md: use correct type in super_1_sync

[mirror_ubuntu-jammy-kernel.git] / drivers / target / target_core_iblock.c

/*******************************************************************************
 * Filename:  target_core_iblock.c
 *
 * This file contains the Storage Engine  <-> Linux BlockIO transport
 * specific functions.
 *
 * (c) Copyright 2003-2013 Datera, Inc.
 *
 * Nicholas A. Bellinger <nab@kernel.org>
 *
 * 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/fs.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/bio.h>
#include <linux/genhd.h>
#include <linux/file.h>
#include <linux/module.h>
#include <scsi/scsi_proto.h>
#include <asm/unaligned.h>

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

#include "target_core_iblock.h"

#define IBLOCK_MAX_BIO_PER_TASK  32     /* max # of bios to submit at a time */
#define IBLOCK_BIO_POOL_SIZE    128

static inline struct iblock_dev *IBLOCK_DEV(struct se_device *dev)
{
        return container_of(dev, struct iblock_dev, dev);
}


static int iblock_attach_hba(struct se_hba *hba, u32 host_id)
{
        pr_debug("CORE_HBA[%d] - TCM iBlock HBA Driver %s on"
                " Generic Target Core Stack %s\n", hba->hba_id,
                IBLOCK_VERSION, TARGET_CORE_VERSION);
        return 0;
}

static void iblock_detach_hba(struct se_hba *hba)
{
}

static struct se_device *iblock_alloc_device(struct se_hba *hba, const char *name)
{
        struct iblock_dev *ib_dev = NULL;

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

        pr_debug( "IBLOCK: Allocated ib_dev for %s\n", name);

        return &ib_dev->dev;
}

static int iblock_configure_device(struct se_device *dev)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
        struct request_queue *q;
        struct block_device *bd = NULL;
        struct blk_integrity *bi;
        fmode_t mode;
        unsigned int max_write_zeroes_sectors;
        int ret = -ENOMEM;

        if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
                pr_err("Missing udev_path= parameters for IBLOCK\n");
                return -EINVAL;
        }

        ret = bioset_init(&ib_dev->ibd_bio_set, IBLOCK_BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
        if (ret) {
                pr_err("IBLOCK: Unable to create bioset\n");
                goto out;
        }

        pr_debug( "IBLOCK: Claiming struct block_device: %s\n",
                        ib_dev->ibd_udev_path);

        mode = FMODE_READ|FMODE_EXCL;
        if (!ib_dev->ibd_readonly)
                mode |= FMODE_WRITE;
        else
                dev->dev_flags |= DF_READ_ONLY;

        bd = blkdev_get_by_path(ib_dev->ibd_udev_path, mode, ib_dev);
        if (IS_ERR(bd)) {
                ret = PTR_ERR(bd);
                goto out_free_bioset;
        }
        ib_dev->ibd_bd = bd;

        q = bdev_get_queue(bd);

        dev->dev_attrib.hw_block_size = bdev_logical_block_size(bd);
        dev->dev_attrib.hw_max_sectors = queue_max_hw_sectors(q);
        dev->dev_attrib.hw_queue_depth = q->nr_requests;

        if (target_configure_unmap_from_queue(&dev->dev_attrib, q))
                pr_debug("IBLOCK: BLOCK Discard support available,"
                         " disabled by default\n");

        /*
         * Enable write same emulation for IBLOCK and use 0xFFFF as
         * the smaller WRITE_SAME(10) only has a two-byte block count.
         */
        max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
        if (max_write_zeroes_sectors)
                dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
        else
                dev->dev_attrib.max_write_same_len = 0xFFFF;

        if (blk_queue_nonrot(q))
                dev->dev_attrib.is_nonrot = 1;

        bi = bdev_get_integrity(bd);
        if (bi) {
                struct bio_set *bs = &ib_dev->ibd_bio_set;

