fs/smb/smbdirect/mr.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   Copyright (C) 2017, Microsoft Corporation.
 *   Copyright (c) 2025, Stefan Metzmacher
 */

#include "internal.h"

/*
 * Allocate MRs used for RDMA read/write
 * The number of MRs will not exceed hardware capability in responder_resources
 * All MRs are kept in mr_list. The MR can be recovered after it's used
 * Recovery is done in smbd_mr_recovery_work. The content of list entry changes
 * as MRs are used and recovered for I/O, but the list links will not change
 */
int smbdirect_connection_create_mr_list(struct smbdirect_socket *sc)
{
	const struct smbdirect_socket_parameters *sp = &sc->parameters;
	struct smbdirect_mr_io *mr;
	int ret;
	u32 i;

	if (sp->responder_resources == 0) {
		smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
			"responder_resources negotiated as 0\n");
		return -EINVAL;
	}

	/* Allocate more MRs (2x) than hardware responder_resources */
	for (i = 0; i < sp->responder_resources * 2; i++) {
		mr = kzalloc_obj(*mr);
		if (!mr) {
			ret = -ENOMEM;
			goto kzalloc_mr_failed;
		}

		kref_init(&mr->kref);
		mutex_init(&mr->mutex);

		mr->mr = ib_alloc_mr(sc->ib.pd,
				     sc->mr_io.type,
				     sp->max_frmr_depth);
		if (IS_ERR(mr->mr)) {
			ret = PTR_ERR(mr->mr);
			smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
				"ib_alloc_mr failed ret=%d (%1pe) type=0x%x max_frmr_depth=%u\n",
				ret, SMBDIRECT_DEBUG_ERR_PTR(ret),
				sc->mr_io.type, sp->max_frmr_depth);
			goto ib_alloc_mr_failed;
		}
		mr->sgt.sgl = kzalloc_objs(struct scatterlist, sp->max_frmr_depth);
		if (!mr->sgt.sgl) {
			ret = -ENOMEM;
			smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
				"failed to allocate sgl, max_frmr_depth=%u\n",
				sp->max_frmr_depth);
			goto kcalloc_sgl_failed;
		}
		mr->state = SMBDIRECT_MR_READY;
		mr->socket = sc;

		list_add_tail(&mr->list, &sc->mr_io.all.list);
		atomic_inc(&sc->mr_io.ready.count);
	}

	return 0;

kcalloc_sgl_failed:
	ib_dereg_mr(mr->mr);
ib_alloc_mr_failed:
	mutex_destroy(&mr->mutex);
	kfree(mr);
kzalloc_mr_failed:
	smbdirect_connection_destroy_mr_list(sc);
	return ret;
}

static void smbdirect_mr_io_disable_locked(struct smbdirect_mr_io *mr)
{
	struct smbdirect_socket *sc = mr->socket;

	lockdep_assert_held(&mr->mutex);

	if (mr->state == SMBDIRECT_MR_DISABLED)
		return;

	if (mr->mr)
		ib_dereg_mr(mr->mr);
	if (mr->sgt.nents)
		ib_dma_unmap_sg(sc->ib.dev, mr->sgt.sgl, mr->sgt.nents, mr->dir);
	kfree(mr->sgt.sgl);

	mr->mr = NULL;
	mr->sgt.sgl = NULL;
	mr->sgt.nents = 0;

	mr->state = SMBDIRECT_MR_DISABLED;
}

static void smbdirect_mr_io_free_locked(struct kref *kref)
{
	struct smbdirect_mr_io *mr =
		container_of(kref, struct smbdirect_mr_io, kref);

	lockdep_assert_held(&mr->mutex);

	/*
	 * smbdirect_mr_io_disable_locked() should already be called!
	 */
	if (WARN_ON_ONCE(mr->state != SMBDIRECT_MR_DISABLED))
		smbdirect_mr_io_disable_locked(mr);

	mutex_unlock(&mr->mutex);
	mutex_destroy(&mr->mutex);
	kfree(mr);
}

void smbdirect_connection_destroy_mr_list(struct smbdirect_socket *sc)
{
	struct smbdirect_mr_io *mr, *tmp;
	LIST_HEAD(all_list);
	unsigned long flags;

	spin_lock_irqsave(&sc->mr_io.all.lock, flags);
	list_splice_tail_init(&sc->mr_io.all.list, &all_list);
	spin_unlock_irqrestore(&sc->mr_io.all.lock, flags);

	list_for_each_entry_safe(mr, tmp, &all_list, list) {
		mutex_lock(&mr->mutex);

		smbdirect_mr_io_disable_locked(mr);
		list_del(&mr->list);
		mr->socket = NULL;

