diff options
Diffstat (limited to 'drivers/block/ublk_drv.c')
| -rw-r--r-- | drivers/block/ublk_drv.c | 1545 |
1 files changed, 1545 insertions, 0 deletions
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c new file mode 100644 index 000000000000..3f1906965ac8 --- /dev/null +++ b/drivers/block/ublk_drv.c @@ -0,0 +1,1545 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Userspace block device - block device which IO is handled from userspace + * + * Take full use of io_uring passthrough command for communicating with + * ublk userspace daemon(ublksrvd) for handling basic IO request. + * + * Copyright 2022 Ming Lei <ming.lei@redhat.com> + * + * (part of code stolen from loop.c) + */ +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/sched.h> +#include <linux/fs.h> +#include <linux/pagemap.h> +#include <linux/file.h> +#include <linux/stat.h> +#include <linux/errno.h> +#include <linux/major.h> +#include <linux/wait.h> +#include <linux/blkdev.h> +#include <linux/init.h> +#include <linux/swap.h> +#include <linux/slab.h> +#include <linux/compat.h> +#include <linux/mutex.h> +#include <linux/writeback.h> +#include <linux/completion.h> +#include <linux/highmem.h> +#include <linux/sysfs.h> +#include <linux/miscdevice.h> +#include <linux/falloc.h> +#include <linux/uio.h> +#include <linux/ioprio.h> +#include <linux/sched/mm.h> +#include <linux/uaccess.h> +#include <linux/cdev.h> +#include <linux/io_uring.h> +#include <linux/blk-mq.h> +#include <linux/delay.h> +#include <linux/mm.h> +#include <asm/page.h> +#include <linux/task_work.h> +#include <uapi/linux/ublk_cmd.h> + +#define UBLK_MINORS (1U << MINORBITS) + +/* All UBLK_F_* have to be included into UBLK_F_ALL */ +#define UBLK_F_ALL (UBLK_F_SUPPORT_ZERO_COPY | UBLK_F_URING_CMD_COMP_IN_TASK) + +struct ublk_rq_data { + struct callback_head work; +}; + +struct ublk_uring_cmd_pdu { + struct request *req; +}; + +/* + * io command is active: sqe cmd is received, and its cqe isn't done + * + * If the flag is set, the io command is owned by ublk driver, and waited + * for incoming blk-mq request from the ublk block device. + * + * If the flag is cleared, the io command will be completed, and owned by + * ublk server. + */ +#define UBLK_IO_FLAG_ACTIVE 0x01 + +/* + * IO command is completed via cqe, and it is being handled by ublksrv, and + * not committed yet + * + * Basically exclusively with UBLK_IO_FLAG_ACTIVE, so can be served for + * cross verification + */ +#define UBLK_IO_FLAG_OWNED_BY_SRV 0x02 + +/* + * IO command is aborted, so this flag is set in case of + * !UBLK_IO_FLAG_ACTIVE. + * + * After this flag is observed, any pending or new incoming request + * associated with this io command will be failed immediately + */ +#define UBLK_IO_FLAG_ABORTED 0x04 + +struct ublk_io { + /* userspace buffer address from io cmd */ + __u64 addr; + unsigned int flags; + int res; + + struct io_uring_cmd *cmd; +}; + +struct ublk_queue { + int q_id; + int q_depth; + + unsigned long flags; + struct task_struct *ubq_daemon; + char *io_cmd_buf; + + unsigned long io_addr; /* mapped vm address */ + unsigned int max_io_sz; + bool abort_work_pending; + unsigned short nr_io_ready; /* how many ios setup */ + struct ublk_device *dev; + struct ublk_io ios[0]; +}; + +#define UBLK_DAEMON_MONITOR_PERIOD (5 * HZ) + +struct ublk_device { + struct gendisk *ub_disk; + + char *__queues; + + unsigned short queue_size; + unsigned short bs_shift; + struct ublksrv_ctrl_dev_info dev_info; + + struct blk_mq_tag_set tag_set; + + struct cdev cdev; + struct device cdev_dev; + +#define UB_STATE_OPEN 0 +#define UB_STATE_USED 1 + unsigned long state; + int ub_number; + + struct mutex mutex; + + spinlock_t mm_lock; + struct mm_struct *mm; + + struct completion completion; + unsigned int nr_queues_ready; + atomic_t nr_aborted_queues; + + /* + * Our ubq->daemon may be killed without any notification, so + * monitor each queue's daemon periodically + */ + struct delayed_work monitor_work; + struct work_struct stop_work; +}; + +static dev_t ublk_chr_devt; +static struct class *ublk_chr_class; + +static DEFINE_IDR(ublk_index_idr); +static DEFINE_SPINLOCK(ublk_idr_lock); +static wait_queue_head_t ublk_idr_wq; /* wait until one idr is freed */ + +static DEFINE_MUTEX(ublk_ctl_mutex); + +static struct miscdevice ublk_misc; + +static inline bool ublk_can_use_task_work(const struct ublk_queue *ubq) +{ + if (IS_BUILTIN(CONFIG_BLK_DEV_UBLK) && + !