                if (!strcmp(bi->profile->name, "T10-DIF-TYPE3-IP") ||
                    !strcmp(bi->profile->name, "T10-DIF-TYPE1-IP")) {
                        pr_err("IBLOCK export of blk_integrity: %s not"
                               " supported\n", bi->profile->name);
                        ret = -ENOSYS;
                        goto out_blkdev_put;
                }

                if (!strcmp(bi->profile->name, "T10-DIF-TYPE3-CRC")) {
                        dev->dev_attrib.pi_prot_type = TARGET_DIF_TYPE3_PROT;
                } else if (!strcmp(bi->profile->name, "T10-DIF-TYPE1-CRC")) {
                        dev->dev_attrib.pi_prot_type = TARGET_DIF_TYPE1_PROT;
                }

                if (dev->dev_attrib.pi_prot_type) {
                        if (bioset_integrity_create(bs, IBLOCK_BIO_POOL_SIZE) < 0) {
                                pr_err("Unable to allocate bioset for PI\n");
                                ret = -ENOMEM;
                                goto out_blkdev_put;
                        }
                        pr_debug("IBLOCK setup BIP bs->bio_integrity_pool: %p\n",
                                 &bs->bio_integrity_pool);
                }
                dev->dev_attrib.hw_pi_prot_type = dev->dev_attrib.pi_prot_type;
        }

        return 0;

out_blkdev_put:
        blkdev_put(ib_dev->ibd_bd, FMODE_WRITE|FMODE_READ|FMODE_EXCL);
out_free_bioset:
        bioset_exit(&ib_dev->ibd_bio_set);
out:
        return ret;
}

static void iblock_dev_call_rcu(struct rcu_head *p)
{
        struct se_device *dev = container_of(p, struct se_device, rcu_head);
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);

        kfree(ib_dev);
}

static void iblock_free_device(struct se_device *dev)
{
        call_rcu(&dev->rcu_head, iblock_dev_call_rcu);
}

static void iblock_destroy_device(struct se_device *dev)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);

        if (ib_dev->ibd_bd != NULL)
                blkdev_put(ib_dev->ibd_bd, FMODE_WRITE|FMODE_READ|FMODE_EXCL);
        bioset_exit(&ib_dev->ibd_bio_set);
}

static unsigned long long iblock_emulate_read_cap_with_block_size(
        struct se_device *dev,
        struct block_device *bd,
        struct request_queue *q)
{
        unsigned long long blocks_long = (div_u64(i_size_read(bd->bd_inode),
                                        bdev_logical_block_size(bd)) - 1);
        u32 block_size = bdev_logical_block_size(bd);

        if (block_size == dev->dev_attrib.block_size)
                return blocks_long;

        switch (block_size) {
        case 4096:
                switch (dev->dev_attrib.block_size) {
                case 2048:
                        blocks_long <<= 1;
                        break;
                case 1024:
                        blocks_long <<= 2;
                        break;
                case 512:
                        blocks_long <<= 3;
                default:
                        break;
                }
                break;
        case 2048:
                switch (dev->dev_attrib.block_size) {
                case 4096:
                        blocks_long >>= 1;
                        break;
                case 1024:
                        blocks_long <<= 1;
                        break;
                case 512:
                        blocks_long <<= 2;
                        break;
                default:
                        break;
                }
                break;
        case 1024:
                switch (dev->dev_attrib.block_size) {
                case 4096:
                        blocks_long >>= 2;
                        break;
                case 2048:
                        blocks_long >>= 1;
                        break;
                case 512:
                        blocks_long <<= 1;
                        break;
                default:
                        break;
                }
                break;
        case 512:
                switch (dev->dev_attrib.block_size) {
                case 4096:
                        blocks_long >>= 3;
                        break;
                case 2048:
                        blocks_long >>= 2;
                        break;
                case 1024:
                        blocks_long >>= 1;
                        break;
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return blocks_long;
}

static void iblock_complete_cmd(struct se_cmd *cmd)
{
        struct iblock_req *ibr = cmd->priv;
        u8 status;