		/*
		 * No kref_put_mutex() as it's already locked.
		 *
		 * If smbdirect_mr_io_free_locked() is called
		 * and the mutex is unlocked and mr is gone,
		 * in that case kref_put() returned 1.
		 *
		 * If kref_put() returned 0 we know that
		 * smbdirect_mr_io_free_locked() didn't
		 * run. Not by us nor by anyone else, as we
		 * still hold the mutex, so we need to unlock.
		 *
		 * If the mr is still registered it will
		 * be dangling (detached from the connection
		 * waiting for smbd_deregister_mr() to be
		 * called in order to free the memory.
		 */
		if (!kref_put(&mr->kref, smbdirect_mr_io_free_locked))
			mutex_unlock(&mr->mutex);
	}
}

/*
 * Get a MR from mr_list. This function waits until there is at least one MR
 * available in the list. There may be several CPUs issuing I/O trying to get MR
 * at the same time, mr_list_lock is used to protect this situation.
 */
static struct smbdirect_mr_io *
smbdirect_connection_get_mr_io(struct smbdirect_socket *sc)
{
	struct smbdirect_mr_io *mr;
	unsigned long flags;
	int ret;

again:
	ret = wait_event_interruptible(sc->mr_io.ready.wait_queue,
				       atomic_read(&sc->mr_io.ready.count) ||
				       sc->status != SMBDIRECT_SOCKET_CONNECTED);
	if (ret) {
		smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
			"wait_event_interruptible ret=%d (%1pe)\n",
			ret, SMBDIRECT_DEBUG_ERR_PTR(ret));
		return NULL;
	}

	if (sc->status != SMBDIRECT_SOCKET_CONNECTED) {
		smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
			"sc->status=%s sc->first_error=%1pe\n",
			smbdirect_socket_status_string(sc->status),
			SMBDIRECT_DEBUG_ERR_PTR(sc->first_error));
		return NULL;
	}

	spin_lock_irqsave(&sc->mr_io.all.lock, flags);
	list_for_each_entry(mr, &sc->mr_io.all.list, list) {
		if (mr->state == SMBDIRECT_MR_READY) {
			mr->state = SMBDIRECT_MR_REGISTERED;
			kref_get(&mr->kref);
			spin_unlock_irqrestore(&sc->mr_io.all.lock, flags);
			atomic_dec(&sc->mr_io.ready.count);
			atomic_inc(&sc->mr_io.used.count);
			return mr;
		}
	}

	spin_unlock_irqrestore(&sc->mr_io.all.lock, flags);
	/*
	 * It is possible that we could fail to get MR because other processes may
	 * try to acquire a MR at the same time. If this is the case, retry it.
	 */
	goto again;
}

static void smbdirect_connection_mr_io_register_done(struct ib_cq *cq, struct ib_wc *wc)
{
	struct smbdirect_mr_io *mr =
		container_of(wc->wr_cqe, struct smbdirect_mr_io, cqe);
	struct smbdirect_socket *sc = mr->socket;

	if (wc->status != IB_WC_SUCCESS) {
		smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
			"wc->status=%s opcode=%d\n",
			ib_wc_status_msg(wc->status), wc->opcode);
		smbdirect_socket_schedule_cleanup(sc, -ECONNABORTED);
	}
}

static void smbdirect_connection_mr_io_local_inv_done(struct ib_cq *cq, struct ib_wc *wc)
{
	struct smbdirect_mr_io *mr =
		container_of(wc->wr_cqe, struct smbdirect_mr_io, cqe);
	struct smbdirect_socket *sc = mr->socket;

	mr->state = SMBDIRECT_MR_INVALIDATED;
	if (wc->status != IB_WC_SUCCESS) {
		smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
			"invalidate failed status=%s\n",
			ib_wc_status_msg(wc->status));
		smbdirect_socket_schedule_cleanup(sc, -ECONNABORTED);
	}
	complete(&mr->invalidate_done);
}

/*
 * Transcribe the pages from an iterator into an MR scatterlist.
 */
static int smbdirect_iter_to_sgt(struct iov_iter *iter,
				 struct sg_table *sgt,
				 unsigned int max_sg)
{
	int ret;

	memset(sgt->sgl, 0, max_sg * sizeof(struct scatterlist));

	ret = extract_iter_to_sg(iter, iov_iter_count(iter), sgt, max_sg, 0);
	WARN_ON(ret < 0);
	if (sgt->nents > 0)
		sg_mark_end(&sgt->sgl[sgt->nents - 1]);