(ubq->flags & UBLK_F_URING_CMD_COMP_IN_TASK)) + return true; + return false; +} + +static struct ublk_device *ublk_get_device(struct ublk_device *ub) +{ + if (kobject_get_unless_zero(&ub->cdev_dev.kobj)) + return ub; + return NULL; +} + +static void ublk_put_device(struct ublk_device *ub) +{ + put_device(&ub->cdev_dev); +} + +static inline struct ublk_queue *ublk_get_queue(struct ublk_device *dev, + int qid) +{ + return (struct ublk_queue *)&(dev->__queues[qid * dev->queue_size]); +} + +static inline bool ublk_rq_has_data(const struct request *rq) +{ + return rq->bio && bio_has_data(rq->bio); +} + +static inline struct ublksrv_io_desc *ublk_get_iod(struct ublk_queue *ubq, + int tag) +{ + return (struct ublksrv_io_desc *) + &(ubq->io_cmd_buf[tag * sizeof(struct ublksrv_io_desc)]); +} + +static inline char *ublk_queue_cmd_buf(struct ublk_device *ub, int q_id) +{ + return ublk_get_queue(ub, q_id)->io_cmd_buf; +} + +static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id) +{ + struct ublk_queue *ubq = ublk_get_queue(ub, q_id); + + return round_up(ubq->q_depth * sizeof(struct ublksrv_io_desc), + PAGE_SIZE); +} + +static void ublk_free_disk(struct gendisk *disk) +{ + struct ublk_device *ub = disk->private_data; + + clear_bit(UB_STATE_USED, &ub->state); + put_device(&ub->cdev_dev); +} + +static const struct block_device_operations ub_fops = { + .owner = THIS_MODULE, + .free_disk = ublk_free_disk, +}; + +#define UBLK_MAX_PIN_PAGES 32 + +struct ublk_map_data { + const struct ublk_queue *ubq; + const struct request *rq; + const struct ublk_io *io; + unsigned max_bytes; +}; + +struct ublk_io_iter { + struct page *pages[UBLK_MAX_PIN_PAGES]; + unsigned pg_off; /* offset in the 1st page in pages */ + int nr_pages; /* how many page pointers in pages */ + struct bio *bio; + struct bvec_iter iter; +}; + +static inline unsigned ublk_copy_io_pages(struct ublk_io_iter *data, + unsigned max_bytes, bool to_vm) +{ + const unsigned total = min_t(unsigned, max_bytes, + PAGE_SIZE - data->pg_off + + ((data->nr_pages - 1) << PAGE_SHIFT)); + unsigned done = 0; + unsigned pg_idx = 0; + + while (done < total) { + struct bio_vec bv = bio_iter_iovec(data->bio, data->iter); + const unsigned int bytes = min3(bv.bv_len, total - done, + (unsigned)(PAGE_SIZE - data->pg_off)); + void *bv_buf = bvec_kmap_local(&bv); + void *pg_buf = kmap_local_page(data->pages[pg_idx]); + + if (to_vm) + memcpy(pg_buf + data->pg_off, bv_buf, bytes); + else + memcpy(bv_buf, pg_buf + data->pg_off, bytes); + + kunmap_local(pg_buf); + kunmap_local(bv_buf); + + /* advance page array */ + data->pg_off += bytes; + if (data->pg_off == PAGE_SIZE) { + pg_idx += 1; + data->pg_off = 0; + } + + done += bytes; + + /* advance bio */ + bio_advance_iter_single(data->bio, &data->iter, bytes); + if (!data->iter.bi_size) { + data->bio = data->bio->bi_next; + if (data->bio == NULL) + break; + data->iter = data->bio->bi_iter; + } + } + + return done; +} + +static inline int ublk_copy_user_pages(struct ublk_map_data *data, + bool to_vm) +{ + const unsigned int gup_flags = to_vm ? FOLL_WRITE : 0; + const unsigned long start_vm = data->io->addr; + unsigned int done = 0; + struct ublk_io_iter iter = { + .pg_off = start_vm & (PAGE_SIZE - 1), + .bio = data->rq->bio, + .iter = data->rq->bio->bi_iter, + }; + const unsigned int nr_pages = round_up(data->max_bytes + + (start_vm & (PAGE_SIZE - 1)), PAGE_SIZE) >> PAGE_SHIFT; + + while (done < nr_pages) { + const unsigned to_pin = min_t(unsigned, UBLK_MAX_PIN_PAGES, + nr_pages - done); + unsigned i, len; + + iter.nr_pages = get_user_pages_fast(start_vm + + (done << PAGE_SHIFT), to_pin, gup_flags, + iter.pages); + if (iter.nr_pages <= 0) + return done == 0 ? iter.nr_pages : done; + len = ublk_copy_io_pages(&iter, data->max_bytes, to_vm); + for (i = 0; i < iter.nr_pages; i++) { + if (to_vm) + set_page_dirty(iter.pages[i]); + put_page(iter.pages[i]); + } + data->max_bytes -= len; + done += iter.nr_pages; + } + + return done; +} + +static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req, + struct ublk_io *io) +{ + const unsigned int rq_bytes = blk_rq_bytes(req); + /* + * no zero copy, we delay copy WRITE request data into ublksrv + * context and the big benefit is that pinning pages in current + * context is pretty fast, see ublk_pin_user_pages + */ + if (req_op(req) != REQ_OP_WRITE && req_op(req) != REQ_OP_FLUSH) + return rq_bytes; + + if (ublk_rq_has_data(req)) { + struct ublk_map_data data = { + .ubq = ubq, + .rq = req, + .io = io, + .max_bytes = rq_bytes, + }; + + ublk_copy_user_pages(&data, true); + + return rq_bytes - data.max_bytes; + } + return rq_bytes; +} + +static int ublk_unmap_io(const struct ublk_queue *ubq, + const struct request *req, + struct ublk_io *io) +{ + const unsigned int rq_bytes = blk_rq_bytes(req); + + if (req_op(req) == REQ_OP_READ && ublk_rq_has_data(req)) { + struct ublk_map_data data = { + .ubq = ubq, + .rq = req, + .io = io, + .max_bytes = io->res, + }; + + WARN_ON_ONCE(io->res > rq_bytes); + + ublk_copy_user_pages(&data, false); + + return io->res - data.max_bytes; + } + return rq_bytes; +} + +static inline unsigned int ublk_req_build_flags(struct request *req) +{ + unsigned flags = 0; + + if (req->cmd_flags & REQ_FAILFAST_DEV) + flags |= UBLK_IO_F_FAILFAST_DEV; + + if (req->cmd_flags & REQ_FAILFAST_TRANSPORT) + flags |= UBLK_IO_F_FAILFAST_TRANSPORT; + + if (req->cmd_flags & REQ_FAILFAST_DRIVER) + flags |= UBLK_IO_F_FAILFAST_DRIVER; + + if (req->cmd_flags & REQ_META) + flags |= UBLK_IO_F_META; + + if (req->cmd_flags & REQ_FUA) + flags |= UBLK_IO_F_FUA; + + if (req->cmd_flags & REQ_NOUNMAP) + flags |= UBLK_IO_F_NOUNMAP; + + if (req->cmd_flags & REQ_SWAP) + flags |= UBLK_IO_F_SWAP; + + return flags; +} + +static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req) +{ + struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag); + struct ublk_io *io = &ubq->ios[req->tag]; + u32 ublk_op; + + switch (req_op(req)) { + case REQ_OP_READ: + ublk_op = UBLK_IO_OP_READ; + break; + case REQ_OP_WRITE: + ublk_op = UBLK_IO_OP_WRITE; + break; + case REQ_OP_FLUSH: + ublk_op = UBLK_IO_OP_FLUSH; + break; + case REQ_OP_DISCARD: + ublk_op = UBLK_IO_OP_DISCARD; + break; + case REQ_OP_WRITE_ZEROES: + ublk_op = UBLK_IO_OP_WRITE_ZEROES; + break; + default: + return BLK_STS_IOERR; + } + + /* need to translate since kernel may change */ + iod->op_flags = ublk_op | ublk_req_build_flags(req); + iod->nr_sectors = blk_rq_sectors(req); + iod->start_sector = blk_rq_pos(req); + iod->addr = io->addr; + + return BLK_STS_OK; +} + +static inline struct ublk_uring_cmd_pdu *ublk_get_uring_cmd_pdu( + struct io_uring_cmd *ioucmd) +{ + return (struct ublk_uring_cmd_pdu *)&ioucmd->pdu; +} + +static bool ubq_daemon_is_dying(struct ublk_queue *ubq) +{ + return ubq->ubq_daemon->flags & PF_EXITING; +} + +/* todo: handle partial completion */ +static void ublk_complete_rq(struct request *req) +{ + struct ublk_queue *ubq = req->mq_hctx->driver_data; + struct ublk_io *io = &ubq->ios[req->tag]; + unsigned int unmapped_bytes; + + /* failed read IO if nothing is read */ + if (!io->res && req_op(req) == REQ_OP_READ) + io->res = -EIO; + + if (io->res < 0) { + blk_mq_end_request(req, errno_to_blk_status(io->res)); + return; + } + + /* + * FLUSH or DISCARD usually won't return bytes returned, so end them + * directly. + * + * Both the two needn't unmap. + */ + if (req_op(req) != REQ_OP_READ && req_op(req) != REQ_OP_WRITE) { + blk_mq_end_request(req, BLK_STS_OK); + return; + } + + /* for READ request, writing data in iod->addr to rq buffers */ + unmapped_bytes = ublk_unmap_io(ubq, req, io); + + /* + * Extremely impossible since we got data filled in just before + * + * Re-read simply for this unlikely case. + */ + if (unlikely(unmapped_bytes < io->res)) + io->res = unmapped_bytes; + + if (blk_update_request(req, BLK_STS_OK, io->res)) + blk_mq_requeue_request(req, true); + else + __blk_mq_end_request(req, BLK_STS_OK); +} + +/* + * __ublk_fail_req() may be called from abort context or ->ubq_daemon + * context during exiting, so lock is required. + * + * Also aborting may not be started yet, keep in mind that one failed + * request may be issued by block layer again. + */ +static void __ublk_fail_req(struct ublk_io *io, struct request *req) +{ + WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE); + + if (!(io->flags & UBLK_IO_FLAG_ABORTED)) { + io->flags |= UBLK_IO_FLAG_ABORTED; + blk_mq_end_request(req, BLK_STS_IOERR); + } +} + +#define UBLK_REQUEUE_DELAY_MS 3 + +static inline void __ublk_rq_task_work(struct request *req) +{ + struct ublk_queue *ubq = req->mq_hctx->driver_data; + struct ublk_device *ub = ubq->dev; + int tag = req->tag; + struct ublk_io *io = &ubq->ios[tag]; + bool task_exiting = current != ubq->ubq_daemon || + (current->flags & PF_EXITING); + unsigned int mapped_bytes; + + pr_devel("%s: complete: op %d, qid %d tag %d io_flags %x addr %llx\n", + __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags, + ublk_get_iod(ubq, req->tag)->addr); + + if (unlikely(task_exiting)) { + blk_mq_end_request(req, BLK_STS_IOERR); + mod_delayed_work(system_wq, &ub->monitor_work, 0); + return; + } + + mapped_bytes = ublk_map_io(ubq, req, io); + + /* partially mapped, update io descriptor */ + if (unlikely(mapped_bytes != blk_rq_bytes(req))) { + /* + * Nothing mapped, retry until we succeed. + * + * We may never succeed in mapping any bytes here because + * of OOM. TODO: reserve one buffer with single page pinned + * for providing forward progress guarantee. + */ + if (unlikely(!mapped_bytes)) { + blk_mq_requeue_request(req, false); + blk_mq_delay_kick_requeue_list(req->q, + UBLK_REQUEUE_DELAY_MS); + return; + } + + ublk_get_iod(ubq, req->tag)->nr_sectors = + mapped_bytes >> 9; + } + + /* mark this cmd owned by ublksrv */ + io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV; + + /* + * clear ACTIVE since we are done with this sqe/cmd slot + * We can only accept io cmd in case of being not active. + */ + io->flags &= ~UBLK_IO_FLAG_ACTIVE; + + /* tell ublksrv one io request