target_core_rd.c

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/*******************************************************************************
 * Filename:  target_core_rd.c
 *
 * This file contains the Storage Engine <-> Ramdisk transport
 * specific functions.
 *
 * Copyright (c) 2003, 2004, 2005 PyX Technologies, Inc.
 * Copyright (c) 2005, 2006, 2007 SBE, Inc.
 * Copyright (c) 2007-2010 Rising Tide Systems
 * Copyright (c) 2008-2010 Linux-iSCSI.org
 *
 * Nicholas A. Bellinger <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 ******************************************************************************/

#include <linux/string.h>
#include <linux/parser.h>
#include <linux/timer.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <scsi/scsi.h>
#include <scsi/scsi_host.h>

#include <target/target_core_base.h>
#include <target/target_core_backend.h>

#include "target_core_rd.h"

static struct se_subsystem_api rd_mcp_template;

/*  rd_attach_hba(): (Part of se_subsystem_api_t template)
 *
 *
 */
static int rd_attach_hba(struct se_hba *hba, u32 host_id)
{
    struct rd_host *rd_host;

    rd_host = kzalloc(sizeof(struct rd_host), GFP_KERNEL);
    if (!rd_host) {
        pr_err("Unable to allocate memory for struct rd_host\n");
        return -ENOMEM;
    }

    rd_host->rd_host_id = host_id;

    hba->hba_ptr = rd_host;

    pr_debug("CORE_HBA[%d] - TCM Ramdisk HBA Driver %s on"
        " Generic Target Core Stack %s\n", hba->hba_id,
        RD_HBA_VERSION, TARGET_CORE_MOD_VERSION);

    return 0;
}

static void rd_detach_hba(struct se_hba *hba)
{
    struct rd_host *rd_host = hba->hba_ptr;

    pr_debug("CORE_HBA[%d] - Detached Ramdisk HBA: %u from"
        " Generic Target Core\n", hba->hba_id, rd_host->rd_host_id);

    kfree(rd_host);
    hba->hba_ptr = NULL;
}

/*  rd_release_device_space():
 *
 *
 */
static void rd_release_device_space(struct rd_dev *rd_dev)
{
    u32 i, j, page_count = 0, sg_per_table;
    struct rd_dev_sg_table *sg_table;
    struct page *pg;
    struct scatterlist *sg;

    if (!rd_dev->sg_table_array || !rd_dev->sg_table_count)
        return;

    sg_table = rd_dev->sg_table_array;

    for (i = 0; i < rd_dev->sg_table_count; i++) {
        sg = sg_table[i].sg_table;
        sg_per_table = sg_table[i].rd_sg_count;

        for (j = 0; j < sg_per_table; j++) {
            pg = sg_page(&sg[j]);
            if (pg) {
                __free_page(pg);
                page_count++;
            }
        }

        kfree(sg);
    }

    pr_debug("CORE_RD[%u] - Released device space for Ramdisk"
        " Device ID: %u, pages %u in %u tables total bytes %lu\n",
        rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count,
        rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE);

    kfree(sg_table);
    rd_dev->sg_table_array = NULL;
    rd_dev->sg_table_count = 0;
}


/*  rd_build_device_space():
 *
 *
 */
static int rd_build_device_space(struct rd_dev *rd_dev)
{
    u32 i = 0, j, page_offset = 0, sg_per_table, sg_tables, total_sg_needed;
    u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
                sizeof(struct scatterlist));
    struct rd_dev_sg_table *sg_table;
    struct page *pg;
    struct scatterlist *sg;

    if (rd_dev->rd_page_count <= 0) {
        pr_err("Illegal page count: %u for Ramdisk device\n",
            rd_dev->rd_page_count);
        return -EINVAL;
    }
    total_sg_needed = rd_dev->rd_page_count;

    sg_tables = (total_sg_needed / max_sg_per_table) + 1;

