block: Abstract out bvec iterator

[mirror_ubuntu-artful-kernel.git] / drivers / scsi / osd / osd_initiator.c

/*
 * osd_initiator - Main body of the osd initiator library.
 *
 * Note: The file does not contain the advanced security functionality which
 * is only needed by the security_manager's initiators.
 *
 * Copyright (C) 2008 Panasas Inc.  All rights reserved.
 *
 * Authors:
 *   Boaz Harrosh <bharrosh@panasas.com>
 *   Benny Halevy <bhalevy@panasas.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. 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.
 *  3. Neither the name of the Panasas company nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/slab.h>
#include <linux/module.h>

#include <scsi/osd_initiator.h>
#include <scsi/osd_sec.h>
#include <scsi/osd_attributes.h>
#include <scsi/osd_sense.h>

#include <scsi/scsi_device.h>

#include "osd_debug.h"

#ifndef __unused
#    define __unused                    __attribute__((unused))
#endif

enum { OSD_REQ_RETRIES = 1 };

MODULE_AUTHOR("Boaz Harrosh <bharrosh@panasas.com>");
MODULE_DESCRIPTION("open-osd initiator library libosd.ko");
MODULE_LICENSE("GPL");

static inline void build_test(void)
{
        /* structures were not packed */
        BUILD_BUG_ON(sizeof(struct osd_capability) != OSD_CAP_LEN);
        BUILD_BUG_ON(sizeof(struct osdv2_cdb) != OSD_TOTAL_CDB_LEN);
        BUILD_BUG_ON(sizeof(struct osdv1_cdb) != OSDv1_TOTAL_CDB_LEN);
}

static const char *_osd_ver_desc(struct osd_request *or)
{
        return osd_req_is_ver1(or) ? "OSD1" : "OSD2";
}

#define ATTR_DEF_RI(id, len) ATTR_DEF(OSD_APAGE_ROOT_INFORMATION, id, len)

static int _osd_get_print_system_info(struct osd_dev *od,
        void *caps, struct osd_dev_info *odi)
{
        struct osd_request *or;
        struct osd_attr get_attrs[] = {
                ATTR_DEF_RI(OSD_ATTR_RI_VENDOR_IDENTIFICATION, 8),
                ATTR_DEF_RI(OSD_ATTR_RI_PRODUCT_IDENTIFICATION, 16),
                ATTR_DEF_RI(OSD_ATTR_RI_PRODUCT_MODEL, 32),
                ATTR_DEF_RI(OSD_ATTR_RI_PRODUCT_REVISION_LEVEL, 4),
                ATTR_DEF_RI(OSD_ATTR_RI_PRODUCT_SERIAL_NUMBER, 64 /*variable*/),
                ATTR_DEF_RI(OSD_ATTR_RI_OSD_NAME, 64 /*variable*/),
                ATTR_DEF_RI(OSD_ATTR_RI_TOTAL_CAPACITY, 8),
                ATTR_DEF_RI(OSD_ATTR_RI_USED_CAPACITY, 8),
                ATTR_DEF_RI(OSD_ATTR_RI_NUMBER_OF_PARTITIONS, 8),
                ATTR_DEF_RI(OSD_ATTR_RI_CLOCK, 6),
                /* IBM-OSD-SIM Has a bug with this one put it last */
                ATTR_DEF_RI(OSD_ATTR_RI_OSD_SYSTEM_ID, 20),
        };
        void *iter = NULL, *pFirst;
        int nelem = ARRAY_SIZE(get_attrs), a = 0;
        int ret;

        or = osd_start_request(od, GFP_KERNEL);
        if (!or)
                return -ENOMEM;

        /* get attrs */
        osd_req_get_attributes(or, &osd_root_object);
        osd_req_add_get_attr_list(or, get_attrs, ARRAY_SIZE(get_attrs));

        ret = osd_finalize_request(or, 0, caps, NULL);
        if (ret)
                goto out;

        ret = osd_execute_request(or);
        if (ret) {
                OSD_ERR("Failed to detect %s => %d\n", _osd_ver_desc(or), ret);
                goto out;
        }

        osd_req_decode_get_attr_list(or, get_attrs, &nelem, &iter);

        OSD_INFO("Detected %s device\n",
                _osd_ver_desc(or));

        pFirst = get_attrs[a++].val_ptr;
        OSD_INFO("VENDOR_IDENTIFICATION  [%s]\n",
                (char *)pFirst);

        pFirst = get_attrs[a++].val_ptr;
        OSD_INFO("PRODUCT_IDENTIFICATION [%s]\n",
                (char *)pFirst);

        pFirst = get_attrs[a++].val_ptr;
        OSD_INFO("PRODUCT_MODEL          [%s]\n",
                (char *)pFirst);

        pFirst = get_attrs[a++].val_ptr;
        OSD_INFO("PRODUCT_REVISION_LEVEL [%u]\n",
                pFirst ? get_unaligned_be32(pFirst) : ~0U);

        pFirst = get_attrs[a++].val_ptr;
        OSD_INFO("PRODUCT_SERIAL_NUMBER  [%s]\n",
                (char *)pFirst);

        odi->osdname_len = get_attrs[a].len;
        /* Avoid NULL for memcmp optimization 0-length is good enough */
        odi->osdname = kzalloc(odi->osdname_len + 1, GFP_KERNEL);
        if (!odi->osdname) {
                ret = -ENOMEM;
                goto out;
        }
        if (odi->osdname_len)
                memcpy(odi->osdname, get_attrs[a].val_ptr, odi->osdname_len);
        OSD_INFO("OSD_NAME               [%s]\n", odi->osdname);
        a++;

        pFirst = get_attrs[a++].val_ptr;
        OSD_INFO("TOTAL_CAPACITY         [0x%llx]\n",
                pFirst ? _LLU(get_unaligned_be64(pFirst)) : ~0ULL);

        pFirst = get_attrs[a++].val_ptr;
        OSD_INFO("USED_CAPACITY          [0x%llx]\n",
                pFirst ? _LLU(get_unaligned_be64(pFirst)) : ~0ULL);

        pFirst = get_attrs[a++].val_ptr;
        OSD_INFO("NUMBER_OF_PARTITIONS   [%llu]\n",
                pFirst ? _LLU(get_unaligned_be64(pFirst)) : ~0ULL);

        if (a >= nelem)
                goto out;

        /* FIXME: Where are the time utilities */
        pFirst = get_attrs[a++].val_ptr;
        OSD_INFO("CLOCK                  [0x%02x%02x%02x%02x%02x%02x]\n",
                ((char *)pFirst)[0], ((char *)pFirst)[1],
                ((char *)pFirst)[2], ((char *)pFirst)[3],
                ((char *)pFirst)[4], ((char *)pFirst)[5]);

        if (a < nelem) { /* IBM-OSD-SIM bug, Might not have it */
                unsigned len = get_attrs[a].len;
                char sid_dump[32*4 + 2]; /* 2nibbles+space+ASCII */

                hex_dump_to_buffer(get_attrs[a].val_ptr, len, 32, 1,
                                   sid_dump, sizeof(sid_dump), true);
                OSD_INFO("OSD_SYSTEM_ID(%d)\n"
                         "        [%s]\n", len, sid_dump);

                if (unlikely(len > sizeof(odi->systemid))) {
                        OSD_ERR("OSD Target error: OSD_SYSTEM_ID too long(%d). "
                                "device idetification might not work\n", len);
                        len = sizeof(odi->systemid);
                }
                odi->systemid_len = len;
                memcpy(odi->systemid, get_attrs[a].val_ptr, len);
                a++;
        }
out:
        osd_end_request(or);
        return ret;
}

int osd_auto_detect_ver(struct osd_dev *od,
        void *caps, struct osd_dev_info *odi)
{
        int ret;

        /* Auto-detect the osd version */
        ret = _osd_get_print_system_info(od, caps, odi);
        if (ret) {
                osd_dev_set_ver(od, OSD_VER1);
                OSD_DEBUG("converting to OSD1\n");
                ret = _osd_get_print_system_info(od, caps, odi);
        }

        return ret;
}
EXPORT_SYMBOL(osd_auto_detect_ver);

static unsigned _osd_req_cdb_len(struct osd_request *or)
{
        return osd_req_is_ver1(or) ? OSDv1_TOTAL_CDB_LEN : OSD_TOTAL_CDB_LEN;
}

static unsigned _osd_req_alist_elem_size(struct osd_request *or, unsigned len)
{
        return osd_req_is_ver1(or) ?
                osdv1_attr_list_elem_size(len) :
                osdv2_attr_list_elem_size(len);
}

static void _osd_req_alist_elem_encode(struct osd_request *or,
        void *attr_last, const struct osd_attr *oa)
{
        if (osd_req_is_ver1(or)) {
                struct osdv1_attributes_list_element *attr = attr_last;

                attr->attr_page = cpu_to_be32(oa->attr_page);
                attr->attr_id = cpu_to_be32(oa->attr_id);
                attr->attr_bytes = cpu_to_be16(oa->len);
                memcpy(attr->attr_val, oa->val_ptr, oa->len);
        } else {
                struct osdv2_attributes_list_element *attr = attr_last;

                attr->attr_page = cpu_to_be32(oa->attr_page);
                attr->attr_id = cpu_to_be32(oa->attr_id);
                attr->attr_bytes = cpu_to_be16(oa->len);
                memcpy(attr->attr_val, oa->val_ptr, oa->len);
        }
}

static int _osd_req_alist_elem_decode(struct osd_request *or,
        void *cur_p, struct osd_attr *oa, unsigned max_bytes)
{
        unsigned inc;
        if (osd_req_is_ver1(or)) {
                struct osdv1_attributes_list_element *attr = cur_p;

                if (max_bytes < sizeof(*attr))
                        return -1;

                oa->len = be16_to_cpu(attr->attr_bytes);
                inc = _osd_req_alist_elem_size(or, oa->len);
                if (inc > max_bytes)
                        return -1;

                oa->attr_page = be32_to_cpu(attr->attr_page);
                oa->attr_id = be32_to_cpu(attr->attr_id);

