/*
 * Copyright (c) 2006, 2020 Oracle and/or its affiliates.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/skbuff.h>
#include <linux/list.h>
#include <linux/errqueue.h>

#include "rds.h"

static unsigned int     rds_exthdr_size[__RDS_EXTHDR_MAX] = {
[RDS_EXTHDR_NONE]       = 0,
[RDS_EXTHDR_VERSION]    = sizeof(struct rds_ext_header_version),
[RDS_EXTHDR_RDMA]       = sizeof(struct rds_ext_header_rdma),
[RDS_EXTHDR_RDMA_DEST]  = sizeof(struct rds_ext_header_rdma_dest),
[RDS_EXTHDR_RDMA_BYTES] = sizeof(struct rds_ext_header_rdma_bytes),
[RDS_EXTHDR_NPATHS]     = sizeof(__be16),
[RDS_EXTHDR_GEN_NUM]    = sizeof(__be32),
[RDS_EXTHDR_SPORT_IDX]  = 1,
};

void rds_message_addref(struct rds_message *rm)
{
        rdsdebug("addref rm %p ref %d\n", rm, refcount_read(&rm->m_refcount));
        refcount_inc(&rm->m_refcount);
}
EXPORT_SYMBOL_GPL(rds_message_addref);

static inline bool rds_zcookie_add(struct rds_msg_zcopy_info *info, u32 cookie)
{
        struct rds_zcopy_cookies *ck = &info->zcookies;
        int ncookies = ck->num;

        if (ncookies == RDS_MAX_ZCOOKIES)
                return false;
        ck->cookies[ncookies] = cookie;
        ck->num =  ++ncookies;
        return true;
}

static struct rds_msg_zcopy_info *rds_info_from_znotifier(struct rds_znotifier *znotif)
{
        return container_of(znotif, struct rds_msg_zcopy_info, znotif);
}

void rds_notify_msg_zcopy_purge(struct rds_msg_zcopy_queue *q)
{
        unsigned long flags;
        LIST_HEAD(copy);
        struct rds_msg_zcopy_info *info, *tmp;

        spin_lock_irqsave(&q->lock, flags);
        list_splice(&q->zcookie_head, &copy);
        INIT_LIST_HEAD(&q->zcookie_head);
        spin_unlock_irqrestore(&q->lock, flags);

        list_for_each_entry_safe(info, tmp, &copy, rs_zcookie_next) {
                list_del(&info->rs_zcookie_next);
                kfree(info);
        }
}

static void rds_rm_zerocopy_callback(struct rds_sock *rs,
                                     struct rds_znotifier *znotif)
{
        struct rds_msg_zcopy_info *info;
        struct rds_msg_zcopy_queue *q;
        u32 cookie = znotif->z_cookie;
        struct rds_zcopy_cookies *ck;
        struct list_head *head;
        unsigned long flags;

        mm_unaccount_pinned_pages(&znotif->z_mmp);
        q = &rs->rs_zcookie_queue;
        spin_lock_irqsave(&q->lock, flags);
        head = &q->zcookie_head;
        if (!list_empty(head)) {
                info = list_first_entry(head, struct rds_msg_zcopy_info,
                                        rs_zcookie_next);
                if (rds_zcookie_add(info, cookie)) {
                        spin_unlock_irqrestore(&q->lock, flags);
                        kfree(rds_info_from_znotifier(znotif));
                        /* caller invokes rds_wake_sk_sleep() */
                        return;
                }
        }

        info = rds_info_from_znotifier(znotif);
        ck = &info->zcookies;
        memset(ck, 0, sizeof(*ck));
        WARN_ON(!rds_zcookie_add(info, cookie));
        list_add_tail(&info->rs_zcookie_next, &q->zcookie_head);

        spin_unlock_irqrestore(&q->lock, flags);
        /* caller invokes rds_wake_sk_sleep() */
}

/*
 * This relies on dma_map_sg() not touching sg[].page during merging.
 */
static void rds_message_purge(struct rds_message *rm)
{
        unsigned long i, flags;
        bool zcopy = false;

        if (unlikely(test_bit(RDS_MSG_PAGEVEC, &rm->m_flags)))
                return;

        spin_lock_irqsave(&rm->m_rs_lock, flags);
        if (rm->m_rs) {
                struct rds_sock *rs = rm->m_rs;

                if (rm->data.op_mmp_znotifier) {
                        zcopy = true;
                        rds_rm_zerocopy_callback(rs, rm->data.op_mmp_znotifier);
                        rds_wake_sk_sleep(rs);
                        rm->data.op_mmp_znotifier = NULL;
                }
                sock_put(rds_rs_to_sk(rs));
                rm->m_rs = NULL;
        }
        spin_unlock_irqrestore(&rm->m_rs_lock, flags);

