// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2020 Oracle. All rights reserved.
 */

#include <linux/sunrpc/svc_rdma.h>
#include <linux/sunrpc/rpc_rdma.h>

#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>

/**
 * pcl_free - Release all memory associated with a parsed chunk list
 * @pcl: parsed chunk list
 *
 */
void pcl_free(struct svc_rdma_pcl *pcl)
{
        while (!list_empty(&pcl->cl_chunks)) {
                struct svc_rdma_chunk *chunk;

                chunk = pcl_first_chunk(pcl);
                list_del(&chunk->ch_list);
                kfree(chunk);
        }
}

static struct svc_rdma_chunk *pcl_alloc_chunk(u32 segcount, u32 position)
{
        struct svc_rdma_chunk *chunk;

        chunk = kmalloc(struct_size(chunk, ch_segments, segcount), GFP_KERNEL);
        if (!chunk)
                return NULL;

        chunk->ch_position = position;
        chunk->ch_length = 0;
        chunk->ch_payload_length = 0;
        chunk->ch_segcount = 0;
        return chunk;
}

static struct svc_rdma_chunk *
pcl_lookup_position(struct svc_rdma_pcl *pcl, u32 position)
{
        struct svc_rdma_chunk *pos;

        pcl_for_each_chunk(pos, pcl) {
                if (pos->ch_position == position)
                        return pos;
        }
        return NULL;
}

static void pcl_insert_position(struct svc_rdma_pcl *pcl,
                                struct svc_rdma_chunk *chunk)
{
        struct svc_rdma_chunk *pos;

        pcl_for_each_chunk(pos, pcl) {
                if (pos->ch_position > chunk->ch_position)
                        break;
        }
        __list_add(&chunk->ch_list, pos->ch_list.prev, &pos->ch_list);
        pcl->cl_count++;
}

static void pcl_set_read_segment(const struct svc_rdma_recv_ctxt *rctxt,
                                 struct svc_rdma_chunk *chunk,
                                 u32 handle, u32 length, u64 offset)
{
        struct svc_rdma_segment *segment;

        segment = &chunk->ch_segments[chunk->ch_segcount];
        segment->rs_handle = handle;
        segment->rs_length = length;
        segment->rs_offset = offset;

        trace_svcrdma_decode_rseg(&rctxt->rc_cid, chunk, segment);

        chunk->ch_length += length;
        chunk->ch_segcount++;
}

/**
 * pcl_alloc_call - Construct a parsed chunk list for the Call body
 * @rctxt: Ingress receive context
 * @p: Start of an un-decoded Read list
 *
 * Assumptions:
 * - The incoming Read list has already been sanity checked.
 * - cl_count is already set to the number of segments in
 *   the un-decoded list.
 * - The list might not be in order by position.
 *
 * Return values:
 *       %true: Parsed chunk list was successfully constructed, and
 *              cl_count is updated to be the number of chunks (ie.
 *              unique positions) in the Read list.
 *      %false: Memory allocation failed.
 */
bool pcl_alloc_call(struct svc_rdma_recv_ctxt *rctxt, __be32 *p)
{
        struct svc_rdma_pcl *pcl = &rctxt->rc_call_pcl;
        unsigned int i, segcount = pcl->cl_count;

        pcl->cl_count = 0;
        for (i = 0; i < segcount; i++) {
                struct svc_rdma_chunk *chunk;
                u32 position, handle, length;
                u64 offset;

                p++;    /* skip the list discriminator */
                p = xdr_decode_read_segment(p, &position, &handle,
                                            &length, &offset);
                if (position != 0)
                        continue;

                if (pcl_is_empty(pcl)) {
                        chunk = pcl_alloc_chunk(segcount, position);
                        if (!chunk)
                                return false;
                        pcl_insert_position(pcl, chunk);
                } else {
                        chunk = list_first_entry(&pcl->cl_chunks,
                                                 struct svc_rdma_chunk,
                                                 ch_list);
                }

                pcl_set_read_segment(rctxt, chunk, handle, length, offset);
        }

        return true;
}

/**
 * pcl_alloc_read - Construct a parsed chunk list for normal Read chunks
 * @rctxt: Ingress receive context
 * @p: Start of an un-decoded Read list
 *
 * Assumptions:
 * - The incoming Read list has already been sanity checked.
 * - cl_count is already set to the number of segments in
 *   the un-decoded list.
 * - The list might not be in order by position.
 *
 * Return values:
 *       %true: Parsed chunk list was successfully constructed, and
 *              cl_count is updated to be the number of chunks (ie.
 *              unique position values) in the Read list.
 *      %false: Memory allocation failed.
 *
 * TODO:
 * - Check for chunk range overlaps
 */
bool pcl_alloc_read(struct svc_rdma_recv_ctxt *rctxt, __be32 *p)
{
        struct svc_rdma_pcl *pcl = &rctxt->rc_read_pcl;
        unsigned int i, segcount = pcl->cl_count;