is coming */ + io_uring_cmd_done(io->cmd, UBLK_IO_RES_OK, 0); +} + +static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd) +{ + struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); + + __ublk_rq_task_work(pdu->req); +} + +static void ublk_rq_task_work_fn(struct callback_head *work) +{ + struct ublk_rq_data *data = container_of(work, + struct ublk_rq_data, work); + struct request *req = blk_mq_rq_from_pdu(data); + + __ublk_rq_task_work(req); +} + +static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx, + const struct blk_mq_queue_data *bd) +{ + struct ublk_queue *ubq = hctx->driver_data; + struct request *rq = bd->rq; + blk_status_t res; + + /* fill iod to slot in io cmd buffer */ + res = ublk_setup_iod(ubq, rq); + if (unlikely(res != BLK_STS_OK)) + return BLK_STS_IOERR; + + blk_mq_start_request(bd->rq); + + if (unlikely(ubq_daemon_is_dying(ubq))) { + fail: + mod_delayed_work(system_wq, &ubq->dev->monitor_work, 0); + return BLK_STS_IOERR; + } + + if (ublk_can_use_task_work(ubq)) { + struct ublk_rq_data *data = blk_mq_rq_to_pdu(rq); + enum task_work_notify_mode notify_mode = bd->last ? + TWA_SIGNAL_NO_IPI : TWA_NONE; + + if (task_work_add(ubq->ubq_daemon, &data->work, notify_mode)) + goto fail; + } else { + struct io_uring_cmd *cmd = ubq->ios[rq->tag].cmd; + struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); + + pdu->req = rq; + io_uring_cmd_complete_in_task(cmd, ublk_rq_task_work_cb); + } + + return BLK_STS_OK; +} + +static void ublk_commit_rqs(struct blk_mq_hw_ctx *hctx) +{ + struct ublk_queue *ubq = hctx->driver_data; + + if (ublk_can_use_task_work(ubq)) + __set_notify_signal(ubq->ubq_daemon); +} + +static int ublk_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data, + unsigned int hctx_idx) +{ + struct ublk_device *ub = driver_data; + struct ublk_queue *ubq = ublk_get_queue(ub, hctx->queue_num); + + hctx->driver_data = ubq; + return 0; +} + +static int ublk_init_rq(struct blk_mq_tag_set *set, struct request *req, + unsigned int hctx_idx, unsigned int numa_node) +{ + struct ublk_rq_data *data = blk_mq_rq_to_pdu(req); + + init_task_work(&data->work, ublk_rq_task_work_fn); + return 0; +} + +static const struct blk_mq_ops ublk_mq_ops = { + .queue_rq = ublk_queue_rq, + .commit_rqs = ublk_commit_rqs, + .init_hctx = ublk_init_hctx, + .init_request = ublk_init_rq, +}; + +static int ublk_ch_open(struct inode *inode, struct file *filp) +{ + struct ublk_device *ub = container_of(inode->i_cdev, + struct ublk_device, cdev); + + if (test_and_set_bit(UB_STATE_OPEN, &ub->state)) + return -EBUSY; + filp->private_data = ub; + return 0; +} + +static int ublk_ch_release(struct inode *inode, struct file *filp) +{ + struct ublk_device *ub = filp->private_data; + + clear_bit(UB_STATE_OPEN, &ub->state); + return 0; +} + +/* map pre-allocated per-queue cmd buffer to ublksrv daemon */ +static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma) +{ + struct ublk_device *ub = filp->private_data; + size_t sz = vma->vm_end - vma->vm_start; + unsigned max_sz = UBLK_MAX_QUEUE_DEPTH * sizeof(struct ublksrv_io_desc); + unsigned long pfn, end, phys_off = vma->vm_pgoff << PAGE_SHIFT; + int q_id, ret = 0; + + spin_lock(&ub->mm_lock); + if (!ub->mm) + ub->mm = current->mm; + if (current->mm != ub->mm) + ret = -EINVAL; + spin_unlock(&ub->mm_lock); + + if (ret) + return ret; + + if (vma->vm_flags & VM_WRITE) + return -EPERM; + + end = UBLKSRV_CMD_BUF_OFFSET + ub->dev_info.nr_hw_queues * max_sz; + if (phys_off < UBLKSRV_CMD_BUF_OFFSET || phys_off >= end) + return -EINVAL; + + q_id = (phys_off - UBLKSRV_CMD_BUF_OFFSET) / max_sz; + pr_devel("%s: qid %d, pid %d, addr %lx pg_off %lx sz %lu\n", + __func__, q_id, current->pid, vma->vm_start, + phys_off, (unsigned long)sz); + + if (sz != ublk_queue_cmd_buf_size(ub, q_id)) + return -EINVAL; + + pfn = virt_to_phys(ublk_queue_cmd_buf(ub, q_id)) >> PAGE_SHIFT; + return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot); +} + +static void ublk_commit_completion(struct ublk_device *ub, + struct ublksrv_io_cmd *ub_cmd) +{ + u32 qid = ub_cmd->q_id, tag = ub_cmd->tag; + struct ublk_queue *ubq = ublk_get_queue(ub, qid); + struct ublk_io *io = &ubq->ios[tag]; + struct request *req; + + /* now this cmd slot is owned by nbd driver */ + io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV; + io->res = ub_cmd->result; + + /* find the io request and complete */ + req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag); + + if (req && likely(!blk_should_fake_timeout(req->q))) + ublk_complete_rq(req); +} + +/* + * When ->ubq_daemon is exiting, either new request is ended immediately, + * or any queued io command is drained, so it is safe to abort queue + * lockless + */ +static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq) +{ + int i; + + if (!ublk_get_device(ub)) + return; + + for (i = 0; i < ubq->q_depth; i++) { + struct ublk_io *io = &ubq->ios[i]; + + if (!