From patchwork Mon Jan 6 14:24:38 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Damien Le Moal X-Patchwork-Id: 13927533 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C0AB41DE8AC for ; Mon, 6 Jan 2025 14:25:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736173524; cv=none; b=TBKekdUhEJuO5jE/57AQN0RjchlS8yJMySRvJDXigclwHj9n+yBbuWPhnoMwwCp/8kGevkEXrsoR8kahcbP88h8sPyq0Uv5ycAOE7+H4UWKMQZXHtnMgjLj+tFn8ZhoiYUtuiGQS2KD3sSePdAPyZJuZQeWH7UnP9PzTLYpa5PI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736173524; c=relaxed/simple; bh=PcyYKO/a29P07LFBROb+TXWwWs+zlhZ/zn9kfCd7/Qg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eqEtNNPMqG9OZItTbHO522iT62ahxk2w1795QTtjEtyrgLsFFArjWnn4eIWl5M59crrXVCexNNIO4UzFKdCQCjPiaH4S7oBg5ollg0jkH3e4OsmmB4ZkggcBlkLQafn+0/VHkp5V8LNFHIDmBvoTcQK/+FoLK02kbC+n1vfkkxQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FUhMhimf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FUhMhimf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA468C4CED6; Mon, 6 Jan 2025 14:25:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736173524; bh=PcyYKO/a29P07LFBROb+TXWwWs+zlhZ/zn9kfCd7/Qg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FUhMhimfFLClu+NjFzVAX28AeztqQy5eNferwJHAZhZv75Fd1jjSsEX0MGf5fQ8Xx TNJuyce7Yh/Ikc9MkNhLJ9eY/jlY9nrkN4Vco0/YanSjryvGwo2CMWPe+bCX0hu7oo n8b2CuEFwfLNDATZ4zAZEdGoYkYwwqXwTJNtafLF4ZH5VmCDPVPrPr7cyzfZRQdRkq CkKas36bDX8ulP3HbWxSwwvhT0rrTejxLFmDrpdsQzpGySnfj167FYqafgwN1UqMbs DZAQmoKipStOO9Sxp9mpFg4tOm6xUs0K5oDGDWWhX5j2bE4r6JsH+chD+kdu+9aQ86 dl/vL3fsTbsMw== From: Damien Le Moal To: Jens Axboe , linux-block@vger.kernel.org Cc: Christoph Hellwig Subject: [PATCH 1/2] block: new zoned loop block device driver Date: Mon, 6 Jan 2025 23:24:38 +0900 Message-ID: <20250106142439.216598-2-dlemoal@kernel.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250106142439.216598-1-dlemoal@kernel.org> References: <20250106142439.216598-1-dlemoal@kernel.org> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The zoned loop block device driver allows a user to create emulated zoned block devices using one regular file per zone as backing storage. Compared to null_blk or scsi_debug, it has the advantage of allowing emulating large zoned devices without requiring the same amount of memory as the capacity of the emulated device. Furthermore, zoned devices emulated with this driver can be re-started after a host reboot without any loss of the state of the device zones, which is something that null_blk and scsi_debug do not support. This initial implementation is simple and does not support zone resource limits. That is, a zoned loop block device limits for the maximum number of open zones and maximum number of active zones is always 0. This driver can be either compiled in-kernel or as a module, named "zloop". Compilation of this driver depends on the block layer support for zoned block device (CONFIG_BLK_DEV_ZONED must be set). Using the zloop driver to create and delete zoned block devices is done by writing commands to the zoned loop control character device file (/dev/zloop-control). Creating a device is done with: $ echo "add [options]" > /dev/zloop-control The options available for the "add" operation cat be listed by reading the zloop-control device file: $ cat /dev/zloop-control add id=%d,capacity_mb=%u,zone_size_mb=%u,zone_capacity_mb=%u,conv_zones=%u,base_dir=%s,nr_queues=%u,queue_depth=%u remove id=%d The options available allow controlling the zoned device total capacity, zone size, zone capactity of sequential zones, total number of conventional zones, base directory for the zones backing file, number of I/O queues and the maximum queue depth of I/O queues. Deleting a device is done using the "remove" command: $ echo "remove id=0" > /dev/zloop-control This implementation passes various tests using zonefs and fio (t/zbd tests) and provides a state machine for zone conditions that is compliant with the T10 ZBC and NVMe ZNS specifications. Co-developed-by: Christoph Hellwig Signed-off-by: Damien Le Moal --- MAINTAINERS | 7 + drivers/block/Kconfig | 16 + drivers/block/Makefile | 1 + drivers/block/zloop.c | 1330 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 1354 insertions(+) create mode 100644 drivers/block/zloop.c diff --git a/MAINTAINERS b/MAINTAINERS index 30cbc3d44cd5..49076a506b6b 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -25972,6 +25972,13 @@ L: linux-kernel@vger.kernel.org S: Maintained F: arch/x86/kernel/cpu/zhaoxin.c +ZONED LOOP DEVICE +M: Damien Le Moal +R: Christoph Hellwig +L: linux-block@vger.kernel.org +S: Maintained +F: drivers/block/zloop.c + ZONEFS FILESYSTEM M: Damien Le Moal M: Naohiro Aota diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index a97f2c40c640..12af52a77cf8 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -413,4 +413,20 @@ config BLKDEV_UBLK_LEGACY_OPCODES source "drivers/block/rnbd/Kconfig" +config BLK_DEV_ZONED_LOOP + tristate "Zoned loopback device support" + depends on BLK_DEV_ZONED + help + Saying Y here will allow you to use create a zoned block device using + regular files for zones (one file per zones). This is useful to test + file systems, device mapper and applications that support zoned block + devices. To create a zoned loop device, no user utility is needed, a + zoned loop device can be created (or re-started) using a command + like: + + echo "create idx=0,zone_size=256m,size=40T,conv_zones=11" > \ + /dev/zloop-control + + If unsure, say N. + endif # BLK_DEV diff --git a/drivers/block/Makefile b/drivers/block/Makefile index 1105a2d4fdcb..097707aca725 100644 --- a/drivers/block/Makefile +++ b/drivers/block/Makefile @@ -41,5 +41,6 @@ obj-$(CONFIG_BLK_DEV_RNBD) += rnbd/ obj-$(CONFIG_BLK_DEV_NULL_BLK) += null_blk/ obj-$(CONFIG_BLK_DEV_UBLK) += ublk_drv.o +obj-$(CONFIG_BLK_DEV_ZONED_LOOP) += zloop.o swim_mod-y := swim.o swim_asm.o diff --git a/drivers/block/zloop.c