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acrn-kernel/drivers/block/ublk_drv.c

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// 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 \
| UBLK_F_NEED_GET_DATA \
| UBLK_F_USER_RECOVERY \
| UBLK_F_USER_RECOVERY_REISSUE)
/* All UBLK_PARAM_TYPE_* should be included here */
#define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD)
struct ublk_rq_data {
struct llist_node node;
struct callback_head work;
};
struct ublk_uring_cmd_pdu {
struct ublk_queue *ubq;
};
/*
* 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
/*
* UBLK_IO_FLAG_NEED_GET_DATA is set because IO command requires
* get data buffer address from ublksrv.
*
* Then, bio data could be copied into this data buffer for a WRITE request
* after the IO command is issued again and UBLK_IO_FLAG_NEED_GET_DATA is unset.
*/
#define UBLK_IO_FLAG_NEED_GET_DATA 0x08
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;
struct llist_head io_cmds;
unsigned long io_addr; /* mapped vm address */
unsigned int max_io_sz;
bool force_abort;
unsigned short nr_io_ready; /* how many ios setup */
struct ublk_device *dev;
struct ublk_io ios[];
};
#define UBLK_DAEMON_MONITOR_PERIOD (5 * HZ)
struct ublk_device {
struct gendisk *ub_disk;
char *__queues;
unsigned int queue_size;
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 ublk_params params;
struct completion completion;
unsigned int nr_queues_ready;
unsigned int nr_privileged_daemon;
/*
* Our ubq->daemon may be killed without any notification, so
* monitor each queue's daemon periodically
*/
struct delayed_work monitor_work;
struct work_struct quiesce_work;
struct work_struct stop_work;
};
/* header of ublk_params */
struct ublk_params_header {
__u32 len;
__u32 types;
};
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 void ublk_dev_param_basic_apply(struct ublk_device *ub)
{
struct request_queue *q = ub->ub_disk->queue;
const struct ublk_param_basic *p = &ub->params.basic;
blk_queue_logical_block_size(q, 1 << p->logical_bs_shift);
blk_queue_physical_block_size(q, 1 << p->physical_bs_shift);
blk_queue_io_min(q, 1 << p->io_min_shift);
blk_queue_io_opt(q, 1 << p->io_opt_shift);
blk_queue_write_cache(q, p->attrs & UBLK_ATTR_VOLATILE_CACHE,
p->attrs & UBLK_ATTR_FUA);
if (p->attrs & UBLK_ATTR_ROTATIONAL)
blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
else
blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
blk_queue_max_hw_sectors(q, p->max_sectors);
blk_queue_chunk_sectors(q, p->chunk_sectors);
blk_queue_virt_boundary(q, p->virt_boundary_mask);
if (p->attrs & UBLK_ATTR_READ_ONLY)
set_disk_ro(ub->ub_disk, true);
set_capacity(ub->ub_disk, p->dev_sectors);
}
static void ublk_dev_param_discard_apply(struct ublk_device *ub)
{
struct request_queue *q = ub->ub_disk->queue;
const struct ublk_param_discard *p = &ub->params.discard;
q->limits.discard_alignment = p->discard_alignment;
q->limits.discard_granularity = p->discard_granularity;
blk_queue_max_discard_sectors(q, p->max_discard_sectors);
blk_queue_max_write_zeroes_sectors(q,
p->max_write_zeroes_sectors);
blk_queue_max_discard_segments(q, p->max_discard_segments);
}
static int ublk_validate_params(const struct ublk_device *ub)
{
/* basic param is the only one which must be set */
if (ub->params.types & UBLK_PARAM_TYPE_BASIC) {
const struct ublk_param_basic *p = &ub->params.basic;