(io->flags & UBLK_IO_FLAG_ACTIVE)) { + struct request *rq; + + /* + * Either we fail the request or ublk_rq_task_work_fn + * will do it + */ + rq = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], i); + if (rq) + __ublk_fail_req(io, rq); + } + } + ublk_put_device(ub); +} + +static void ublk_daemon_monitor_work(struct work_struct *work) +{ + struct ublk_device *ub = + container_of(work, struct ublk_device, monitor_work.work); + int i; + + for (i = 0; i < ub->dev_info.nr_hw_queues; i++) { + struct ublk_queue *ubq = ublk_get_queue(ub, i); + + if (ubq_daemon_is_dying(ubq)) { + schedule_work(&ub->stop_work); + + /* abort queue is for making forward progress */ + ublk_abort_queue(ub, ubq); + } + } + + /* + * We can't schedule monitor work after ublk_remove() is started. + * + * No need ub->mutex, monitor work are canceled after state is marked + * as DEAD, so DEAD state is observed reliably. + */ + if (ub->dev_info.state != UBLK_S_DEV_DEAD) + schedule_delayed_work(&ub->monitor_work, + UBLK_DAEMON_MONITOR_PERIOD); +} + +static void ublk_cancel_queue(struct ublk_queue *ubq) +{ + int i; + + for (i = 0; i < ubq->q_depth; i++) { + struct ublk_io *io = &ubq->ios[i]; + + if (io->flags & UBLK_IO_FLAG_ACTIVE) + io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0); + } +} + +/* Cancel all pending commands, must be called after del_gendisk() returns */ +static void ublk_cancel_dev(struct ublk_device *ub) +{ + int i; + + for (i = 0; i < ub->dev_info.nr_hw_queues; i++) + ublk_cancel_queue(ublk_get_queue(ub, i)); +} + +static void ublk_stop_dev(struct ublk_device *ub) +{ + mutex_lock(&ub->mutex); + if (ub->dev_info.state != UBLK_S_DEV_LIVE) + goto unlock; + + del_gendisk(ub->ub_disk); + ub->dev_info.state = UBLK_S_DEV_DEAD; + ub->dev_info.ublksrv_pid = -1; + ublk_cancel_dev(ub); + put_disk(ub->ub_disk); + ub->ub_disk = NULL; + unlock: + mutex_unlock(&ub->mutex); + cancel_delayed_work_sync(&ub->monitor_work); +} + +static inline bool ublk_queue_ready(struct ublk_queue *ubq) +{ + return ubq->nr_io_ready == ubq->q_depth; +} + +/* device can only be started after all IOs are ready */ +static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq) +{ + mutex_lock(&ub->mutex); + ubq->nr_io_ready++; + if (ublk_queue_ready(ubq)) { + ubq->ubq_daemon = current; + get_task_struct(ubq->ubq_daemon); + ub->nr_queues_ready++; + } + if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues) + complete_all(&ub->completion); + mutex_unlock(&ub->mutex); +} + +static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) +{ + struct ublksrv_io_cmd *ub_cmd = (struct ublksrv_io_cmd *)cmd->cmd; + struct ublk_device *ub = cmd->file->private_data; + struct ublk_queue *ubq; + struct ublk_io *io; + u32 cmd_op = cmd->cmd_op; + unsigned tag = ub_cmd->tag; + int ret = -EINVAL; + + pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n", + __func__, cmd->cmd_op, ub_cmd->q_id, tag, + ub_cmd->result); + + if (!(issue_flags & IO_URING_F_SQE128)) + goto out; + + if (ub_cmd->q_id >= ub->dev_info.nr_hw_queues) + goto out; + + ubq = ublk_get_queue(ub, ub_cmd->q_id); + if (!ubq || ub_cmd->q_id != ubq->q_id) + goto out; + + if (ubq->ubq_daemon && ubq->ubq_daemon != current) + goto out; + + if (tag >= ubq->q_depth) + goto out; + + io = &ubq->ios[tag]; + + /* there is pending io cmd, something must be wrong */ + if (io->flags & UBLK_IO_FLAG_ACTIVE) { + ret = -EBUSY; + goto out; + } + + switch (cmd_op) { + case UBLK_IO_FETCH_REQ: + /* UBLK_IO_FETCH_REQ is only allowed before queue is setup */ + if (ublk_queue_ready(ubq)) { + ret = -EBUSY; + goto out; + } + /* + * The io is being handled by server, so COMMIT_RQ is expected + * instead of FETCH_REQ + */ + if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV) + goto out; + /* FETCH_RQ has to provide IO buffer */ + if (!ub_cmd->addr) + goto out; + io->cmd = cmd; + io->flags |= UBLK_IO_FLAG_ACTIVE; + io->addr = ub_cmd->addr; + + ublk_mark_io_ready(ub, ubq); + break; + case UBLK_IO_COMMIT_AND_FETCH_REQ: + /* FETCH_RQ has to provide IO buffer */ + if (!ub_cmd->addr) + goto out; + if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)) + goto out; + io->addr = ub_cmd->addr; + io->flags |= UBLK_IO_FLAG_ACTIVE; + io->cmd = cmd; + ublk_commit_completion(ub, ub_cmd); + break; + default: + goto out; + } + return -EIOCBQUEUED; + + out: + io_uring_cmd_done(cmd, ret, 0); + pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n", + __func__, cmd_op, tag, ret, io->flags); + return -EIOCBQUEUED; +} + +static const struct file_operations ublk_ch_fops = { + .owner = THIS_MODULE, + .open = ublk_ch_open, + .release = ublk_ch_release, + .llseek = no_llseek, + .uring_cmd = ublk_ch_uring_cmd, + .mmap = ublk_ch_mmap, +}; + +static void ublk_deinit_queue(struct