                /* OSD1: On empty attributes we return a pointer to 2 bytes
                 * of zeros. This keeps similar behaviour with OSD2.
                 * (See below)
                 */
                oa->val_ptr = likely(oa->len) ? attr->attr_val :
                                                (u8 *)&attr->attr_bytes;
        } else {
                struct osdv2_attributes_list_element *attr = cur_p;

                if (max_bytes < sizeof(*attr))
                        return -1;

                oa->len = be16_to_cpu(attr->attr_bytes);
                inc = _osd_req_alist_elem_size(or, oa->len);
                if (inc > max_bytes)
                        return -1;

                oa->attr_page = be32_to_cpu(attr->attr_page);
                oa->attr_id = be32_to_cpu(attr->attr_id);

                /* OSD2: For convenience, on empty attributes, we return 8 bytes
                 * of zeros here. This keeps the same behaviour with OSD2r04,
                 * and is nice with null terminating ASCII fields.
                 * oa->val_ptr == NULL marks the end-of-list, or error.
                 */
                oa->val_ptr = likely(oa->len) ? attr->attr_val : attr->reserved;
        }
        return inc;
}

static unsigned _osd_req_alist_size(struct osd_request *or, void *list_head)
{
        return osd_req_is_ver1(or) ?
                osdv1_list_size(list_head) :
                osdv2_list_size(list_head);
}

static unsigned _osd_req_sizeof_alist_header(struct osd_request *or)
{
        return osd_req_is_ver1(or) ?
                sizeof(struct osdv1_attributes_list_header) :
                sizeof(struct osdv2_attributes_list_header);
}

static void _osd_req_set_alist_type(struct osd_request *or,
        void *list, int list_type)
{
        if (osd_req_is_ver1(or)) {
                struct osdv1_attributes_list_header *attr_list = list;

                memset(attr_list, 0, sizeof(*attr_list));
                attr_list->type = list_type;
        } else {
                struct osdv2_attributes_list_header *attr_list = list;

                memset(attr_list, 0, sizeof(*attr_list));
                attr_list->type = list_type;
        }
}

static bool _osd_req_is_alist_type(struct osd_request *or,
        void *list, int list_type)
{
        if (!list)
                return false;

        if (osd_req_is_ver1(or)) {
                struct osdv1_attributes_list_header *attr_list = list;

                return attr_list->type == list_type;
        } else {
                struct osdv2_attributes_list_header *attr_list = list;

                return attr_list->type == list_type;
        }
}

/* This is for List-objects not Attributes-Lists */
static void _osd_req_encode_olist(struct osd_request *or,
        struct osd_obj_id_list *list)
{
        struct osd_cdb_head *cdbh = osd_cdb_head(&or->cdb);

        if (osd_req_is_ver1(or)) {
                cdbh->v1.list_identifier = list->list_identifier;
                cdbh->v1.start_address = list->continuation_id;
        } else {
                cdbh->v2.list_identifier = list->list_identifier;
                cdbh->v2.start_address = list->continuation_id;
        }
}

static osd_cdb_offset osd_req_encode_offset(struct osd_request *or,
        u64 offset, unsigned *padding)
{
        return __osd_encode_offset(offset, padding,
                        osd_req_is_ver1(or) ?
                                OSDv1_OFFSET_MIN_SHIFT : OSD_OFFSET_MIN_SHIFT,
                        OSD_OFFSET_MAX_SHIFT);
}

static struct osd_security_parameters *
_osd_req_sec_params(struct osd_request *or)
{
        struct osd_cdb *ocdb = &or->cdb;

        if (osd_req_is_ver1(or))
                return (struct osd_security_parameters *)&ocdb->v1.sec_params;
        else
                return (struct osd_security_parameters *)&ocdb->v2.sec_params;
}

void osd_dev_init(struct osd_dev *osdd, struct scsi_device *scsi_device)
{
        memset(osdd, 0, sizeof(*osdd));
        osdd->scsi_device = scsi_device;
        osdd->def_timeout = BLK_DEFAULT_SG_TIMEOUT;
#ifdef OSD_VER1_SUPPORT
        osdd->version = OSD_VER2;
#endif
        /* TODO: Allocate pools for osd_request attributes ... */
}
EXPORT_SYMBOL(osd_dev_init);

void osd_dev_fini(struct osd_dev *osdd)
{
        /* TODO: De-allocate pools */

        osdd->scsi_device = NULL;
}
EXPORT_SYMBOL(osd_dev_fini);

static struct osd_request *_osd_request_alloc(gfp_t gfp)
{
        struct osd_request *or;

        /* TODO: Use mempool with one saved request */
        or = kzalloc(sizeof(*or), gfp);
        return or;
}

static void _osd_request_free(struct osd_request *or)
{
        kfree(or);
}

struct osd_request *osd_start_request(struct osd_dev *dev, gfp_t gfp)
{
        struct osd_request *or;

        or = _osd_request_alloc(gfp);
        if (!or)
                return NULL;

        or->osd_dev = dev;
        or->alloc_flags = gfp;
        or->timeout = dev->def_timeout;
        or->retries = OSD_REQ_RETRIES;

        return or;
}
EXPORT_SYMBOL(osd_start_request);

static void _osd_free_seg(struct osd_request *or __unused,
        struct _osd_req_data_segment *seg)
{
        if (!seg->buff || !seg->alloc_size)
                return;

        kfree(seg->buff);
        seg->buff = NULL;
        seg->alloc_size = 0;
}

static void _put_request(struct request *rq)
{
        /*
         * If osd_finalize_request() was called but the request was not
         * executed through the block layer, then we must release BIOs.
         * TODO: Keep error code in or->async_error. Need to audit all
         *       code paths.
         */
        if (unlikely(rq->bio))
                blk_end_request(rq, -ENOMEM, blk_rq_bytes(rq));
        else
                blk_put_request(rq);
}

void osd_end_request(struct osd_request *or)
{
        struct request *rq = or->request;

        if (rq) {
                if (rq->next_rq) {
                        _put_request(rq->next_rq);
                        rq->next_rq = NULL;
                }

                _put_request(rq);
        }

        _osd_free_seg(or, &or->get_attr);
        _osd_free_seg(or, &or->enc_get_attr);
        _osd_free_seg(or, &or->set_attr);
        _osd_free_seg(or, &or->cdb_cont);

        _osd_request_free(or);
}
EXPORT_SYMBOL(osd_end_request);

static void _set_error_resid(struct osd_request *or, struct request *req,
                             int error)
{
        or->async_error = error;
        or->req_errors = req->errors ? : error;
        or->sense_len = req->sense_len;
        if (or->out.req)
                or->out.residual = or->out.req->resid_len;
        if (or->in.req)
                or->in.residual = or->in.req->resid_len;
}

int osd_execute_request(struct osd_request *or)
{
        int error = blk_execute_rq(or->request->q, NULL, or->request, 0);

        _set_error_resid(or, or->request, error);
        return error;
}
EXPORT_SYMBOL(osd_execute_request);

static void osd_request_async_done(struct request *req, int error)
{
        struct osd_request *or = req->end_io_data;

        _set_error_resid(or, req, error);
        if (req->next_rq) {
                __blk_put_request(req->q, req->next_rq);
                req->next_rq = NULL;
        }

        __blk_put_request(req->q, req);
        or->request = NULL;
        or->in.req = NULL;
        or->out.req = NULL;

        if (or->async_done)
                or->async_done(or, or->async_private);
        else
                osd_end_request(or);
}

int osd_execute_request_async(struct osd_request *or,
        osd_req_done_fn *done, void *private)
{
        or->request->end_io_data = or;
        or->async_private = private;
        or->async_done = done;

        blk_execute_rq_nowait(or->request->q, NULL, or->request, 0,
                              osd_request_async_done);
        return 0;
}
EXPORT_SYMBOL(osd_execute_request_async);

u8 sg_out_pad_buffer[1 << OSDv1_OFFSET_MIN_SHIFT];
u8 sg_in_pad_buffer[1 << OSDv1_OFFSET_MIN_SHIFT];

static int _osd_realloc_seg(struct osd_request *or,
        struct _osd_req_data_segment *seg, unsigned max_bytes)
{
        void *buff;

        if (seg->alloc_size >= max_bytes)
                return 0;

        buff = krealloc(seg->buff, max_bytes, or->alloc_flags);
        if (!buff) {
                OSD_ERR("Failed to Realloc %d-bytes was-%d\n", max_bytes,
                        seg->alloc_size);
                return -ENOMEM;
        }

        memset(buff + seg->alloc_size, 0, max_bytes - seg->alloc_size);
        seg->buff = buff;
        seg->alloc_size = max_bytes;
        return 0;
}

static int _alloc_cdb_cont(struct osd_request *or, unsigned total_bytes)
{
        OSD_DEBUG("total_bytes=%d\n", total_bytes);
        return _osd_realloc_seg(or, &or->cdb_cont, total_bytes);
}

static int _alloc_set_attr_list(struct osd_request *or,
        const struct osd_attr *oa, unsigned nelem, unsigned add_bytes)
{
        unsigned total_bytes = add_bytes;

        for (; nelem; --nelem, ++oa)
                total_bytes += _osd_req_alist_elem_size(or, oa->len);

