[PATCH v6 17/25] rnbd: client: main functionality

Jack Wang
2019-12-30T10:30:10Z

From: Jack Wang <jinpu.wang@cloud.ionos.com>

This is main functionality of rnbd-client module, which provides
interface to map remote device as local block device /dev/rnbd<N>
and feeds RTRS with IO requests.

Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
drivers/block/rnbd/rnbd-clt.c | 1743 +++++++++++++++++++++++++++++++++
1 file changed, 1743 insertions(+)
create mode 100644 drivers/block/rnbd/rnbd-clt.c

diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c
new file mode 100644
index 000000000000..4d2c8475a6e5
--- /dev/null
+++ b/drivers/block/rnbd/rnbd-clt.c
@@ -0,0 +1,1743 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * InfiniBand Network Block Driver
+ *
+ * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
+ *
+ * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
+ *
+ * Copyright (c) 2019 1&1 IONOS SE. All rights reserved.
+ */
+
+#undef pr_fmt
+#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
+
+#include <linux/module.h>
+#include <linux/blkdev.h>
+#include <linux/hdreg.h>
+#include <linux/scatterlist.h>
+#include <linux/idr.h>
+
+#include "rnbd-clt.h"
+
+MODULE_DESCRIPTION("InfiniBand Network Block Device Client");
+MODULE_LICENSE("GPL");
+
+static int rnbd_client_major;
+static DEFINE_IDA(index_ida);
+static DEFINE_MUTEX(ida_lock);
+static DEFINE_MUTEX(sess_lock);
+static LIST_HEAD(sess_list);
+
+/*
+ * Maximum number of partitions an instance can have.
+ * 6 bits = 64 minors = 63 partitions (one minor is used for the device itself)
+ */
+#define RNBD_PART_BITS 6
+
+static inline bool rnbd_clt_get_sess(struct rnbd_clt_session *sess)
+{
+ return refcount_inc_not_zero(&sess->refcount);
+}
+
+static void free_sess(struct rnbd_clt_session *sess);
+
+static void rnbd_clt_put_sess(struct rnbd_clt_session *sess)
+{
+ might_sleep();
+
+ if (refcount_dec_and_test(&sess->refcount))
+ free_sess(sess);
+}
+
+static inline bool rnbd_clt_dev_is_mapped(struct rnbd_clt_dev *dev)
+{
+ return dev->dev_state == DEV_STATE_MAPPED;
+}
+
+static void rnbd_clt_put_dev(struct rnbd_clt_dev *dev)
+{
+ might_sleep();
+
+ if (refcount_dec_and_test(&dev->refcount)) {
+ mutex_lock(&ida_lock);
+ ida_simple_remove(&index_ida, dev->clt_device_id);
+ mutex_unlock(&ida_lock);
+ kfree(dev->hw_queues);
+ rnbd_clt_put_sess(dev->sess);
+ kfree(dev);
+ }
+}
+
+static inline bool rnbd_clt_get_dev(struct rnbd_clt_dev *dev)
+{
+ return refcount_inc_not_zero(&dev->refcount);
+}
+
+static int rnbd_clt_set_dev_attr(struct rnbd_clt_dev *dev,
+ const struct rnbd_msg_open_rsp *rsp)
+{
+ struct rnbd_clt_session *sess = dev->sess;
+
+ if (unlikely(!rsp->logical_block_size))
+ return -EINVAL;
+
+ dev->device_id = le32_to_cpu(rsp->device_id);
+ dev->nsectors = le64_to_cpu(rsp->nsectors);
+ dev->logical_block_size = le16_to_cpu(rsp->logical_block_size);
+ dev->physical_block_size = le16_to_cpu(rsp->physical_block_size);
+ dev->max_write_same_sectors = le32_to_cpu(rsp->max_write_same_sectors);
+ dev->max_discard_sectors = le32_to_cpu(rsp->max_discard_sectors);
+ dev->discard_granularity = le32_to_cpu(rsp->discard_granularity);
+ dev->discard_alignment = le32_to_cpu(rsp->discard_alignment);
+ dev->secure_discard = le16_to_cpu(rsp->secure_discard);
+ dev->rotational = rsp->rotational;
+
+ dev->max_hw_sectors = sess->max_io_size / dev->logical_block_size;
+ dev->max_segments = BMAX_SEGMENTS;
+
+ dev->max_hw_sectors = min_t(u32, dev->max_hw_sectors,
+ le32_to_cpu(rsp->max_hw_sectors));
+ dev->max_segments = min_t(u16, dev->max_segments,
+ le16_to_cpu(rsp->max_segments));
+
+ return 0;
+}
+
+static int rnbd_clt_change_capacity(struct rnbd_clt_dev *dev,
+ size_t new_nsectors)
+{
+ int err = 0;
+
+ rnbd_clt_info(dev, "Device size changed from %zu to %zu sectors\n",
+ dev->nsectors, new_nsectors);
+ dev->nsectors = new_nsectors;
+ set_capacity(dev->gd,
+ dev->nsectors * (dev->logical_block_size /
+ SECTOR_SIZE));
+ err = revalidate_disk(dev->gd);
+ if (err)
+ rnbd_clt_err(dev,
+ "Failed to change device size from %zu to %zu, err: %d\n",
+ dev->nsectors, new_nsectors, err);
+ return err;
+}
+
+static int process_msg_open_rsp(struct rnbd_clt_dev *dev,
+ struct rnbd_msg_open_rsp *rsp)
+{
+ int err = 0;
+
+ mutex_lock(&dev->lock);
+ if (dev->dev_state == DEV_STATE_UNMAPPED) {
+ rnbd_clt_info(dev,
+ "Ignoring Open-Response message from server for unmapped device\n");
+ err = -ENOENT;
+ goto out;
+ }
+ if (dev->dev_state == DEV_STATE_MAPPED_DISCONNECTED) {
+ u64 nsectors = le64_to_cpu(rsp->nsectors);
+
+ /*
+ * If the device was remapped and the size changed in the
+ * meantime we need to revalidate it
+ */
+ if (dev->nsectors != nsectors)
+ rnbd_clt_change_capacity(dev, nsectors);
+ rnbd_clt_info(dev, "Device online, device remapped successfully\n");
+ }
+ err = rnbd_clt_set_dev_attr(dev, rsp);
+ if (unlikely(err))
+ goto out;
+ dev->dev_state = DEV_STATE_MAPPED;
+
+out:
+ mutex_unlock(&dev->lock);
+
+ return err;
+}
+
+int rnbd_clt_resize_disk(struct rnbd_clt_dev *dev, size_t newsize)
+{
+ int ret = 0;
+
+ mutex_lock(&dev->lock);
+ if (dev->dev_state != DEV_STATE_MAPPED) {
+ pr_err("Failed to set new size of the device, device is not opened\n");
+ ret = -ENOENT;
+ goto out;
+ }
+ ret = rnbd_clt_change_capacity(dev, newsize);
+
+out:
+ mutex_unlock(&dev->lock);
+
+ return ret;
+}
+
+static inline void rnbd_clt_dev_requeue(struct rnbd_queue *q)
+{
+ if (WARN_ON(!q->hctx))
+ return;
+
+ /* We can come here from interrupt, thus async=true */
+ blk_mq_run_hw_queue(q->hctx, true);
+}
+
+enum {
+ RNBD_DELAY_10ms = 10,
+ RNBD_DELAY_IFBUSY = -1,
+};
+
+/**
+ * rnbd_get_cpu_qlist() - finds a list with HW queues to be rerun
+ * @sess: Session to find a queue for
+ * @cpu: Cpu to start the search from
+ *
+ * Description:
+ * Each CPU has a list of HW queues, which needs to be rerun. If a list
+ * is not empty - it is marked with a bit. This function finds first
+ * set bit in a bitmap and returns corresponding CPU list.