if (p->logical_bs_shift > PAGE_SHIFT || p->logical_bs_shift < 9)
return -EINVAL;
if (p->logical_bs_shift > p->physical_bs_shift)
return -EINVAL;
if (p->max_sectors > (ub->dev_info.max_io_buf_bytes >> 9))
return -EINVAL;
} else
return -EINVAL;
if (ub->params.types & UBLK_PARAM_TYPE_DISCARD) {
const struct ublk_param_discard *p = &ub->params.discard;
/* So far, only support single segment discard */
if (p->max_discard_sectors && p->max_discard_segments != 1)
return -EINVAL;
if (!p->discard_granularity)
return -EINVAL;
}
return 0;
}
static int ublk_apply_params(struct ublk_device *ub)
{
if (!(ub->params.types & UBLK_PARAM_TYPE_BASIC))
return -EINVAL;
ublk_dev_param_basic_apply(ub);
if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
ublk_dev_param_discard_apply(ub);
return 0;
}
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 inline bool ublk_need_get_data(const struct ublk_queue *ubq)
{
if (ubq->flags & UBLK_F_NEED_GET_DATA)
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 inline bool ublk_queue_can_use_recovery_reissue(
struct ublk_queue *ubq)
{
if ((ubq->flags & UBLK_F_USER_RECOVERY) &&
(ubq->flags & UBLK_F_USER_RECOVERY_REISSUE))
return true;
return false;
}
static inline bool ublk_queue_can_use_recovery(
struct ublk_queue *ubq)
{
if (ubq->flags & UBLK_F_USER_RECOVERY)
return true;
return false;
}
static inline bool ublk_can_use_recovery(struct ublk_device *ub)
{
if (ub->dev_info.flags & UBLK_F_USER_RECOVERY)
return true;
return false;
}
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 inline 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);
}
/*
* Since __ublk_rq_task_work always fails requests immediately during
* exiting, __ublk_fail_req() is only called from abort context during
* exiting. So lock is unnecessary.
*
* 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_queue *ubq, 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;
if (ublk_queue_can_use_recovery_reissue(ubq))
blk_mq_requeue_request(req, false);
else
blk_mq_end_request(req, BLK_STS_IOERR);
}
}
static void ubq_complete_io_cmd(struct ublk_io *io, int res,
unsigned issue_flags)
{
/* 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, res, 0, issue_flags);
}
#define UBLK_REQUEUE_DELAY_MS 3
static inline void __ublk_abort_rq(struct ublk_queue *ubq,
struct request *rq)
{
/* We cannot process this rq so just requeue it. */
if (ublk_queue_can_use_recovery(ubq))
blk_mq_requeue_request(rq, false);
else
blk_mq_end_request(rq, BLK_STS_IOERR);
mod_delayed_work(system_wq, &ubq->dev->monitor_work, 0);
}
static inline void __ublk_rq_task_work(struct request *req,
unsigned issue_flags)
{
struct ublk_queue *ubq = req->mq_hctx->driver_data;
int tag = req->tag;
struct ublk_io *io = &ubq->ios[tag];
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);
/*
* Task is exiting if either:
*
* (1) current != ubq_daemon.
* io_uring_cmd_complete_in_task() tries to run task_work
* in a workqueue if ubq_daemon(cmd's task) is PF_EXITING.
*
* (2) current->flags & PF_EXITING.
*/
if (unlikely(current != ubq->ubq_daemon || current->flags & PF_EXITING)) {
__ublk_abort_rq(ubq, req);
return;
}
if (ublk_need_get_data(ubq) &&
(req_op(req) == REQ_OP_WRITE ||
req_op(req) == REQ_OP_FLUSH)) {
/*
* We have not handled UBLK_IO_NEED_GET_DATA command yet,
* so immepdately pass UBLK_IO_RES_NEED_GET_DATA to ublksrv
* and notify it.