ublk_device *ub, int q_id) +{ + int size = ublk_queue_cmd_buf_size(ub, q_id); + struct ublk_queue *ubq = ublk_get_queue(ub, q_id); + + if (ubq->ubq_daemon) + put_task_struct(ubq->ubq_daemon); + if (ubq->io_cmd_buf) + free_pages((unsigned long)ubq->io_cmd_buf, get_order(size)); +} + +static int ublk_init_queue(struct ublk_device *ub, int q_id) +{ + struct ublk_queue *ubq = ublk_get_queue(ub, q_id); + gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO; + void *ptr; + int size; + + ubq->flags = ub->dev_info.flags; + ubq->q_id = q_id; + ubq->q_depth = ub->dev_info.queue_depth; + size = ublk_queue_cmd_buf_size(ub, q_id); + + ptr = (void *) __get_free_pages(gfp_flags, get_order(size)); + if (!ptr) + return -ENOMEM; + + ubq->io_cmd_buf = ptr; + ubq->dev = ub; + return 0; +} + +static void ublk_deinit_queues(struct ublk_device *ub) +{ + int nr_queues = ub->dev_info.nr_hw_queues; + int i; + + if (!ub->__queues) + return; + + for (i = 0; i < nr_queues; i++) + ublk_deinit_queue(ub, i); + kfree(ub->__queues); +} + +static int ublk_init_queues(struct ublk_device *ub) +{ + int nr_queues = ub->dev_info.nr_hw_queues; + int depth = ub->dev_info.queue_depth; + int ubq_size = sizeof(struct ublk_queue) + depth * sizeof(struct ublk_io); + int i, ret = -ENOMEM; + + ub->queue_size = ubq_size; + ub->__queues = kcalloc(nr_queues, ubq_size, GFP_KERNEL); + if (!ub->__queues) + return ret; + + for (i = 0; i < nr_queues; i++) { + if (ublk_init_queue(ub, i)) + goto fail; + } + + init_completion(&ub->completion); + return 0; + + fail: + ublk_deinit_queues(ub); + return ret; +} + +static int ublk_alloc_dev_number(struct ublk_device *ub, int idx) +{ + int i = idx; + int err; + + spin_lock(&ublk_idr_lock); + /* allocate id, if @id >= 0, we're requesting that specific id */ + if (i >= 0) { + err = idr_alloc(&ublk_index_idr, ub, i, i + 1, GFP_NOWAIT); + if (err == -ENOSPC) + err = -EEXIST; + } else { + err = idr_alloc(&ublk_index_idr, ub, 0, 0, GFP_NOWAIT); + } + spin_unlock(&ublk_idr_lock); + + if (err >= 0) + ub->ub_number = err; + + return err; +} + +static void ublk_free_dev_number(struct ublk_device *ub) +{ + spin_lock(&ublk_idr_lock); + idr_remove(&ublk_index_idr, ub->ub_number); + wake_up_all(&ublk_idr_wq); + spin_unlock(&ublk_idr_lock); +} + +static void ublk_cdev_rel(struct device *dev) +{ + struct ublk_device *ub = container_of(dev, struct ublk_device, cdev_dev); + + blk_mq_free_tag_set(&ub->tag_set); + ublk_deinit_queues(ub); + ublk_free_dev_number(ub); + mutex_destroy(&ub->mutex); + kfree(ub); +} + +static int ublk_add_chdev(struct ublk_device *ub) +{ + struct device *dev = &ub->cdev_dev; + int minor = ub->ub_number; + int ret; + + dev->parent = ublk_misc.this_device; + dev->devt = MKDEV(MAJOR(ublk_chr_devt), minor); + dev->class = ublk_chr_class; + dev->release = ublk_cdev_rel; + device_initialize(dev); + + ret = dev_set_name(dev, "ublkc%d", minor); + if (ret) + goto fail; + + cdev_init(&ub->cdev, &ublk_ch_fops); + ret = cdev_device_add(&ub->cdev, dev); + if (ret) + goto fail; + return 0; + fail: + put_device(dev); + return ret; +} + +static void ublk_stop_work_fn(struct work_struct *work) +{ + struct ublk_device *ub = + container_of(work, struct ublk_device, stop_work); + + ublk_stop_dev(ub); +} + +/* align maximum I/O size to PAGE_SIZE */ +static void ublk_align_max_io_size(struct ublk_device *ub) +{ + unsigned int max_rq_bytes = ub->dev_info.rq_max_blocks << ub->bs_shift; + + ub->dev_info.rq_max_blocks = + round_down(max_rq_bytes, PAGE_SIZE) >> ub->bs_shift; +} + +static int ublk_add_tag_set(struct ublk_device *ub) +{ + ub->tag_set.ops = &ublk_mq_ops; + ub->tag_set.nr_hw_queues = ub->dev_info.nr_hw_queues; + ub->tag_set.queue_depth = ub->dev_info.queue_depth; + ub->tag_set.numa_node = NUMA_NO_NODE; + ub->tag_set.cmd_size = sizeof(struct ublk_rq_data); + ub->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; + ub->tag_set.driver_data = ub; + return blk_mq_alloc_tag_set(&ub->tag_set); +} + +static void ublk_remove(struct ublk_device *ub) +{ + ublk_stop_dev(ub); + cancel_work_sync(&ub->stop_work); + cdev_device_del(&ub->cdev, &ub->cdev_dev); + put_device(&ub->cdev_dev); +} + +static struct ublk_device *ublk_get_device_from_id(int idx) +{ + struct ublk_device *ub = NULL; + + if (idx < 0) + return NULL; + + spin_lock(&ublk_idr_lock); + ub = idr_find(&ublk_index_idr, idx); + if (ub) + ub = ublk_get_device(ub); + spin_unlock(&ublk_idr_lock); + + return ub; +} + +static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + int ublksrv_pid = (int)header->data[0]; + unsigned long dev_blocks = header->data[1]; + struct ublk_device *ub; + struct gendisk *disk; + int ret = -EINVAL; + + if (ublksrv_pid <= 0) + return -EINVAL; + + ub = ublk_get_device_from_id(header->dev_id); + if (!ub) + return -EINVAL; + + wait_for_completion_interruptible(&ub->completion); + + schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD); + + mutex_lock(&ub->mutex); + if (ub->dev_info.state == UBLK_S_DEV_LIVE || + test_bit(UB_STATE_USED, &ub->state)) { + ret = -EEXIST; + goto out_unlock; + } + + /* We may get disk size updated */ + if (dev_blocks) + ub->dev_info.dev_blocks = dev_blocks; + + disk = blk_mq_alloc_disk(&ub->tag_set, ub); + if (IS_ERR(disk)) { + ret = PTR_ERR(disk); + goto out_unlock; + } + sprintf(disk->disk_name, "ublkb%d", ub->ub_number); + disk->fops = &ub_fops; + disk->private_data = ub; + + blk_queue_logical_block_size(disk->queue, ub->dev_info.block_size); + blk_queue_physical_block_size(disk->queue, ub->dev_info.block_size); + blk_queue_io_min(disk->queue, ub->dev_info.block_size); + blk_queue_max_hw_sectors(disk->queue, + ub->dev_info.rq_max_blocks << (ub->bs_shift - 9)); + disk->queue->limits.discard_granularity = PAGE_SIZE; + blk_queue_max_discard_sectors(disk->queue, UINT_MAX >> 9); + blk_queue_max_write_zeroes_sectors(disk->queue, UINT_MAX >> 9); + + set_capacity(disk, ub->dev_info.dev_blocks << (ub->bs_shift - 9)); + + ub->dev_info.ublksrv_pid = ublksrv_pid; + ub->ub_disk = disk; + get_device(&ub->cdev_dev); + ret = add_disk(disk); + if (ret) { + put_disk(disk); + goto out_unlock; + } + set_bit(UB_STATE_USED, &ub->state); + ub->dev_info.state = UBLK_S_DEV_LIVE; +out_unlock: + mutex_unlock(&ub->mutex); + ublk_put_device(ub); + return ret; +} + +static int ublk_ctrl_get_queue_affinity(struct io_uring_cmd *cmd) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + void __user *argp = (void __user *)(unsigned long)header->addr; + struct ublk_device *ub; + cpumask_var_t cpumask; + unsigned long queue; + unsigned int retlen; + unsigned int i; + int ret = -EINVAL; + + if (header->len * BITS_PER_BYTE < nr_cpu_ids) + return -EINVAL; + if (header->len & (sizeof(unsigned long)-1)) + return -EINVAL; + if (!header->addr) + return -EINVAL; + + ub = ublk_get_device_from_id(header->dev_id); + if (!ub) + return -EINVAL; + + queue = header->data[0]; + if (queue >= ub->dev_info.nr_hw_queues) + goto out_put_device; + + ret = -ENOMEM; + if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) + goto out_put_device; + + for_each_possible_cpu(i) { + if (ub->tag_set.map[HCTX_TYPE_DEFAULT].mq_map[i] == queue) + cpumask_set_cpu(i, cpumask); + } + + ret = -EFAULT; + retlen = min_t(unsigned short, header->len, cpumask_size()); + if (copy_to_user(argp, cpumask, retlen)) + goto out_free_cpumask; + if (retlen != header->len && + clear_user(argp + retlen, header->len - retlen)) + goto out_free_cpumask; + + ret = 0; +out_free_cpumask: + free_cpumask_var(cpumask); +out_put_device: + ublk_put_device(ub); + return ret; +} + +static inline void ublk_dump_dev_info(struct ublksrv_ctrl_dev_info *info) +{ + pr_devel("%s: dev id %d flags %llx\n", __func__, + info->dev_id, info->flags); + pr_devel("\t nr_hw_queues %d queue_depth %d block size %d dev_capacity %lld\n", + info->nr_hw_queues, info->queue_depth, + info->block_size, info->dev_blocks); +} + +static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + void __user *argp = (void __user *)(unsigned long)header->addr; + struct ublksrv_ctrl_dev_info info; + struct ublk_device *ub; + int ret = -EINVAL; + + if (header->len < sizeof(info) || !header->addr) + return -EINVAL; + if (header->queue_id != (u16)-1) { + pr_warn("%s: queue_id is wrong %x\n", + __func__, header->queue_id); + return -EINVAL; + } + if (copy_from_user(&info, argp, sizeof(info))) + return -EFAULT; + ublk_dump_dev_info(&info); + if (header->dev_id != info.dev_id) { + pr_warn("%s: dev id not match %u %u\n", + __func__, header->dev_id, info.dev_id); + return -EINVAL; + } + + ret = mutex_lock_killable(&ublk_ctl_mutex); + if (ret) + return ret; + + ret = -ENOMEM; + ub = kzalloc(sizeof(*ub), GFP_KERNEL); + if (!ub) + goto out_unlock; + mutex_init(&ub->mutex); + spin_lock_init(&ub->mm_lock); + INIT_WORK(&ub->stop_work, ublk_stop_work_fn); + INIT_DELAYED_WORK(&ub->monitor_work, ublk_daemon_monitor_work); + + ret = ublk_alloc_dev_number(ub, header->dev_id); + if (ret < 0) + goto out_free_ub; + + memcpy(&ub->dev_info, &info, sizeof(info)); + + /* update device id */ + ub->dev_info.dev_id = ub->ub_number; + + /* + * 64bit flags will be copied back to userspace as feature + * negotiation result, so have to clear flags which driver + * doesn't support yet, then userspace can get correct flags + * (features) to handle. + */ + ub->dev_info.flags &= UBLK_F_ALL; + + /* We are not ready to support zero copy */ + ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY; + + ub->bs_shift = ilog2(ub->dev_info.block_size); + ub->dev_info.nr_hw_queues = min_t(unsigned int, + ub->dev_info.nr_hw_queues, nr_cpu_ids); + ublk_align_max_io_size(ub); + + ret = ublk_init_queues(ub); + if (ret) + goto