+ */
+static struct rnbd_cpu_qlist *
+rnbd_get_cpu_qlist(struct rnbd_clt_session *sess, int cpu)
+{
+ int bit;
+
+ /* First half */
+ bit = find_next_bit(sess->cpu_queues_bm, nr_cpu_ids, cpu);
+ if (bit < nr_cpu_ids) {
+ return per_cpu_ptr(sess->cpu_queues, bit);
+ } else if (cpu != 0) {
+ /* Second half */
+ bit = find_next_bit(sess->cpu_queues_bm, cpu, 0);
+ if (bit < cpu)
+ return per_cpu_ptr(sess->cpu_queues, bit);
+ }
+
+ return NULL;
+}
+
+static inline int nxt_cpu(int cpu)
+{
+ return (cpu + 1) % nr_cpu_ids;
+}
+
+/**
+ * rnbd_rerun_if_needed() - rerun next queue marked as stopped
+ * @sess: Session to rerun a queue on
+ *
+ * Description:
+ * Each CPU has it's own list of HW queues, which should be rerun.
+ * Function finds such list with HW queues, takes a list lock, picks up
+ * the first HW queue out of the list and requeues it.
+ *
+ * Return:
+ * True if the queue was requeued, false otherwise.
+ *
+ * Context:
+ * Does not matter.
+ */
+static inline bool rnbd_rerun_if_needed(struct rnbd_clt_session *sess)
+{
+ struct rnbd_queue *q = NULL;
+ struct rnbd_cpu_qlist *cpu_q;
+ unsigned long flags;
+ int *cpup;
+
+ /*
+ * To keep fairness and not to let other queues starve we always
+ * try to wake up someone else in round-robin manner. That of course
+ * increases latency but queues always have a chance to be executed.
+ */
+ cpup = get_cpu_ptr(sess->cpu_rr);
+ for (cpu_q = rnbd_get_cpu_qlist(sess, nxt_cpu(*cpup)); cpu_q;
+ cpu_q = rnbd_get_cpu_qlist(sess, nxt_cpu(cpu_q->cpu))) {
+ if (!spin_trylock_irqsave(&cpu_q->requeue_lock, flags))
+ continue;
+ if (likely(test_bit(cpu_q->cpu, sess->cpu_queues_bm))) {
+ q = list_first_entry_or_null(&cpu_q->requeue_list,
+ typeof(*q), requeue_list);
+ if (WARN_ON(!q))
+ goto clear_bit;
+ list_del_init(&q->requeue_list);
+ clear_bit_unlock(0, &q->in_list);
+
+ if (list_empty(&cpu_q->requeue_list)) {
+ /* Clear bit if nothing is left */
+clear_bit:
+ clear_bit(cpu_q->cpu, sess->cpu_queues_bm);
+ }
+ }
+ spin_unlock_irqrestore(&cpu_q->requeue_lock, flags);
+
+ if (q)
+ break;
+ }
+
+ /**
+ * Saves the CPU that is going to be requeued on the per-cpu var. Just
+ * incrementing it doesn't work because rnbd_get_cpu_qlist() will
+ * always return the first CPU with something on the queue list when the
+ * value stored on the var is greater than the last CPU with something
+ * on the list.
+ */
+ if (cpu_q)
+ *cpup = cpu_q->cpu;
+ put_cpu_var(sess->cpu_rr);
+
+ if (q)
+ rnbd_clt_dev_requeue(q);
+
+ return !!q;
+}
+
+/**
+ * rnbd_rerun_all_if_idle() - rerun all queues left in the list if
+ * session is idling (there are no requests
+ * in-flight).
+ * @sess: Session to rerun the queues on
+ *
+ * Description:
+ * This function tries to rerun all stopped queues if there are no
+ * requests in-flight anymore. This function tries to solve an obvious
+ * problem, when number of tags < than number of queues (hctx), which
+ * are stopped and put to sleep. If last permit, which has been just put,
+ * does not wake up all left queues (hctxs), IO requests hang forever.
+ *
+ * That can happen when all number of permits, say N, have been exhausted
+ * from one CPU, and we have many block devices per session, say M.
+ * Each block device has it's own queue (hctx) for each CPU, so eventually
+ * we can put that number of queues (hctxs) to sleep: M x nr_cpu_ids.
+ * If number of permits N < M x nr_cpu_ids finally we will get an IO hang.
+ *
+ * To avoid this hang last caller of rnbd_put_permit() (last caller is the
+ * one who observes sess->busy == 0) must wake up all remaining queues.
+ *
+ * Context:
+ * Does not matter.
+ */
+static inline void rnbd_rerun_all_if_idle(struct rnbd_clt_session *sess)
+{
+ bool requeued;
+
+ do {
+ requeued = rnbd_rerun_if_needed(sess);
+ } while (atomic_read(&sess->busy) == 0 && requeued);
+}
+
+static struct rtrs_permit *rnbd_get_permit(struct rnbd_clt_session *sess,
+ enum rtrs_clt_con_type con_type,
+ int wait)
+{
+ struct rtrs_permit *permit;
+
+ permit = rtrs_clt_get_permit(sess->rtrs, con_type,
+ wait ? RTRS_PERMIT_WAIT :
+ RTRS_PERMIT_NOWAIT);
+ if (likely(permit))
+ /* We have a subtle rare case here, when all permits can be
+ * consumed before busy counter increased. This is safe,
+ * because loser will get NULL as a permit, observe 0 busy
+ * counter and immediately restart the queue himself.
+ */
+ atomic_inc(&sess->busy);
+
+ return permit;
+}
+
+static void rnbd_put_permit(struct rnbd_clt_session *sess,
+ struct rtrs_permit *permit)
+{
+ rtrs_clt_put_permit(sess->rtrs, permit);
+ atomic_dec(&sess->busy);
+ /* Paired with rnbd_clt_dev_add_to_requeue(). Decrement first
+ * and then check queue bits.
+ */
+ smp_mb__after_atomic();
+ rnbd_rerun_all_if_idle(sess);
+}
+
+static struct rnbd_iu *rnbd_get_iu(struct rnbd_clt_session *sess,
+ enum rtrs_clt_con_type con_type,
+ int wait)
+{
+ struct rnbd_iu *iu;
+ struct rtrs_permit *permit;
+
+ permit = rnbd_get_permit(sess, con_type,
+ wait ? RTRS_PERMIT_WAIT :
+ RTRS_PERMIT_NOWAIT);
+ if (unlikely(!permit))
+ return NULL;
+ iu = rtrs_permit_to_pdu(permit);
+ iu->permit = permit;
+ /* yes, rtrs_permit_from_pdu() can be nice here,
+ * but also we have to think about MQ mode
+ */
+ /*
+ * 1st reference is dropped after finishing sending a "user" message,
+ * 2nd reference is dropped after confirmation with the response is
+ * returned.
+ * 1st and 2nd can happen in any order, so the rnbd_iu should be
+ * released (rtrs_permit returned to ibbtrs) only leased after both
+ * are finished.