        for (i = 0; i < rm->data.op_nents; i++) {
                /* XXX will have to put_page for page refs */
                if (!zcopy)
                        __free_page(sg_page(&rm->data.op_sg[i]));
                else
                        put_page(sg_page(&rm->data.op_sg[i]));
        }
        rm->data.op_nents = 0;

        if (rm->rdma.op_active)
                rds_rdma_free_op(&rm->rdma);
        if (rm->rdma.op_rdma_mr)
                kref_put(&rm->rdma.op_rdma_mr->r_kref, __rds_put_mr_final);

        if (rm->atomic.op_active)
                rds_atomic_free_op(&rm->atomic);
        if (rm->atomic.op_rdma_mr)
                kref_put(&rm->atomic.op_rdma_mr->r_kref, __rds_put_mr_final);
}

void rds_message_put(struct rds_message *rm)
{
        rdsdebug("put rm %p ref %d\n", rm, refcount_read(&rm->m_refcount));
        WARN(!refcount_read(&rm->m_refcount), "danger refcount zero on %p\n", rm);
        if (refcount_dec_and_test(&rm->m_refcount)) {
                BUG_ON(!list_empty(&rm->m_sock_item));
                BUG_ON(!list_empty(&rm->m_conn_item));
                rds_message_purge(rm);

                kfree(rm);
        }
}
EXPORT_SYMBOL_GPL(rds_message_put);

void rds_message_populate_header(struct rds_header *hdr, __be16 sport,
                                 __be16 dport, u64 seq)
{
        hdr->h_flags = 0;
        hdr->h_sport = sport;
        hdr->h_dport = dport;
        hdr->h_sequence = cpu_to_be64(seq);
        /* see rds_find_next_ext_space for reason why we memset the
         * ext header
         */
        memset(hdr->h_exthdr, RDS_EXTHDR_NONE, RDS_HEADER_EXT_SPACE);
}
EXPORT_SYMBOL_GPL(rds_message_populate_header);

/*
 * Find the next place we can add an RDS header extension with
 * specific length. Extension headers are pushed one after the
 * other. In the following, the number after the colon is the number
 * of bytes:
 *
 * [ type1:1 dta1:len1 [ type2:1 dta2:len2 ] ... ] RDS_EXTHDR_NONE
 *
 * If the extension headers fill the complete extension header space
 * (16 bytes), the trailing RDS_EXTHDR_NONE is omitted.
 */
static int rds_find_next_ext_space(struct rds_header *hdr, unsigned int len,
                                   u8 **ext_start)
{
        unsigned int ext_len;
        unsigned int type;
        int ind = 0;

        while ((ind + 1 + len) <= RDS_HEADER_EXT_SPACE) {
                if (hdr->h_exthdr[ind] == RDS_EXTHDR_NONE) {
                        *ext_start = hdr->h_exthdr + ind;
                        return 0;
                }

                type = hdr->h_exthdr[ind];

                ext_len = (type < __RDS_EXTHDR_MAX) ? rds_exthdr_size[type] : 0;
                WARN_ONCE(!ext_len, "Unknown ext hdr type %d\n", type);
                if (!ext_len)
                        return -EINVAL;

                /* ind points to a valid ext hdr with known length */
                ind += 1 + ext_len;
        }

        /* no room for extension */
        return -ENOSPC;
}

/* The ext hdr space is prefilled with zero from the kzalloc() */
int rds_message_add_extension(struct rds_header *hdr,
                              unsigned int type, const void *data)
{
        unsigned char *dst;
        unsigned int len;

        len = (type < __RDS_EXTHDR_MAX) ? rds_exthdr_size[type] : 0;
        if (!len)
                return 0;

        if (rds_find_next_ext_space(hdr, len, &dst))
                return 0;

        *dst++ = type;
        memcpy(dst, data, len);

        return 1;
}
EXPORT_SYMBOL_GPL(rds_message_add_extension);

/*
 * If a message has extension headers, retrieve them here.
 * Call like this:
 *
 * unsigned int pos = 0;
 *
 * while (1) {
 *      buflen = sizeof(buffer);
 *      type = rds_message_next_extension(hdr, &pos, buffer, &buflen);
 *      if (type == RDS_EXTHDR_NONE)
 *              break;
 *      ...
 * }
 */
int rds_message_next_extension(struct rds_header *hdr,
                unsigned int *pos, void *buf, unsigned int *buflen)
{
        unsigned int offset, ext_type, ext_len;
        u8 *src = hdr->h_exthdr;

        offset = *pos;
        if (offset >= RDS_HEADER_EXT_SPACE)
                goto none;

