Linux 3.16-rc2

[linux/fpc-iii.git] / fs / exofs / ore.c

/*
 * Copyright (C) 2005, 2006
 * Avishay Traeger (avishay@gmail.com)
 * Copyright (C) 2008, 2009
 * Boaz Harrosh <bharrosh@panasas.com>
 *
 * This file is part of exofs.
 *
 * exofs 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.  Since it is based on ext2, and the only
 * valid version of GPL for the Linux kernel is version 2, the only valid
 * version of GPL for exofs is version 2.
 *
 * exofs 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 exofs; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/slab.h>
#include <linux/module.h>
#include <asm/div64.h>
#include <linux/lcm.h>

#include "ore_raid.h"

MODULE_AUTHOR("Boaz Harrosh <bharrosh@panasas.com>");
MODULE_DESCRIPTION("Objects Raid Engine ore.ko");
MODULE_LICENSE("GPL");

/* ore_verify_layout does a couple of things:
 * 1. Given a minimum number of needed parameters fixes up the rest of the
 *    members to be operatonals for the ore. The needed parameters are those
 *    that are defined by the pnfs-objects layout STD.
 * 2. Check to see if the current ore code actually supports these parameters
 *    for example stripe_unit must be a multple of the system PAGE_SIZE,
 *    and etc...
 * 3. Cache some havily used calculations that will be needed by users.
 */

enum { BIO_MAX_PAGES_KMALLOC =
                (PAGE_SIZE - sizeof(struct bio)) / sizeof(struct bio_vec),};

int ore_verify_layout(unsigned total_comps, struct ore_layout *layout)
{
        u64 stripe_length;

        switch (layout->raid_algorithm) {
        case PNFS_OSD_RAID_0:
                layout->parity = 0;
                break;
        case PNFS_OSD_RAID_5:
                layout->parity = 1;
                break;
        case PNFS_OSD_RAID_PQ:
                layout->parity = 2;
                break;
        case PNFS_OSD_RAID_4:
        default:
                ORE_ERR("Only RAID_0/5/6 for now received-enum=%d\n",
                        layout->raid_algorithm);
                return -EINVAL;
        }
        if (0 != (layout->stripe_unit & ~PAGE_MASK)) {
                ORE_ERR("Stripe Unit(0x%llx)"
                          " must be Multples of PAGE_SIZE(0x%lx)\n",
                          _LLU(layout->stripe_unit), PAGE_SIZE);
                return -EINVAL;
        }
        if (layout->group_width) {
                if (!layout->group_depth) {
                        ORE_ERR("group_depth == 0 && group_width != 0\n");
                        return -EINVAL;
                }
                if (total_comps < (layout->group_width * layout->mirrors_p1)) {
                        ORE_ERR("Data Map wrong, "
                                "numdevs=%d < group_width=%d * mirrors=%d\n",
                                total_comps, layout->group_width,
                                layout->mirrors_p1);
                        return -EINVAL;
                }
                layout->group_count = total_comps / layout->mirrors_p1 /
                                                layout->group_width;
        } else {
                if (layout->group_depth) {
                        printk(KERN_NOTICE "Warning: group_depth ignored "
                                "group_width == 0 && group_depth == %lld\n",
                                _LLU(layout->group_depth));
                }
                layout->group_width = total_comps / layout->mirrors_p1;
                layout->group_depth = -1;
                layout->group_count = 1;
        }

        stripe_length = (u64)layout->group_width * layout->stripe_unit;
        if (stripe_length >= (1ULL << 32)) {
                ORE_ERR("Stripe_length(0x%llx) >= 32bit is not supported\n",
                        _LLU(stripe_length));
                return -EINVAL;
        }

        layout->max_io_length =
                (BIO_MAX_PAGES_KMALLOC * PAGE_SIZE - layout->stripe_unit) *
                                        (layout->group_width - layout->parity);
        if (layout->parity) {
                unsigned stripe_length =
                                (layout->group_width - layout->parity) *
                                layout->stripe_unit;

                layout->max_io_length /= stripe_length;
                layout->max_io_length *= stripe_length;
        }
        ORE_DBGMSG("max_io_length=0x%lx\n", layout->max_io_length);

        return 0;
}
EXPORT_SYMBOL(ore_verify_layout);

static u8 *_ios_cred(struct ore_io_state *ios, unsigned index)
{
        return ios->oc->comps[index & ios->oc->single_comp].cred;
}

static struct osd_obj_id *_ios_obj(struct ore_io_state *ios, unsigned index)
{
        return &ios->oc->comps[index & ios->oc->single_comp].obj;
}

static struct osd_dev *_ios_od(struct ore_io_state *ios, unsigned index)
{
        ORE_DBGMSG2("oc->first_dev=%d oc->numdevs=%d i=%d oc->ods=%p\n",
                    ios->oc->first_dev, ios->oc->numdevs, index,
                    ios->oc->ods);

        return ore_comp_dev(ios->oc, index);
}

int  _ore_get_io_state(struct ore_layout *layout,
                        struct ore_components *oc, unsigned numdevs,
                        unsigned sgs_per_dev, unsigned num_par_pages,
                        struct ore_io_state **pios)
{
        struct ore_io_state *ios;
        struct page **pages;
        struct osd_sg_entry *sgilist;
        struct __alloc_all_io_state {
                struct ore_io_state ios;
                struct ore_per_dev_state per_dev[numdevs];
                union {
                        struct osd_sg_entry sglist[sgs_per_dev * numdevs];
                        struct page *pages[num_par_pages];
                };
        } *_aios;