        if (!refcount_dec_and_test(&ibr->pending))
                return;

        if (atomic_read(&ibr->ib_bio_err_cnt))
                status = SAM_STAT_CHECK_CONDITION;
        else
                status = SAM_STAT_GOOD;

        target_complete_cmd(cmd, status);
        kfree(ibr);
}

static void iblock_bio_done(struct bio *bio)
{
        struct se_cmd *cmd = bio->bi_private;
        struct iblock_req *ibr = cmd->priv;

        if (bio->bi_status) {
                pr_err("bio error: %p,  err: %d\n", bio, bio->bi_status);
                /*
                 * Bump the ib_bio_err_cnt and release bio.
                 */
                atomic_inc(&ibr->ib_bio_err_cnt);
                smp_mb__after_atomic();
        }

        bio_put(bio);

        iblock_complete_cmd(cmd);
}

static struct bio *
iblock_get_bio(struct se_cmd *cmd, sector_t lba, u32 sg_num, int op,
               int op_flags)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(cmd->se_dev);
        struct bio *bio;

        /*
         * Only allocate as many vector entries as the bio code allows us to,
         * we'll loop later on until we have handled the whole request.
         */
        if (sg_num > BIO_MAX_PAGES)
                sg_num = BIO_MAX_PAGES;

        bio = bio_alloc_bioset(GFP_NOIO, sg_num, &ib_dev->ibd_bio_set);
        if (!bio) {
                pr_err("Unable to allocate memory for bio\n");
                return NULL;
        }

        bio_set_dev(bio, ib_dev->ibd_bd);
        bio->bi_private = cmd;
        bio->bi_end_io = &iblock_bio_done;
        bio->bi_iter.bi_sector = lba;
        bio_set_op_attrs(bio, op, op_flags);

        return bio;
}

static void iblock_submit_bios(struct bio_list *list)
{
        struct blk_plug plug;
        struct bio *bio;

        blk_start_plug(&plug);
        while ((bio = bio_list_pop(list)))
                submit_bio(bio);
        blk_finish_plug(&plug);
}

static void iblock_end_io_flush(struct bio *bio)
{
        struct se_cmd *cmd = bio->bi_private;

        if (bio->bi_status)
                pr_err("IBLOCK: cache flush failed: %d\n", bio->bi_status);

        if (cmd) {
                if (bio->bi_status)
                        target_complete_cmd(cmd, SAM_STAT_CHECK_CONDITION);
                else
                        target_complete_cmd(cmd, SAM_STAT_GOOD);
        }

        bio_put(bio);
}

/*
 * Implement SYCHRONIZE CACHE.  Note that we can't handle lba ranges and must
 * always flush the whole cache.
 */
static sense_reason_t
iblock_execute_sync_cache(struct se_cmd *cmd)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(cmd->se_dev);
        int immed = (cmd->t_task_cdb[1] & 0x2);
        struct bio *bio;

        /*
         * If the Immediate bit is set, queue up the GOOD response
         * for this SYNCHRONIZE_CACHE op.
         */
        if (immed)
                target_complete_cmd(cmd, SAM_STAT_GOOD);

        bio = bio_alloc(GFP_KERNEL, 0);
        bio->bi_end_io = iblock_end_io_flush;
        bio_set_dev(bio, ib_dev->ibd_bd);
        bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
        if (!immed)
                bio->bi_private = cmd;
        submit_bio(bio);
        return 0;
}

static sense_reason_t
iblock_execute_unmap(struct se_cmd *cmd, sector_t lba, sector_t nolb)
{
        struct block_device *bdev = IBLOCK_DEV(cmd->se_dev)->ibd_bd;
        struct se_device *dev = cmd->se_dev;
        int ret;