b/drivers/block/zloop.c new file mode 100644 index 000000000000..b0b398b9aad0 --- /dev/null +++ b/drivers/block/zloop.c @@ -0,0 +1,1330 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2025, Christoph Hellwig. + * Copyright (c) 2025, Western Digital Corporation or its affiliates. + * + * Zoned Loop Device driver - exports a zoned block device using one file per + * zone as backing storage. + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * Options for adding (and removing) a device. + */ +enum { + ZLOOP_OPT_ERR = 0, + ZLOOP_OPT_ID = (1 << 0), + ZLOOP_OPT_CAPACITY = (1 << 1), + ZLOOP_OPT_ZONE_SIZE = (1 << 2), + ZLOOP_OPT_ZONE_CAPACITY = (1 << 3), + ZLOOP_OPT_NR_CONV_ZONES = (1 << 4), + ZLOOP_OPT_BASE_DIR = (1 << 5), + ZLOOP_OPT_NR_QUEUES = (1 << 6), + ZLOOP_OPT_QUEUE_DEPTH = (1 << 7), +}; + +static const match_table_t zloop_opt_tokens = { + { ZLOOP_OPT_ID, "id=%d" }, + { ZLOOP_OPT_CAPACITY, "capacity_mb=%u" }, + { ZLOOP_OPT_ZONE_SIZE, "zone_size_mb=%u" }, + { ZLOOP_OPT_ZONE_CAPACITY, "zone_capacity_mb=%u" }, + { ZLOOP_OPT_NR_CONV_ZONES, "conv_zones=%u" }, + { ZLOOP_OPT_BASE_DIR, "base_dir=%s" }, + { ZLOOP_OPT_NR_QUEUES, "nr_queues=%u" }, + { ZLOOP_OPT_QUEUE_DEPTH, "queue_depth=%u" }, + { ZLOOP_OPT_ERR, NULL } +}; + +/* Default values for the "add" operation. */ +#define ZLOOP_DEF_ID -1 +#define ZLOOP_DEF_ZONE_SIZE ((256ULL * SZ_1M) >> SECTOR_SHIFT) +#define ZLOOP_DEF_NR_ZONES 64 +#define ZLOOP_DEF_NR_CONV_ZONES 8 +#define ZLOOP_DEF_BASE_DIR "/var/local/zloop" +#define ZLOOP_DEF_NR_QUEUES 1 +#define ZLOOP_DEF_QUEUE_DEPTH 64 + +/* Arbitrary limit on the zone size (16GB). */ +#define ZLOOP_MAX_ZONE_SIZE_MB 16384 + +struct zloop_options { + unsigned int mask; + int id; + sector_t capacity; + sector_t zone_size; + sector_t zone_capacity; + unsigned int nr_conv_zones; + char *base_dir; + unsigned int nr_queues; + unsigned int queue_depth; +}; + +/* + * Device states. + */ +enum { + Zlo_creating = 0, + Zlo_live, + Zlo_deleting, +}; + +enum zloop_zone_flags { + ZLOOP_ZONE_CONV = 0, + ZLOOP_ZONE_SEQ_ERROR, +}; + +struct zloop_zone { + struct file *file; + + unsigned long flags; + struct mutex lock; + enum blk_zone_cond cond; + sector_t start; + sector_t wp; + + gfp_t old_gfp_mask; +}; + +struct zloop_device { + unsigned int id; + unsigned int state; + + struct blk_mq_tag_set tag_set; + struct gendisk *disk; + + spinlock_t work_lock; + struct workqueue_struct *workqueue; + struct work_struct work; + struct list_head cmd_list; + + const char *base_dir; + struct file *data_dir; + + unsigned int zone_shift; + sector_t zone_size; + sector_t zone_capacity; + unsigned int nr_zones; + unsigned int nr_conv_zones; + + struct zloop_zone zones[] __counted_by(nr_zones); +}; + +struct zloop_cmd { + struct list_head entry; + atomic_t ref; + sector_t sector; + sector_t nr_sectors; + long ret; + struct kiocb iocb; + struct bio_vec *bvec; +}; + +static DEFINE_IDR(zloop_index_idr); +static DEFINE_MUTEX(zloop_ctl_mutex); + +static unsigned int rq_zone_no(struct request *rq) +{ + struct zloop_device *zlo = rq->q->queuedata; + + return blk_rq_pos(rq) >> zlo->zone_shift; +} + +static int zloop_update_seq_zone(struct zloop_device *zlo, unsigned int zone_no) +{ + struct zloop_zone *zone = &zlo->zones[zone_no]; + struct kstat stat; + sector_t file_sectors; + int ret; + + lockdep_assert_held(&zone->lock); + + ret = vfs_getattr(&zone->file->f_path, &stat, STATX_SIZE, 0); + if (ret < 0) { + pr_err("Failed to get zone %u file stat (err=%d)\n", + zone_no, ret); + set_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags); + return ret; + } + + file_sectors = stat.size >> SECTOR_SHIFT; + if (file_sectors > zlo->zone_capacity) { + pr_err("Zone %u file too large (%llu sectors > %llu)\n", + zone_no, file_sectors, zlo->zone_capacity); + return -EINVAL; + } + + if (!file_sectors) { + zone->cond = BLK_ZONE_COND_EMPTY; + zone->wp = zone->start; + } else if (file_sectors == zlo->zone_capacity) { + zone->cond = BLK_ZONE_COND_FULL; + zone->wp = zone->start + zlo->zone_size; + } else { + zone->cond = BLK_ZONE_COND_CLOSED; + zone->wp = zone->start + file_sectors; + } + + return 0; +} + +static int zloop_open_zone(struct zloop_device *zlo, unsigned int zone_no) +{ + struct zloop_zone *zone = &zlo->zones[zone_no]; + int ret = 0; + + if (test_bit(ZLOOP_ZONE_CONV, &zone->flags)) + return -EIO; + + mutex_lock(&zone->lock); + + if (test_and_clear_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags)) { + ret = zloop_update_seq_zone(zlo, zone_no); + if (ret) + goto unlock; + } + + switch (zone->cond) { + case BLK_ZONE_COND_EXP_OPEN: + break; + case BLK_ZONE_COND_EMPTY: + case BLK_ZONE_COND_CLOSED: + case BLK_ZONE_COND_IMP_OPEN: + zone->cond = BLK_ZONE_COND_EXP_OPEN; + break; + case BLK_ZONE_COND_FULL: + default: + ret = -EIO; + break; + } + +unlock: + mutex_unlock(&zone->lock); + + return ret; +} + +static int zloop_close_zone(struct zloop_device *zlo, unsigned int zone_no) +{ + struct zloop_zone *zone = &zlo->zones[zone_no]; + int ret = 0; + + if (test_bit(ZLOOP_ZONE_CONV, &zone->flags)) + return -EIO; + + mutex_lock(&zone->lock); + + if (test_and_clear_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags)) { + ret = zloop_update_seq_zone(zlo, zone_no); + if (ret) + goto unlock; + } + + switch (zone->cond) { + case BLK_ZONE_COND_CLOSED: + break; + case BLK_ZONE_COND_IMP_OPEN: + case BLK_ZONE_COND_EXP_OPEN: + if (zone->wp == zone->start) + zone->cond = BLK_ZONE_COND_EMPTY; + else + zone->cond = BLK_ZONE_COND_CLOSED; + break; + case BLK_ZONE_COND_EMPTY: + case BLK_ZONE_COND_FULL: + default: + ret = -EIO; + break; + } + +unlock: + mutex_unlock(&zone->lock); + + return ret; +} + +static int zloop_reset_zone(struct zloop_device *zlo, unsigned int zone_no) +{ + struct zloop_zone *zone = &zlo->zones[zone_no]; + + if (test_bit(ZLOOP_ZONE_CONV, &zone->flags)) + return -EIO; + + if (vfs_truncate(&zone->file->f_path, 