*/
if (!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA)) {
io->flags |= UBLK_IO_FLAG_NEED_GET_DATA;
pr_devel("%s: need get data. op %d, qid %d tag %d io_flags %x\n",
__func__, io->cmd->cmd_op, ubq->q_id,
req->tag, io->flags);
ubq_complete_io_cmd(io, UBLK_IO_RES_NEED_GET_DATA, issue_flags);
return;
}
/*
* We have handled UBLK_IO_NEED_GET_DATA command,
* so clear UBLK_IO_FLAG_NEED_GET_DATA now and just
* do the copy work.
*/
io->flags &= ~UBLK_IO_FLAG_NEED_GET_DATA;
/* update iod->addr because ublksrv may have passed a new io buffer */
ublk_get_iod(ubq, req->tag)->addr = io->addr;
pr_devel("%s: update iod->addr: 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);
}
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;
}
ubq_complete_io_cmd(io, UBLK_IO_RES_OK, issue_flags);
}
static inline void ublk_forward_io_cmds(struct ublk_queue *ubq,
unsigned issue_flags)
{
struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
struct ublk_rq_data *data, *tmp;
io_cmds = llist_reverse_order(io_cmds);
llist_for_each_entry_safe(data, tmp, io_cmds, node)
__ublk_rq_task_work(blk_mq_rq_from_pdu(data), issue_flags);
}
static inline void ublk_abort_io_cmds(struct ublk_queue *ubq)
{
struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
struct ublk_rq_data *data, *tmp;
llist_for_each_entry_safe(data, tmp, io_cmds, node)
__ublk_abort_rq(ubq, blk_mq_rq_from_pdu(data));
}
static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd, unsigned issue_flags)
{
struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
struct ublk_queue *ubq = pdu->ubq;
ublk_forward_io_cmds(ubq, issue_flags);
}
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);
struct ublk_queue *ubq = req->mq_hctx->driver_data;
unsigned issue_flags = IO_URING_F_UNLOCKED;
ublk_forward_io_cmds(ubq, issue_flags);
}
static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq)
{
struct ublk_rq_data *data = blk_mq_rq_to_pdu(rq);
struct ublk_io *io;
if (!llist_add(&data->node, &ubq->io_cmds))
return;
io = &ubq->ios[rq->tag];
/*
* If the check pass, we know that this is a re-issued request aborted
* previously in monitor_work because the ubq_daemon(cmd's task) is
* PF_EXITING. We cannot call io_uring_cmd_complete_in_task() anymore
* because this ioucmd's io_uring context may be freed now if no inflight
* ioucmd exists. Otherwise we may cause null-deref in ctx->fallback_work.
*
* Note: monitor_work sets UBLK_IO_FLAG_ABORTED and ends this request(releasing
* the tag). Then the request is re-started(allocating the tag) and we are here.
* Since releasing/allocating a tag implies smp_mb(), finding UBLK_IO_FLAG_ABORTED
* guarantees that here is a re-issued request aborted previously.
*/
if (unlikely(io->flags & UBLK_IO_FLAG_ABORTED)) {
ublk_abort_io_cmds(ubq);
} else if (ublk_can_use_task_work(ubq)) {
if (task_work_add(ubq->ubq_daemon, &data->work,
TWA_SIGNAL_NO_IPI))
ublk_abort_io_cmds(ubq);
} else {
struct io_uring_cmd *cmd = io->cmd;
struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
pdu->ubq = ubq;
io_uring_cmd_complete_in_task(cmd, ublk_rq_task_work_cb);
}
}
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;
/* With recovery feature enabled, force_abort is set in
* ublk_stop_dev() before calling del_gendisk(). We have to
* abort all requeued and new rqs here to let del_gendisk()
* move on. Besides, we cannot not call io_uring_cmd_complete_in_task()
* to avoid UAF on io_uring ctx.
*
* Note: force_abort is guaranteed to be seen because it is set
* before request queue is unqiuesced.