        OSD_DEBUG("total_bytes=%d\n", total_bytes);
        return _osd_realloc_seg(or, &or->set_attr, total_bytes);
}

static int _alloc_get_attr_desc(struct osd_request *or, unsigned max_bytes)
{
        OSD_DEBUG("total_bytes=%d\n", max_bytes);
        return _osd_realloc_seg(or, &or->enc_get_attr, max_bytes);
}

static int _alloc_get_attr_list(struct osd_request *or)
{
        OSD_DEBUG("total_bytes=%d\n", or->get_attr.total_bytes);
        return _osd_realloc_seg(or, &or->get_attr, or->get_attr.total_bytes);
}

/*
 * Common to all OSD commands
 */

static void _osdv1_req_encode_common(struct osd_request *or,
        __be16 act, const struct osd_obj_id *obj, u64 offset, u64 len)
{
        struct osdv1_cdb *ocdb = &or->cdb.v1;

        /*
         * For speed, the commands
         *      OSD_ACT_PERFORM_SCSI_COMMAND    , V1 0x8F7E, V2 0x8F7C
         *      OSD_ACT_SCSI_TASK_MANAGEMENT    , V1 0x8F7F, V2 0x8F7D
         * are not supported here. Should pass zero and set after the call
         */
        act &= cpu_to_be16(~0x0080); /* V1 action code */

        OSD_DEBUG("OSDv1 execute opcode 0x%x\n", be16_to_cpu(act));

        ocdb->h.varlen_cdb.opcode = VARIABLE_LENGTH_CMD;
        ocdb->h.varlen_cdb.additional_cdb_length = OSD_ADDITIONAL_CDB_LENGTH;
        ocdb->h.varlen_cdb.service_action = act;

        ocdb->h.partition = cpu_to_be64(obj->partition);
        ocdb->h.object = cpu_to_be64(obj->id);
        ocdb->h.v1.length = cpu_to_be64(len);
        ocdb->h.v1.start_address = cpu_to_be64(offset);
}

static void _osdv2_req_encode_common(struct osd_request *or,
         __be16 act, const struct osd_obj_id *obj, u64 offset, u64 len)
{
        struct osdv2_cdb *ocdb = &or->cdb.v2;

        OSD_DEBUG("OSDv2 execute opcode 0x%x\n", be16_to_cpu(act));

        ocdb->h.varlen_cdb.opcode = VARIABLE_LENGTH_CMD;
        ocdb->h.varlen_cdb.additional_cdb_length = OSD_ADDITIONAL_CDB_LENGTH;
        ocdb->h.varlen_cdb.service_action = act;

        ocdb->h.partition = cpu_to_be64(obj->partition);
        ocdb->h.object = cpu_to_be64(obj->id);
        ocdb->h.v2.length = cpu_to_be64(len);
        ocdb->h.v2.start_address = cpu_to_be64(offset);
}

static void _osd_req_encode_common(struct osd_request *or,
        __be16 act, const struct osd_obj_id *obj, u64 offset, u64 len)
{
        if (osd_req_is_ver1(or))
                _osdv1_req_encode_common(or, act, obj, offset, len);
        else
                _osdv2_req_encode_common(or, act, obj, offset, len);
}

/*
 * Device commands
 */
/*TODO: void osd_req_set_master_seed_xchg(struct osd_request *, ...); */
/*TODO: void osd_req_set_master_key(struct osd_request *, ...); */

void osd_req_format(struct osd_request *or, u64 tot_capacity)
{
        _osd_req_encode_common(or, OSD_ACT_FORMAT_OSD, &osd_root_object, 0,
                                tot_capacity);
}
EXPORT_SYMBOL(osd_req_format);

int osd_req_list_dev_partitions(struct osd_request *or,
        osd_id initial_id, struct osd_obj_id_list *list, unsigned nelem)
{
        return osd_req_list_partition_objects(or, 0, initial_id, list, nelem);
}
EXPORT_SYMBOL(osd_req_list_dev_partitions);

static void _osd_req_encode_flush(struct osd_request *or,
        enum osd_options_flush_scope_values op)
{
        struct osd_cdb_head *ocdb = osd_cdb_head(&or->cdb);

        ocdb->command_specific_options = op;
}

void osd_req_flush_obsd(struct osd_request *or,
        enum osd_options_flush_scope_values op)
{
        _osd_req_encode_common(or, OSD_ACT_FLUSH_OSD, &osd_root_object, 0, 0);
        _osd_req_encode_flush(or, op);
}
EXPORT_SYMBOL(osd_req_flush_obsd);

/*TODO: void osd_req_perform_scsi_command(struct osd_request *,
        const u8 *cdb, ...); */
/*TODO: void osd_req_task_management(struct osd_request *, ...); */

/*
 * Partition commands
 */
static void _osd_req_encode_partition(struct osd_request *or,
        __be16 act, osd_id partition)
{
        struct osd_obj_id par = {
                .partition = partition,
                .id = 0,
        };

        _osd_req_encode_common(or, act, &par, 0, 0);
}

void osd_req_create_partition(struct osd_request *or, osd_id partition)
{
        _osd_req_encode_partition(or, OSD_ACT_CREATE_PARTITION, partition);
}
EXPORT_SYMBOL(osd_req_create_partition);

void osd_req_remove_partition(struct osd_request *or, osd_id partition)
{
        _osd_req_encode_partition(or, OSD_ACT_REMOVE_PARTITION, partition);
}
EXPORT_SYMBOL(osd_req_remove_partition);

/*TODO: void osd_req_set_partition_key(struct osd_request *,
        osd_id partition, u8 new_key_id[OSD_CRYPTO_KEYID_SIZE],
        u8 seed[OSD_CRYPTO_SEED_SIZE]); */

static int _osd_req_list_objects(struct osd_request *or,
        __be16 action, const struct osd_obj_id *obj, osd_id initial_id,
        struct osd_obj_id_list *list, unsigned nelem)
{
        struct request_queue *q = osd_request_queue(or->osd_dev);
        u64 len = nelem * sizeof(osd_id) + sizeof(*list);
        struct bio *bio;

        _osd_req_encode_common(or, action, obj, (u64)initial_id, len);

        if (list->list_identifier)
                _osd_req_encode_olist(or, list);

        WARN_ON(or->in.bio);
        bio = bio_map_kern(q, list, len, or->alloc_flags);
        if (IS_ERR(bio)) {
                OSD_ERR("!!! Failed to allocate list_objects BIO\n");
                return PTR_ERR(bio);
        }

        bio->bi_rw &= ~REQ_WRITE;
        or->in.bio = bio;
        or->in.total_bytes = bio->bi_iter.bi_size;
        return 0;
}

int osd_req_list_partition_collections(struct osd_request *or,
        osd_id partition, osd_id initial_id, struct osd_obj_id_list *list,
        unsigned nelem)
{
        struct osd_obj_id par = {
                .partition = partition,
                .id = 0,
        };

        return osd_req_list_collection_objects(or, &par, initial_id, list,
                                               nelem);
}
EXPORT_SYMBOL(osd_req_list_partition_collections);

int osd_req_list_partition_objects(struct osd_request *or,
        osd_id partition, osd_id initial_id, struct osd_obj_id_list *list,
        unsigned nelem)
{
        struct osd_obj_id par = {
                .partition = partition,
                .id = 0,
        };

        return _osd_req_list_objects(or, OSD_ACT_LIST, &par, initial_id, list,
                                     nelem);
}
EXPORT_SYMBOL(osd_req_list_partition_objects);

void osd_req_flush_partition(struct osd_request *or,
        osd_id partition, enum osd_options_flush_scope_values op)
{
        _osd_req_encode_partition(or, OSD_ACT_FLUSH_PARTITION, partition);
        _osd_req_encode_flush(or, op);
}
EXPORT_SYMBOL(osd_req_flush_partition);

/*
 * Collection commands
 */
/*TODO: void osd_req_create_collection(struct osd_request *,
        const struct osd_obj_id *); */
/*TODO: void osd_req_remove_collection(struct osd_request *,
        const struct osd_obj_id *); */

int osd_req_list_collection_objects(struct osd_request *or,
        const struct osd_obj_id *obj, osd_id initial_id,
        struct osd_obj_id_list *list, unsigned nelem)
{
        return _osd_req_list_objects(or, OSD_ACT_LIST_COLLECTION, obj,
                                     initial_id, list, nelem);
}
EXPORT_SYMBOL(osd_req_list_collection_objects);

/*TODO: void query(struct osd_request *, ...); V2 */

void osd_req_flush_collection(struct osd_request *or,
        const struct osd_obj_id *obj, enum osd_options_flush_scope_values op)
{
        _osd_req_encode_common(or, OSD_ACT_FLUSH_PARTITION, obj, 0, 0);
        _osd_req_encode_flush(or, op);
}
EXPORT_SYMBOL(osd_req_flush_collection);