	return ret;
}

/*
 * Register memory for RDMA read/write
 * iter: the buffer to register memory with
 * writing: true if this is a RDMA write (SMB read), false for RDMA read
 * need_invalidate: true if this MR needs to be locally invalidated after I/O
 * return value: the MR registered, NULL if failed.
 */
struct smbdirect_mr_io *
smbdirect_connection_register_mr_io(struct smbdirect_socket *sc,
				    struct iov_iter *iter,
				    bool writing,
				    bool need_invalidate)
{
	const struct smbdirect_socket_parameters *sp = &sc->parameters;
	struct smbdirect_mr_io *mr;
	int ret, num_pages, num_mapped;
	struct ib_reg_wr *reg_wr;

	num_pages = iov_iter_npages(iter, sp->max_frmr_depth + 1);
	if (num_pages > sp->max_frmr_depth) {
		smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
			"num_pages=%d max_frmr_depth=%d\n",
			num_pages, sp->max_frmr_depth);
		WARN_ON_ONCE(1);
		return NULL;
	}

	mr = smbdirect_connection_get_mr_io(sc);
	if (!mr) {
		smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
			"smbdirect_connection_get_mr_io returning NULL\n");
		return NULL;
	}

	mutex_lock(&mr->mutex);

	mr->dir = writing ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
	mr->need_invalidate = need_invalidate;
	mr->sgt.nents = 0;
	mr->sgt.orig_nents = 0;

	smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_INFO,
		"num_pages=%u count=%zu depth=%u\n",
		num_pages, iov_iter_count(iter), sp->max_frmr_depth);
	smbdirect_iter_to_sgt(iter, &mr->sgt, sp->max_frmr_depth);

	num_mapped = ib_dma_map_sg(sc->ib.dev, mr->sgt.sgl, mr->sgt.nents, mr->dir);
	if (!num_mapped) {
		smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
			"ib_dma_map_sg num_pages=%u dir=%x num_mapped=%d\n",
			num_pages, mr->dir, num_mapped);
		ret = -EIO;
		goto dma_map_error;
	}

	ret = ib_map_mr_sg(mr->mr, mr->sgt.sgl, num_mapped, NULL, PAGE_SIZE);
	if (ret != num_mapped) {
		smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
			"ib_map_mr_sg failed ret = %d num_mapped = %u\n",
			ret, num_mapped);
		if (ret >= 0)
			ret = -EIO;
		goto map_mr_error;
	}

	ib_update_fast_reg_key(mr->mr, ib_inc_rkey(mr->mr->rkey));
	reg_wr = &mr->wr;
	reg_wr->wr.opcode = IB_WR_REG_MR;
	mr->cqe.done = smbdirect_connection_mr_io_register_done;
	reg_wr->wr.wr_cqe = &mr->cqe;
	reg_wr->wr.num_sge = 0;
	reg_wr->wr.send_flags = IB_SEND_SIGNALED;
	reg_wr->mr = mr->mr;
	reg_wr->key = mr->mr->rkey;
	reg_wr->access = writing ?
			IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
			IB_ACCESS_REMOTE_READ;

	/*
	 * There is no need for waiting for complemtion on ib_post_send
	 * on IB_WR_REG_MR. Hardware enforces a barrier and order of execution
	 * on the next ib_post_send when we actually send I/O to remote peer
	 */
	ret = ib_post_send(sc->ib.qp, &reg_wr->wr, NULL);
	if (!ret) {
		/*
		 * smbdirect_connection_get_mr_io() gave us a reference
		 * via kref_get(&mr->kref), we keep that and let
		 * the caller use smbdirect_connection_deregister_mr_io()
		 * to remove it again.
		 */
		mutex_unlock(&mr->mutex);
		return mr;
	}

	smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
		"ib_post_send failed ret=%d (%1pe) reg_wr->key=0x%x\n",
		ret, SMBDIRECT_DEBUG_ERR_PTR(ret), reg_wr->key);

map_mr_error:
	ib_dma_unmap_sg(sc->ib.dev, mr->sgt.sgl, mr->sgt.nents, mr->dir);

dma_map_error:
	mr->sgt.nents = 0;
	mr->state = SMBDIRECT_MR_ERROR;
	atomic_dec(&sc->mr_io.used.count);

	smbdirect_socket_schedule_cleanup(sc, ret);