        ret = blkdev_issue_discard(bdev,
                                   target_to_linux_sector(dev, lba),
                                   target_to_linux_sector(dev,  nolb),
                                   GFP_KERNEL, 0);
        if (ret < 0) {
                pr_err("blkdev_issue_discard() failed: %d\n", ret);
                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
        }

        return 0;
}

static sense_reason_t
iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        struct scatterlist *sg = &cmd->t_data_sg[0];
        unsigned char *buf, *not_zero;
        int ret;

        buf = kmap(sg_page(sg)) + sg->offset;
        if (!buf)
                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
        /*
         * Fall back to block_execute_write_same() slow-path if
         * incoming WRITE_SAME payload does not contain zeros.
         */
        not_zero = memchr_inv(buf, 0x00, cmd->data_length);
        kunmap(sg_page(sg));

        if (not_zero)
                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

        ret = blkdev_issue_zeroout(bdev,
                                target_to_linux_sector(dev, cmd->t_task_lba),
                                target_to_linux_sector(dev,
                                        sbc_get_write_same_sectors(cmd)),
                                GFP_KERNEL, false);
        if (ret)
                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

        target_complete_cmd(cmd, GOOD);
        return 0;
}

static sense_reason_t
iblock_execute_write_same(struct se_cmd *cmd)
{
        struct block_device *bdev = IBLOCK_DEV(cmd->se_dev)->ibd_bd;
        struct iblock_req *ibr;
        struct scatterlist *sg;
        struct bio *bio;
        struct bio_list list;
        struct se_device *dev = cmd->se_dev;
        sector_t block_lba = target_to_linux_sector(dev, cmd->t_task_lba);
        sector_t sectors = target_to_linux_sector(dev,
                                        sbc_get_write_same_sectors(cmd));

        if (cmd->prot_op) {
                pr_err("WRITE_SAME: Protection information with IBLOCK"
                       " backends not supported\n");
                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
        }
        sg = &cmd->t_data_sg[0];

        if (cmd->t_data_nents > 1 ||
            sg->length != cmd->se_dev->dev_attrib.block_size) {
                pr_err("WRITE_SAME: Illegal SGL t_data_nents: %u length: %u"
                        " block_size: %u\n", cmd->t_data_nents, sg->length,
                        cmd->se_dev->dev_attrib.block_size);
                return TCM_INVALID_CDB_FIELD;
        }

        if (bdev_write_zeroes_sectors(bdev)) {
                if (!iblock_execute_zero_out(bdev, cmd))
                        return 0;
        }

        ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
        if (!ibr)
                goto fail;
        cmd->priv = ibr;

        bio = iblock_get_bio(cmd, block_lba, 1, REQ_OP_WRITE, 0);
        if (!bio)
                goto fail_free_ibr;

        bio_list_init(&list);
        bio_list_add(&list, bio);

        refcount_set(&ibr->pending, 1);

        while (sectors) {
                while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
                                != sg->length) {

                        bio = iblock_get_bio(cmd, block_lba, 1, REQ_OP_WRITE,
                                             0);
                        if (!bio)
                                goto fail_put_bios;

                        refcount_inc(&ibr->pending);
                        bio_list_add(&list, bio);
                }

                /* Always in 512 byte units for Linux/Block */
                block_lba += sg->length >> SECTOR_SHIFT;
                sectors -= 1;
        }

        iblock_submit_bios(&list);
        return 0;

fail_put_bios:
        while ((bio = bio_list_pop(&list)))
                bio_put(bio);
fail_free_ibr:
        kfree(ibr);
fail:
        return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}

enum {
        Opt_udev_path, Opt_readonly, Opt_force, Opt_err
};

static match_table_t tokens = {
        {Opt_udev_path, "udev_path=%s"},
        {Opt_readonly, "readonly=%d"},
        {Opt_force, "force=%d"},
        {Opt_err, NULL}
};

static ssize_t iblock_set_configfs_dev_params(struct se_device *dev,
                const char *page, ssize_t count)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
        char *orig, *ptr, *arg_p, *opts;
        substring_t args[MAX_OPT_ARGS];
        int ret = 0, token;
        unsigned long tmp_readonly;