*/
if (ublk_queue_can_use_recovery(ubq) && unlikely(ubq->force_abort))
return BLK_STS_IOERR;
blk_mq_start_request(bd->rq);
if (unlikely(ubq_daemon_is_dying(ubq))) {
__ublk_abort_rq(ubq, rq);
return BLK_STS_OK;
}
ublk_queue_cmd(ubq, rq);
return BLK_STS_OK;
}
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,
.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(ubq, 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)) {
if (ublk_queue_can_use_recovery(ubq))
schedule_work(&ub->quiesce_work);
else
schedule_work(&ub->stop_work);
/* abort queue is for making forward progress */
ublk_abort_queue(ub, ubq);
}
}
/*
* We can't schedule monitor work after ub's state is not UBLK_S_DEV_LIVE.
* after ublk_remove() or __ublk_quiesce_dev() is started.
*
* No need ub->mutex, monitor work are canceled after state is marked
* as not LIVE, so new state is observed reliably.
*/
if (ub->dev_info.state == UBLK_S_DEV_LIVE)
schedule_delayed_work(&ub->monitor_work,
UBLK_DAEMON_MONITOR_PERIOD);
}
static inline bool ublk_queue_ready(struct ublk_queue *ubq)
{
return ubq->nr_io_ready == ubq->q_depth;
}
static void ublk_cancel_queue(struct ublk_queue *ubq)
{
int i;
if (!ublk_queue_ready(ubq))
return;
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,
IO_URING_F_UNLOCKED);
}
/* all io commands are canceled */
ubq->nr_io_ready = 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 bool ublk_check_inflight_rq(struct request *rq, void *data)
{
bool *idle = data;
if (blk_mq_request_started(rq)) {
*idle = false;
return false;
}
return true;
}
static void ublk_wait_tagset_rqs_idle(struct ublk_device *ub)
{
bool idle;
WARN_ON_ONCE(!blk_queue_quiesced(ub->ub_disk->queue));
while (true) {
idle = true;
blk_mq_tagset_busy_iter(&ub->tag_set,
ublk_check_inflight_rq, &idle);
if (idle)
break;
msleep(UBLK_REQUEUE_DELAY_MS);
}
}
static void __ublk_quiesce_dev(struct ublk_device *ub)
{
pr_devel("%s: quiesce ub: dev_id %d state %s\n",
__func__, ub->dev_info.dev_id,
ub->dev_info.state == UBLK_S_DEV_LIVE ?
"LIVE" : "QUIESCED");
blk_mq_quiesce_queue(ub->ub_disk->queue);
ublk_wait_tagset_rqs_idle(ub);
ub->dev_info.state = UBLK_S_DEV_QUIESCED;
ublk_cancel_dev(ub);
/* we are going to release task_struct of ubq_daemon and resets
* ->ubq_daemon to NULL. So in monitor_work, check on ubq_daemon causes UAF.
* Besides, monitor_work is not necessary in QUIESCED state since we have
* already scheduled quiesce_work and quiesced all ubqs.
*
* Do not let monitor_work schedule itself if state it QUIESCED. And we cancel
* it here and re-schedule it in END_USER_RECOVERY to avoid UAF.
*/
cancel_delayed_work_sync(&ub->monitor_work);
}
static void ublk_quiesce_work_fn(struct work_struct *work)
{
struct ublk_device *ub =
container_of(work, struct ublk_device, quiesce_work);
mutex_lock(&ub->mutex);
if (ub->dev_info.state != UBLK_S_DEV_LIVE)
goto unlock;
__ublk_quiesce_dev(ub);
unlock:
mutex_unlock(&ub->mutex);
}
static void ublk_unquiesce_dev(struct ublk_device *ub)
{
int i;
pr_devel("%s: unquiesce ub: dev_id %d state %s\n",
__func__, ub->dev_info.dev_id,
ub->dev_info.state == UBLK_S_DEV_LIVE ?
"LIVE" : "QUIESCED");
/* quiesce_work has run. We let requeued rqs be aborted
* before running fallback_wq. "force_abort" must be seen
* after request queue is unqiuesced. Then del_gendisk()
* can move on.