/*TODO: void get_member_attrs(struct osd_request *, ...); V2 */
/*TODO: void set_member_attrs(struct osd_request *, ...); V2 */

/*
 * Object commands
 */
void osd_req_create_object(struct osd_request *or, struct osd_obj_id *obj)
{
        _osd_req_encode_common(or, OSD_ACT_CREATE, obj, 0, 0);
}
EXPORT_SYMBOL(osd_req_create_object);

void osd_req_remove_object(struct osd_request *or, struct osd_obj_id *obj)
{
        _osd_req_encode_common(or, OSD_ACT_REMOVE, obj, 0, 0);
}
EXPORT_SYMBOL(osd_req_remove_object);


/*TODO: void osd_req_create_multi(struct osd_request *or,
        struct osd_obj_id *first, struct osd_obj_id_list *list, unsigned nelem);
*/

void osd_req_write(struct osd_request *or,
        const struct osd_obj_id *obj, u64 offset,
        struct bio *bio, u64 len)
{
        _osd_req_encode_common(or, OSD_ACT_WRITE, obj, offset, len);
        WARN_ON(or->out.bio || or->out.total_bytes);
        WARN_ON(0 == (bio->bi_rw & REQ_WRITE));
        or->out.bio = bio;
        or->out.total_bytes = len;
}
EXPORT_SYMBOL(osd_req_write);

int osd_req_write_kern(struct osd_request *or,
        const struct osd_obj_id *obj, u64 offset, void* buff, u64 len)
{
        struct request_queue *req_q = osd_request_queue(or->osd_dev);
        struct bio *bio = bio_map_kern(req_q, buff, len, GFP_KERNEL);

        if (IS_ERR(bio))
                return PTR_ERR(bio);

        bio->bi_rw |= REQ_WRITE; /* FIXME: bio_set_dir() */
        osd_req_write(or, obj, offset, bio, len);
        return 0;
}
EXPORT_SYMBOL(osd_req_write_kern);

/*TODO: void osd_req_append(struct osd_request *,
        const struct osd_obj_id *, struct bio *data_out); */
/*TODO: void osd_req_create_write(struct osd_request *,
        const struct osd_obj_id *, struct bio *data_out, u64 offset); */
/*TODO: void osd_req_clear(struct osd_request *,
        const struct osd_obj_id *, u64 offset, u64 len); */
/*TODO: void osd_req_punch(struct osd_request *,
        const struct osd_obj_id *, u64 offset, u64 len); V2 */

void osd_req_flush_object(struct osd_request *or,
        const struct osd_obj_id *obj, enum osd_options_flush_scope_values op,
        /*V2*/ u64 offset, /*V2*/ u64 len)
{
        if (unlikely(osd_req_is_ver1(or) && (offset || len))) {
                OSD_DEBUG("OSD Ver1 flush on specific range ignored\n");
                offset = 0;
                len = 0;
        }

        _osd_req_encode_common(or, OSD_ACT_FLUSH, obj, offset, len);
        _osd_req_encode_flush(or, op);
}
EXPORT_SYMBOL(osd_req_flush_object);

void osd_req_read(struct osd_request *or,
        const struct osd_obj_id *obj, u64 offset,
        struct bio *bio, u64 len)
{
        _osd_req_encode_common(or, OSD_ACT_READ, obj, offset, len);
        WARN_ON(or->in.bio || or->in.total_bytes);
        WARN_ON(bio->bi_rw & REQ_WRITE);
        or->in.bio = bio;
        or->in.total_bytes = len;
}
EXPORT_SYMBOL(osd_req_read);

int osd_req_read_kern(struct osd_request *or,
        const struct osd_obj_id *obj, u64 offset, void* buff, u64 len)
{
        struct request_queue *req_q = osd_request_queue(or->osd_dev);
        struct bio *bio = bio_map_kern(req_q, buff, len, GFP_KERNEL);

        if (IS_ERR(bio))
                return PTR_ERR(bio);

        osd_req_read(or, obj, offset, bio, len);
        return 0;
}
EXPORT_SYMBOL(osd_req_read_kern);

static int _add_sg_continuation_descriptor(struct osd_request *or,
        const struct osd_sg_entry *sglist, unsigned numentries, u64 *len)
{
        struct osd_sg_continuation_descriptor *oscd;
        u32 oscd_size;
        unsigned i;
        int ret;

        oscd_size = sizeof(*oscd) + numentries * sizeof(oscd->entries[0]);

        if (!or->cdb_cont.total_bytes) {
                /* First time, jump over the header, we will write to:
                 *      cdb_cont.buff + cdb_cont.total_bytes
                 */
                or->cdb_cont.total_bytes =
                                sizeof(struct osd_continuation_segment_header);
        }

        ret = _alloc_cdb_cont(or, or->cdb_cont.total_bytes + oscd_size);
        if (unlikely(ret))
                return ret;

        oscd = or->cdb_cont.buff + or->cdb_cont.total_bytes;
        oscd->hdr.type = cpu_to_be16(SCATTER_GATHER_LIST);
        oscd->hdr.pad_length = 0;
        oscd->hdr.length = cpu_to_be32(oscd_size - sizeof(*oscd));

        *len = 0;
        /* copy the sg entries and convert to network byte order */
        for (i = 0; i < numentries; i++) {
                oscd->entries[i].offset = cpu_to_be64(sglist[i].offset);
                oscd->entries[i].len    = cpu_to_be64(sglist[i].len);
                *len += sglist[i].len;
        }

        or->cdb_cont.total_bytes += oscd_size;
        OSD_DEBUG("total_bytes=%d oscd_size=%d numentries=%d\n",
                  or->cdb_cont.total_bytes, oscd_size, numentries);
        return 0;
}

static int _osd_req_finalize_cdb_cont(struct osd_request *or, const u8 *cap_key)
{
        struct request_queue *req_q = osd_request_queue(or->osd_dev);
        struct bio *bio;
        struct osd_cdb_head *cdbh = osd_cdb_head(&or->cdb);
        struct osd_continuation_segment_header *cont_seg_hdr;

        if (!or->cdb_cont.total_bytes)
                return 0;

        cont_seg_hdr = or->cdb_cont.buff;
        cont_seg_hdr->format = CDB_CONTINUATION_FORMAT_V2;
        cont_seg_hdr->service_action = cdbh->varlen_cdb.service_action;

        /* create a bio for continuation segment */
        bio = bio_map_kern(req_q, or->cdb_cont.buff, or->cdb_cont.total_bytes,
                           GFP_KERNEL);
        if (IS_ERR(bio))
                return PTR_ERR(bio);

        bio->bi_rw |= REQ_WRITE;

        /* integrity check the continuation before the bio is linked
         * with the other data segments since the continuation
         * integrity is separate from the other data segments.
         */
        osd_sec_sign_data(cont_seg_hdr->integrity_check, bio, cap_key);

        cdbh->v2.cdb_continuation_length = cpu_to_be32(or->cdb_cont.total_bytes);

        /* we can't use _req_append_segment, because we need to link in the
         * continuation bio to the head of the bio list - the
         * continuation segment (if it exists) is always the first segment in
         * the out data buffer.
         */
        bio->bi_next = or->out.bio;
        or->out.bio = bio;
        or->out.total_bytes += or->cdb_cont.total_bytes;

        return 0;
}

/* osd_req_write_sg: Takes a @bio that points to the data out buffer and an
 * @sglist that has the scatter gather entries. Scatter-gather enables a write
 * of multiple none-contiguous areas of an object, in a single call. The extents
 * may overlap and/or be in any order. The only constrain is that:
 *      total_bytes(sglist) >= total_bytes(bio)
 */
int osd_req_write_sg(struct osd_request *or,
        const struct osd_obj_id *obj, struct bio *bio,
        const struct osd_sg_entry *sglist, unsigned numentries)
{
        u64 len;
        int ret = _add_sg_continuation_descriptor(or, sglist, numentries, &len);

        if (ret)
                return ret;
        osd_req_write(or, obj, 0, bio, len);

        return 0;
}
EXPORT_SYMBOL(osd_req_write_sg);

/* osd_req_read_sg: Read multiple extents of an object into @bio
 * See osd_req_write_sg
 */
int osd_req_read_sg(struct osd_request *or,
        const struct osd_obj_id *obj, struct bio *bio,
        const struct osd_sg_entry *sglist, unsigned numentries)
{
        u64 len;
        u64 off;
        int ret;

        if (numentries > 1) {
                off = 0;
                ret = _add_sg_continuation_descriptor(or, sglist, numentries,
                                                      &len);
                if (ret)
                        return ret;
        } else {
                /* Optimize the case of single segment, read_sg is a
                 * bidi operation.
                 */
                len = sglist->len;
                off = sglist->offset;
        }
        osd_req_read(or, obj, off, bio, len);

        return 0;
}
EXPORT_SYMBOL(osd_req_read_sg);