        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_udev_path:
                        if (ib_dev->ibd_bd) {
                                pr_err("Unable to set udev_path= while"
                                        " ib_dev->ibd_bd exists\n");
                                ret = -EEXIST;
                                goto out;
                        }
                        if (match_strlcpy(ib_dev->ibd_udev_path, &args[0],
                                SE_UDEV_PATH_LEN) == 0) {
                                ret = -EINVAL;
                                break;
                        }
                        pr_debug("IBLOCK: Referencing UDEV path: %s\n",
                                        ib_dev->ibd_udev_path);
                        ib_dev->ibd_flags |= IBDF_HAS_UDEV_PATH;
                        break;
                case Opt_readonly:
                        arg_p = match_strdup(&args[0]);
                        if (!arg_p) {
                                ret = -ENOMEM;
                                break;
                        }
                        ret = kstrtoul(arg_p, 0, &tmp_readonly);
                        kfree(arg_p);
                        if (ret < 0) {
                                pr_err("kstrtoul() failed for"
                                                " readonly=\n");
                                goto out;
                        }
                        ib_dev->ibd_readonly = tmp_readonly;
                        pr_debug("IBLOCK: readonly: %d\n", ib_dev->ibd_readonly);
                        break;
                case Opt_force:
                        break;
                default:
                        break;
                }
        }

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

static ssize_t iblock_show_configfs_dev_params(struct se_device *dev, char *b)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
        struct block_device *bd = ib_dev->ibd_bd;
        char buf[BDEVNAME_SIZE];
        ssize_t bl = 0;

        if (bd)
                bl += sprintf(b + bl, "iBlock device: %s",
                                bdevname(bd, buf));
        if (ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)
                bl += sprintf(b + bl, "  UDEV PATH: %s",
                                ib_dev->ibd_udev_path);
        bl += sprintf(b + bl, "  readonly: %d\n", ib_dev->ibd_readonly);

        bl += sprintf(b + bl, "        ");
        if (bd) {
                bl += sprintf(b + bl, "Major: %d Minor: %d  %s\n",
                        MAJOR(bd->bd_dev), MINOR(bd->bd_dev), (!bd->bd_contains) ?
                        "" : (bd->bd_holder == ib_dev) ?
                        "CLAIMED: IBLOCK" : "CLAIMED: OS");
        } else {
                bl += sprintf(b + bl, "Major: 0 Minor: 0\n");
        }

        return bl;
}

static int
iblock_alloc_bip(struct se_cmd *cmd, struct bio *bio,
                 struct sg_mapping_iter *miter)
{
        struct se_device *dev = cmd->se_dev;
        struct blk_integrity *bi;
        struct bio_integrity_payload *bip;
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
        int rc;
        size_t resid, len;

        bi = bdev_get_integrity(ib_dev->ibd_bd);
        if (!bi) {
                pr_err("Unable to locate bio_integrity\n");
                return -ENODEV;
        }

        bip = bio_integrity_alloc(bio, GFP_NOIO,
                        min_t(unsigned int, cmd->t_prot_nents, BIO_MAX_PAGES));
        if (IS_ERR(bip)) {
                pr_err("Unable to allocate bio_integrity_payload\n");
                return PTR_ERR(bip);
        }

        bip->bip_iter.bi_size = bio_integrity_bytes(bi, bio_sectors(bio));
        bip_set_seed(bip, bio->bi_iter.bi_sector);

        pr_debug("IBLOCK BIP Size: %u Sector: %llu\n", bip->bip_iter.bi_size,
                 (unsigned long long)bip->bip_iter.bi_sector);

        resid = bip->bip_iter.bi_size;
        while (resid > 0 && sg_miter_next(miter)) {