*/
for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
ublk_get_queue(ub, i)->force_abort = true;
blk_mq_unquiesce_queue(ub->ub_disk->queue);
/* We may have requeued some rqs in ublk_quiesce_queue() */
blk_mq_kick_requeue_list(ub->ub_disk->queue);
}
static void ublk_stop_dev(struct ublk_device *ub)
{
mutex_lock(&ub->mutex);
if (ub->dev_info.state == UBLK_S_DEV_DEAD)
goto unlock;
if (ublk_can_use_recovery(ub)) {
if (ub->dev_info.state == UBLK_S_DEV_LIVE)
__ublk_quiesce_dev(ub);
ublk_unquiesce_dev(ub);
}
del_gendisk(ub->ub_disk);
ub->dev_info.state = UBLK_S_DEV_DEAD;
ub->dev_info.ublksrv_pid = -1;
put_disk(ub->ub_disk);
ub->ub_disk = NULL;
unlock:
ublk_cancel_dev(ub);
mutex_unlock(&ub->mutex);
cancel_delayed_work_sync(&ub->monitor_work);
}
/* 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 (capable(CAP_SYS_ADMIN))
ub->nr_privileged_daemon++;
}
if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues)
complete_all(&ub->completion);
mutex_unlock(&ub->mutex);
}
static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id,
int tag)
{
struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
struct request *req = blk_mq_tag_to_rq(ub->tag_set.tags[q_id], tag);
ublk_queue_cmd(ubq, req);
}
static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
unsigned int issue_flags,
struct ublksrv_io_cmd *ub_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;
struct request *req;
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;
}
/*
* ensure that the user issues UBLK_IO_NEED_GET_DATA
* iff the driver have set the UBLK_IO_FLAG_NEED_GET_DATA.
*/
if ((!!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA))
^ (cmd_op == UBLK_IO_NEED_GET_DATA))
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 NEED GET DATA is not enabled */
if (!ub_cmd->addr && !ublk_need_get_data(ubq))
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:
req = blk_mq_tag_to_rq(ub->tag_set.tags[ub_cmd->q_id], tag);
/*
* COMMIT_AND_FETCH_REQ has to provide IO buffer if NEED GET DATA is
* not enabled or it is Read IO.
*/
if (!ub_cmd->addr && (!ublk_need_get_data(ubq) || req_op(req) == REQ_OP_READ))
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;
case UBLK_IO_NEED_GET_DATA:
if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
goto out;
io->addr = ub_cmd->addr;
io->cmd = cmd;
io->flags |= UBLK_IO_FLAG_ACTIVE;
ublk_handle_need_get_data(ub, ub_cmd->q_id, ub_cmd->tag);
break;
default:
goto out;
}
return -EIOCBQUEUED;
out:
io_uring_cmd_done(cmd, ret, 0, issue_flags);
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 int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
{
struct ublksrv_io_cmd *ub_src = (struct ublksrv_io_cmd *) cmd->cmd;
struct ublksrv_io_cmd ub_cmd;
/*
* Not necessary for async retry, but let's keep it simple and always
* copy the values to avoid any potential reuse.
*/
ub_cmd.q_id = READ_ONCE(ub_src->q_id);
ub_cmd.tag = READ_ONCE(ub_src->tag);
ub_cmd.result = READ_ONCE(ub_src->result);
ub_cmd.addr = READ_ONCE(ub_src->addr);
return __ublk_ch_uring_cmd(cmd, issue_flags, &ub_cmd);
}
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 max io buffer size with PAGE_SIZE */
static void ublk_align_max_io_size(struct ublk_device *ub)
{
unsigned int max_io_bytes = ub->dev_info.max_io_buf_bytes;
ub->dev_info.max_io_buf_bytes =
round_down(max_io_bytes, PAGE_SIZE);
}
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);
cancel_work_sync(&ub->quiesce_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];
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;
}
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;
ub->dev_info.ublksrv_pid = ublksrv_pid;
ub->ub_disk = disk;
ret = ublk_apply_params(ub);
if (ret)
goto out_put_disk;
/* don't probe partitions if any one ubq daemon is un-trusted */
if (ub->nr_privileged_daemon != ub->nr_queues_ready)
set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
get_device(&ub->cdev_dev);
ub->dev_info.state = UBLK_S_DEV_LIVE;
ret = add_disk(disk);
if (ret) {
/*
* Has to drop the reference since ->free_disk won't be
* called in case of add_disk failure.