+ */
+ atomic_set(&iu->refcount, 2);
+ init_waitqueue_head(&iu->comp.wait);
+ iu->comp.errno = INT_MAX;
+
+ return iu;
+}
+
+static void rnbd_put_iu(struct rnbd_clt_session *sess, struct rnbd_iu *iu)
+{
+ if (atomic_dec_and_test(&iu->refcount))
+ rnbd_put_permit(sess, iu->permit);
+}
+
+static void rnbd_softirq_done_fn(struct request *rq)
+{
+ struct rnbd_clt_dev *dev = rq->rq_disk->private_data;
+ struct rnbd_clt_session *sess = dev->sess;
+ struct rnbd_iu *iu;
+
+ iu = blk_mq_rq_to_pdu(rq);
+ rnbd_put_permit(sess, iu->permit);
+ blk_mq_end_request(rq, iu->status);
+}
+
+static void msg_io_conf(void *priv, int errno)
+{
+ struct rnbd_iu *iu = priv;
+ struct rnbd_clt_dev *dev = iu->dev;
+ struct request *rq = iu->rq;
+
+ iu->status = errno ? BLK_STS_IOERR : BLK_STS_OK;
+
+ blk_mq_complete_request(rq);
+
+ if (errno)
+ rnbd_clt_info_rl(dev, "%s I/O failed with err: %d\n",
+ rq_data_dir(rq) == READ ? "read" : "write",
+ errno);
+}
+
+static void wake_up_iu_comp(struct rnbd_iu *iu, int errno)
+{
+ iu->comp.errno = errno;
+ wake_up(&iu->comp.wait);
+}
+
+static void msg_conf(void *priv, int errno)
+{
+ struct rnbd_iu *iu = priv;
+
+ iu->errno = errno;
+ schedule_work(&iu->work);
+}
+
+enum {
+ NO_WAIT = 0,
+ WAIT = 1
+};
+
+static int send_usr_msg(struct rtrs_clt *rtrs, int dir,
+ struct rnbd_iu *iu, struct kvec *vec, size_t nr,
+ size_t len, struct scatterlist *sg, unsigned int sg_len,
+ void (*conf)(struct work_struct *work),
+ int *errno, bool wait)
+{
+ int err;
+
+ INIT_WORK(&iu->work, conf);
+ err = rtrs_clt_request(dir, msg_conf, rtrs, iu->permit,
+ iu, vec, nr, len, sg, sg_len);
+ if (!err && wait) {
+ wait_event(iu->comp.wait, iu->comp.errno != INT_MAX);
+ *errno = iu->comp.errno;
+ } else {
+ *errno = 0;
+ }
+
+ return err;
+}
+
+static void msg_close_conf(struct work_struct *work)
+{
+ struct rnbd_iu *iu = container_of(work, struct rnbd_iu, work);
+ struct rnbd_clt_dev *dev = iu->dev;
+
+ wake_up_iu_comp(iu, iu->errno);
+ rnbd_put_iu(dev->sess, iu);
+ rnbd_clt_put_dev(dev);
+}
+
+static int send_msg_close(struct rnbd_clt_dev *dev, u32 device_id, bool wait)
+{
+ struct rnbd_clt_session *sess = dev->sess;
+ struct rnbd_msg_close msg;
+ struct rnbd_iu *iu;
+ struct kvec vec = {
+ .iov_base = &msg,
+ .iov_len = sizeof(msg)
+ };
+ int err, errno;
+
+ iu = rnbd_get_iu(sess, RTRS_USR_CON, RTRS_PERMIT_WAIT);
+ if (unlikely(!iu))
+ return -ENOMEM;
+
+ iu->buf = NULL;
+ iu->dev = dev;
+
+ sg_mark_end(&iu->sglist[0]);
+
+ msg.hdr.type = cpu_to_le16(RNBD_MSG_CLOSE);
+ msg.device_id = cpu_to_le32(device_id);
+
+ WARN_ON(!rnbd_clt_get_dev(dev));
+ err = send_usr_msg(sess->rtrs, WRITE, iu, &vec, 1, 0, NULL, 0,
+ msg_close_conf, &errno, wait);
+ if (unlikely(err)) {
+ rnbd_clt_put_dev(dev);
+ rnbd_put_iu(sess, iu);
+ } else {
+ err = errno;
+ }
+
+ rnbd_put_iu(sess, iu);
+ return err;
+}
+
+static void msg_open_conf(struct work_struct *work)
+{
+ struct rnbd_iu *iu = container_of(work, struct rnbd_iu, work);
+ struct rnbd_msg_open_rsp *rsp = iu->buf;
+ struct rnbd_clt_dev *dev = iu->dev;
+ int errno = iu->errno;
+
+ if (errno) {
+ rnbd_clt_err(dev,
+ "Opening failed, server responded: %d\n",
+ errno);
+ } else {
+ errno = process_msg_open_rsp(dev, rsp);
+ if (unlikely(errno)) {
+ u32 device_id = le32_to_cpu(rsp->device_id);
+ /*
+ * If server thinks its fine, but we fail to process
+ * then be nice and send a close to server.
+ */
+ (void)send_msg_close(dev, device_id, NO_WAIT);
+ }
+ }
+ kfree(rsp);
+ wake_up_iu_comp(iu, errno);
+ rnbd_put_iu(dev->sess, iu);
+ rnbd_clt_put_dev(dev);
+}
+
+static void msg_sess_info_conf(struct work_struct *work)
+{
+ struct rnbd_iu *iu = container_of(work, struct rnbd_iu, work);
+ struct rnbd_msg_sess_info_rsp *rsp = iu->buf;
+ struct rnbd_clt_session *sess = iu->sess;
+
+ if (likely(!iu->errno))
+ sess->ver = min_t(u8, rsp->ver, RNBD_PROTO_VER_MAJOR);
+
+ kfree(rsp);
+ wake_up_iu_comp(iu, iu->errno);
+ rnbd_put_iu(sess, iu);
+ rnbd_clt_put_sess(sess);
+}
+
+static int send_msg_open(struct rnbd_clt_dev *dev, bool wait)
+{
+ struct rnbd_clt_session *sess = dev->sess;
+ struct rnbd_msg_open_rsp *rsp;
+ struct rnbd_msg_open msg;
+ struct rnbd_iu *iu;
+ struct kvec vec = {
+ .iov_base = &msg,
+ .iov_len = sizeof(msg)
+ };
+ int err, errno;
+
+ rsp = kzalloc(sizeof(*rsp), GFP_KERNEL);
+ if (unlikely(!rsp))
+ return -ENOMEM;
+
+ iu = rnbd_get_iu(sess, RTRS_USR_CON, RTRS_PERMIT_WAIT);
+ if (unlikely(!iu)) {
+ kfree(rsp);
+ return -ENOMEM;
+ }
+
+ iu->buf = rsp;
+ iu->dev = dev;
+
+ sg_init_one(iu->sglist, rsp, sizeof(*rsp));
+
+ msg.hdr.type = cpu_to_le16(RNBD_MSG_OPEN);
+ msg.access_mode = dev->access_mode;
+ strlcpy(msg.dev_name, dev->pathname, sizeof(msg.dev_name));
+
+ WARN_ON(!rnbd_clt_get_dev(dev));
+ err = send_usr_msg(sess->rtrs, READ, iu,
+ &vec, 1, sizeof(*rsp), iu->sglist, 1,
+ msg_open_conf, &errno, wait);
+ if (unlikely(err)) {
+ rnbd_clt_put_dev(dev);
+ rnbd_put_iu(sess, iu);
+ kfree(rsp);
+ } else {
+ err = errno;
+ }
+
+ rnbd_put_iu(sess, iu);
+ return err;
+}
+
+static int send_msg_sess_info(struct rnbd_clt_session *sess, bool wait)
+{
+ struct rnbd_msg_sess_info_rsp *rsp;
+ struct rnbd_msg_sess_info msg;
+ struct rnbd_iu *iu;
+ struct kvec vec = {
+ .iov_base = &msg,
+ .iov_len = sizeof(msg)
+ };
+ int err, errno;
+
+ rsp = kzalloc(sizeof(*rsp), GFP_KERNEL);
+ if (unlikely(!rsp))
+ return -ENOMEM;
+
+ iu = rnbd_get_iu(sess, RTRS_USR_CON, RTRS_PERMIT_WAIT);
+ if (unlikely(!iu)) {
+ kfree(rsp);
+ return -ENOMEM;
+ }
+
+ iu->buf = rsp;
+ iu->sess = sess;
+
+ sg_init_one(iu->sglist, rsp, sizeof(*rsp));
+
+ msg.hdr.type = cpu_to_le16(RNBD_MSG_SESS_INFO);
+ msg.ver = RNBD_PROTO_VER_MAJOR;
+
+ if (unlikely(!rnbd_clt_get_sess(sess))) {
+ /*
+ * That can happen only in one case, when RTRS has restablished
+ * the connection and link_ev() is called, but session is almost
+ * dead, last reference on session is put and caller is waiting
+ * for RTRS to close everything.