0)) { + set_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags); + return -EIO; + } + + mutex_lock(&zone->lock); + zone->cond = BLK_ZONE_COND_EMPTY; + zone->wp = zone->start; + clear_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags); + mutex_unlock(&zone->lock); + + return 0; +} + +static int zloop_reset_all_zones(struct request *rq) +{ + struct zloop_device *zlo = rq->q->queuedata; + unsigned int i; + int ret; + + for (i = zlo->nr_conv_zones; i < zlo->nr_zones; i++) { + ret = zloop_reset_zone(zlo, i); + if (ret) + return ret; + } + + return 0; +} + +static int zloop_finish_zone(struct zloop_device *zlo, unsigned int zone_no) +{ + struct zloop_zone *zone = &zlo->zones[zone_no]; + + if (test_bit(ZLOOP_ZONE_CONV, &zone->flags)) + return -EIO; + + if (vfs_truncate(&zone->file->f_path, zlo->zone_size << SECTOR_SHIFT)) { + set_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags); + return -EIO; + } + + mutex_lock(&zone->lock); + zone->cond = BLK_ZONE_COND_FULL; + zone->wp = zone->start + zlo->zone_size; + clear_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags); + mutex_unlock(&zone->lock); + + return 0; +} + +static void zloop_put_cmd(struct zloop_cmd *cmd) +{ + struct request *rq = blk_mq_rq_from_pdu(cmd); + + if (!atomic_dec_and_test(&cmd->ref)) + return; + kfree(cmd->bvec); + cmd->bvec = NULL; + if (likely(!blk_should_fake_timeout(rq->q))) + blk_mq_complete_request(rq); +} + +static void zloop_rw_complete(struct kiocb *iocb, long ret) +{ + struct zloop_cmd *cmd = container_of(iocb, struct zloop_cmd, iocb); + + cmd->ret = ret; + zloop_put_cmd(cmd); +} + +static void zloop_rw(struct zloop_cmd *cmd) +{ + struct request *rq = blk_mq_rq_from_pdu(cmd); + struct zloop_device *zlo = rq->q->queuedata; + unsigned int zone_no = rq_zone_no(rq); + sector_t sector = blk_rq_pos(rq); + sector_t nr_sectors = blk_rq_sectors(rq); + bool is_append = req_op(rq) == REQ_OP_ZONE_APPEND; + bool is_write = req_op(rq) == REQ_OP_WRITE || is_append; + int rw = is_write ? ITER_SOURCE : ITER_DEST; + struct req_iterator rq_iter; + struct zloop_zone *zone; + struct iov_iter iter; + struct bio_vec tmp; + sector_t zone_end; + int nr_bvec = 0; + int ret; + + cmd->sector = sector; + cmd->nr_sectors = nr_sectors; + + /* We should never get an I/O beyond the device capacity. */ + if (WARN_ON_ONCE(zone_no >= zlo->nr_zones)) { + ret = -EIO; + goto out; + } + zone = &zlo->zones[zone_no]; + zone_end = zone->start + zlo->zone_capacity; + + /* + * The block layer should never send requests that are not fully + * contained within the zone. + */ + if (WARN_ON_ONCE(sector + nr_sectors > zone->start + zlo->zone_size)) { + ret = -EIO; + goto out; + } + + if (test_and_clear_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags)) { + mutex_lock(&zone->lock); + ret = zloop_update_seq_zone(zlo, zone_no); + mutex_unlock(&zone->lock); + if (ret) + goto out; + } + + if (!test_bit(ZLOOP_ZONE_CONV, &zone->flags) && is_write) { + mutex_lock(&zone->lock); + + if (is_append) { + sector = zone->wp; + cmd->sector = sector; + } + + /* + * Write operations must be aligned to the write pointer and + * fully contained within the zone capacity. + */ + if (sector != zone->wp || zone->wp + nr_sectors > zone_end) { + pr_err("Zone %u: unaligned write: sect %llu, wp %llu\n", + zone_no, sector, zone->wp); + mutex_unlock(&zone->lock); + ret = -EIO; + goto out; + } + + /* Implicitly open the target zone. */ + if (zone->cond == BLK_ZONE_COND_CLOSED || + zone->cond == BLK_ZONE_COND_EMPTY) + zone->cond = BLK_ZONE_COND_IMP_OPEN; + + /* + * Advance the write pointer of sequential zones. If the write + * fails, the wp position will be corrected when the next I/O + * copmpletes. + */ + zone->wp += nr_sectors; + if (zone->wp == zone_end) + zone->cond = BLK_ZONE_COND_FULL; + + mutex_unlock(&zone->lock); + } + + rq_for_each_bvec(tmp, rq, rq_iter) + nr_bvec++; + + if (rq->bio != rq->biotail) { + struct bio_vec *bvec; + + cmd->bvec = kmalloc_array(nr_bvec, sizeof(*cmd->bvec), GFP_NOIO); + if (!cmd->bvec) { + ret = -EIO; + goto out; + } + + /* + * The bios of the request may be started from the middle of + * the 'bvec' because of bio splitting, so we can't directly + * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec + * API will take care of all details for us. + */ + bvec = cmd->bvec; + rq_for_each_bvec(tmp, rq, rq_iter) { + *bvec = tmp; + bvec++; + } + iov_iter_bvec(&iter, rw, cmd->bvec, nr_bvec, blk_rq_bytes(rq)); + } else { + /* + * Same here, this bio may be started from the middle of the + * 'bvec' because of bio splitting, so offset from the bvec + * must be passed to iov iterator + */ + iov_iter_bvec(&iter, rw, + __bvec_iter_bvec(rq->bio->bi_io_vec, rq->bio->bi_iter), + nr_bvec, blk_rq_bytes(rq)); + iter.iov_offset = rq->bio->bi_iter.bi_bvec_done; + } + + cmd->iocb.ki_pos = (sector - zone->start) << SECTOR_SHIFT; + cmd->iocb.ki_filp = zone->file; + cmd->iocb.ki_complete = zloop_rw_complete; + cmd->iocb.ki_flags = IOCB_DIRECT; + cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); + + if (rw == ITER_SOURCE) + ret = zone->file->f_op->write_iter(&cmd->iocb, &iter); + else + ret = zone->file->f_op->read_iter(&cmd->iocb, &iter); +out: + if (ret != -EIOCBQUEUED) + zloop_rw_complete(&cmd->iocb, ret); + zloop_put_cmd(cmd); +} + +static void zloop_handle_cmd(struct zloop_cmd *cmd) +{ + struct request *rq = blk_mq_rq_from_pdu(cmd); + struct zloop_device *zlo = rq->q->queuedata; + + atomic_set(&cmd->ref, 2); + cmd->ret = 0; + + switch (req_op(rq)) { + case REQ_OP_READ: + case REQ_OP_WRITE: + case REQ_OP_ZONE_APPEND: + /* + * zloop_rw() always executes asynchronously or completes + * directly. + */ + zloop_rw(cmd); + return; + case REQ_OP_FLUSH: + /* + * sync the entire fs containing the zone files instead of + * walking all files + */ + if (sync_filesystem(file_inode(zlo->data_dir)->i_sb)) + cmd->ret = -EIO; + break; + case