    sg_table = kzalloc(sg_tables * sizeof(struct rd_dev_sg_table), GFP_KERNEL);
    if (!sg_table) {
        pr_err("Unable to allocate memory for Ramdisk"
            " scatterlist tables\n");
        return -ENOMEM;
    }

    rd_dev->sg_table_array = sg_table;
    rd_dev->sg_table_count = sg_tables;

    while (total_sg_needed) {
        sg_per_table = (total_sg_needed > max_sg_per_table) ?
            max_sg_per_table : total_sg_needed;

        sg = kzalloc(sg_per_table * sizeof(struct scatterlist),
                GFP_KERNEL);
        if (!sg) {
            pr_err("Unable to allocate scatterlist array"
                " for struct rd_dev\n");
            return -ENOMEM;
        }

        sg_init_table(sg, sg_per_table);

        sg_table[i].sg_table = sg;
        sg_table[i].rd_sg_count = sg_per_table;
        sg_table[i].page_start_offset = page_offset;
        sg_table[i++].page_end_offset = (page_offset + sg_per_table)
                        - 1;

        for (j = 0; j < sg_per_table; j++) {
            pg = alloc_pages(GFP_KERNEL, 0);
            if (!pg) {
                pr_err("Unable to allocate scatterlist"
                    " pages for struct rd_dev_sg_table\n");
                return -ENOMEM;
            }
            sg_assign_page(&sg[j], pg);
            sg[j].length = PAGE_SIZE;
        }

        page_offset += sg_per_table;
        total_sg_needed -= sg_per_table;
    }

    pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u space of"
        " %u pages in %u tables\n", rd_dev->rd_host->rd_host_id,
        rd_dev->rd_dev_id, rd_dev->rd_page_count,
        rd_dev->sg_table_count);

    return 0;
}

static void *rd_allocate_virtdevice(struct se_hba *hba, const char *name)
{
    struct rd_dev *rd_dev;
    struct rd_host *rd_host = hba->hba_ptr;

    rd_dev = kzalloc(sizeof(struct rd_dev), GFP_KERNEL);
    if (!rd_dev) {
        pr_err("Unable to allocate memory for struct rd_dev\n");
        return NULL;
    }

    rd_dev->rd_host = rd_host;

    return rd_dev;
}

static struct se_device *rd_create_virtdevice(struct se_hba *hba,
        struct se_subsystem_dev *se_dev, void *p)
{
    struct se_device *dev;
    struct se_dev_limits dev_limits;
    struct rd_dev *rd_dev = p;
    struct rd_host *rd_host = hba->hba_ptr;
    int dev_flags = 0, ret;
    char prod[16], rev[4];

    memset(&dev_limits, 0, sizeof(struct se_dev_limits));

    ret = rd_build_device_space(rd_dev);
    if (ret < 0)
        goto fail;

    snprintf(prod, 16, "RAMDISK-MCP");
    snprintf(rev, 4, "%s", RD_MCP_VERSION);

    dev_limits.limits.logical_block_size = RD_BLOCKSIZE;
    dev_limits.limits.max_hw_sectors = UINT_MAX;
    dev_limits.limits.max_sectors = UINT_MAX;
    dev_limits.hw_queue_depth = RD_MAX_DEVICE_QUEUE_DEPTH;
    dev_limits.queue_depth = RD_DEVICE_QUEUE_DEPTH;

    dev = transport_add_device_to_core_hba(hba,
            &rd_mcp_template, se_dev, dev_flags, rd_dev,
            &dev_limits, prod, rev);
    if (!dev)
        goto fail;

    rd_dev->rd_dev_id = rd_host->rd_host_dev_id_count++;

    pr_debug("CORE_RD[%u] - Added TCM MEMCPY Ramdisk Device ID: %u of"
        " %u pages in %u tables, %lu total bytes\n",
        rd_host->rd_host_id, rd_dev->rd_dev_id, rd_dev->rd_page_count,
        rd_dev->sg_table_count,
        (unsigned long)(rd_dev->rd_page_count * PAGE_SIZE));