+ */
+ err = -ENODEV;
+ goto put_iu;
+ }
+ err = send_usr_msg(sess->rtrs, READ, iu,
+ &vec, 1, sizeof(*rsp), iu->sglist, 1,
+ msg_sess_info_conf, &errno, wait);
+ if (unlikely(err)) {
+ rnbd_clt_put_sess(sess);
+put_iu:
+ rnbd_put_iu(sess, iu);
+ kfree(rsp);
+ } else {
+ err = errno;
+ }
+
+ rnbd_put_iu(sess, iu);
+ return err;
+}
+
+static void set_dev_states_to_disconnected(struct rnbd_clt_session *sess)
+{
+ struct rnbd_clt_dev *dev;
+
+ mutex_lock(&sess->lock);
+ list_for_each_entry(dev, &sess->devs_list, list) {
+ rnbd_clt_err(dev, "Device disconnected.\n");
+
+ mutex_lock(&dev->lock);
+ if (dev->dev_state == DEV_STATE_MAPPED)
+ dev->dev_state = DEV_STATE_MAPPED_DISCONNECTED;
+ mutex_unlock(&dev->lock);
+ }
+ mutex_unlock(&sess->lock);
+}
+
+static void remap_devs(struct rnbd_clt_session *sess)
+{
+ struct rnbd_clt_dev *dev;
+ struct rtrs_attrs attrs;
+ int err;
+
+ /*
+ * Careful here: we are called from RTRS link event directly,
+ * thus we can't send any RTRS request and wait for response
+ * or RTRS will not be able to complete request with failure
+ * if something goes wrong (failing of outstanding requests
+ * happens exactly from the context where we are blocking now).
+ *
+ * So to avoid deadlocks each usr message sent from here must
+ * be asynchronous.
+ */
+
+ err = send_msg_sess_info(sess, NO_WAIT);
+ if (unlikely(err)) {
+ pr_err("send_msg_sess_info(\"%s\"): %d\n", sess->sessname, err);
+ return;
+ }
+
+ rtrs_clt_query(sess->rtrs, &attrs);
+ mutex_lock(&sess->lock);
+ sess->max_io_size = attrs.max_io_size;
+
+ list_for_each_entry(dev, &sess->devs_list, list) {
+ bool skip;
+
+ mutex_lock(&dev->lock);
+ skip = (dev->dev_state == DEV_STATE_INIT);
+ mutex_unlock(&dev->lock);
+ if (skip)
+ /*
+ * When device is establishing connection for the first
+ * time - do not remap, it will be closed soon.
+ */
+ continue;
+
+ rnbd_clt_info(dev, "session reconnected, remapping device\n");
+ err = send_msg_open(dev, NO_WAIT);
+ if (unlikely(err)) {
+ rnbd_clt_err(dev, "send_msg_open(): %d\n", err);
+ break;
+ }
+ }
+ mutex_unlock(&sess->lock);
+}
+
+static void rnbd_clt_link_ev(void *priv, enum rtrs_clt_link_ev ev)
+{
+ struct rnbd_clt_session *sess = priv;
+
+ switch (ev) {
+ case RTRS_CLT_LINK_EV_DISCONNECTED:
+ set_dev_states_to_disconnected(sess);
+ break;
+ case RTRS_CLT_LINK_EV_RECONNECTED:
+ remap_devs(sess);
+ break;
+ default:
+ pr_err("Unknown session event received (%d), session: %s\n",
+ ev, sess->sessname);
+ }
+}
+
+static void rnbd_init_cpu_qlists(struct rnbd_cpu_qlist __percpu *cpu_queues)
+{
+ unsigned int cpu;
+ struct rnbd_cpu_qlist *cpu_q;
+
+ for_each_possible_cpu(cpu) {
+ cpu_q = per_cpu_ptr(cpu_queues, cpu);
+
+ cpu_q->cpu = cpu;
+ INIT_LIST_HEAD(&cpu_q->requeue_list);
+ spin_lock_init(&cpu_q->requeue_lock);
+ }
+}
+
+static void destroy_mq_tags(struct rnbd_clt_session *sess)
+{
+ if (sess->tag_set.tags)
+ blk_mq_free_tag_set(&sess->tag_set);
+}
+
+static inline void wake_up_rtrs_waiters(struct rnbd_clt_session *sess)
+{
+ sess->rtrs_ready = true;
+ wake_up_all(&sess->rtrs_waitq);
+}
+
+static void close_rtrs(struct rnbd_clt_session *sess)
+{
+ might_sleep();
+
+ if (!IS_ERR_OR_NULL(sess->rtrs)) {
+ rtrs_clt_close(sess->rtrs);
+ sess->rtrs = NULL;
+ wake_up_rtrs_waiters(sess);
+ }
+}
+
+static void free_sess(struct rnbd_clt_session *sess)
+{
+ WARN_ON(!list_empty(&sess->devs_list));
+
+ might_sleep();
+
+ close_rtrs(sess);
+ destroy_mq_tags(sess);
+ if (!list_empty(&sess->list)) {
+ mutex_lock(&sess_lock);
+ list_del(&sess->list);
+ mutex_unlock(&sess_lock);
+ }
+ free_percpu(sess->cpu_queues);
+ free_percpu(sess->cpu_rr);
+ kfree(sess);
+}
+
+static struct rnbd_clt_session *alloc_sess(const char *sessname)
+{
+ struct rnbd_clt_session *sess;
+ int err, cpu;
+
+ sess = kzalloc_node(sizeof(*sess), GFP_KERNEL, NUMA_NO_NODE);
+ if (unlikely(!sess)) {
+ pr_err("Failed to create session %s, allocating session struct failed\n",
+ sessname);
+ return ERR_PTR(-ENOMEM);
+ }
+ strlcpy(sess->sessname, sessname, sizeof(sess->sessname));
+ atomic_set(&sess->busy, 0);
+ mutex_init(&sess->lock);
+ INIT_LIST_HEAD(&sess->devs_list);
+ INIT_LIST_HEAD(&sess->list);
+ bitmap_zero(sess->cpu_queues_bm, NR_CPUS);
+ init_waitqueue_head(&sess->rtrs_waitq);
+ refcount_set(&sess->refcount, 1);
+
+ sess->cpu_queues = alloc_percpu(struct rnbd_cpu_qlist);
+ if (unlikely(!sess->cpu_queues)) {
+ pr_err("Failed to create session to %s, alloc of percpu var (cpu_queues) failed\n",
+ sessname);
+ err = -ENOMEM;
+ goto err;
+ }
+ rnbd_init_cpu_qlists(sess->cpu_queues);
+
+ /**
+ * That is simple percpu variable which stores cpu indeces, which are
+ * incremented on each access. We need that for the sake of fairness
+ * to wake up queues in a round-robin manner.