        /* Get the extension type and length. For now, the
         * length is implied by the extension type. */
        ext_type = src[offset++];

        if (ext_type == RDS_EXTHDR_NONE || ext_type >= __RDS_EXTHDR_MAX)
                goto none;
        ext_len = rds_exthdr_size[ext_type];
        if (offset + ext_len > RDS_HEADER_EXT_SPACE)
                goto none;

        *pos = offset + ext_len;
        if (ext_len < *buflen)
                *buflen = ext_len;
        memcpy(buf, src + offset, *buflen);
        return ext_type;

none:
        *pos = RDS_HEADER_EXT_SPACE;
        *buflen = 0;
        return RDS_EXTHDR_NONE;
}

int rds_message_add_rdma_dest_extension(struct rds_header *hdr, u32 r_key, u32 offset)
{
        struct rds_ext_header_rdma_dest ext_hdr;

        ext_hdr.h_rdma_rkey = cpu_to_be32(r_key);
        ext_hdr.h_rdma_offset = cpu_to_be32(offset);
        return rds_message_add_extension(hdr, RDS_EXTHDR_RDMA_DEST, &ext_hdr);
}
EXPORT_SYMBOL_GPL(rds_message_add_rdma_dest_extension);

/*
 * Each rds_message is allocated with extra space for the scatterlist entries
 * rds ops will need. This is to minimize memory allocation count. Then, each rds op
 * can grab SGs when initializing its part of the rds_message.
 */
struct rds_message *rds_message_alloc(unsigned int extra_len, gfp_t gfp)
{
        struct rds_message *rm;

        if (extra_len > KMALLOC_MAX_SIZE - sizeof(struct rds_message))
                return NULL;

        rm = kzalloc(sizeof(struct rds_message) + extra_len, gfp);
        if (!rm)
                goto out;

        rm->m_used_sgs = 0;
        rm->m_total_sgs = extra_len / sizeof(struct scatterlist);

        refcount_set(&rm->m_refcount, 1);
        INIT_LIST_HEAD(&rm->m_sock_item);
        INIT_LIST_HEAD(&rm->m_conn_item);
        spin_lock_init(&rm->m_rs_lock);
        init_waitqueue_head(&rm->m_flush_wait);

out:
        return rm;
}

/*
 * RDS ops use this to grab SG entries from the rm's sg pool.
 */
struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents)
{
        struct scatterlist *sg_first = (struct scatterlist *) &rm[1];
        struct scatterlist *sg_ret;

        if (nents <= 0) {
                pr_warn("rds: alloc sgs failed! nents <= 0\n");
                return ERR_PTR(-EINVAL);
        }

        if (rm->m_used_sgs + nents > rm->m_total_sgs) {
                pr_warn("rds: alloc sgs failed! total %d used %d nents %d\n",
                        rm->m_total_sgs, rm->m_used_sgs, nents);
                return ERR_PTR(-ENOMEM);
        }

        sg_ret = &sg_first[rm->m_used_sgs];
        sg_init_table(sg_ret, nents);
        rm->m_used_sgs += nents;

        return sg_ret;
}

struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned int total_len)
{
        struct rds_message *rm;
        unsigned int i;
        int num_sgs = DIV_ROUND_UP(total_len, PAGE_SIZE);
        int extra_bytes = num_sgs * sizeof(struct scatterlist);

        rm = rds_message_alloc(extra_bytes, GFP_NOWAIT);
        if (!rm)
                return ERR_PTR(-ENOMEM);

        set_bit(RDS_MSG_PAGEVEC, &rm->m_flags);
        rm->m_inc.i_hdr.h_len = cpu_to_be32(total_len);
        rm->data.op_nents = DIV_ROUND_UP(total_len, PAGE_SIZE);
        rm->data.op_sg = rds_message_alloc_sgs(rm, num_sgs);
        if (IS_ERR(rm->data.op_sg)) {
                void *err = ERR_CAST(rm->data.op_sg);
                rds_message_put(rm);
                return err;
        }

        for (i = 0; i < rm->data.op_nents; ++i) {
                sg_set_page(&rm->data.op_sg[i],
                                virt_to_page((void *)page_addrs[i]),
                                PAGE_SIZE, 0);
        }

        return rm;
}

static int rds_message_zcopy_from_user(struct rds_message *rm, struct iov_iter *from)
{
        struct scatterlist *sg;
        int ret = 0;
        int length = iov_iter_count(from);
        struct rds_msg_zcopy_info *info;

        rm->m_inc.i_hdr.h_len = cpu_to_be32(iov_iter_count(from));