    return dev;

fail:
    rd_release_device_space(rd_dev);
    return ERR_PTR(ret);
}

static void rd_free_device(void *p)
{
    struct rd_dev *rd_dev = p;

    rd_release_device_space(rd_dev);
    kfree(rd_dev);
}

static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page)
{
    u32 i;
    struct rd_dev_sg_table *sg_table;

    for (i = 0; i < rd_dev->sg_table_count; i++) {
        sg_table = &rd_dev->sg_table_array[i];
        if ((sg_table->page_start_offset <= page) &&
            (sg_table->page_end_offset >= page))
            return sg_table;
    }

    pr_err("Unable to locate struct rd_dev_sg_table for page: %u\n",
            page);

    return NULL;
}

static int rd_execute_rw(struct se_cmd *cmd)
{
    struct scatterlist *sgl = cmd->t_data_sg;
    u32 sgl_nents = cmd->t_data_nents;
    enum dma_data_direction data_direction = cmd->data_direction;
    struct se_device *se_dev = cmd->se_dev;
    struct rd_dev *dev = se_dev->dev_ptr;
    struct rd_dev_sg_table *table;
    struct scatterlist *rd_sg;
    struct sg_mapping_iter m;
    u32 rd_offset;
    u32 rd_size;
    u32 rd_page;
    u32 src_len;
    u64 tmp;

    tmp = cmd->t_task_lba * se_dev->se_sub_dev->se_dev_attrib.block_size;
    rd_offset = do_div(tmp, PAGE_SIZE);
    rd_page = tmp;
    rd_size = cmd->data_length;

    table = rd_get_sg_table(dev, rd_page);
    if (!table)
        return -EINVAL;

    rd_sg = &table->sg_table[rd_page - table->page_start_offset];

    pr_debug("RD[%u]: %s LBA: %llu, Size: %u Page: %u, Offset: %u\n",
            dev->rd_dev_id,
            data_direction == DMA_FROM_DEVICE ? "Read" : "Write",
            cmd->t_task_lba, rd_size, rd_page, rd_offset);

    src_len = PAGE_SIZE - rd_offset;
    sg_miter_start(&m, sgl, sgl_nents,
            data_direction == DMA_FROM_DEVICE ?
                SG_MITER_TO_SG : SG_MITER_FROM_SG);
    while (rd_size) {
        u32 len;
        void *rd_addr;

        sg_miter_next(&m);
        len = min((u32)m.length, src_len);
        m.consumed = len;

        rd_addr = sg_virt(rd_sg) + rd_offset;

        if (data_direction == DMA_FROM_DEVICE)
            memcpy(m.addr, rd_addr, len);
        else
            memcpy(rd_addr, m.addr, len);

        rd_size -= len;
        if (!rd_size)
            continue;

        src_len -= len;
        if (src_len) {
            rd_offset += len;
            continue;
        }

        /* rd page completed, next one please */
        rd_page++;
        rd_offset = 0;
        src_len = PAGE_SIZE;
        if (rd_page <= table->page_end_offset) {
            rd_sg++;
            continue;
        }

        table = rd_get_sg_table(dev, rd_page);
        if (!table) {
            sg_miter_stop(&m);
            return -EINVAL;
        }

        /* since we increment, the first sg entry is correct */
        rd_sg = table->sg_table;
    }
    sg_miter_stop(&m);

    target_complete_cmd(cmd, SAM_STAT_GOOD);
    return 0;
}

enum {
    Opt_rd_pages, Opt_err
};

static match_table_t tokens = {
    {Opt_rd_pages, "rd_pages=%d"},
    {Opt_err, NULL}
};

static ssize_t rd_set_configfs_dev_params(
    struct se_hba *hba,
    struct se_subsystem_dev *se_dev,
    const char *page,
    ssize_t count)
{
    struct rd_dev *rd_dev = se_dev->se_dev_su_ptr;
    char *orig, *ptr, *opts;
    substring_t args[MAX_OPT_ARGS];
    int ret = 0, arg, token;