*/
ub->dev_info.state = UBLK_S_DEV_DEAD;
ublk_put_device(ub);
goto out_put_disk;
}
set_bit(UB_STATE_USED, &ub->state);
out_put_disk:
if (ret)
put_disk(disk);
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\n",
info->nr_hw_queues, info->queue_depth);
}
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->quiesce_work, ublk_quiesce_work_fn);
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;
if (!IS_BUILTIN(CONFIG_BLK_DEV_UBLK))
ub->dev_info.flags |= UBLK_F_URING_CMD_COMP_IN_TASK;
/* We are not ready to support zero copy */
ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY;
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);
cancel_work_sync(&ub->quiesce_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_get_params(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_params_header ph;
struct ublk_device *ub;
int ret;
if (header->len <= sizeof(ph) || !header->addr)
return -EINVAL;
if (copy_from_user(&ph, argp, sizeof(ph)))
return -EFAULT;
if (ph.len > header->len || !ph.len)
return -EINVAL;
if (ph.len > sizeof(struct ublk_params))
ph.len = sizeof(struct ublk_params);
ub = ublk_get_device_from_id(header->dev_id);
if (!ub)
return -EINVAL;
mutex_lock(&ub->mutex);
if (copy_to_user(argp, &ub->params, ph.len))
ret = -EFAULT;
else
ret = 0;
mutex_unlock(&ub->mutex);
ublk_put_device(ub);
return ret;
}
static int ublk_ctrl_set_params(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_params_header ph;
struct ublk_device *ub;
int ret = -EFAULT;
if (header->len <= sizeof(ph) || !header->addr)
return -EINVAL;
if (copy_from_user(&ph, argp, sizeof(ph)))
return -EFAULT;
if (ph.len > header->len || !ph.len || !ph.types)
return -EINVAL;
if (ph.len > sizeof(struct ublk_params))
ph.len = sizeof(struct ublk_params);
ub = ublk_get_device_from_id(header->dev_id);
if (!ub)
return -EINVAL;
/* parameters can only be changed when device isn't live */
mutex_lock(&ub->mutex);
if (ub->dev_info.state == UBLK_S_DEV_LIVE) {
ret = -EACCES;
} else if (copy_from_user(&ub->params, argp, ph.len)) {
ret = -EFAULT;
} else {
/* clear all we don't support yet */
ub->params.types &= UBLK_PARAM_TYPE_ALL;
ret = ublk_validate_params(ub);
if (ret)
ub->params.types = 0;
}
mutex_unlock(&ub->mutex);
ublk_put_device(ub);
return ret;
}
static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)
{
int i;
WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq)));
/* All old ioucmds have to be completed */
WARN_ON_ONCE(ubq->nr_io_ready);
/* old daemon is PF_EXITING, put it now */
put_task_struct(ubq->ubq_daemon);
/* We have to reset it to NULL, otherwise ub won't accept new FETCH_REQ */
ubq->ubq_daemon = NULL;
for (i = 0; i < ubq->q_depth; i++) {
struct ublk_io *io = &ubq->ios[i];
/* forget everything now and be ready for new FETCH_REQ */
io->flags = 0;
io->cmd = NULL;
io->addr = 0;
}
}
static int ublk_ctrl_start_recovery(struct io_uring_cmd *cmd)
{
struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
struct ublk_device *ub;
int ret = -EINVAL;
int i;
ub = ublk_get_device_from_id(header->dev_id);
if (!ub)
return ret;
mutex_lock(&ub->mutex);
if (!ublk_can_use_recovery(ub))
goto out_unlock;
/*
* START_RECOVERY is only allowd after:
*
* (1) UB_STATE_OPEN is not set, which means the dying process is exited
* and related io_uring ctx is freed so file struct of /dev/ublkcX is
* released.