        /*
         * now allocate and copy in the data payload.
         */
        sg = rm->data.op_sg;

        info = kzalloc_obj(*info);
        if (!info)
                return -ENOMEM;
        INIT_LIST_HEAD(&info->rs_zcookie_next);
        rm->data.op_mmp_znotifier = &info->znotif;
        if (mm_account_pinned_pages(&rm->data.op_mmp_znotifier->z_mmp,
                                    length)) {
                ret = -ENOMEM;
                goto err;
        }
        while (iov_iter_count(from)) {
                struct page *pages;
                size_t start;
                ssize_t copied;

                copied = iov_iter_get_pages2(from, &pages, PAGE_SIZE,
                                            1, &start);
                if (copied < 0) {
                        struct mmpin *mmp;
                        int i;

                        for (i = 0; i < rm->data.op_nents; i++)
                                put_page(sg_page(&rm->data.op_sg[i]));
                        mmp = &rm->data.op_mmp_znotifier->z_mmp;
                        mm_unaccount_pinned_pages(mmp);
                        ret = -EFAULT;
                        goto err;
                }
                length -= copied;
                sg_set_page(sg, pages, copied, start);
                rm->data.op_nents++;
                sg++;
        }
        WARN_ON_ONCE(length != 0);
        return ret;
err:
        kfree(info);
        rm->data.op_mmp_znotifier = NULL;
        return ret;
}

int rds_message_copy_from_user(struct rds_message *rm, struct iov_iter *from,
                               bool zcopy)
{
        unsigned long to_copy, nbytes;
        unsigned long sg_off;
        struct scatterlist *sg;
        int ret = 0;

        rm->m_inc.i_hdr.h_len = cpu_to_be32(iov_iter_count(from));

        /* now allocate and copy in the data payload.  */
        sg = rm->data.op_sg;
        sg_off = 0; /* Dear gcc, sg->page will be null from kzalloc. */

        if (zcopy)
                return rds_message_zcopy_from_user(rm, from);

        while (iov_iter_count(from)) {
                if (!sg_page(sg)) {
                        ret = rds_page_remainder_alloc(sg, iov_iter_count(from),
                                                       GFP_HIGHUSER);
                        if (ret)
                                return ret;
                        rm->data.op_nents++;
                        sg_off = 0;
                }

                to_copy = min_t(unsigned long, iov_iter_count(from),
                                sg->length - sg_off);

                rds_stats_add(s_copy_from_user, to_copy);
                nbytes = copy_page_from_iter(sg_page(sg), sg->offset + sg_off,
                                             to_copy, from);
                if (nbytes != to_copy)
                        return -EFAULT;

                sg_off += to_copy;

                if (sg_off == sg->length)
                        sg++;
        }

        return ret;
}

int rds_message_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to)
{
        struct rds_message *rm;
        struct scatterlist *sg;
        unsigned long to_copy;
        unsigned long vec_off;
        int copied;
        int ret;
        u32 len;

        rm = container_of(inc, struct rds_message, m_inc);
        len = be32_to_cpu(rm->m_inc.i_hdr.h_len);

        sg = rm->data.op_sg;
        vec_off = 0;
        copied = 0;

        while (iov_iter_count(to) && copied < len) {
                to_copy = min_t(unsigned long, iov_iter_count(to),
                                sg->length - vec_off);
                to_copy = min_t(unsigned long, to_copy, len - copied);

                rds_stats_add(s_copy_to_user, to_copy);
                ret = copy_page_to_iter(sg_page(sg), sg->offset + vec_off,
                                        to_copy, to);
                if (ret != to_copy)
                        return -EFAULT;

                vec_off += to_copy;
                copied += to_copy;

                if (vec_off == sg->length) {
                        vec_off = 0;
                        sg++;
                }
        }

        return copied;
}

/*
 * If the message is still on the send queue, wait until the transport
 * is done with it. This is particularly important for RDMA operations.
 */
void rds_message_wait(struct rds_message *rm)
{
        wait_event_interruptible(rm->m_flush_wait,
                        !test_bit(RDS_MSG_MAPPED, &rm->m_flags));
}

void rds_message_unmapped(struct rds_message *rm)
{
        clear_bit(RDS_MSG_MAPPED, &rm->m_flags);
        wake_up_interruptible(&rm->m_flush_wait);
}
EXPORT_SYMBOL_GPL(rds_message_unmapped);