    opts = kstrdup(page, GFP_KERNEL);
    if (!opts)
        return -ENOMEM;

    orig = opts;

    while ((ptr = strsep(&opts, ",\n")) != NULL) {
        if (!*ptr)
            continue;

        token = match_token(ptr, tokens, args);
        switch (token) {
        case Opt_rd_pages:
            match_int(args, &arg);
            rd_dev->rd_page_count = arg;
            pr_debug("RAMDISK: Referencing Page"
                " Count: %u\n", rd_dev->rd_page_count);
            rd_dev->rd_flags |= RDF_HAS_PAGE_COUNT;
            break;
        default:
            break;
        }
    }

    kfree(orig);
    return (!ret) ? count : ret;
}

static ssize_t rd_check_configfs_dev_params(struct se_hba *hba, struct se_subsystem_dev *se_dev)
{
    struct rd_dev *rd_dev = se_dev->se_dev_su_ptr;

    if (!(rd_dev->rd_flags & RDF_HAS_PAGE_COUNT)) {
        pr_debug("Missing rd_pages= parameter\n");
        return -EINVAL;
    }

    return 0;
}

static ssize_t rd_show_configfs_dev_params(
    struct se_hba *hba,
    struct se_subsystem_dev *se_dev,
    char *b)
{
    struct rd_dev *rd_dev = se_dev->se_dev_su_ptr;
    ssize_t bl = sprintf(b, "TCM RamDisk ID: %u  RamDisk Makeup: rd_mcp\n",
            rd_dev->rd_dev_id);
    bl += sprintf(b + bl, "        PAGES/PAGE_SIZE: %u*%lu"
            "  SG_table_count: %u\n", rd_dev->rd_page_count,
            PAGE_SIZE, rd_dev->sg_table_count);
    return bl;
}

static u32 rd_get_device_rev(struct se_device *dev)
{
    return SCSI_SPC_2; /* Returns SPC-3 in Initiator Data */
}

static u32 rd_get_device_type(struct se_device *dev)
{
    return TYPE_DISK;
}

static sector_t rd_get_blocks(struct se_device *dev)
{
    struct rd_dev *rd_dev = dev->dev_ptr;
    unsigned long long blocks_long = ((rd_dev->rd_page_count * PAGE_SIZE) /
            dev->se_sub_dev->se_dev_attrib.block_size) - 1;

    return blocks_long;
}

static struct spc_ops rd_spc_ops = {
    .execute_rw     = rd_execute_rw,
};

static int rd_parse_cdb(struct se_cmd *cmd)
{
    return sbc_parse_cdb(cmd, &rd_spc_ops);
}

static struct se_subsystem_api rd_mcp_template = {
    .name           = "rd_mcp",
    .transport_type     = TRANSPORT_PLUGIN_VHBA_VDEV,
    .attach_hba     = rd_attach_hba,
    .detach_hba     = rd_detach_hba,
    .allocate_virtdevice    = rd_allocate_virtdevice,
    .create_virtdevice  = rd_create_virtdevice,
    .free_device        = rd_free_device,
    .parse_cdb      = rd_parse_cdb,
    .check_configfs_dev_params = rd_check_configfs_dev_params,
    .set_configfs_dev_params = rd_set_configfs_dev_params,
    .show_configfs_dev_params = rd_show_configfs_dev_params,
    .get_device_rev     = rd_get_device_rev,
    .get_device_type    = rd_get_device_type,
    .get_blocks     = rd_get_blocks,
};

int __init rd_module_init(void)
{
    int ret;

    ret = transport_subsystem_register(&rd_mcp_template);
    if (ret < 0) {
        return ret;
    }

    return 0;
}

void rd_module_exit(void)
{
    transport_subsystem_release(&rd_mcp_template);
}