +{ + struct device *dev; + + dev = &cbdt->device; + device_initialize(dev); + device_set_pm_not_required(dev); + dev->bus = &cbd_bus_type; + dev->type = &cbd_transport_type; + dev->parent = &cbd_root_dev; + + dev_set_name(&cbdt->device, "transport%d", cbdt->id); + + return device_add(&cbdt->device); +} + + +static int cbdt_validate(struct cbd_transport *cbdt) +{ + u16 flags; + + if (le64_to_cpu(cbdt->transport_info->magic) != CBD_TRANSPORT_MAGIC) { + cbdt_err(cbdt, "unexpected magic: %llx\n", + le64_to_cpu(cbdt->transport_info->magic)); + return -EINVAL; + } + + flags = le16_to_cpu(cbdt->transport_info->flags); +#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN) + if (!(flags & CBDT_INFO_F_BIGENDIAN)) { + cbdt_err(cbdt, "transport is not big endian\n"); + return -EINVAL; + } +#else + if (flags & CBDT_INFO_F_BIGENDIAN) { + cbdt_err(cbdt, "transport is big endian\n"); + return -EINVAL; + } +#endif + +#ifndef CONFIG_CBD_CRC + if (flags & CBDT_INFO_F_CRC) { + cbdt_err(cbdt, "transport expects CBD_CRC enabled.\n"); + return -ENOTSUPP; + } +#endif + + return 0; +} + +int cbdt_unregister(u32 tid) +{ + struct cbd_transport *cbdt; + + cbdt = cbd_transports[tid]; + if (!cbdt) { + pr_err("tid: %u, is not registered\n", tid); + return -EINVAL; + } + + mutex_lock(&cbdt->lock); + if (!list_empty(&cbdt->backends) || !list_empty(&cbdt->devices)) { + mutex_unlock(&cbdt->lock); + return -EBUSY; + } + mutex_unlock(&cbdt->lock); + + cbd_blkdevs_exit(cbdt); + cbd_segments_exit(cbdt); + cbd_backends_exit(cbdt); + cbd_hosts_exit(cbdt); + + cbd_host_unregister(cbdt); + cbdt->transport_info->hosts_registered--; + + device_unregister(&cbdt->device); + cbdt_dax_release(cbdt); + cbdt_destroy(cbdt); + module_put(THIS_MODULE); + + return 0; +} + +static bool cbdt_register_allowed(struct cbd_transport *cbdt) +{ + struct cbd_transport_info *transport_info; + + transport_info = cbdt->transport_info; + + if (transport_info->hosts_registered >= CBDT_HOSTS_MAX) { + cbdt_err(cbdt, "too many hosts registered: %u (max %u).", + transport_info->hosts_registered, + CBDT_HOSTS_MAX); + return false; + } + + return true; +} + +int cbdt_register(struct cbdt_register_options *opts) +{ + struct cbd_transport *cbdt; + int ret; + + if (!try_module_get(THIS_MODULE)) + return -ENODEV; + + if (!strstr(opts->path, "/dev/pmem")) { + pr_err("%s: path (%s) is not pmem\n", + __func__, opts->path); + ret = -EINVAL; + goto module_put; + } + + cbdt = cbdt_alloc(); + if (!cbdt) { + ret = -ENOMEM; + goto module_put; + } + + ret = cbdt_dax_init(cbdt, opts->path); + if (ret) + goto cbdt_destroy; + + if (!cbdt_register_allowed(cbdt)) { + ret = -EINVAL; + goto dax_release; + } + + if (opts->format) { + ret = cbd_transport_format(cbdt, opts->force); + if (ret < 0) + goto dax_release; + } + + ret = cbdt_validate(cbdt); + if (ret) + goto dax_release; + + ret = cbd_transport_init(cbdt); + if (ret) + goto dax_release; + + ret = cbd_host_register(cbdt, opts->hostname); + if (ret) + goto dev_unregister; + + if (cbd_hosts_init(cbdt) || cbd_backends_init(cbdt) || + cbd_segments_init(cbdt) || cbd_blkdevs_init(cbdt)) { + ret = -ENOMEM; + goto devs_exit; + } + + cbdt->transport_info->hosts_registered++; + + return 0; + +devs_exit: + cbd_blkdevs_exit(cbdt); + cbd_segments_exit(cbdt); + cbd_backends_exit(cbdt); + cbd_hosts_exit(cbdt); + + cbd_host_unregister(cbdt); +dev_unregister: + device_unregister(&cbdt->device); +dax_release: + cbdt_dax_release(cbdt); +cbdt_destroy: + cbdt_destroy(cbdt); +module_put: + module_put(THIS_MODULE); + + return ret; +} + +void cbdt_add_backend(struct cbd_transport *cbdt, struct cbd_backend *cbdb) +{ + mutex_lock(&cbdt->lock); + list_add(&cbdb->node, &cbdt->backends); + mutex_unlock(&cbdt->lock); +} + +void cbdt_del_backend(struct cbd_transport *cbdt, struct cbd_backend *cbdb) +{ + if (list_empty(&cbdb->node)) + return; + + mutex_lock(&cbdt->lock); + list_del_init(&cbdb->node); + mutex_unlock(&cbdt->lock); +} + +struct cbd_backend *cbdt_get_backend(struct cbd_transport *cbdt, u32 id) +{ + struct cbd_backend *backend; + + mutex_lock(&cbdt->lock); + list_for_each_entry(backend, &cbdt->backends, node) { + if (backend->backend_id == id) + goto out; + } + backend = NULL; +out: + mutex_unlock(&cbdt->lock); + return backend; +} + +void cbdt_add_blkdev(struct cbd_transport *cbdt, struct cbd_blkdev *blkdev) +{ + mutex_lock(&cbdt->lock); + list_add(&blkdev->node, &cbdt->devices); + mutex_unlock(&cbdt->lock); +} + +void cbdt_del_blkdev(struct cbd_transport *cbdt, struct cbd_blkdev *blkdev) +{ + if (list_empty(&blkdev->node)) + return; + + mutex_lock(&cbdt->lock); + list_del_init(&blkdev->node); + mutex_unlock(&cbdt->lock); +} + +struct cbd_blkdev *cbdt_get_blkdev(struct cbd_transport *cbdt, u32 id) +{ + struct cbd_blkdev *dev; + + mutex_lock(&cbdt->lock); + list_for_each_entry(dev, &cbdt->devices, node) { + if (dev->blkdev_id == id) + goto out; + } + dev = NULL; +out: + mutex_unlock(&cbdt->lock); + return dev; +} + +struct page *cbdt_page(struct cbd_transport *cbdt, u64 transport_off, u32 *page_off) +{ + long access_size; + pfn_t pfn; + + access_size = dax_direct_access(cbdt->dax_dev, transport_off >> PAGE_SHIFT, + 1, DAX_ACCESS, NULL, &pfn); + if (access_size < 0) + return NULL; + + if (page_off) + *page_off = transport_off & PAGE_MASK; + + return pfn_t_to_page(pfn); +}