+ */
+ sess->cpu_rr = alloc_percpu(int);
+ if (unlikely(!sess->cpu_rr)) {
+ pr_err("Failed to create session %s, alloc of percpu var (cpu_rr) failed\n",
+ sessname);
+ err = -ENOMEM;
+ goto err;
+ }
+ for_each_possible_cpu(cpu)
+ * per_cpu_ptr(sess->cpu_rr, cpu) = cpu;
+
+ return sess;
+
+err:
+ free_sess(sess);
+
+ return ERR_PTR(err);
+}
+
+static int wait_for_rtrs_connection(struct rnbd_clt_session *sess)
+{
+ wait_event(sess->rtrs_waitq, sess->rtrs_ready);
+ if (IS_ERR_OR_NULL(sess->rtrs))
+ return -ECONNRESET;
+
+ return 0;
+}
+
+static void wait_for_rtrs_disconnection(struct rnbd_clt_session *sess)
+__releases(&sess_lock)
+__acquires(&sess_lock)
+{
+ DEFINE_WAIT_FUNC(wait, autoremove_wake_function);
+
+ prepare_to_wait(&sess->rtrs_waitq, &wait, TASK_UNINTERRUPTIBLE);
+ if (IS_ERR_OR_NULL(sess->rtrs)) {
+ finish_wait(&sess->rtrs_waitq, &wait);
+ return;
+ }
+ mutex_unlock(&sess_lock);
+ /* After unlock session can be freed, so careful */
+ schedule();
+ mutex_lock(&sess_lock);
+}
+
+static struct rnbd_clt_session *__find_and_get_sess(const char *sessname)
+__releases(&sess_lock)
+__acquires(&sess_lock)
+{
+ struct rnbd_clt_session *sess;
+ int err;
+
+again:
+ list_for_each_entry(sess, &sess_list, list) {
+ if (strcmp(sessname, sess->sessname))
+ continue;
+
+ if (unlikely(sess->rtrs_ready && IS_ERR_OR_NULL(sess->rtrs)))
+ /*
+ * No RTRS connection, session is dying.
+ */
+ continue;
+
+ if (likely(rnbd_clt_get_sess(sess))) {
+ /*
+ * Alive session is found, wait for RTRS connection.
+ */
+ mutex_unlock(&sess_lock);
+ err = wait_for_rtrs_connection(sess);
+ if (unlikely(err))
+ rnbd_clt_put_sess(sess);
+ mutex_lock(&sess_lock);
+
+ if (unlikely(err))
+ /* Session is dying, repeat the loop */
+ goto again;
+
+ return sess;
+ }
+ /*
+ * Ref is 0, session is dying, wait for RTRS disconnect
+ * in order to avoid session names clashes.
+ */
+ wait_for_rtrs_disconnection(sess);
+ /*
+ * RTRS is disconnected and soon session will be freed,
+ * so repeat a loop.
+ */
+ goto again;
+ }
+
+ return NULL;
+}
+
+static struct rnbd_clt_session *find_and_get_sess(const char *sessname)
+{
+ struct rnbd_clt_session *sess;
+
+ mutex_lock(&sess_lock);
+ sess = __find_and_get_sess(sessname);
+ mutex_unlock(&sess_lock);
+
+ return sess;
+}
+
+static struct rnbd_clt_session *
+find_and_get_or_insert_sess(struct rnbd_clt_session *sess)
+{
+ struct rnbd_clt_session *found;
+
+ mutex_lock(&sess_lock);
+ found = __find_and_get_sess(sess->sessname);
+ if (!found)
+ list_add(&sess->list, &sess_list);
+ mutex_unlock(&sess_lock);
+
+ return found;
+}
+
+static int rnbd_client_open(struct block_device *block_device, fmode_t mode)
+{
+ struct rnbd_clt_dev *dev = block_device->bd_disk->private_data;
+
+ if (dev->read_only && (mode & FMODE_WRITE))
+ return -EPERM;
+
+ if (dev->dev_state == DEV_STATE_UNMAPPED ||
+ !rnbd_clt_get_dev(dev))
+ return -EIO;
+
+ return 0;
+}
+
+static void rnbd_client_release(struct gendisk *gen, fmode_t mode)
+{
+ struct rnbd_clt_dev *dev = gen->private_data;
+
+ rnbd_clt_put_dev(dev);
+}
+
+static int rnbd_client_getgeo(struct block_device *block_device,
+ struct hd_geometry *geo)
+{
+ u64 size;
+ struct rnbd_clt_dev *dev;
+
+ dev = block_device->bd_disk->private_data;
+ size = dev->size * (dev->logical_block_size / SECTOR_SIZE);
+ geo->cylinders = (size & ~0x3f) >> 6; /* size/64 */
+ geo->heads = 4;
+ geo->sectors = 16;
+ geo->start = 0;
+
+ return 0;
+}
+
+static const struct block_device_operations rnbd_client_ops = {
+ .owner = THIS_MODULE,
+ .open = rnbd_client_open,
+ .release = rnbd_client_release,
+ .getgeo = rnbd_client_getgeo
+};
+
+static size_t rnbd_clt_get_sg_size(struct scatterlist *sglist, u32 len)
+{
+ struct scatterlist *sg;
+ size_t tsize = 0;
+ int i;
+
+ for_each_sg(sglist, sg, len, i)
+ tsize += sg->length;
+ return tsize;
+}
+
+static int rnbd_client_xfer_request(struct rnbd_clt_dev *dev,
+ struct request *rq,
+ struct rnbd_iu *iu)
+{
+ struct rtrs_clt *rtrs = dev->sess->rtrs;
+ struct rtrs_permit *permit = iu->permit;
+ struct rnbd_msg_io msg;
+ unsigned int sg_cnt = 0;
+ struct kvec vec;
+ size_t size;
+ int err;
+
+ iu->rq = rq;
+ iu->dev = dev;
+ msg.sector = cpu_to_le64(blk_rq_pos(rq));
+ msg.bi_size = cpu_to_le32(blk_rq_bytes(rq));
+ msg.rw = cpu_to_le32(rq_to_rnbd_flags(rq));
+ msg.prio = cpu_to_le16(req_get_ioprio(rq));
+
+ /*
+ * We only support discards with single segment for now.
+ * See queue limits.
+ */
+ if (req_op(rq) != REQ_OP_DISCARD)
+ sg_cnt = blk_rq_map_sg(dev->queue, rq, iu->sglist);
+
+ if (sg_cnt == 0)
+ /* Do not forget to mark the end */
+ sg_mark_end(&iu->sglist[0]);
+
+ msg.hdr.type = cpu_to_le16(RNBD_MSG_IO);
+ msg.device_id = cpu_to_le32(dev->device_id);
+
+ vec = (struct kvec) {
+ .iov_base = &msg,
+ .iov_len = sizeof(msg)
+ };
+ size = rnbd_clt_get_sg_size(iu->sglist, sg_cnt);
+ err = rtrs_clt_request(rq_data_dir(rq), msg_io_conf, rtrs, permit,
+ iu, &vec, 1, size, iu->sglist, sg_cnt);
+ if (unlikely(err)) {
+ rnbd_clt_err_rl(dev, "RTRS failed to transfer IO, err: %d\n",
+ err);
+ return err;
+ }
+
+ return 0;
+}
+
+/**
+ * rnbd_clt_dev_add_to_requeue() - add device to requeue if session is busy
+ * @dev: Device to be checked
+ * @q: Queue to be added to the requeue list if required
+ *
+ * Description:
+ * If session is busy, that means someone will requeue us when resources
+ * are freed. If session is not doing anything - device is not added to
+ * the list and @false is returned.
+ */
+static inline bool rnbd_clt_dev_add_to_requeue(struct rnbd_clt_dev *dev,
+ struct rnbd_queue *q)
+{
+ struct rnbd_clt_session *sess = dev->sess;
+ struct rnbd_cpu_qlist *cpu_q;
+ unsigned long flags;
+ bool added = true;
+ bool need_set;
+
+ cpu_q = get_cpu_ptr(sess->cpu_queues);
+ spin_lock_irqsave(&cpu_q->requeue_lock, flags);
+
+ if (likely(!test_and_set_bit_lock(0, &q->in_list))) {
+ if (WARN_ON(!list_empty(&q->requeue_list)))
+ goto unlock;
+
+ need_set = !test_bit(cpu_q->cpu, sess->cpu_queues_bm);
+ if (need_set) {
+ set_bit(cpu_q->cpu, sess->cpu_queues_bm);
+ /* Paired with rnbd_put_permit(). Set a bit first
+ * and then observe the busy counter.
+ */
+ smp_mb__before_atomic();
+ }
+ if (likely(atomic_read(&sess->busy))) {
+ list_add_tail(&q->requeue_list, &cpu_q->requeue_list);
+ } else {
+ /* Very unlikely, but possible: busy counter was
+ * observed as zero. Drop all bits and return
+ * false to restart the queue by ourselves.