REQ_OP_ZONE_RESET: + cmd->ret = zloop_reset_zone(zlo, rq_zone_no(rq)); + break; + case REQ_OP_ZONE_RESET_ALL: + cmd->ret = zloop_reset_all_zones(rq); + break; + case REQ_OP_ZONE_FINISH: + cmd->ret = zloop_finish_zone(zlo, rq_zone_no(rq)); + break; + case REQ_OP_ZONE_OPEN: + cmd->ret = zloop_open_zone(zlo, rq_zone_no(rq)); + break; + case REQ_OP_ZONE_CLOSE: + cmd->ret = zloop_close_zone(zlo, rq_zone_no(rq)); + break; + default: + WARN_ON_ONCE(1); + pr_err("Unsupported operation %d\n", req_op(rq)); + cmd->ret = -EOPNOTSUPP; + break; + } + + blk_mq_complete_request(rq); +} + +static struct zloop_cmd *zloop_get_cmd(struct zloop_device *zlo) +{ + struct zloop_cmd *cmd; + + spin_lock_irq(&zlo->work_lock); + cmd = list_first_entry_or_null(&zlo->cmd_list, struct zloop_cmd, entry); + if (cmd) + list_del_init(&cmd->entry); + spin_unlock_irq(&zlo->work_lock); + + return cmd; +} + +static void zloop_workfn(struct work_struct *work) +{ + struct zloop_device *zlo = container_of(work, struct zloop_device, work); + int orig_flags = current->flags; + struct zloop_cmd *cmd; + + current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; + while ((cmd = zloop_get_cmd(zlo))) { + zloop_handle_cmd(cmd); + cond_resched(); + } + current->flags = orig_flags; +} + +static void zloop_complete_rq(struct request *rq) +{ + struct zloop_cmd *cmd = blk_mq_rq_to_pdu(rq); + struct zloop_device *zlo = rq->q->queuedata; + unsigned int zone_no = cmd->sector >> zlo->zone_shift; + struct zloop_zone *zone = &zlo->zones[zone_no]; + blk_status_t sts = BLK_STS_OK; + + switch (req_op(rq)) { + case REQ_OP_READ: + if (cmd->ret < 0) + pr_err("Zone %u: failed read sector %llu, %llu sectors\n", + zone_no, cmd->sector, cmd->nr_sectors); + + if (cmd->ret >= 0 && cmd->ret != blk_rq_bytes(rq)) { + /* short read */ + struct bio *bio; + + __rq_for_each_bio(bio, rq) + zero_fill_bio(bio); + } + break; + case REQ_OP_WRITE: + case REQ_OP_ZONE_APPEND: + if (cmd->ret < 0) + pr_err("Zone %u: failed %swrite sector %llu, %llu sectors\n", + zone_no, + req_op(rq) == REQ_OP_WRITE ? "" : "append ", + cmd->sector, cmd->nr_sectors); + + if (cmd->ret >= 0 && cmd->ret != blk_rq_bytes(rq)) { + pr_err("Zone %u: partial write %ld/%u B\n", + zone_no, cmd->ret, blk_rq_bytes(rq)); + cmd->ret = -EIO; + } + + if (cmd->ret < 0 && !test_bit(ZLOOP_ZONE_CONV, &zone->flags)) { + /* + * A write to a sequential zone file failed: mark the + * zone as having an error. This will be corrected and + * cleared when the next IO is submitted. + */ + set_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags); + } + break; + default: + break; + } + + if (cmd->ret < 0) + sts = errno_to_blk_status(cmd->ret); + blk_mq_end_request(rq, sts); +} + +static blk_status_t zloop_queue_rq(struct blk_mq_hw_ctx *hctx, + const struct blk_mq_queue_data *bd) +{ + struct request *rq = bd->rq; + struct zloop_cmd *cmd = blk_mq_rq_to_pdu(rq); + struct zloop_device *zlo = rq->q->queuedata; + + if (zlo->state == Zlo_deleting) + return BLK_STS_IOERR; + + blk_mq_start_request(rq); + + spin_lock_irq(&zlo->work_lock); + list_add_tail(&cmd->entry, &zlo->cmd_list); + queue_work(zlo->workqueue, &zlo->work); + spin_unlock_irq(&zlo->work_lock); + return BLK_STS_OK; +} + +static const struct blk_mq_ops zloop_mq_ops = { + .queue_rq = zloop_queue_rq, + .complete = zloop_complete_rq, +}; + +static int zloop_open(struct gendisk *disk, blk_mode_t mode) +{ + struct zloop_device *zlo = disk->private_data; + int ret; + + ret = mutex_lock_killable(&zloop_ctl_mutex); + if (ret) + return ret; + + if (zlo->state != Zlo_live) + ret = -ENXIO; + mutex_unlock(&zloop_ctl_mutex); + return ret; +} + +static int zloop_report_zones(struct gendisk *disk, sector_t sector, + unsigned int nr_zones, report_zones_cb cb, void *data) +{ + struct zloop_device *zlo = disk->private_data; + struct blk_zone blkz = {}; + unsigned int first, i; + int ret; + + first = disk_zone_no(disk, sector); + if (first >= zlo->nr_zones) + return 0; + nr_zones = min(nr_zones, zlo->nr_zones - first); + + for (i = 0; i < nr_zones; i++) { + unsigned int zone_no = first + i; + struct zloop_zone *zone = &zlo->zones[zone_no]; + + mutex_lock(&zone->lock); + + if (test_and_clear_bit(ZLOOP_ZONE_SEQ_ERROR, &zone->flags)) { + ret = zloop_update_seq_zone(zlo, zone_no); + if (ret) { + mutex_unlock(&zone->lock); + return ret; + } + } + + blkz.start = zone->start; + blkz.len = zlo->zone_size; + blkz.wp = zone->wp; + blkz.cond = zone->cond; + if (test_bit(ZLOOP_ZONE_CONV, &zone->flags)) { + blkz.type = BLK_ZONE_TYPE_CONVENTIONAL; + blkz.capacity = zlo->zone_size; + } else { + blkz.type = BLK_ZONE_TYPE_SEQWRITE_REQ; + blkz.capacity = zlo->zone_capacity; + } + + mutex_unlock(&zone->lock); + + ret = cb(&blkz, i, data); + if (ret) + return ret; + } + + return nr_zones; +} + +static void zloop_free_disk(struct gendisk *disk) +{ + struct zloop_device *zlo = disk->private_data; + unsigned int i; + + for (i = 0; i < zlo->nr_zones; i++) { + struct zloop_zone *zone = &zlo->zones[i]; + + mapping_set_gfp_mask(zone->file->f_mapping, + zone->old_gfp_mask); + fput(zone->file); + } + + fput(zlo->data_dir); + destroy_workqueue(zlo->workqueue); + kfree(zlo->base_dir); + kvfree(zlo); +} + +static const struct block_device_operations zloop_fops = { + .owner = THIS_MODULE, + .open = zloop_open, + .report_zones = zloop_report_zones, + .free_disk = zloop_free_disk, +}; + +__printf(3, 4) +static struct file *zloop_filp_open_fmt(int oflags, umode_t mode, + const char *fmt, ...) +{ + struct file *file; + va_list ap; + char *p; + + va_start(ap, fmt); + p = kvasprintf(GFP_KERNEL, fmt, ap); + va_end(ap); + + if (!p) + return ERR_PTR(-ENOMEM); + file = filp_open(p, oflags, mode); + kfree(p); + return file; +} + +static int zloop_init_zone(struct zloop_device *zlo, unsigned int zone_no, + bool restore) +{ + struct zloop_zone *zone = &zlo->zones[zone_no]; + int oflags = O_RDWR | O_DIRECT; + struct