/* SG-list write/read Kern API
 *
 * osd_req_{write,read}_sg_kern takes an array of @buff pointers and an array
 * of sg_entries. @numentries indicates how many pointers and sg_entries there
 * are.  By requiring an array of buff pointers. This allows a caller to do a
 * single write/read and scatter into multiple buffers.
 * NOTE: Each buffer + len should not cross a page boundary.
 */
static struct bio *_create_sg_bios(struct osd_request *or,
        void **buff, const struct osd_sg_entry *sglist, unsigned numentries)
{
        struct request_queue *q = osd_request_queue(or->osd_dev);
        struct bio *bio;
        unsigned i;

        bio = bio_kmalloc(GFP_KERNEL, numentries);
        if (unlikely(!bio)) {
                OSD_DEBUG("Failed to allocate BIO size=%u\n", numentries);
                return ERR_PTR(-ENOMEM);
        }

        for (i = 0; i < numentries; i++) {
                unsigned offset = offset_in_page(buff[i]);
                struct page *page = virt_to_page(buff[i]);
                unsigned len = sglist[i].len;
                unsigned added_len;

                BUG_ON(offset + len > PAGE_SIZE);
                added_len = bio_add_pc_page(q, bio, page, len, offset);
                if (unlikely(len != added_len)) {
                        OSD_DEBUG("bio_add_pc_page len(%d) != added_len(%d)\n",
                                  len, added_len);
                        bio_put(bio);
                        return ERR_PTR(-ENOMEM);
                }
        }

        return bio;
}

int osd_req_write_sg_kern(struct osd_request *or,
        const struct osd_obj_id *obj, void **buff,
        const struct osd_sg_entry *sglist, unsigned numentries)
{
        struct bio *bio = _create_sg_bios(or, buff, sglist, numentries);
        if (IS_ERR(bio))
                return PTR_ERR(bio);

        bio->bi_rw |= REQ_WRITE;
        osd_req_write_sg(or, obj, bio, sglist, numentries);

        return 0;
}
EXPORT_SYMBOL(osd_req_write_sg_kern);

int osd_req_read_sg_kern(struct osd_request *or,
        const struct osd_obj_id *obj, void **buff,
        const struct osd_sg_entry *sglist, unsigned numentries)
{
        struct bio *bio = _create_sg_bios(or, buff, sglist, numentries);
        if (IS_ERR(bio))
                return PTR_ERR(bio);

        osd_req_read_sg(or, obj, bio, sglist, numentries);

        return 0;
}
EXPORT_SYMBOL(osd_req_read_sg_kern);



void osd_req_get_attributes(struct osd_request *or,
        const struct osd_obj_id *obj)
{
        _osd_req_encode_common(or, OSD_ACT_GET_ATTRIBUTES, obj, 0, 0);
}
EXPORT_SYMBOL(osd_req_get_attributes);

void osd_req_set_attributes(struct osd_request *or,
        const struct osd_obj_id *obj)
{
        _osd_req_encode_common(or, OSD_ACT_SET_ATTRIBUTES, obj, 0, 0);
}
EXPORT_SYMBOL(osd_req_set_attributes);

/*
 * Attributes List-mode
 */

int osd_req_add_set_attr_list(struct osd_request *or,
        const struct osd_attr *oa, unsigned nelem)
{
        unsigned total_bytes = or->set_attr.total_bytes;
        void *attr_last;
        int ret;

        if (or->attributes_mode &&
            or->attributes_mode != OSD_CDB_GET_SET_ATTR_LISTS) {
                WARN_ON(1);
                return -EINVAL;
        }
        or->attributes_mode = OSD_CDB_GET_SET_ATTR_LISTS;

        if (!total_bytes) { /* first-time: allocate and put list header */
                total_bytes = _osd_req_sizeof_alist_header(or);
                ret = _alloc_set_attr_list(or, oa, nelem, total_bytes);
                if (ret)
                        return ret;
                _osd_req_set_alist_type(or, or->set_attr.buff,
                                        OSD_ATTR_LIST_SET_RETRIEVE);
        }
        attr_last = or->set_attr.buff + total_bytes;

        for (; nelem; --nelem) {
                unsigned elem_size = _osd_req_alist_elem_size(or, oa->len);

                total_bytes += elem_size;
                if (unlikely(or->set_attr.alloc_size < total_bytes)) {
                        or->set_attr.total_bytes = total_bytes - elem_size;
                        ret = _alloc_set_attr_list(or, oa, nelem, total_bytes);
                        if (ret)
                                return ret;
                        attr_last =
                                or->set_attr.buff + or->set_attr.total_bytes;
                }

                _osd_req_alist_elem_encode(or, attr_last, oa);

                attr_last += elem_size;
                ++oa;
        }

        or->set_attr.total_bytes = total_bytes;
        return 0;
}
EXPORT_SYMBOL(osd_req_add_set_attr_list);

static int _req_append_segment(struct osd_request *or,
        unsigned padding, struct _osd_req_data_segment *seg,
        struct _osd_req_data_segment *last_seg, struct _osd_io_info *io)
{
        void *pad_buff;
        int ret;

        if (padding) {
                /* check if we can just add it to last buffer */
                if (last_seg &&
                    (padding <= last_seg->alloc_size - last_seg->total_bytes))
                        pad_buff = last_seg->buff + last_seg->total_bytes;
                else
                        pad_buff = io->pad_buff;

                ret = blk_rq_map_kern(io->req->q, io->req, pad_buff, padding,
                                       or->alloc_flags);
                if (ret)
                        return ret;
                io->total_bytes += padding;
        }

        ret = blk_rq_map_kern(io->req->q, io->req, seg->buff, seg->total_bytes,
                               or->alloc_flags);
        if (ret)
                return ret;

        io->total_bytes += seg->total_bytes;
        OSD_DEBUG("padding=%d buff=%p total_bytes=%d\n", padding, seg->buff,
                  seg->total_bytes);
        return 0;
}

static int _osd_req_finalize_set_attr_list(struct osd_request *or)
{
        struct osd_cdb_head *cdbh = osd_cdb_head(&or->cdb);
        unsigned padding;
        int ret;

        if (!or->set_attr.total_bytes) {
                cdbh->attrs_list.set_attr_offset = OSD_OFFSET_UNUSED;
                return 0;
        }

        cdbh->attrs_list.set_attr_bytes = cpu_to_be32(or->set_attr.total_bytes);
        cdbh->attrs_list.set_attr_offset =
                osd_req_encode_offset(or, or->out.total_bytes, &padding);

        ret = _req_append_segment(or, padding, &or->set_attr,
                                  or->out.last_seg, &or->out);
        if (ret)
                return ret;

        or->out.last_seg = &or->set_attr;
        return 0;
}

int osd_req_add_get_attr_list(struct osd_request *or,
        const struct osd_attr *oa, unsigned nelem)
{
        unsigned total_bytes = or->enc_get_attr.total_bytes;
        void *attr_last;
        int ret;

        if (or->attributes_mode &&
            or->attributes_mode != OSD_CDB_GET_SET_ATTR_LISTS) {
                WARN_ON(1);
                return -EINVAL;
        }
        or->attributes_mode = OSD_CDB_GET_SET_ATTR_LISTS;

        /* first time calc data-in list header size */
        if (!or->get_attr.total_bytes)
                or->get_attr.total_bytes = _osd_req_sizeof_alist_header(or);

        /* calc data-out info */
        if (!total_bytes) { /* first-time: allocate and put list header */
                unsigned max_bytes;

                total_bytes = _osd_req_sizeof_alist_header(or);
                max_bytes = total_bytes +
                        nelem * sizeof(struct osd_attributes_list_attrid);
                ret = _alloc_get_attr_desc(or, max_bytes);
                if (ret)
                        return ret;

                _osd_req_set_alist_type(or, or->enc_get_attr.buff,
                                        OSD_ATTR_LIST_GET);
        }
        attr_last = or->enc_get_attr.buff + total_bytes;

        for (; nelem; --nelem) {
                struct osd_attributes_list_attrid *attrid;
                const unsigned cur_size = sizeof(*attrid);

                total_bytes += cur_size;
                if (unlikely(or->enc_get_attr.alloc_size < total_bytes)) {
                        or->enc_get_attr.total_bytes = total_bytes - cur_size;
                        ret = _alloc_get_attr_desc(or,
                                        total_bytes + nelem * sizeof(*attrid));
                        if (ret)
                                return ret;
                        attr_last = or->enc_get_attr.buff +
                                or->enc_get_attr.total_bytes;
                }

                attrid = attr_last;
                attrid->attr_page = cpu_to_be32(oa->attr_page);
                attrid->attr_id = cpu_to_be32(oa->attr_id);

                attr_last += cur_size;

                /* calc data-in size */
                or->get_attr.total_bytes +=
                        _osd_req_alist_elem_size(or, oa->len);
                ++oa;
        }

        or->enc_get_attr.total_bytes = total_bytes;

        OSD_DEBUG(
               "get_attr.total_bytes=%u(%u) enc_get_attr.total_bytes=%u(%Zu)\n",
               or->get_attr.total_bytes,
               or->get_attr.total_bytes - _osd_req_sizeof_alist_header(or),
               or->enc_get_attr.total_bytes,
               (or->enc_get_attr.total_bytes - _osd_req_sizeof_alist_header(or))
                        / sizeof(struct osd_attributes_list_attrid));

        return 0;
}
EXPORT_SYMBOL(osd_req_add_get_attr_list);

static int _osd_req_finalize_get_attr_list(struct osd_request *or)
{
        struct osd_cdb_head *cdbh = osd_cdb_head(&or->cdb);
        unsigned out_padding;
        unsigned in_padding;
        int ret;

        if (!or->enc_get_attr.total_bytes) {
                cdbh->attrs_list.get_attr_desc_offset = OSD_OFFSET_UNUSED;
                cdbh->attrs_list.get_attr_offset = OSD_OFFSET_UNUSED;
                return 0;
        }

        ret = _alloc_get_attr_list(or);
        if (ret)
                return ret;