+ */
+ if (need_set)
+ clear_bit(cpu_q->cpu, sess->cpu_queues_bm);
+ clear_bit_unlock(0, &q->in_list);
+ added = false;
+ }
+ }
+unlock:
+ spin_unlock_irqrestore(&cpu_q->requeue_lock, flags);
+ put_cpu_ptr(sess->cpu_queues);
+
+ return added;
+}
+
+static void rnbd_clt_dev_kick_mq_queue(struct rnbd_clt_dev *dev,
+ struct blk_mq_hw_ctx *hctx,
+ int delay)
+{
+ struct rnbd_queue *q = hctx->driver_data;
+
+ if (delay != RNBD_DELAY_IFBUSY)
+ blk_mq_delay_run_hw_queue(hctx, delay);
+ else if (unlikely(!rnbd_clt_dev_add_to_requeue(dev, q)))
+ /*
+ * If session is not busy we have to restart
+ * the queue ourselves.
+ */
+ blk_mq_delay_run_hw_queue(hctx, RNBD_DELAY_10ms);
+}
+
+static blk_status_t rnbd_queue_rq(struct blk_mq_hw_ctx *hctx,
+ const struct blk_mq_queue_data *bd)
+{
+ struct request *rq = bd->rq;
+ struct rnbd_clt_dev *dev = rq->rq_disk->private_data;
+ struct rnbd_iu *iu = blk_mq_rq_to_pdu(rq);
+ int err;
+
+ if (unlikely(!rnbd_clt_dev_is_mapped(dev)))
+ return BLK_STS_IOERR;
+
+ iu->permit = rnbd_get_permit(dev->sess, RTRS_IO_CON,
+ RTRS_PERMIT_NOWAIT);
+ if (unlikely(!iu->permit)) {
+ rnbd_clt_dev_kick_mq_queue(dev, hctx, RNBD_DELAY_IFBUSY);
+ return BLK_STS_RESOURCE;
+ }
+
+ blk_mq_start_request(rq);
+ err = rnbd_client_xfer_request(dev, rq, iu);
+ if (likely(err == 0))
+ return BLK_STS_OK;
+ if (unlikely(err == -EAGAIN || err == -ENOMEM)) {
+ rnbd_clt_dev_kick_mq_queue(dev, hctx, RNBD_DELAY_10ms);
+ rnbd_put_permit(dev->sess, iu->permit);
+ return BLK_STS_RESOURCE;
+ }
+
+ rnbd_put_permit(dev->sess, iu->permit);
+ return BLK_STS_IOERR;
+}
+
+static int rnbd_init_request(struct blk_mq_tag_set *set, struct request *rq,
+ unsigned int hctx_idx, unsigned int numa_node)
+{
+ struct rnbd_iu *iu = blk_mq_rq_to_pdu(rq);
+
+ sg_init_table(iu->sglist, BMAX_SEGMENTS);
+ return 0;
+}
+
+static struct blk_mq_ops rnbd_mq_ops = {
+ .queue_rq = rnbd_queue_rq,
+ .init_request = rnbd_init_request,
+ .complete = rnbd_softirq_done_fn,
+};
+
+static int setup_mq_tags(struct rnbd_clt_session *sess)
+{
+ struct blk_mq_tag_set *tags = &sess->tag_set;
+
+ memset(tags, 0, sizeof(*tags));
+ tags->ops = &rnbd_mq_ops;
+ tags->queue_depth = sess->queue_depth;
+ tags->numa_node = NUMA_NO_NODE;
+ tags->flags = BLK_MQ_F_SHOULD_MERGE |
+ BLK_MQ_F_TAG_SHARED;
+ tags->cmd_size = sizeof(struct rnbd_iu);
+ tags->nr_hw_queues = num_online_cpus();
+
+ return blk_mq_alloc_tag_set(tags);
+}
+
+static struct rnbd_clt_session *
+find_and_get_or_create_sess(const char *sessname,
+ const struct rtrs_addr *paths,
+ size_t path_cnt)
+{
+ struct rnbd_clt_session *sess, *found;
+ struct rtrs_attrs attrs;
+ int err;
+
+ sess = find_and_get_sess(sessname);
+ if (sess)
+ return sess;
+
+ sess = alloc_sess(sessname);
+ if (IS_ERR(sess))
+ return sess;
+
+ found = find_and_get_or_insert_sess(sess);
+ if (unlikely(found)) {
+ free_sess(sess);
+
+ return found;
+ }
+ /*
+ * Nothing was found, establish rtrs connection and proceed further.
+ */
+ sess->rtrs = rtrs_clt_open(sess, rnbd_clt_link_ev, sessname,
+ paths, path_cnt, RTRS_PORT,
+ sizeof(struct rnbd_iu),
+ RECONNECT_DELAY, BMAX_SEGMENTS,
+ MAX_RECONNECTS);
+ if (IS_ERR(sess->rtrs)) {
+ err = PTR_ERR(sess->rtrs);
+ goto wake_up_and_put;
+ }
+ rtrs_clt_query(sess->rtrs, &attrs);
+ sess->max_io_size = attrs.max_io_size;
+ sess->queue_depth = attrs.queue_depth;
+
+ err = setup_mq_tags(sess);
+ if (unlikely(err))
+ goto close_rtrs;
+
+ err = send_msg_sess_info(sess, WAIT);
+ if (unlikely(err))
+ goto close_rtrs;
+
+ wake_up_rtrs_waiters(sess);
+
+ return sess;
+
+close_rtrs:
+ close_rtrs(sess);
+put_sess:
+ rnbd_clt_put_sess(sess);
+
+ return ERR_PTR(err);
+
+wake_up_and_put:
+ wake_up_rtrs_waiters(sess);
+ goto put_sess;
+}
+
+static inline void rnbd_init_hw_queue(struct rnbd_clt_dev *dev,
+ struct rnbd_queue *q,
+ struct blk_mq_hw_ctx *hctx)
+{
+ INIT_LIST_HEAD(&q->requeue_list);
+ q->dev = dev;
+ q->hctx = hctx;
+}
+
+static void rnbd_init_mq_hw_queues(struct rnbd_clt_dev *dev)
+{
+ int i;
+ struct blk_mq_hw_ctx *hctx;
+ struct rnbd_queue *q;
+
+ queue_for_each_hw_ctx(dev->queue, hctx, i) {
+ q = &dev->hw_queues[i];
+ rnbd_init_hw_queue(dev, q, hctx);
+ hctx->driver_data = q;
+ }
+}
+
+static int index_to_minor(int index)
+{
+ return index << RNBD_PART_BITS;
+}
+
+static int minor_to_index(int minor)
+{
+ return minor >> RNBD_PART_BITS;
+}
+
+static int setup_mq_dev(struct rnbd_clt_dev *dev)
+{
+ dev->queue = blk_mq_init_queue(&dev->sess->tag_set);
+ if (IS_ERR(dev->queue)) {
+ rnbd_clt_err(dev, "Initializing multiqueue queue failed, err: %ld\n",
+ PTR_ERR(dev->queue));
+ return PTR_ERR(dev->queue);
+ }
+ rnbd_init_mq_hw_queues(dev);
+ return 0;
+}
+
+static void setup_request_queue(struct rnbd_clt_dev *dev)
+{
+ blk_queue_logical_block_size(dev->queue, dev->logical_block_size);
+ blk_queue_physical_block_size(dev->queue, dev->physical_block_size);
+ blk_queue_max_hw_sectors(dev->queue, dev->max_hw_sectors);
+ blk_queue_max_write_same_sectors(dev->queue,
+ dev->max_write_same_sectors);
+
+ /*
+ * we don't support discards to "discontiguous" segments
+ * in on request
+ */
+ blk_queue_max_discard_segments(dev->queue, 1);
+
+ blk_queue_max_discard_sectors(dev->queue, dev->max_discard_sectors);
+ dev->queue->limits.discard_granularity = dev->discard_granularity;
+ dev->queue->limits.discard_alignment = dev->discard_alignment;
+ if (dev->max_discard_sectors)
+ blk_queue_flag_set(QUEUE_FLAG_DISCARD, dev->queue);
+ if (dev->secure_discard)
+ blk_queue_flag_set(QUEUE_FLAG_SECERASE, dev->queue);
+