kstat stat; + sector_t file_sectors; + int ret; + + mutex_init(&zone->lock); + zone->start = (sector_t)zone_no << zlo->zone_shift; + + if (!restore) + oflags |= O_CREAT; + + if (zone_no < zlo->nr_conv_zones) { + /* Conventional zone file. */ + set_bit(ZLOOP_ZONE_CONV, &zone->flags); + zone->cond = BLK_ZONE_COND_NOT_WP; + zone->wp = U64_MAX; + + zone->file = zloop_filp_open_fmt(oflags, 0600, "%s/%u/cnv-%06u", + zlo->base_dir, zlo->id, zone_no); + if (IS_ERR(zone->file)) { + pr_err("Failed to open zone %u file %s/%u/cnv-%06u (err=%ld)", + zone_no, zlo->base_dir, zlo->id, zone_no, + PTR_ERR(zone->file)); + return PTR_ERR(zone->file); + } + + ret = vfs_getattr(&zone->file->f_path, &stat, STATX_SIZE, 0); + if (ret < 0) { + pr_err("Failed to get zone %u file stat\n", zone_no); + return ret; + } + file_sectors = stat.size >> SECTOR_SHIFT; + + if (restore && file_sectors != zlo->zone_size) { + pr_err("Invalid conventional zone %u file size (%llu sectors != %llu)\n", + zone_no, file_sectors, zlo->zone_capacity); + return ret; + } + + ret = vfs_truncate(&zone->file->f_path, + zlo->zone_size << SECTOR_SHIFT); + if (ret < 0) { + pr_err("Failed to truncate zone %u file (err=%d)\n", + zone_no, ret); + return ret; + } + + return 0; + } + + /* Sequential zone file. */ + zone->file = zloop_filp_open_fmt(oflags, 0600, "%s/%u/seq-%06u", + zlo->base_dir, zlo->id, zone_no); + if (IS_ERR(zone->file)) { + pr_err("Failed to open zone %u file %s/%u/seq-%06u (err=%ld)", + zone_no, zlo->base_dir, zlo->id, zone_no, + PTR_ERR(zone->file)); + return PTR_ERR(zone->file); + } + + mutex_lock(&zone->lock); + ret = zloop_update_seq_zone(zlo, zone_no); + mutex_unlock(&zone->lock); + + return ret; +} + +static bool zloop_dev_exists(struct zloop_device *zlo) +{ + struct file *cnv, *seq; + bool exists; + + cnv = zloop_filp_open_fmt(O_RDONLY, 0600, "%s/%u/cnv-%06u", + zlo->base_dir, zlo->id, 0); + seq = zloop_filp_open_fmt(O_RDONLY, 0600, "%s/%u/seq-%06u", + zlo->base_dir, zlo->id, 0); + exists = !IS_ERR(cnv) || !IS_ERR(seq); + + if (!IS_ERR(cnv)) + fput(cnv); + if (!IS_ERR(seq)) + fput(seq); + + return exists; +} + +static int zloop_ctl_add(struct zloop_options *opts) +{ + struct queue_limits lim = { + .max_hw_sectors = SZ_1M >> SECTOR_SHIFT, + .max_hw_zone_append_sectors = SZ_1M >> SECTOR_SHIFT, + .chunk_sectors = opts->zone_size, + .features = BLK_FEAT_ZONED, + }; + unsigned int nr_zones, i, j; + struct zloop_device *zlo; + int block_size; + int ret = -EINVAL; + bool restore; + + __module_get(THIS_MODULE); + + nr_zones = opts->capacity >> ilog2(opts->zone_size); + if (opts->nr_conv_zones >= nr_zones) { + pr_err("Invalid number of conventional zones %u\n", + opts->nr_conv_zones); + goto out; + } + + zlo = kvzalloc(struct_size(zlo, zones, nr_zones), GFP_KERNEL); + if (!zlo) { + ret = -ENOMEM; + goto out; + } + zlo->state = Zlo_creating; + + ret = mutex_lock_killable(&zloop_ctl_mutex); + if (ret) + goto out_free_dev; + + /* Allocate id, if @opts->id >= 0, we're requesting that specific id */ + if (opts->id >= 0) { + ret = idr_alloc(&zloop_index_idr, zlo, + opts->id, opts->id + 1, GFP_KERNEL); + if (ret == -ENOSPC) + ret = -EEXIST; + } else { + ret = idr_alloc(&zloop_index_idr, zlo, 0, 0, GFP_KERNEL); + } + mutex_unlock(&zloop_ctl_mutex); + if (ret < 0) + goto out_free_dev; + + zlo->id = ret; + spin_lock_init(&zlo->work_lock); + INIT_WORK(&zlo->work, zloop_workfn); + INIT_LIST_HEAD(&zlo->cmd_list); + zlo->zone_shift = ilog2(opts->zone_size); + zlo->zone_size = opts->zone_size; + if (opts->zone_capacity) + zlo->zone_capacity = opts->zone_capacity; + else + zlo->zone_capacity = zlo->zone_size; + zlo->nr_zones = nr_zones; + zlo->nr_conv_zones = opts->nr_conv_zones; + + zlo->workqueue = alloc_workqueue("zloop%d", WQ_UNBOUND | WQ_FREEZABLE, + 0, zlo->id); + if (!zlo->workqueue) { + ret = -ENOMEM; + goto out_free_idr; + } + + if (opts->base_dir) + zlo->base_dir = kstrdup(opts->base_dir, GFP_KERNEL); + else + zlo->base_dir = kstrdup(ZLOOP_DEF_BASE_DIR, GFP_KERNEL); + if (!zlo->base_dir) { + ret = -ENOMEM; + goto out_destroy_workqueue; + } + + zlo->data_dir = zloop_filp_open_fmt(O_RDONLY | O_DIRECTORY, 0, "%s/%u", + zlo->base_dir, zlo->id); + if (IS_ERR(zlo->data_dir)) { + ret = PTR_ERR(zlo->data_dir); + pr_warn("Failed to open directory %s/%u (err=%d)\n", + zlo->base_dir, zlo->id, ret); + goto out_free_base_dir; + } + + /* Use the FS block size as the device sector size. */ + block_size = file_inode(zlo->data_dir)->i_sb->s_blocksize; + if (block_size > SZ_4K) { + pr_warn("Unsupported FS block size %d B > 4096\n", + block_size); + goto out_close_data_dir; + } + lim.physical_block_size = block_size; + lim.logical_block_size = block_size; + + /* + * If we already have zone files, we are restoring a device created by a + * previous add operation. In this case, zloop_init_zone() will check + * that the zone files are consistent with the zone configuration given. + */ + restore = zloop_dev_exists(zlo); + for (i = 0; i < nr_zones; i++) { + ret = zloop_init_zone(zlo, i, restore); + if (ret) + goto out_close_files; + } + + zlo->tag_set.ops = &zloop_mq_ops; + zlo->tag_set.nr_hw_queues = opts->nr_queues; + zlo->tag_set.queue_depth = opts->queue_depth; + zlo->tag_set.numa_node = NUMA_NO_NODE; + zlo->tag_set.cmd_size = sizeof(struct zloop_cmd); + zlo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; + zlo->tag_set.driver_data = zlo; + + ret = blk_mq_alloc_tag_set(&zlo->tag_set); + if (ret) { + pr_err("blk_mq_alloc_tag_set failed (err=%d)\n", ret); + goto out_close_files; + } + + zlo->disk = blk_mq_alloc_disk(&zlo->tag_set, &lim, zlo); + if (IS_ERR(zlo->disk)) { + pr_err("blk_mq_alloc_disk failed (err=%d)\n", ret); + ret = PTR_ERR(zlo->disk); + goto out_cleanup_tags; + } + zlo->disk->flags = GENHD_FL_NO_PART; + zlo->disk->fops = &zloop_fops; + zlo->disk->private_data = zlo; + sprintf(zlo->disk->disk_name, "zloop%d", zlo->id); + set_capacity(zlo->disk, (u64)lim.chunk_sectors * zlo->nr_zones); + + if (blk_revalidate_disk_zones(zlo->disk)) + goto out_cleanup_disk; + + ret = add_disk(zlo->disk); + if (ret) { + pr_err("add_disk failed (err=%d)\n", ret); + goto out_cleanup_disk; + } + + mutex_lock(&zloop_ctl_mutex); + zlo->state = Zlo_live; + mutex_unlock(&zloop_ctl_mutex); + + pr_info("Added device %d\n", zlo->id); + + return 0; + +out_cleanup_disk: + put_disk(zlo->disk); +out_cleanup_tags: + blk_mq_free_tag_set(&zlo->tag_set); +out_close_files: + for (j = 0; j < i; j++) { + struct zloop_zone *zone = &zlo->zones[j]; + + if (!IS_ERR_OR_NULL(zone->file)) + fput(zone->file); + } +out_close_data_dir: + fput(zlo->data_dir); +out_free_base_dir: + kfree(zlo->base_dir); +out_destroy_workqueue: + destroy_workqueue(zlo->workqueue); +out_free_idr: + mutex_lock(&zloop_ctl_mutex); + idr_remove(&zloop_index_idr, zlo->id); + mutex_unlock(&zloop_ctl_mutex); +out_free_dev: + kvfree(zlo); +out: + module_put(THIS_MODULE); + if (ret == -ENOENT) + ret = -EINVAL; + return ret; +} + +static int zloop_ctl_remove(struct zloop_options *opts) +{ + struct zloop_device *zlo; + int ret; + + if (!(opts->mask & ZLOOP_OPT_ID)) { + pr_err("No ID specified\n"); + return -EINVAL; + } + + ret = mutex_lock_killable(&zloop_ctl_mutex); + if (ret) + return ret; + + zlo = idr_find(&zloop_index_idr, opts->id); + if (!zlo || zlo->state == Zlo_creating) { + ret = -ENODEV; + } else if (zlo->state == Zlo_deleting) { + ret = -EINVAL; + } else { + idr_remove(&zloop_index_idr, zlo->id); + zlo->state = Zlo_deleting; + } + + mutex_unlock(&zloop_ctl_mutex); + if (ret) + return ret; + + del_gendisk(zlo->disk); + put_disk(zlo->disk); + blk_mq_free_tag_set(&zlo->tag_set); + + pr_info("Removed device %d\n", opts->id); + + module_put(THIS_MODULE); + + return 0; +} + +static int zloop_parse_options(struct zloop_options *opts, const char *buf) +{ + substring_t args[MAX_OPT_ARGS]; + char *options, *o, *p; + unsigned int token; + int ret = 0; + + /* Set defaults. */ + opts->mask = 0; + opts->id = ZLOOP_DEF_ID; + opts->capacity = ZLOOP_DEF_ZONE_SIZE * ZLOOP_DEF_NR_ZONES; + opts->zone_size = ZLOOP_DEF_ZONE_SIZE; + opts->nr_conv_zones = ZLOOP_DEF_NR_CONV_ZONES; + opts->nr_queues = ZLOOP_DEF_NR_QUEUES; + opts->queue_depth = ZLOOP_DEF_QUEUE_DEPTH; + + if (!buf) + return 0; + + /* Skip leading spaces before the options. */ + while (isspace(*buf)) + buf++; + + options = o = kstrdup(buf, GFP_KERNEL); + if (!options) + return -ENOMEM; + + /* Parse the options, doing only some light invalid value checks. */ + while ((p = strsep(&o, ",\n")) != NULL) { + if (!*p) + continue; + + token = match_token(p, zloop_opt_tokens, args); + opts->mask |= token; + switch (token) { + case ZLOOP_OPT_ID: + if (match_int(args, &opts->id)) { + ret = -EINVAL; + goto out; + } + break; + case ZLOOP_OPT_CAPACITY: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + if (!token) { + pr_err("Invalid capacity\n"); + ret = -EINVAL; + goto out; + } + opts->capacity = + ((sector_t)token * SZ_1M) >> SECTOR_SHIFT; + break; + case ZLOOP_OPT_ZONE_SIZE: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + if (!token || token > ZLOOP_MAX_ZONE_SIZE_MB || + !is_power_of_2(token)) { + pr_err("Invalid zone size %u\n", token); + ret = -EINVAL; + goto out; + } + opts->zone_size = + ((sector_t)token * SZ_1M) >> SECTOR_SHIFT; + break; + case ZLOOP_OPT_ZONE_CAPACITY: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + if (!token) { + pr_err("Invalid zone capacity\n"); + ret = -EINVAL; + goto out; + } + opts->zone_capacity = + ((sector_t)token * SZ_1M) >> SECTOR_SHIFT; + break; + case ZLOOP_OPT_NR_CONV_ZONES: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + opts->nr_conv_zones = token; + break; + case ZLOOP_OPT_BASE_DIR: + p = match_strdup(args); + if (!p) { + ret = -ENOMEM; + goto out; + } + kfree(opts->base_dir); + opts->base_dir = p; + break; + case ZLOOP_OPT_NR_QUEUES: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + if (!token) { + pr_err("Invalid number of queues\n"); + ret = -EINVAL; + goto out; + } + opts->nr_queues = min(token, num_online_cpus()); + break; + case ZLOOP_OPT_QUEUE_DEPTH: + if (match_uint(args, &token)) { + ret = -EINVAL; + goto out; + } + if (!token) { + pr_err("Invalid queue depth\n"); + ret = -EINVAL; + goto out; + } + opts->queue_depth = token; + break; + case ZLOOP_OPT_ERR: + default: + pr_warn("unknown parameter or missing value '%s'\n", p); + ret = -EINVAL; + goto out; + } + } + + ret = -EINVAL; + if (opts->capacity <= opts->zone_size) { + pr_err("Invalid capacity\n"); + goto out; + } + + if (opts->zone_capacity > opts->zone_size) { + pr_err("Invalid zone capacity\n"); + goto out; + } + + ret = 0; +out: + kfree(options); + return ret; +} + +enum { + ZLOOP_CTL_ADD, + ZLOOP_CTL_REMOVE, +}; + +static struct zloop_ctl_op { + int code; + const char *name; +} zloop_ctl_ops[] = { + { ZLOOP_CTL_ADD, "add" }, + { ZLOOP_CTL_REMOVE, "remove" }, + { -1, NULL }, +}; + +static ssize_t zloop_ctl_write(struct file *file, const char __user *ubuf, + size_t count, loff_t *pos) +{ + struct zloop_options opts = { }; + struct zloop_ctl_op *op; + const char *buf, *opts_buf; + int i, ret; + + if (count > PAGE_SIZE) + return -ENOMEM; + + buf = memdup_user_nul(ubuf, count); + if (IS_ERR(buf)) + return PTR_ERR(buf); + + for (i = 0; i < ARRAY_SIZE(zloop_ctl_ops); i++) { + op = &zloop_ctl_ops[i]; + if (!op->name) { + pr_err("Invalid operation\n"); + ret = -EINVAL; + goto out; + } + if (!strncmp(buf, op->name, strlen(op->name))) + break; + } + + if (count <= strlen(op->name)) + opts_buf = NULL; + else + opts_buf = buf + strlen(op->name); + + ret = zloop_parse_options(&opts, opts_buf); + if (ret) { + pr_err("Failed to parse options\n"); + goto out; + } + + switch (op->code) { + case ZLOOP_CTL_ADD: + ret = zloop_ctl_add(&opts); + break; + case ZLOOP_CTL_REMOVE: + ret = zloop_ctl_remove(&opts); + break; + default: + pr_err("Invalid operation\n"); + ret = -EINVAL; + goto out; + } + +out: + kfree(opts.base_dir); + kfree(buf); + return ret ? ret : count; +} + +static int zloop_ctl_show(struct seq_file *seq_file, void *private) +{ + const struct match_token *tok; + int i; + + /* Add operation */ + seq_printf(seq_file, "%s ", zloop_ctl_ops[0].name); + for (i = 0; i < ARRAY_SIZE(zloop_opt_tokens); i++) { + tok = &zloop_opt_tokens[i]; + if (tok->token == ZLOOP_OPT_ERR) + break; + if (i) + seq_putc(seq_file, ','); + seq_puts(seq_file, tok->pattern); + } + seq_putc(seq_file, '\n'); + + /* Remove operation */ + seq_printf(seq_file, "%s ", zloop_ctl_ops[1].name); + seq_puts(seq_file, "id=%d\n"); + + return 0; +} + +static int zloop_ctl_open(struct inode *inode, struct file *file) +{ + file->private_data = NULL; + return single_open(file, zloop_ctl_show, NULL); +} + +static int zloop_ctl_release(struct inode *inode, struct file *file) +{ + return single_release(inode, file); +} + +static const struct file_operations zloop_ctl_fops = { + .owner = THIS_MODULE, + .open = zloop_ctl_open, + .release = zloop_ctl_release, + .write = zloop_ctl_write, + .read = seq_read, +}; + +static struct miscdevice zloop_misc = { + .minor = MISC_DYNAMIC_MINOR, + .name = "zloop-control", + .fops = &zloop_ctl_fops, +}; + +static int __init zloop_init(void) +{ + int ret; + + ret = misc_register(&zloop_misc); + if (ret) { + pr_err("Failed to register misc device: %d\n", ret); + return ret; + } + pr_info("Module loaded\n"); + + return 0; +} + +static void __exit zloop_exit(void) +{ + misc_deregister(&zloop_misc); + idr_destroy(&zloop_index_idr); +} + +module_init(zloop_init); +module_exit(zloop_exit); + +MODULE_DESCRIPTION("Zoned loopback device"); +MODULE_LICENSE("GPL"); From patchwork Mon Jan 6 14:24:39 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Damien Le Moal X-Patchwork-Id: 13927534 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 78A731DED6F for ; Mon, 6 Jan 2025 14:25:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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Mon, 6 Jan 2025 14:25:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736173525; bh=HZ6vRpGjF2vwoVVmQsFuodSLd1FyoTszqVaNB9HBZ9k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C4NrhUJ3u6WbL1CnEQG/N1o9Sk1WHilP5pS393giaHg/mA5EOENMxE0lTUuX2rcoz lkU1Zoen50D+m+5bKRNyH2ChOSvZCRD5wuHIA8v1EZc74XuXVqPrxXJzjA3HBMyokh t7d5T+tltXnnCDkVMPVUT6/YwfjNx6nERO6Zv/89jTSITqgZnIRrgxDyvFBztlF0az Xe5QKmyOueZCjDWH0XGkkK9l9F1WwZWlPTLCaa9Lnwao21U6znkqxBo5g7Wh9xhusO 3z2xa2yDnmySLHPb1qwOejyUaFXAAObeK+Kg5owEhtjf37S+yfroMRZsk/FPQLRWQU W2+ge3Mr/SFeg== From: Damien Le Moal To: Jens Axboe , linux-block@vger.kernel.org Cc: Christoph Hellwig Subject: [PATCH 2/2] Documentation: Document the new zoned loop block device driver Date: Mon, 6 Jan 2025 23:24:39 +0900 Message-ID: <20250106142439.216598-3-dlemoal@kernel.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250106142439.216598-1-dlemoal@kernel.org> References: <20250106142439.216598-1-dlemoal@kernel.org> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Introduce the zoned_loop.rst documentation file under admin-guide/blockdev to document the zoned loop block device driver. An overview of the driver is provided and its usage to create and delete zoned devices described. Signed-off-by: Damien Le Moal --- Documentation/admin-guide/blockdev/index.rst | 1 + .../admin-guide/blockdev/zoned_loop.rst | 168 ++++++++++++++++++ MAINTAINERS | 1 + 3 files changed, 170 insertions(+) create mode 100644 Documentation/admin-guide/blockdev/zoned_loop.rst diff --git a/Documentation/admin-guide/blockdev/index.rst b/Documentation/admin-guide/blockdev/index.rst index 957ccf617797..3262397ebe8f 100644 --- a/Documentation/admin-guide/blockdev/index.rst +++ b/Documentation/admin-guide/blockdev/index.rst @@ -11,6 +11,7 @@ Block Devices nbd paride ramdisk + zoned_loop zram drbd/index diff --git a/Documentation/admin-guide/blockdev/zoned_loop.rst b/Documentation/admin-guide/blockdev/zoned_loop.rst new file mode 100644 index 000000000000..e437f501b0ae --- /dev/null +++ b/Documentation/admin-guide/blockdev/zoned_loop.rst @@ -0,0 +1,168 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======================= +Zoned Loop Block Device +======================= + +.. Contents: + + 1) Overview + 2) Creating a Zoned Device + 3) Deleting a Zoned Device + 4) Example + + +1) Overview +----------- + +The zoned loop block device driver (zloop) allows a user to create a zoned block +device using one regular file per zone as backing storage. This driver does not +directly control any hardware and uses read, write and truncate operations to +regular files of a file system to emulate a zoned block device. + +Using zloop, zoned block devices with a configurable capacity, zone size and +number of conventional zones can be created. The storage for each zone of the +device is implemented using a regular file with a maximum size equal to the zone +size. The size of a file backing a conventional zone is always equal to the zone +size. The size of a file backing a sequential zone indicates the amount of data +sequentially written to the file, that is, the size of the file directly +indicates the position of the write pointer of the zone. + +When resetting a sequential zone, its backing file size is truncated to zero. +Conversely, for a zone finish operation, the backing file is truncated to the +zone size. With this, the maximum capacity of a zloop zoned block device created +can be larger configured to be larger than the storage space available on the +backing file system. Of course, for such configuration, writing more data than +the storage space available on the backing file system will result in write +errors. + +The zoned loop block device driver implements a complete zone transition state +machine. That is, zones can be empty, implicitly opened, explicitly opened, +closed or full. The current implementation does not support any limits on the +maximum number of open and active zones. + +No user tools are necessary to create and delete zloop devices. + +2) Creating a Zoned Device +-------------------------- + +Once the zloop module is loaded (or if zloop is compiled in the kernel), the +character device file /dev/zloop-control can be used to add a zloop device. +This is done by writing an "add" command directly to the /dev/zloop-control +device:: + + $ modprobe zloop + $ ls -l /dev/zloop* + crw-------. 