        /* The out-going buffer info update */
        OSD_DEBUG("out-going\n");
        cdbh->attrs_list.get_attr_desc_bytes =
                cpu_to_be32(or->enc_get_attr.total_bytes);

        cdbh->attrs_list.get_attr_desc_offset =
                osd_req_encode_offset(or, or->out.total_bytes, &out_padding);

        ret = _req_append_segment(or, out_padding, &or->enc_get_attr,
                                  or->out.last_seg, &or->out);
        if (ret)
                return ret;
        or->out.last_seg = &or->enc_get_attr;

        /* The incoming buffer info update */
        OSD_DEBUG("in-coming\n");
        cdbh->attrs_list.get_attr_alloc_length =
                cpu_to_be32(or->get_attr.total_bytes);

        cdbh->attrs_list.get_attr_offset =
                osd_req_encode_offset(or, or->in.total_bytes, &in_padding);

        ret = _req_append_segment(or, in_padding, &or->get_attr, NULL,
                                  &or->in);
        if (ret)
                return ret;
        or->in.last_seg = &or->get_attr;

        return 0;
}

int osd_req_decode_get_attr_list(struct osd_request *or,
        struct osd_attr *oa, int *nelem, void **iterator)
{
        unsigned cur_bytes, returned_bytes;
        int n;
        const unsigned sizeof_attr_list = _osd_req_sizeof_alist_header(or);
        void *cur_p;

        if (!_osd_req_is_alist_type(or, or->get_attr.buff,
                                    OSD_ATTR_LIST_SET_RETRIEVE)) {
                oa->attr_page = 0;
                oa->attr_id = 0;
                oa->val_ptr = NULL;
                oa->len = 0;
                *iterator = NULL;
                return 0;
        }

        if (*iterator) {
                BUG_ON((*iterator < or->get_attr.buff) ||
                     (or->get_attr.buff + or->get_attr.alloc_size < *iterator));
                cur_p = *iterator;
                cur_bytes = (*iterator - or->get_attr.buff) - sizeof_attr_list;
                returned_bytes = or->get_attr.total_bytes;
        } else { /* first time decode the list header */
                cur_bytes = sizeof_attr_list;
                returned_bytes = _osd_req_alist_size(or, or->get_attr.buff) +
                                        sizeof_attr_list;

                cur_p = or->get_attr.buff + sizeof_attr_list;

                if (returned_bytes > or->get_attr.alloc_size) {
                        OSD_DEBUG("target report: space was not big enough! "
                                  "Allocate=%u Needed=%u\n",
                                  or->get_attr.alloc_size,
                                  returned_bytes + sizeof_attr_list);

                        returned_bytes =
                                or->get_attr.alloc_size - sizeof_attr_list;
                }
                or->get_attr.total_bytes = returned_bytes;
        }

        for (n = 0; (n < *nelem) && (cur_bytes < returned_bytes); ++n) {
                int inc = _osd_req_alist_elem_decode(or, cur_p, oa,
                                                 returned_bytes - cur_bytes);

                if (inc < 0) {
                        OSD_ERR("BAD FOOD from target. list not valid!"
                                "c=%d r=%d n=%d\n",
                                cur_bytes, returned_bytes, n);
                        oa->val_ptr = NULL;
                        cur_bytes = returned_bytes; /* break the caller loop */
                        break;
                }

                cur_bytes += inc;
                cur_p += inc;
                ++oa;
        }

        *iterator = (returned_bytes - cur_bytes) ? cur_p : NULL;
        *nelem = n;
        return returned_bytes - cur_bytes;
}
EXPORT_SYMBOL(osd_req_decode_get_attr_list);

/*
 * Attributes Page-mode
 */

int osd_req_add_get_attr_page(struct osd_request *or,
        u32 page_id, void *attar_page, unsigned max_page_len,
        const struct osd_attr *set_one_attr)
{
        struct osd_cdb_head *cdbh = osd_cdb_head(&or->cdb);

        if (or->attributes_mode &&
            or->attributes_mode != OSD_CDB_GET_ATTR_PAGE_SET_ONE) {
                WARN_ON(1);
                return -EINVAL;
        }
        or->attributes_mode = OSD_CDB_GET_ATTR_PAGE_SET_ONE;

        or->get_attr.buff = attar_page;
        or->get_attr.total_bytes = max_page_len;

        cdbh->attrs_page.get_attr_page = cpu_to_be32(page_id);
        cdbh->attrs_page.get_attr_alloc_length = cpu_to_be32(max_page_len);

        if (!set_one_attr || !set_one_attr->attr_page)
                return 0; /* The set is optional */

        or->set_attr.buff = set_one_attr->val_ptr;
        or->set_attr.total_bytes = set_one_attr->len;

        cdbh->attrs_page.set_attr_page = cpu_to_be32(set_one_attr->attr_page);
        cdbh->attrs_page.set_attr_id = cpu_to_be32(set_one_attr->attr_id);
        cdbh->attrs_page.set_attr_length = cpu_to_be32(set_one_attr->len);
        return 0;
}
EXPORT_SYMBOL(osd_req_add_get_attr_page);

static int _osd_req_finalize_attr_page(struct osd_request *or)
{
        struct osd_cdb_head *cdbh = osd_cdb_head(&or->cdb);
        unsigned in_padding, out_padding;
        int ret;

        /* returned page */
        cdbh->attrs_page.get_attr_offset =
                osd_req_encode_offset(or, or->in.total_bytes, &in_padding);

        ret = _req_append_segment(or, in_padding, &or->get_attr, NULL,
                                  &or->in);
        if (ret)
                return ret;

        if (or->set_attr.total_bytes == 0)
                return 0;

        /* set one value */
        cdbh->attrs_page.set_attr_offset =
                osd_req_encode_offset(or, or->out.total_bytes, &out_padding);

        ret = _req_append_segment(or, out_padding, &or->set_attr, NULL,
                                  &or->out);
        return ret;
}

static inline void osd_sec_parms_set_out_offset(bool is_v1,
        struct osd_security_parameters *sec_parms, osd_cdb_offset offset)
{
        if (is_v1)
                sec_parms->v1.data_out_integrity_check_offset = offset;
        else
                sec_parms->v2.data_out_integrity_check_offset = offset;
}

static inline void osd_sec_parms_set_in_offset(bool is_v1,
        struct osd_security_parameters *sec_parms, osd_cdb_offset offset)
{
        if (is_v1)
                sec_parms->v1.data_in_integrity_check_offset = offset;
        else
                sec_parms->v2.data_in_integrity_check_offset = offset;
}

static int _osd_req_finalize_data_integrity(struct osd_request *or,
        bool has_in, bool has_out, struct bio *out_data_bio, u64 out_data_bytes,
        const u8 *cap_key)
{
        struct osd_security_parameters *sec_parms = _osd_req_sec_params(or);
        int ret;

        if (!osd_is_sec_alldata(sec_parms))
                return 0;

        if (has_out) {
                struct _osd_req_data_segment seg = {
                        .buff = &or->out_data_integ,
                        .total_bytes = sizeof(or->out_data_integ),
                };
                unsigned pad;

                or->out_data_integ.data_bytes = cpu_to_be64(out_data_bytes);
                or->out_data_integ.set_attributes_bytes = cpu_to_be64(
                        or->set_attr.total_bytes);
                or->out_data_integ.get_attributes_bytes = cpu_to_be64(
                        or->enc_get_attr.total_bytes);

                osd_sec_parms_set_out_offset(osd_req_is_ver1(or), sec_parms,
                        osd_req_encode_offset(or, or->out.total_bytes, &pad));

                ret = _req_append_segment(or, pad, &seg, or->out.last_seg,
                                          &or->out);
                if (ret)
                        return ret;
                or->out.last_seg = NULL;

                /* they are now all chained to request sign them all together */
                osd_sec_sign_data(&or->out_data_integ, out_data_bio,
                                  cap_key);
        }

        if (has_in) {
                struct _osd_req_data_segment seg = {
                        .buff = &or->in_data_integ,
                        .total_bytes = sizeof(or->in_data_integ),
                };
                unsigned pad;

                osd_sec_parms_set_in_offset(osd_req_is_ver1(or), sec_parms,
                        osd_req_encode_offset(or, or->in.total_bytes, &pad));

                ret = _req_append_segment(or, pad, &seg, or->in.last_seg,
                                          &or->in);
                if (ret)
                        return ret;

                or->in.last_seg = NULL;
        }

        return 0;
}

/*
 * osd_finalize_request and helpers
 */
static struct request *_make_request(struct request_queue *q, bool has_write,
                              struct _osd_io_info *oii, gfp_t flags)
{
        if (oii->bio)
                return blk_make_request(q, oii->bio, flags);
        else {
                struct request *req;

                req = blk_get_request(q, has_write ? WRITE : READ, flags);
                if (unlikely(!req))
                        return ERR_PTR(-ENOMEM);

                return req;
        }
}

static int _init_blk_request(struct osd_request *or,
        bool has_in, bool has_out)
{
        gfp_t flags = or->alloc_flags;
        struct scsi_device *scsi_device = or->osd_dev->scsi_device;
        struct request_queue *q = scsi_device->request_queue;
        struct request *req;
        int ret;