+ blk_queue_flag_set(QUEUE_FLAG_SAME_COMP, dev->queue);
+ blk_queue_flag_set(QUEUE_FLAG_SAME_FORCE, dev->queue);
+ blk_queue_max_segments(dev->queue, dev->max_segments);
+ blk_queue_io_opt(dev->queue, dev->sess->max_io_size);
+ blk_queue_virt_boundary(dev->queue, 4095);
+ blk_queue_write_cache(dev->queue, true, true);
+ dev->queue->queuedata = dev;
+}
+
+static void rnbd_clt_setup_gen_disk(struct rnbd_clt_dev *dev, int idx)
+{
+ dev->gd->major = rnbd_client_major;
+ dev->gd->first_minor = index_to_minor(idx);
+ dev->gd->fops = &rnbd_client_ops;
+ dev->gd->queue = dev->queue;
+ dev->gd->private_data = dev;
+ snprintf(dev->gd->disk_name, sizeof(dev->gd->disk_name), "rnbd%d",
+ idx);
+ pr_debug("disk_name=%s, capacity=%zu\n",
+ dev->gd->disk_name,
+ dev->nsectors * (dev->logical_block_size / SECTOR_SIZE)
+ );
+
+ set_capacity(dev->gd, dev->nsectors * (dev->logical_block_size /
+ SECTOR_SIZE));
+
+ if (dev->access_mode == RNBD_ACCESS_RO) {
+ dev->read_only = true;
+ set_disk_ro(dev->gd, true);
+ } else {
+ dev->read_only = false;
+ }
+
+ if (!dev->rotational)
+ blk_queue_flag_set(QUEUE_FLAG_NONROT, dev->queue);
+}
+
+static void rnbd_clt_add_gen_disk(struct rnbd_clt_dev *dev)
+{
+ add_disk(dev->gd);
+}
+
+static int rnbd_client_setup_device(struct rnbd_clt_session *sess,
+ struct rnbd_clt_dev *dev, int idx)
+{
+ int err;
+
+ dev->size = dev->nsectors * dev->logical_block_size;
+
+ err = setup_mq_dev(dev);
+ if (err)
+ return err;
+
+ setup_request_queue(dev);
+
+ dev->gd = alloc_disk_node(1 << RNBD_PART_BITS, NUMA_NO_NODE);
+ if (!dev->gd) {
+ rnbd_clt_err(dev, "Failed to allocate disk node\n");
+ blk_cleanup_queue(dev->queue);
+ return -ENOMEM;
+ }
+
+ rnbd_clt_setup_gen_disk(dev, idx);
+
+ return 0;
+}
+
+static struct rnbd_clt_dev *init_dev(struct rnbd_clt_session *sess,
+ enum rnbd_access_mode access_mode,
+ const char *pathname)
+{
+ struct rnbd_clt_dev *dev;
+ int ret;
+
+ dev = kzalloc_node(sizeof(*dev), GFP_KERNEL, NUMA_NO_NODE);
+ if (!dev)
+ return ERR_PTR(-ENOMEM);
+
+ dev->hw_queues = kcalloc(nr_cpu_ids, sizeof(*dev->hw_queues),
+ GFP_KERNEL);
+ if (unlikely(!dev->hw_queues)) {
+ pr_err("Failed to initialize device '%s' from session %s, allocating hw_queues failed.",
+ pathname, sess->sessname);
+ ret = -ENOMEM;
+ goto out_alloc;
+ }
+
+ mutex_lock(&ida_lock);
+ ret = ida_simple_get(&index_ida, 0, minor_to_index(1 << MINORBITS),
+ GFP_KERNEL);
+ mutex_unlock(&ida_lock);
+ if (ret < 0) {
+ pr_err("Failed to initialize device '%s' from session %s, allocating idr failed, err: %d\n",
+ pathname, sess->sessname, ret);
+ goto out_queues;
+ }
+ dev->clt_device_id = ret;
+ dev->sess = sess;
+ dev->access_mode = access_mode;
+ strlcpy(dev->pathname, pathname, sizeof(dev->pathname));
+ mutex_init(&dev->lock);
+ refcount_set(&dev->refcount, 1);
+ dev->dev_state = DEV_STATE_INIT;
+
+ /*
+ * Here we called from sysfs entry, thus clt-sysfs is
+ * responsible that session will not disappear.
+ */
+ WARN_ON(!rnbd_clt_get_sess(sess));
+
+ return dev;
+
+out_queues:
+ kfree(dev->hw_queues);
+out_alloc:
+ kfree(dev);
+ return ERR_PTR(ret);
+}
+
+static bool __exists_dev(const char *pathname)
+{
+ struct rnbd_clt_session *sess;
+ struct rnbd_clt_dev *dev;
+ bool found = false;
+
+ list_for_each_entry(sess, &sess_list, list) {
+ mutex_lock(&sess->lock);
+ list_for_each_entry(dev, &sess->devs_list, list) {
+ if (!strncmp(dev->pathname, pathname,
+ sizeof(dev->pathname))) {
+ found = true;
+ break;
+ }
+ }
+ mutex_unlock(&sess->lock);
+ if (found)
+ break;
+ }
+
+ return found;
+}
+
+static bool exists_devpath(const char *pathname)
+{
+ bool found;
+
+ mutex_lock(&sess_lock);
+ found = __exists_dev(pathname);
+ mutex_unlock(&sess_lock);
+
+ return found;
+}
+
+static bool insert_dev_if_not_exists_devpath(const char *pathname,
+ struct rnbd_clt_session *sess,
+ struct rnbd_clt_dev *dev)
+{
+ bool found;
+
+ mutex_lock(&sess_lock);
+ found = __exists_dev(pathname);
+ if (!found) {
+ mutex_lock(&sess->lock);
+ list_add_tail(&dev->list, &sess->devs_list);
+ mutex_unlock(&sess->lock);
+ }
+ mutex_unlock(&sess_lock);
+
+ return found;
+}
+
+static void delete_dev(struct rnbd_clt_dev *dev)
+{
+ struct rnbd_clt_session *sess = dev->sess;
+
+ mutex_lock(&sess->lock);
+ list_del(&dev->list);
+ mutex_unlock(&sess->lock);
+}
+
+struct rnbd_clt_dev *rnbd_clt_map_device(const char *sessname,
+ struct rtrs_addr *paths,
+ size_t path_cnt,
+ const char *pathname,
+ enum rnbd_access_mode access_mode)
+{
+ struct rnbd_clt_session *sess;
+ struct rnbd_clt_dev *dev;
+ int ret;
+
+ if (unlikely(exists_devpath(pathname)))
+ return ERR_PTR(-EEXIST);
+
+ sess = find_and_get_or_create_sess(sessname, paths, path_cnt);
+ if (IS_ERR(sess))
+ return ERR_CAST(sess);
+
+ dev = init_dev(sess, access_mode, pathname);
+ if (IS_ERR(dev)) {
+ pr_err("map_device: failed to map device '%s' from session %s, can't initialize device, err: %ld\n",
+ pathname, sess->sessname, PTR_ERR(dev));
+ ret = PTR_ERR(dev);
+ goto put_sess;
+ }
+ if (unlikely(insert_dev_if_not_exists_devpath(pathname, sess, dev))) {
+ ret = -EEXIST;
+ goto put_dev;
+ }
+ ret = send_msg_open(dev, WAIT);
+ if (unlikely(ret)) {
+ rnbd_clt_err(dev,
+ "map_device: failed, can't open remote device, err: %d\n",
+ ret);
+ goto del_dev;
+ }
+ mutex_lock(&dev->lock);
+ pr_debug("Opened remote device: session=%s, path='%s'\n",
+ sess->sessname, pathname);
+ ret = rnbd_client_setup_device(sess, dev, dev->clt_device_id);
+ if (ret) {
+ rnbd_clt_err(dev,
+ "map_device: Failed to configure device, err: %d\n",
+ ret);
+ mutex_unlock(&dev->lock);