1 root root 10, 123 Jan 6 19:18 /dev/zloop-control + + $ mkdir -p + $ echo "add [options]" > /dev/zloop-control + +The options available for the add command can be listed by reading the +/dev/zloop-control device:: + + $ cat /dev/zloop-control + add id=%d,capacity_mb=%u,zone_size_mb=%u,zone_capacity_mb=%u,conv_zones=%u,base_dir=%s,nr_queues=%u,queue_depth=%u + remove id=%d + +In more details, the options that can be used with the "add" command are as +follows. + +================ =========================================================== +id Device number (the X in /dev/zloopX). + Default: automatically assigned. +capacity_mb Device total capacity in MiB. This is always rounded up to + the nearest higher multiple of the zone size. + Default: 16384 MiB (16 GiB). +zone_size_mb Device zone size in MiB. Default: 256 MiB. +zone_capacity_mb Device zone capacity (must always be equal to or lower than + the zone size. Default: zone size. +conv_zones Total number of conventioanl zones starting from sector 0. + Default: 8. +base_dir Path to the base directoy where to create the directory + containing the zone files of the device. + Default=/var/local/zloop. + The device directory containing the zone files is always + named with the device ID. E.g. the default zone file + directory for /dev/zloop0 is /var/local/zloop/0. +nr_queues Number of I/O queues of the zoned block device. This value is + always capped by the number of online CPUs + Default: 1 +queue_depth Maximum I/O queue depth per I/O queue. + Default: 64 +================ =========================================================== + +3) Deleting a Zoned Device +-------------------------- + +Deleting an unused zoned loop block device is done by issuing the "remove" +command to /dev/zloop-control, specifying the ID of the device to remove:: + + $ echo "remove id=X" > /dev/zloop-control + +The remove command does not have any option. + +A zoned device that was removed can be re-added again without any change to the +state of the device zones: the device zones are restored to their last state +before the device was removed. Adding again a zoned device after it was removed +must always be done using the same configuration as when the device was first +added. If a zone configuration change is detected, an error will be returned and +the zoned device will not be created. + +To fully delete a zoned device, after executing the remove operation, the device +base directory containing the backing files of the device zones must be deleted. + +4) Example +---------- + +The following sequence of commands creates a 2GB zoned device with zones of 64 +MB and a zone capacity of 63 MB:: + + $ modprobe zloop + $ mkdir -p /var/local/zloop/0 + $ echo "add capacity_mb=2048,zone_size_mb=64,zone_capacity=63MB" > /dev/zloop-control + +For the device created (/dev/zloop0), the zone backing files are all created +under the default base directory (/var/local/zloop):: + + $ ls -l /var/local/zloop/0 + total 0 + -rw-------. 1 root root 67108864 Jan 6 22:23 cnv-000000 + -rw-------. 1 root root 67108864 Jan 6 22:23 cnv-000001 + -rw-------. 1 root root 67108864 Jan 6 22:23 cnv-000002 + -rw-------. 1 root root 67108864 Jan 6 22:23 cnv-000003 + -rw-------. 1 root root 67108864 Jan 6 22:23 cnv-000004 + -rw-------. 1 root root 67108864 Jan 6 22:23 cnv-000005 + -rw-------. 1 root root 67108864 Jan 6 22:23 cnv-000006 + -rw-------. 1 root root 67108864 Jan 6 22:23 cnv-000007 + -rw-------. 1 root root 0 Jan 6 22:23 seq-000008 + -rw-------. 1 root root 0 Jan 6 22:23 seq-000009 + ... + +The zoned device created (/dev/zloop0) can then be used normally:: + + $ lsblk -z + NAME ZONED ZONE-SZ ZONE-NR ZONE-AMAX ZONE-OMAX ZONE-APP ZONE-WGRAN + zloop0 host-managed 64M 32 0 0 1M 4K + $ blkzone report /dev/zloop0 + start: 0x000000000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)] + start: 0x000020000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)] + start: 0x000040000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)] + start: 0x000060000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)] + start: 0x000080000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)] + start: 0x0000a0000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)] + start: 0x0000c0000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)] + start: 0x0000e0000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)] + start: 0x000100000, len 0x020000, cap 0x01f800, wptr 0x000000 reset:0 non-seq:0, zcond: 1(em) [type: 2(SEQ_WRITE_REQUIRED)] + start: 0x000120000, len 0x020000, cap 0x01f800, wptr 0x000000 reset:0 non-seq:0, zcond: 1(em) [type: 2(SEQ_WRITE_REQUIRED)] + ... + +Deleting this device is done using the command:: + + $ echo "remove id=0" > /dev/zloop-control + +The removed device can be re-added again using the same "add" command as when +the device was first created. To fully delete a zoned device, its backing files +should also be deleted after executing the remove command:: + + $ rm -r /var/local/zloop/0 diff --git a/MAINTAINERS b/MAINTAINERS index 49076a506b6b..a61b5d2827af 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -25977,6 +25977,7 @@ M: Damien Le Moal R: Christoph Hellwig L: linux-block@vger.kernel.org S: Maintained +F: Documentation/admin-guide/blockdev/zoned_loop.rst F: drivers/block/zloop.c ZONEFS FILESYSTEM