        req = _make_request(q, has_out, has_out ? &or->out : &or->in, flags);
        if (IS_ERR(req)) {
                ret = PTR_ERR(req);
                goto out;
        }

        or->request = req;
        req->cmd_type = REQ_TYPE_BLOCK_PC;
        req->cmd_flags |= REQ_QUIET;

        req->timeout = or->timeout;
        req->retries = or->retries;
        req->sense = or->sense;
        req->sense_len = 0;

        if (has_out) {
                or->out.req = req;
                if (has_in) {
                        /* allocate bidi request */
                        req = _make_request(q, false, &or->in, flags);
                        if (IS_ERR(req)) {
                                OSD_DEBUG("blk_get_request for bidi failed\n");
                                ret = PTR_ERR(req);
                                goto out;
                        }
                        req->cmd_type = REQ_TYPE_BLOCK_PC;
                        or->in.req = or->request->next_rq = req;
                }
        } else if (has_in)
                or->in.req = req;

        ret = 0;
out:
        OSD_DEBUG("or=%p has_in=%d has_out=%d => %d, %p\n",
                        or, has_in, has_out, ret, or->request);
        return ret;
}

int osd_finalize_request(struct osd_request *or,
        u8 options, const void *cap, const u8 *cap_key)
{
        struct osd_cdb_head *cdbh = osd_cdb_head(&or->cdb);
        bool has_in, has_out;
         /* Save for data_integrity without the cdb_continuation */
        struct bio *out_data_bio = or->out.bio;
        u64 out_data_bytes = or->out.total_bytes;
        int ret;

        if (options & OSD_REQ_FUA)
                cdbh->options |= OSD_CDB_FUA;

        if (options & OSD_REQ_DPO)
                cdbh->options |= OSD_CDB_DPO;

        if (options & OSD_REQ_BYPASS_TIMESTAMPS)
                cdbh->timestamp_control = OSD_CDB_BYPASS_TIMESTAMPS;

        osd_set_caps(&or->cdb, cap);

        has_in = or->in.bio || or->get_attr.total_bytes;
        has_out = or->out.bio || or->cdb_cont.total_bytes ||
                or->set_attr.total_bytes || or->enc_get_attr.total_bytes;

        ret = _osd_req_finalize_cdb_cont(or, cap_key);
        if (ret) {
                OSD_DEBUG("_osd_req_finalize_cdb_cont failed\n");
                return ret;
        }
        ret = _init_blk_request(or, has_in, has_out);
        if (ret) {
                OSD_DEBUG("_init_blk_request failed\n");
                return ret;
        }

        or->out.pad_buff = sg_out_pad_buffer;
        or->in.pad_buff = sg_in_pad_buffer;

        if (!or->attributes_mode)
                or->attributes_mode = OSD_CDB_GET_SET_ATTR_LISTS;
        cdbh->command_specific_options |= or->attributes_mode;
        if (or->attributes_mode == OSD_CDB_GET_ATTR_PAGE_SET_ONE) {
                ret = _osd_req_finalize_attr_page(or);
                if (ret) {
                        OSD_DEBUG("_osd_req_finalize_attr_page failed\n");
                        return ret;
                }
        } else {
                /* TODO: I think that for the GET_ATTR command these 2 should
                 * be reversed to keep them in execution order (for embeded
                 * targets with low memory footprint)
                 */
                ret = _osd_req_finalize_set_attr_list(or);
                if (ret) {
                        OSD_DEBUG("_osd_req_finalize_set_attr_list failed\n");
                        return ret;
                }

                ret = _osd_req_finalize_get_attr_list(or);
                if (ret) {
                        OSD_DEBUG("_osd_req_finalize_get_attr_list failed\n");
                        return ret;
                }
        }

        ret = _osd_req_finalize_data_integrity(or, has_in, has_out,
                                               out_data_bio, out_data_bytes,
                                               cap_key);
        if (ret)
                return ret;

        osd_sec_sign_cdb(&or->cdb, cap_key);

        or->request->cmd = or->cdb.buff;
        or->request->cmd_len = _osd_req_cdb_len(or);

        return 0;
}
EXPORT_SYMBOL(osd_finalize_request);

static bool _is_osd_security_code(int code)
{
        return  (code == osd_security_audit_value_frozen) ||
                (code == osd_security_working_key_frozen) ||
                (code == osd_nonce_not_unique) ||
                (code == osd_nonce_timestamp_out_of_range) ||
                (code == osd_invalid_dataout_buffer_integrity_check_value);
}

#define OSD_SENSE_PRINT1(fmt, a...) \
        do { \
                if (__cur_sense_need_output) \
                        OSD_ERR(fmt, ##a); \
        } while (0)

#define OSD_SENSE_PRINT2(fmt, a...) OSD_SENSE_PRINT1("    " fmt, ##a)

int osd_req_decode_sense_full(struct osd_request *or,
        struct osd_sense_info *osi, bool silent,
        struct osd_obj_id *bad_obj_list __unused, int max_obj __unused,
        struct osd_attr *bad_attr_list, int max_attr)
{
        int sense_len, original_sense_len;
        struct osd_sense_info local_osi;
        struct scsi_sense_descriptor_based *ssdb;
        void *cur_descriptor;
#if (CONFIG_SCSI_OSD_DPRINT_SENSE == 0)
        const bool __cur_sense_need_output = false;
#else
        bool __cur_sense_need_output = !silent;
#endif
        int ret;

        if (likely(!or->req_errors))
                return 0;

        osi = osi ? : &local_osi;
        memset(osi, 0, sizeof(*osi));

        ssdb = (typeof(ssdb))or->sense;
        sense_len = or->sense_len;
        if ((sense_len < (int)sizeof(*ssdb) || !ssdb->sense_key)) {
                OSD_ERR("Block-layer returned error(0x%x) but "
                        "sense_len(%u) || key(%d) is empty\n",
                        or->req_errors, sense_len, ssdb->sense_key);
                goto analyze;
        }

        if ((ssdb->response_code != 0x72) && (ssdb->response_code != 0x73)) {
                OSD_ERR("Unrecognized scsi sense: rcode=%x length=%d\n",
                        ssdb->response_code, sense_len);
                goto analyze;
        }

        osi->key = ssdb->sense_key;
        osi->additional_code = be16_to_cpu(ssdb->additional_sense_code);
        original_sense_len = ssdb->additional_sense_length + 8;

#if (CONFIG_SCSI_OSD_DPRINT_SENSE == 1)
        if (__cur_sense_need_output)
                __cur_sense_need_output = (osi->key > scsi_sk_recovered_error);
#endif
        OSD_SENSE_PRINT1("Main Sense information key=0x%x length(%d, %d) "
                        "additional_code=0x%x async_error=%d errors=0x%x\n",
                        osi->key, original_sense_len, sense_len,
                        osi->additional_code, or->async_error,
                        or->req_errors);

        if (original_sense_len < sense_len)
                sense_len = original_sense_len;

        cur_descriptor = ssdb->ssd;
        sense_len -= sizeof(*ssdb);
        while (sense_len > 0) {
                struct scsi_sense_descriptor *ssd = cur_descriptor;
                int cur_len = ssd->additional_length + 2;

                sense_len -= cur_len;

                if (sense_len < 0)
                        break; /* sense was truncated */

                switch (ssd->descriptor_type) {
                case scsi_sense_information:
                case scsi_sense_command_specific_information:
                {
                        struct scsi_sense_command_specific_data_descriptor
                                *sscd = cur_descriptor;

                        osi->command_info =
                                get_unaligned_be64(&sscd->information) ;
                        OSD_SENSE_PRINT2(
                                "command_specific_information 0x%llx \n",
                                _LLU(osi->command_info));
                        break;
                }
                case scsi_sense_key_specific:
                {
                        struct scsi_sense_key_specific_data_descriptor
                                *ssks = cur_descriptor;

                        osi->sense_info = get_unaligned_be16(&ssks->value);
                        OSD_SENSE_PRINT2(
                                "sense_key_specific_information %u"
                                "sksv_cd_bpv_bp (0x%x)\n",
                                osi->sense_info, ssks->sksv_cd_bpv_bp);
                        break;
                }
                case osd_sense_object_identification:
                { /*FIXME: Keep first not last, Store in array*/
                        struct osd_sense_identification_data_descriptor
                                *osidd = cur_descriptor;

                        osi->not_initiated_command_functions =
                                le32_to_cpu(osidd->not_initiated_functions);
                        osi->completed_command_functions =
                                le32_to_cpu(osidd->completed_functions);
                        osi->obj.partition = be64_to_cpu(osidd->partition_id);
                        osi->obj.id = be64_to_cpu(osidd->object_id);
                        OSD_SENSE_PRINT2(
                                "object_identification pid=0x%llx oid=0x%llx\n",
                                _LLU(osi->obj.partition), _LLU(osi->obj.id));
                        OSD_SENSE_PRINT2(
                                "not_initiated_bits(%x) "
                                "completed_command_bits(%x)\n",
                                osi->not_initiated_command_functions,
                                osi->completed_command_functions);
                        break;
                }
                case osd_sense_response_integrity_check:
                {
                        struct osd_sense_response_integrity_check_descriptor
                                *osricd = cur_descriptor;
                        const unsigned len =
                                          sizeof(osricd->integrity_check_value);
                        char key_dump[len*4 + 2]; /* 2nibbles+space+ASCII */