                len = min_t(size_t, miter->length, resid);
                rc = bio_integrity_add_page(bio, miter->page, len,
                                            offset_in_page(miter->addr));
                if (rc != len) {
                        pr_err("bio_integrity_add_page() failed; %d\n", rc);
                        sg_miter_stop(miter);
                        return -ENOMEM;
                }

                pr_debug("Added bio integrity page: %p length: %zu offset: %lu\n",
                          miter->page, len, offset_in_page(miter->addr));

                resid -= len;
                if (len < miter->length)
                        miter->consumed -= miter->length - len;
        }
        sg_miter_stop(miter);

        return 0;
}

static sense_reason_t
iblock_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
                  enum dma_data_direction data_direction)
{
        struct se_device *dev = cmd->se_dev;
        sector_t block_lba = target_to_linux_sector(dev, cmd->t_task_lba);
        struct iblock_req *ibr;
        struct bio *bio;
        struct bio_list list;
        struct scatterlist *sg;
        u32 sg_num = sgl_nents;
        unsigned bio_cnt;
        int i, rc, op, op_flags = 0;
        struct sg_mapping_iter prot_miter;

        if (data_direction == DMA_TO_DEVICE) {
                struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
                struct request_queue *q = bdev_get_queue(ib_dev->ibd_bd);
                /*
                 * Force writethrough using REQ_FUA if a volatile write cache
                 * is not enabled, or if initiator set the Force Unit Access bit.
                 */
                op = REQ_OP_WRITE;
                if (test_bit(QUEUE_FLAG_FUA, &q->queue_flags)) {
                        if (cmd->se_cmd_flags & SCF_FUA)
                                op_flags = REQ_FUA;
                        else if (!test_bit(QUEUE_FLAG_WC, &q->queue_flags))
                                op_flags = REQ_FUA;
                }
        } else {
                op = REQ_OP_READ;
        }

        ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
        if (!ibr)
                goto fail;
        cmd->priv = ibr;

        if (!sgl_nents) {
                refcount_set(&ibr->pending, 1);
                iblock_complete_cmd(cmd);
                return 0;
        }

        bio = iblock_get_bio(cmd, block_lba, sgl_nents, op, op_flags);
        if (!bio)
                goto fail_free_ibr;

        bio_list_init(&list);
        bio_list_add(&list, bio);

        refcount_set(&ibr->pending, 2);
        bio_cnt = 1;

        if (cmd->prot_type && dev->dev_attrib.pi_prot_type)
                sg_miter_start(&prot_miter, cmd->t_prot_sg, cmd->t_prot_nents,
                               op == REQ_OP_READ ? SG_MITER_FROM_SG :
                                                   SG_MITER_TO_SG);

        for_each_sg(sgl, sg, sgl_nents, i) {
                /*
                 * XXX: if the length the device accepts is shorter than the
                 *      length of the S/G list entry this will cause and
                 *      endless loop.  Better hope no driver uses huge pages.
                 */
                while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
                                != sg->length) {
                        if (cmd->prot_type && dev->dev_attrib.pi_prot_type) {
                                rc = iblock_alloc_bip(cmd, bio, &prot_miter);
                                if (rc)
                                        goto fail_put_bios;
                        }

                        if (bio_cnt >= IBLOCK_MAX_BIO_PER_TASK) {
                                iblock_submit_bios(&list);
                                bio_cnt = 0;
                        }

                        bio = iblock_get_bio(cmd, block_lba, sg_num, op,
                                             op_flags);
                        if (!bio)
                                goto fail_put_bios;

                        refcount_inc(&ibr->pending);
                        bio_list_add(&list, bio);
                        bio_cnt++;
                }