*
* (2) UBLK_S_DEV_QUIESCED is set, which means the quiesce_work:
* (a)has quiesced request queue
* (b)has requeued every inflight rqs whose io_flags is ACTIVE
* (c)has requeued/aborted every inflight rqs whose io_flags is NOT ACTIVE
* (d)has completed/camceled all ioucmds owned by ther dying process
*/
if (test_bit(UB_STATE_OPEN, &ub->state) ||
ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
ret = -EBUSY;
goto out_unlock;
}
pr_devel("%s: start recovery for dev id %d.\n", __func__, header->dev_id);
for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
ublk_queue_reinit(ub, ublk_get_queue(ub, i));
/* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */
ub->mm = NULL;
ub->nr_queues_ready = 0;
ub->nr_privileged_daemon = 0;
init_completion(&ub->completion);
ret = 0;
out_unlock:
mutex_unlock(&ub->mutex);
ublk_put_device(ub);
return ret;
}
static int ublk_ctrl_end_recovery(struct io_uring_cmd *cmd)
{
struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
int ublksrv_pid = (int)header->data[0];
struct ublk_device *ub;
int ret = -EINVAL;
ub = ublk_get_device_from_id(header->dev_id);
if (!ub)
return ret;
pr_devel("%s: Waiting for new ubq_daemons(nr: %d) are ready, dev id %d...\n",
__func__, ub->dev_info.nr_hw_queues, header->dev_id);
/* wait until new ubq_daemon sending all FETCH_REQ */
wait_for_completion_interruptible(&ub->completion);
pr_devel("%s: All new ubq_daemons(nr: %d) are ready, dev id %d\n",
__func__, ub->dev_info.nr_hw_queues, header->dev_id);
mutex_lock(&ub->mutex);
if (!ublk_can_use_recovery(ub))
goto out_unlock;
if (ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
ret = -EBUSY;
goto out_unlock;
}
ub->dev_info.ublksrv_pid = ublksrv_pid;
pr_devel("%s: new ublksrv_pid %d, dev id %d\n",
__func__, ublksrv_pid, header->dev_id);
blk_mq_unquiesce_queue(ub->ub_disk->queue);
pr_devel("%s: queue unquiesced, dev id %d.\n",
__func__, header->dev_id);
blk_mq_kick_requeue_list(ub->ub_disk->queue);
ub->dev_info.state = UBLK_S_DEV_LIVE;
schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
ret = 0;
out_unlock:
mutex_unlock(&ub->mutex);
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;
if (issue_flags & IO_URING_F_NONBLOCK)
return -EAGAIN;
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;
case UBLK_CMD_GET_PARAMS:
ret = ublk_ctrl_get_params(cmd);
break;
case UBLK_CMD_SET_PARAMS:
ret = ublk_ctrl_set_params(cmd);
break;
case UBLK_CMD_START_USER_RECOVERY:
ret = ublk_ctrl_start_recovery(cmd);
break;
case UBLK_CMD_END_USER_RECOVERY:
ret = ublk_ctrl_end_recovery(cmd);
break;
default:
break;
}
out:
io_uring_cmd_done(cmd, ret, 0, issue_flags);
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;
idr_for_each_entry(&ublk_index_idr, ub, id)
ublk_remove(ub);
class_destroy(ublk_chr_class);
misc_deregister(&ublk_misc);
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");
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