                        hex_dump_to_buffer(osricd->integrity_check_value, len,
                                       32, 1, key_dump, sizeof(key_dump), true);
                        OSD_SENSE_PRINT2("response_integrity [%s]\n", key_dump);
                }
                case osd_sense_attribute_identification:
                {
                        struct osd_sense_attributes_data_descriptor
                                *osadd = cur_descriptor;
                        unsigned len = min(cur_len, sense_len);
                        struct osd_sense_attr *pattr = osadd->sense_attrs;

                        while (len >= sizeof(*pattr)) {
                                u32 attr_page = be32_to_cpu(pattr->attr_page);
                                u32 attr_id = be32_to_cpu(pattr->attr_id);

                                if (!osi->attr.attr_page) {
                                        osi->attr.attr_page = attr_page;
                                        osi->attr.attr_id = attr_id;
                                }

                                if (bad_attr_list && max_attr) {
                                        bad_attr_list->attr_page = attr_page;
                                        bad_attr_list->attr_id = attr_id;
                                        bad_attr_list++;
                                        max_attr--;
                                }

                                len -= sizeof(*pattr);
                                OSD_SENSE_PRINT2(
                                        "osd_sense_attribute_identification"
                                        "attr_page=0x%x attr_id=0x%x\n",
                                        attr_page, attr_id);
                        }
                }
                /*These are not legal for OSD*/
                case scsi_sense_field_replaceable_unit:
                        OSD_SENSE_PRINT2("scsi_sense_field_replaceable_unit\n");
                        break;
                case scsi_sense_stream_commands:
                        OSD_SENSE_PRINT2("scsi_sense_stream_commands\n");
                        break;
                case scsi_sense_block_commands:
                        OSD_SENSE_PRINT2("scsi_sense_block_commands\n");
                        break;
                case scsi_sense_ata_return:
                        OSD_SENSE_PRINT2("scsi_sense_ata_return\n");
                        break;
                default:
                        if (ssd->descriptor_type <= scsi_sense_Reserved_last)
                                OSD_SENSE_PRINT2(
                                        "scsi_sense Reserved descriptor (0x%x)",
                                        ssd->descriptor_type);
                        else
                                OSD_SENSE_PRINT2(
                                        "scsi_sense Vendor descriptor (0x%x)",
                                        ssd->descriptor_type);
                }

                cur_descriptor += cur_len;
        }

analyze:
        if (!osi->key) {
                /* scsi sense is Empty, the request was never issued to target
                 * linux return code might tell us what happened.
                 */
                if (or->async_error == -ENOMEM)
                        osi->osd_err_pri = OSD_ERR_PRI_RESOURCE;
                else
                        osi->osd_err_pri = OSD_ERR_PRI_UNREACHABLE;
                ret = or->async_error;
        } else if (osi->key <= scsi_sk_recovered_error) {
                osi->osd_err_pri = 0;
                ret = 0;
        } else if (osi->additional_code == scsi_invalid_field_in_cdb) {
                if (osi->cdb_field_offset == OSD_CFO_STARTING_BYTE) {
                        osi->osd_err_pri = OSD_ERR_PRI_CLEAR_PAGES;
                        ret = -EFAULT; /* caller should recover from this */
                } else if (osi->cdb_field_offset == OSD_CFO_OBJECT_ID) {
                        osi->osd_err_pri = OSD_ERR_PRI_NOT_FOUND;
                        ret = -ENOENT;
                } else if (osi->cdb_field_offset == OSD_CFO_PERMISSIONS) {
                        osi->osd_err_pri = OSD_ERR_PRI_NO_ACCESS;
                        ret = -EACCES;
                } else {
                        osi->osd_err_pri = OSD_ERR_PRI_BAD_CRED;
                        ret = -EINVAL;
                }
        } else if (osi->additional_code == osd_quota_error) {
                osi->osd_err_pri = OSD_ERR_PRI_NO_SPACE;
                ret = -ENOSPC;
        } else if (_is_osd_security_code(osi->additional_code)) {
                osi->osd_err_pri = OSD_ERR_PRI_BAD_CRED;
                ret = -EINVAL;
        } else {
                osi->osd_err_pri = OSD_ERR_PRI_EIO;
                ret = -EIO;
        }

        if (!or->out.residual)
                or->out.residual = or->out.total_bytes;
        if (!or->in.residual)
                or->in.residual = or->in.total_bytes;

        return ret;
}
EXPORT_SYMBOL(osd_req_decode_sense_full);

/*
 * Implementation of osd_sec.h API
 * TODO: Move to a separate osd_sec.c file at a later stage.
 */

enum { OSD_SEC_CAP_V1_ALL_CAPS =
        OSD_SEC_CAP_APPEND | OSD_SEC_CAP_OBJ_MGMT | OSD_SEC_CAP_REMOVE   |
        OSD_SEC_CAP_CREATE | OSD_SEC_CAP_SET_ATTR | OSD_SEC_CAP_GET_ATTR |
        OSD_SEC_CAP_WRITE  | OSD_SEC_CAP_READ     | OSD_SEC_CAP_POL_SEC  |
        OSD_SEC_CAP_GLOBAL | OSD_SEC_CAP_DEV_MGMT
};

enum { OSD_SEC_CAP_V2_ALL_CAPS =
        OSD_SEC_CAP_V1_ALL_CAPS | OSD_SEC_CAP_QUERY | OSD_SEC_CAP_M_OBJECT
};

void osd_sec_init_nosec_doall_caps(void *caps,
        const struct osd_obj_id *obj, bool is_collection, const bool is_v1)
{
        struct osd_capability *cap = caps;
        u8 type;
        u8 descriptor_type;

        if (likely(obj->id)) {
                if (unlikely(is_collection)) {
                        type = OSD_SEC_OBJ_COLLECTION;
                        descriptor_type = is_v1 ? OSD_SEC_OBJ_DESC_OBJ :
                                                  OSD_SEC_OBJ_DESC_COL;
                } else {
                        type = OSD_SEC_OBJ_USER;
                        descriptor_type = OSD_SEC_OBJ_DESC_OBJ;
                }
                WARN_ON(!obj->partition);
        } else {
                type = obj->partition ? OSD_SEC_OBJ_PARTITION :
                                        OSD_SEC_OBJ_ROOT;
                descriptor_type = OSD_SEC_OBJ_DESC_PAR;
        }

        memset(cap, 0, sizeof(*cap));

        cap->h.format = OSD_SEC_CAP_FORMAT_VER1;
        cap->h.integrity_algorithm__key_version = 0; /* MAKE_BYTE(0, 0); */
        cap->h.security_method = OSD_SEC_NOSEC;
/*      cap->expiration_time;
        cap->AUDIT[30-10];
        cap->discriminator[42-30];
        cap->object_created_time; */
        cap->h.object_type = type;
        osd_sec_set_caps(&cap->h, OSD_SEC_CAP_V1_ALL_CAPS);
        cap->h.object_descriptor_type = descriptor_type;
        cap->od.obj_desc.policy_access_tag = 0;
        cap->od.obj_desc.allowed_partition_id = cpu_to_be64(obj->partition);
        cap->od.obj_desc.allowed_object_id = cpu_to_be64(obj->id);
}
EXPORT_SYMBOL(osd_sec_init_nosec_doall_caps);

/* FIXME: Extract version from caps pointer.
 *        Also Pete's target only supports caps from OSDv1 for now
 */
void osd_set_caps(struct osd_cdb *cdb, const void *caps)
{
        bool is_ver1 = true;
        /* NOTE: They start at same address */
        memcpy(&cdb->v1.caps, caps, is_ver1 ? OSDv1_CAP_LEN : OSD_CAP_LEN);
}

bool osd_is_sec_alldata(struct osd_security_parameters *sec_parms __unused)
{
        return false;
}

void osd_sec_sign_cdb(struct osd_cdb *ocdb __unused, const u8 *cap_key __unused)
{
}

void osd_sec_sign_data(void *data_integ __unused,
                       struct bio *bio __unused, const u8 *cap_key __unused)
{
}

/*
 * Declared in osd_protocol.h
 * 4.12.5 Data-In and Data-Out buffer offsets
 * byte offset = mantissa * (2^(exponent+8))
 * Returns the smallest allowed encoded offset that contains given @offset
 * The actual encoded offset returned is @offset + *@padding.
 */
osd_cdb_offset __osd_encode_offset(
        u64 offset, unsigned *padding, int min_shift, int max_shift)
{
        u64 try_offset = -1, mod, align;
        osd_cdb_offset be32_offset;
        int shift;

        *padding = 0;
        if (!offset)
                return 0;

        for (shift = min_shift; shift < max_shift; ++shift) {
                try_offset = offset >> shift;
                if (try_offset < (1 << OSD_OFFSET_MAX_BITS))
                        break;
        }

        BUG_ON(shift == max_shift);

        align = 1 << shift;
        mod = offset & (align - 1);
        if (mod) {
                *padding = align - mod;
                try_offset += 1;
        }

        try_offset |= ((shift - 8) & 0xf) << 28;
        be32_offset = cpu_to_be32((u32)try_offset);

        OSD_DEBUG("offset=%llu mantissa=%llu exp=%d encoded=%x pad=%d\n",
                 _LLU(offset), _LLU(try_offset & 0x0FFFFFFF), shift,
                 be32_offset, *padding);
        return be32_offset;
}