	/*
	 * smbdirect_connection_get_mr_io() gave us a reference
	 * via kref_get(&mr->kref), we need to remove it again
	 * on error.
	 *
	 * No kref_put_mutex() as it's already locked.
	 *
	 * If smbdirect_mr_io_free_locked() is called
	 * and the mutex is unlocked and mr is gone,
	 * in that case kref_put() returned 1.
	 *
	 * If kref_put() returned 0 we know that
	 * smbdirect_mr_io_free_locked() didn't
	 * run. Not by us nor by anyone else, as we
	 * still hold the mutex, so we need to unlock.
	 */
	if (!kref_put(&mr->kref, smbdirect_mr_io_free_locked))
		mutex_unlock(&mr->mutex);
	return NULL;
}
EXPORT_SYMBOL_GPL(smbdirect_connection_register_mr_io);

void smbdirect_mr_io_fill_buffer_descriptor(struct smbdirect_mr_io *mr,
					    struct smbdirect_buffer_descriptor_v1 *v1)
{
	mutex_lock(&mr->mutex);
	if (mr->state == SMBDIRECT_MR_REGISTERED) {
		v1->offset = cpu_to_le64(mr->mr->iova);
		v1->token = cpu_to_le32(mr->mr->rkey);
		v1->length = cpu_to_le32(mr->mr->length);
	} else {
		v1->offset = cpu_to_le64(U64_MAX);
		v1->token = cpu_to_le32(U32_MAX);
		v1->length = cpu_to_le32(U32_MAX);
	}
	mutex_unlock(&mr->mutex);
}
EXPORT_SYMBOL_GPL(smbdirect_mr_io_fill_buffer_descriptor);

/*
 * Deregister a MR after I/O is done
 * This function may wait if remote invalidation is not used
 * and we have to locally invalidate the buffer to prevent data is being
 * modified by remote peer after upper layer consumes it
 */
void smbdirect_connection_deregister_mr_io(struct smbdirect_mr_io *mr)
{
	struct smbdirect_socket *sc = mr->socket;
	int ret = 0;

lock_again:
	mutex_lock(&mr->mutex);
	if (mr->state == SMBDIRECT_MR_DISABLED)
		goto put_kref;

	if (sc->status != SMBDIRECT_SOCKET_CONNECTED) {
		smbdirect_mr_io_disable_locked(mr);
		goto put_kref;
	}

	if (mr->need_invalidate) {
		struct ib_send_wr *wr = &mr->inv_wr;

		/* Need to finish local invalidation before returning */
		wr->opcode = IB_WR_LOCAL_INV;
		mr->cqe.done = smbdirect_connection_mr_io_local_inv_done;
		wr->wr_cqe = &mr->cqe;
		wr->num_sge = 0;
		wr->ex.invalidate_rkey = mr->mr->rkey;
		wr->send_flags = IB_SEND_SIGNALED;

		init_completion(&mr->invalidate_done);
		ret = ib_post_send(sc->ib.qp, wr, NULL);
		if (ret) {
			smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
				"ib_post_send failed ret=%d (%1pe)\n",
				ret, SMBDIRECT_DEBUG_ERR_PTR(ret));
			smbdirect_mr_io_disable_locked(mr);
			smbdirect_socket_schedule_cleanup(sc, ret);
			goto done;
		}

		/*
		 * We still hold the reference to mr
		 * so we can unlock while waiting.
		 */
		mutex_unlock(&mr->mutex);
		wait_for_completion(&mr->invalidate_done);
		mr->need_invalidate = false;
		goto lock_again;
	} else
		/*
		 * For remote invalidation, just set it to SMBDIRECT_MR_INVALIDATED
		 * and defer to mr_recovery_work to recover the MR for next use
		 */
		mr->state = SMBDIRECT_MR_INVALIDATED;

	if (mr->sgt.nents) {
		ib_dma_unmap_sg(sc->ib.dev, mr->sgt.sgl, mr->sgt.nents, mr->dir);
		mr->sgt.nents = 0;
	}

	WARN_ONCE(mr->state != SMBDIRECT_MR_INVALIDATED,
		  "mr->state[%u] != SMBDIRECT_MR_INVALIDATED[%u]\n",
		  mr->state, SMBDIRECT_MR_INVALIDATED);
	mr->state = SMBDIRECT_MR_READY;
	if (atomic_inc_return(&sc->mr_io.ready.count) == 1)
		wake_up(&sc->mr_io.ready.wait_queue);

done:
	atomic_dec(&sc->mr_io.used.count);

put_kref:
	/*
	 * No kref_put_mutex() as it's already locked.
	 *
	 * If smbdirect_mr_io_free_locked() is called
	 * and the mutex is unlocked and mr is gone,
	 * in that case kref_put() returned 1.
	 *
	 * If kref_put() returned 0 we know that
	 * smbdirect_mr_io_free_locked() didn't
	 * run. Not by us nor by anyone else, as we
	 * still hold the mutex, so we need to unlock
	 * and keep the mr in SMBDIRECT_MR_READY or
	 * SMBDIRECT_MR_ERROR state.
	 */
	if (!kref_put(&mr->kref, smbdirect_mr_io_free_locked))
		mutex_unlock(&mr->mutex);
}
EXPORT_SYMBOL_GPL(smbdirect_connection_deregister_mr_io);