+ goto del_dev;
+ }
+
+ rnbd_clt_info(dev,
+ "map_device: Device mapped as %s (nsectors: %zu, logical_block_size: %d, physical_block_size: %d, max_write_same_sectors: %d, max_discard_sectors: %d, discard_granularity: %d, discard_alignment: %d, secure_discard: %d, max_segments: %d, max_hw_sectors: %d, rotational: %d)\n",
+ dev->gd->disk_name, dev->nsectors,
+ dev->logical_block_size, dev->physical_block_size,
+ dev->max_write_same_sectors, dev->max_discard_sectors,
+ dev->discard_granularity, dev->discard_alignment,
+ dev->secure_discard, dev->max_segments,
+ dev->max_hw_sectors, dev->rotational);
+
+ mutex_unlock(&dev->lock);
+
+ rnbd_clt_add_gen_disk(dev);
+ rnbd_clt_put_sess(sess);
+
+ return dev;
+
+del_dev:
+ delete_dev(dev);
+put_dev:
+ rnbd_clt_put_dev(dev);
+put_sess:
+ rnbd_clt_put_sess(sess);
+
+ return ERR_PTR(ret);
+}
+
+static void destroy_gen_disk(struct rnbd_clt_dev *dev)
+{
+ del_gendisk(dev->gd);
+ blk_cleanup_queue(dev->queue);
+ put_disk(dev->gd);
+}
+
+static void destroy_sysfs(struct rnbd_clt_dev *dev,
+ const struct attribute *sysfs_self)
+{
+ rnbd_clt_remove_dev_symlink(dev);
+ if (dev->kobj.state_initialized) {
+ if (sysfs_self)
+ /* To avoid deadlock firstly remove itself */
+ sysfs_remove_file_self(&dev->kobj, sysfs_self);
+ kobject_del(&dev->kobj);
+ kobject_put(&dev->kobj);
+ }
+}
+
+int rnbd_clt_unmap_device(struct rnbd_clt_dev *dev, bool force,
+ const struct attribute *sysfs_self)
+{
+ struct rnbd_clt_session *sess = dev->sess;
+ int refcount, ret = 0;
+ bool was_mapped;
+
+ mutex_lock(&dev->lock);
+ if (dev->dev_state == DEV_STATE_UNMAPPED) {
+ rnbd_clt_info(dev, "Device is already being unmapped\n");
+ ret = -EALREADY;
+ goto err;
+ }
+ refcount = refcount_read(&dev->refcount);
+ if (!force && refcount > 1) {
+ rnbd_clt_err(dev,
+ "Closing device failed, device is in use, (%d device users)\n",
+ refcount - 1);
+ ret = -EBUSY;
+ goto err;
+ }
+ was_mapped = (dev->dev_state == DEV_STATE_MAPPED);
+ dev->dev_state = DEV_STATE_UNMAPPED;
+ mutex_unlock(&dev->lock);
+
+ delete_dev(dev);
+ destroy_sysfs(dev, sysfs_self);
+ destroy_gen_disk(dev);
+ if (was_mapped && sess->rtrs)
+ send_msg_close(dev, dev->device_id, WAIT);
+
+ rnbd_clt_info(dev, "Device is unmapped\n");
+
+ /* Likely last reference put */
+ rnbd_clt_put_dev(dev);
+
+ /*
+ * Here device and session can be vanished!
+ */
+
+ return 0;
+err:
+ mutex_unlock(&dev->lock);
+
+ return ret;
+}
+
+int rnbd_clt_remap_device(struct rnbd_clt_dev *dev)
+{
+ int err;
+
+ mutex_lock(&dev->lock);
+ if (likely(dev->dev_state == DEV_STATE_MAPPED_DISCONNECTED))
+ err = 0;
+ else if (dev->dev_state == DEV_STATE_UNMAPPED)
+ err = -ENODEV;
+ else if (dev->dev_state == DEV_STATE_MAPPED)
+ err = -EALREADY;
+ else
+ err = -EBUSY;
+ mutex_unlock(&dev->lock);
+ if (likely(!err)) {
+ rnbd_clt_info(dev, "Remapping device.\n");
+ err = send_msg_open(dev, WAIT);
+ if (unlikely(err))
+ rnbd_clt_err(dev, "remap_device: %d\n", err);
+ }
+
+ return err;
+}
+
+static void unmap_device_work(struct work_struct *work)
+{
+ struct rnbd_clt_dev *dev;
+
+ dev = container_of(work, typeof(*dev), unmap_on_rmmod_work);
+ rnbd_clt_unmap_device(dev, true, NULL);
+}
+
+static void rnbd_destroy_sessions(void)
+{
+ struct rnbd_clt_session *sess, *sn;
+ struct rnbd_clt_dev *dev, *tn;
+
+ /* Firstly forbid access through sysfs interface */
+ rnbd_clt_destroy_default_group();
+ rnbd_clt_destroy_sysfs_files();
+
+ /*
+ * Here at this point there is no any concurrent access to sessions
+ * list and devices list:
+ * 1. New session or device can'be be created - session sysfs files
+ * are removed.
+ * 2. Device or session can't be removed - module reference is taken
+ * into account in unmap device sysfs callback.
+ * 3. No IO requests inflight - each file open of block_dev increases
+ * module reference in get_disk().
+ *
+ * But still there can be user requests inflights, which are sent by
+ * asynchronous send_msg_*() functions, thus before unmapping devices
+ * RTRS session must be explicitly closed.
+ */
+
+ list_for_each_entry_safe(sess, sn, &sess_list, list) {
+ WARN_ON(!rnbd_clt_get_sess(sess));
+ close_rtrs(sess);
+ list_for_each_entry_safe(dev, tn, &sess->devs_list, list) {
+ /*
+ * Here unmap happens in parallel for only one reason:
+ * blk_cleanup_queue() takes around half a second, so
+ * on huge amount of devices the whole module unload
+ * procedure takes minutes.
+ */
+ INIT_WORK(&dev->unmap_on_rmmod_work, unmap_device_work);
+ queue_work(system_long_wq, &dev->unmap_on_rmmod_work);
+ }
+ rnbd_clt_put_sess(sess);
+ }
+ /* Wait for all scheduled unmap works */
+ flush_workqueue(system_long_wq);
+ WARN_ON(!list_empty(&sess_list));
+}
+
+static int __init rnbd_client_init(void)
+{
+ int err = 0;
+
+ pr_info("Loading module %s, proto %s:\n",
+ KBUILD_MODNAME, RNBD_PROTO_VER_STRING);
+
+ rnbd_client_major = register_blkdev(rnbd_client_major, "rnbd");
+ if (rnbd_client_major <= 0) {
+ pr_err("Failed to load module, block device registration failed\n");
+ return -EBUSY;
+ }
+
+ err = rnbd_clt_create_sysfs_files();
+ if (err) {
+ pr_err("Failed to load module, creating sysfs device files failed, err: %d\n",
+ err);
+ unregister_blkdev(rnbd_client_major, "rnbd");
+ }
+
+ return err;
+}
+
+static void __exit rnbd_client_exit(void)
+{
+ pr_info("Unloading module\n");
+ rnbd_destroy_sessions();
+ unregister_blkdev(rnbd_client_major, "rnbd");
+ ida_destroy(&index_ida);
+ pr_info("Module unloaded\n");
+}
+
+module_init(rnbd_client_init);
+module_exit(rnbd_client_exit);
--
2.17.1