        pcl->cl_count = 0;
        for (i = 0; i < segcount; i++) {
                struct svc_rdma_chunk *chunk;
                u32 position, handle, length;
                u64 offset;

                p++;    /* skip the list discriminator */
                p = xdr_decode_read_segment(p, &position, &handle,
                                            &length, &offset);
                if (position == 0)
                        continue;

                chunk = pcl_lookup_position(pcl, position);
                if (!chunk) {
                        chunk = pcl_alloc_chunk(segcount, position);
                        if (!chunk)
                                return false;
                        pcl_insert_position(pcl, chunk);
                }

                pcl_set_read_segment(rctxt, chunk, handle, length, offset);
        }

        return true;
}

/**
 * pcl_alloc_write - Construct a parsed chunk list from a Write list
 * @rctxt: Ingress receive context
 * @pcl: Parsed chunk list to populate
 * @p: Start of an un-decoded Write list
 *
 * Assumptions:
 * - The incoming Write list has already been sanity checked, and
 * - cl_count is set to the number of chunks in the un-decoded list.
 *
 * Return values:
 *       %true: Parsed chunk list was successfully constructed.
 *      %false: Memory allocation failed.
 */
bool pcl_alloc_write(struct svc_rdma_recv_ctxt *rctxt,
                     struct svc_rdma_pcl *pcl, __be32 *p)
{
        struct svc_rdma_segment *segment;
        struct svc_rdma_chunk *chunk;
        unsigned int i, j;
        u32 segcount;

        for (i = 0; i < pcl->cl_count; i++) {
                p++;    /* skip the list discriminator */
                segcount = be32_to_cpup(p++);

                chunk = pcl_alloc_chunk(segcount, 0);
                if (!chunk)
                        return false;
                list_add_tail(&chunk->ch_list, &pcl->cl_chunks);

                for (j = 0; j < segcount; j++) {
                        segment = &chunk->ch_segments[j];
                        p = xdr_decode_rdma_segment(p, &segment->rs_handle,
                                                    &segment->rs_length,
                                                    &segment->rs_offset);
                        trace_svcrdma_decode_wseg(&rctxt->rc_cid, chunk, j);

                        chunk->ch_length += segment->rs_length;
                        chunk->ch_segcount++;
                }
        }
        return true;
}

static int pcl_process_region(const struct xdr_buf *xdr,
                              unsigned int offset, unsigned int length,
                              int (*actor)(const struct xdr_buf *, void *),
                              void *data)
{
        struct xdr_buf subbuf;

        if (!length)
                return 0;
        if (xdr_buf_subsegment(xdr, &subbuf, offset, length))
                return -EMSGSIZE;
        return actor(&subbuf, data);
}

/**
 * pcl_process_nonpayloads - Process non-payload regions inside @xdr
 * @pcl: Chunk list to process
 * @xdr: xdr_buf to process
 * @actor: Function to invoke on each non-payload region
 * @data: Arguments for @actor
 *
 * This mechanism must ignore not only result payloads that were already
 * sent via RDMA Write, but also XDR padding for those payloads that
 * the upper layer has added.
 *
 * Assumptions:
 *  The xdr->len and ch_position fields are aligned to 4-byte multiples.
 *
 * Returns:
 *   On success, zero,
 *   %-EMSGSIZE on XDR buffer overflow, or
 *   The return value of @actor
 */
int pcl_process_nonpayloads(const struct svc_rdma_pcl *pcl,
                            const struct xdr_buf *xdr,
                            int (*actor)(const struct xdr_buf *, void *),
                            void *data)
{
        struct svc_rdma_chunk *chunk, *next;
        unsigned int start;
        int ret;

        chunk = pcl_first_chunk(pcl);

        /* No result payloads were generated */
        if (!chunk || !chunk->ch_payload_length)
                return actor(xdr, data);

        /* Process the region before the first result payload */
        ret = pcl_process_region(xdr, 0, chunk->ch_position, actor, data);
        if (ret < 0)
                return ret;

        /* Process the regions between each middle result payload */
        while ((next = pcl_next_chunk(pcl, chunk))) {
                if (!next->ch_payload_length)
                        break;

                start = pcl_chunk_end_offset(chunk);
                ret = pcl_process_region(xdr, start, next->ch_position - start,
                                         actor, data);
                if (ret < 0)
                        return ret;

                chunk = next;
        }

        /* Process the region after the last result payload */
        start = pcl_chunk_end_offset(chunk);
        ret = pcl_process_region(xdr, start, xdr->len - start, actor, data);
        if (ret < 0)
                return ret;

        return 0;
}