                /* Always in 512 byte units for Linux/Block */
                block_lba += sg->length >> SECTOR_SHIFT;
                sg_num--;
        }

        if (cmd->prot_type && dev->dev_attrib.pi_prot_type) {
                rc = iblock_alloc_bip(cmd, bio, &prot_miter);
                if (rc)
                        goto fail_put_bios;
        }

        iblock_submit_bios(&list);
        iblock_complete_cmd(cmd);
        return 0;

fail_put_bios:
        while ((bio = bio_list_pop(&list)))
                bio_put(bio);
fail_free_ibr:
        kfree(ibr);
fail:
        return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}

static sector_t iblock_get_blocks(struct se_device *dev)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
        struct block_device *bd = ib_dev->ibd_bd;
        struct request_queue *q = bdev_get_queue(bd);

        return iblock_emulate_read_cap_with_block_size(dev, bd, q);
}

static sector_t iblock_get_alignment_offset_lbas(struct se_device *dev)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
        struct block_device *bd = ib_dev->ibd_bd;
        int ret;

        ret = bdev_alignment_offset(bd);
        if (ret == -1)
                return 0;

        /* convert offset-bytes to offset-lbas */
        return ret / bdev_logical_block_size(bd);
}

static unsigned int iblock_get_lbppbe(struct se_device *dev)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
        struct block_device *bd = ib_dev->ibd_bd;
        int logs_per_phys = bdev_physical_block_size(bd) / bdev_logical_block_size(bd);

        return ilog2(logs_per_phys);
}

static unsigned int iblock_get_io_min(struct se_device *dev)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
        struct block_device *bd = ib_dev->ibd_bd;

        return bdev_io_min(bd);
}

static unsigned int iblock_get_io_opt(struct se_device *dev)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
        struct block_device *bd = ib_dev->ibd_bd;

        return bdev_io_opt(bd);
}

static struct sbc_ops iblock_sbc_ops = {
        .execute_rw             = iblock_execute_rw,
        .execute_sync_cache     = iblock_execute_sync_cache,
        .execute_write_same     = iblock_execute_write_same,
        .execute_unmap          = iblock_execute_unmap,
};

static sense_reason_t
iblock_parse_cdb(struct se_cmd *cmd)
{
        return sbc_parse_cdb(cmd, &iblock_sbc_ops);
}

static bool iblock_get_write_cache(struct se_device *dev)
{
        struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
        struct block_device *bd = ib_dev->ibd_bd;
        struct request_queue *q = bdev_get_queue(bd);

        return test_bit(QUEUE_FLAG_WC, &q->queue_flags);
}

static const struct target_backend_ops iblock_ops = {
        .name                   = "iblock",
        .inquiry_prod           = "IBLOCK",
        .inquiry_rev            = IBLOCK_VERSION,
        .owner                  = THIS_MODULE,
        .attach_hba             = iblock_attach_hba,
        .detach_hba             = iblock_detach_hba,
        .alloc_device           = iblock_alloc_device,
        .configure_device       = iblock_configure_device,
        .destroy_device         = iblock_destroy_device,
        .free_device            = iblock_free_device,
        .parse_cdb              = iblock_parse_cdb,
        .set_configfs_dev_params = iblock_set_configfs_dev_params,
        .show_configfs_dev_params = iblock_show_configfs_dev_params,
        .get_device_type        = sbc_get_device_type,
        .get_blocks             = iblock_get_blocks,
        .get_alignment_offset_lbas = iblock_get_alignment_offset_lbas,
        .get_lbppbe             = iblock_get_lbppbe,
        .get_io_min             = iblock_get_io_min,
        .get_io_opt             = iblock_get_io_opt,
        .get_write_cache        = iblock_get_write_cache,
        .tb_dev_attrib_attrs    = sbc_attrib_attrs,
};

static int __init iblock_module_init(void)
{
        return transport_backend_register(&iblock_ops);
}

static void __exit iblock_module_exit(void)
{
        target_backend_unregister(&iblock_ops);
}

MODULE_DESCRIPTION("TCM IBLOCK subsystem plugin");
MODULE_AUTHOR("nab@Linux-iSCSI.org");
MODULE_LICENSE("GPL");

module_init(iblock_module_init);
module_exit(iblock_module_exit);