out_free_dev_number; + + ret = ublk_add_tag_set(ub); + if (ret) + goto out_deinit_queues; + + ret = -EFAULT; + if (copy_to_user(argp, &ub->dev_info, sizeof(info))) + goto out_free_tag_set; + + /* + * Add the char dev so that ublksrv daemon can be setup. + * ublk_add_chdev() will cleanup everything if it fails. + */ + ret = ublk_add_chdev(ub); + goto out_unlock; + +out_free_tag_set: + blk_mq_free_tag_set(&ub->tag_set); +out_deinit_queues: + ublk_deinit_queues(ub); +out_free_dev_number: + ublk_free_dev_number(ub); +out_free_ub: + mutex_destroy(&ub->mutex); + kfree(ub); +out_unlock: + mutex_unlock(&ublk_ctl_mutex); + return ret; +} + +static inline bool ublk_idr_freed(int id) +{ + void *ptr; + + spin_lock(&ublk_idr_lock); + ptr = idr_find(&ublk_index_idr, id); + spin_unlock(&ublk_idr_lock); + + return ptr == NULL; +} + +static int ublk_ctrl_del_dev(int idx) +{ + struct ublk_device *ub; + int ret; + + ret = mutex_lock_killable(&ublk_ctl_mutex); + if (ret) + return ret; + + ub = ublk_get_device_from_id(idx); + if (ub) { + ublk_remove(ub); + ublk_put_device(ub); + ret = 0; + } else { + ret = -ENODEV; + } + + /* + * Wait until the idr is removed, then it can be reused after + * DEL_DEV command is returned. + */ + if (!ret) + wait_event(ublk_idr_wq, ublk_idr_freed(idx)); + mutex_unlock(&ublk_ctl_mutex); + + return ret; +} + +static inline void ublk_ctrl_cmd_dump(struct io_uring_cmd *cmd) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + + pr_devel("%s: cmd_op %x, dev id %d qid %d data %llx buf %llx len %u\n", + __func__, cmd->cmd_op, header->dev_id, header->queue_id, + header->data[0], header->addr, header->len); +} + +static int ublk_ctrl_stop_dev(struct io_uring_cmd *cmd) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + struct ublk_device *ub; + + ub = ublk_get_device_from_id(header->dev_id); + if (!ub) + return -EINVAL; + + ublk_stop_dev(ub); + cancel_work_sync(&ub->stop_work); + + ublk_put_device(ub); + return 0; +} + +static int ublk_ctrl_get_dev_info(struct io_uring_cmd *cmd) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + void __user *argp = (void __user *)(unsigned long)header->addr; + struct ublk_device *ub; + int ret = 0; + + if (header->len < sizeof(struct ublksrv_ctrl_dev_info) || !header->addr) + return -EINVAL; + + ub = ublk_get_device_from_id(header->dev_id); + if (!ub) + return -EINVAL; + + if (copy_to_user(argp, &ub->dev_info, sizeof(ub->dev_info))) + ret = -EFAULT; + ublk_put_device(ub); + + return ret; +} + +static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, + unsigned int issue_flags) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + int ret = -EINVAL; + + ublk_ctrl_cmd_dump(cmd); + + if (!(issue_flags & IO_URING_F_SQE128)) + goto out; + + ret = -EPERM; + if (!capable(CAP_SYS_ADMIN)) + goto out; + + ret = -ENODEV; + switch (cmd->cmd_op) { + case UBLK_CMD_START_DEV: + ret = ublk_ctrl_start_dev(cmd); + break; + case UBLK_CMD_STOP_DEV: + ret = ublk_ctrl_stop_dev(cmd); + break; + case UBLK_CMD_GET_DEV_INFO: + ret = ublk_ctrl_get_dev_info(cmd); + break; + case UBLK_CMD_ADD_DEV: + ret = ublk_ctrl_add_dev(cmd); + break; + case UBLK_CMD_DEL_DEV: + ret = ublk_ctrl_del_dev(header->dev_id); + break; + case UBLK_CMD_GET_QUEUE_AFFINITY: + ret = ublk_ctrl_get_queue_affinity(cmd); + break; + default: + break; + } + out: + io_uring_cmd_done(cmd, ret, 0); + pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n", + __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id); + return -EIOCBQUEUED; +} + +static const struct file_operations ublk_ctl_fops = { + .open = nonseekable_open, + .uring_cmd = ublk_ctrl_uring_cmd, + .owner = THIS_MODULE, + .llseek = noop_llseek, +}; + +static struct miscdevice ublk_misc = { + .minor = MISC_DYNAMIC_MINOR, + .name = "ublk-control", + .fops = &ublk_ctl_fops, +}; + +static int __init ublk_init(void) +{ + int ret; + + init_waitqueue_head(&ublk_idr_wq); + + ret = misc_register(&ublk_misc); + if (ret) + return ret; + + ret = alloc_chrdev_region(&ublk_chr_devt, 0, UBLK_MINORS, "ublk-char"); + if (ret) + goto unregister_mis; + + ublk_chr_class = class_create(THIS_MODULE, "ublk-char"); + if (IS_ERR(ublk_chr_class)) { + ret = PTR_ERR(ublk_chr_class); + goto free_chrdev_region; + } + return 0; + +free_chrdev_region: + unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS); +unregister_mis: + misc_deregister(&ublk_misc); + return ret; +} + +static void __exit ublk_exit(void) +{ + struct ublk_device *ub; + int id; + + class_destroy(ublk_chr_class); + + misc_deregister(&ublk_misc); + + idr_for_each_entry(&ublk_index_idr, ub, id) + ublk_remove(ub); + + idr_destroy(&ublk_index_idr); + unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS); +} + +module_init(ublk_init); +module_exit(ublk_exit); + +MODULE_AUTHOR("Ming Lei <ming.lei@redhat.com>"); +MODULE_LICENSE("GPL"); |