        if (likely(sizeof(*_aios) <= PAGE_SIZE)) {
                _aios = kzalloc(sizeof(*_aios), GFP_KERNEL);
                if (unlikely(!_aios)) {
                        ORE_DBGMSG("Failed kzalloc bytes=%zd\n",
                                   sizeof(*_aios));
                        *pios = NULL;
                        return -ENOMEM;
                }
                pages = num_par_pages ? _aios->pages : NULL;
                sgilist = sgs_per_dev ? _aios->sglist : NULL;
                ios = &_aios->ios;
        } else {
                struct __alloc_small_io_state {
                        struct ore_io_state ios;
                        struct ore_per_dev_state per_dev[numdevs];
                } *_aio_small;
                union __extra_part {
                        struct osd_sg_entry sglist[sgs_per_dev * numdevs];
                        struct page *pages[num_par_pages];
                } *extra_part;

                _aio_small = kzalloc(sizeof(*_aio_small), GFP_KERNEL);
                if (unlikely(!_aio_small)) {
                        ORE_DBGMSG("Failed alloc first part bytes=%zd\n",
                                   sizeof(*_aio_small));
                        *pios = NULL;
                        return -ENOMEM;
                }
                extra_part = kzalloc(sizeof(*extra_part), GFP_KERNEL);
                if (unlikely(!extra_part)) {
                        ORE_DBGMSG("Failed alloc second part bytes=%zd\n",
                                   sizeof(*extra_part));
                        kfree(_aio_small);
                        *pios = NULL;
                        return -ENOMEM;
                }

                pages = num_par_pages ? extra_part->pages : NULL;
                sgilist = sgs_per_dev ? extra_part->sglist : NULL;
                /* In this case the per_dev[0].sgilist holds the pointer to
                 * be freed
                 */
                ios = &_aio_small->ios;
                ios->extra_part_alloc = true;
        }

        if (pages) {
                ios->parity_pages = pages;
                ios->max_par_pages = num_par_pages;
        }
        if (sgilist) {
                unsigned d;

                for (d = 0; d < numdevs; ++d) {
                        ios->per_dev[d].sglist = sgilist;
                        sgilist += sgs_per_dev;
                }
                ios->sgs_per_dev = sgs_per_dev;
        }

        ios->layout = layout;
        ios->oc = oc;
        *pios = ios;
        return 0;
}

/* Allocate an io_state for only a single group of devices
 *
 * If a user needs to call ore_read/write() this version must be used becase it
 * allocates extra stuff for striping and raid.
 * The ore might decide to only IO less then @length bytes do to alignmets
 * and constrains as follows:
 * - The IO cannot cross group boundary.
 * - In raid5/6 The end of the IO must align at end of a stripe eg.
 *   (@offset + @length) % strip_size == 0. Or the complete range is within a
 *   single stripe.
 * - Memory condition only permitted a shorter IO. (A user can use @length=~0
 *   And check the returned ios->length for max_io_size.)
 *
 * The caller must check returned ios->length (and/or ios->nr_pages) and
 * re-issue these pages that fall outside of ios->length
 */
int  ore_get_rw_state(struct ore_layout *layout, struct ore_components *oc,
                      bool is_reading, u64 offset, u64 length,
                      struct ore_io_state **pios)
{
        struct ore_io_state *ios;
        unsigned numdevs = layout->group_width * layout->mirrors_p1;
        unsigned sgs_per_dev = 0, max_par_pages = 0;
        int ret;

        if (layout->parity && length) {
                unsigned data_devs = layout->group_width - layout->parity;
                unsigned stripe_size = layout->stripe_unit * data_devs;
                unsigned pages_in_unit = layout->stripe_unit / PAGE_SIZE;
                u32 remainder;
                u64 num_stripes;
                u64 num_raid_units;

                num_stripes = div_u64_rem(length, stripe_size, &remainder);
                if (remainder)
                        ++num_stripes;

                num_raid_units =  num_stripes * layout->parity;

                if (is_reading) {
                        /* For reads add per_dev sglist array */
                        /* TODO: Raid 6 we need twice more. Actually:
                        *         num_stripes / LCMdP(W,P);
                        *         if (W%P != 0) num_stripes *= parity;
                        */

                        /* first/last seg is split */
                        num_raid_units += layout->group_width;
                        sgs_per_dev = div_u64(num_raid_units, data_devs) + 2;
                } else {
                        /* For Writes add parity pages array. */
                        max_par_pages = num_raid_units * pages_in_unit *
                                                sizeof(struct page *);
                }
        }

        ret = _ore_get_io_state(layout, oc, numdevs, sgs_per_dev, max_par_pages,
                                pios);
        if (unlikely(ret))
                return ret;

        ios = *pios;
        ios->reading = is_reading;
        ios->offset = offset;

        if (length) {
                ore_calc_stripe_info(layout, offset, length, &ios->si);
                ios->length = ios->si.length;
                ios->nr_pages = ((ios->offset & (PAGE_SIZE - 1)) +
                                 ios->length + PAGE_SIZE - 1) / PAGE_SIZE;
                if (layout->parity)
                        _ore_post_alloc_raid_stuff(ios);
        }

        return 0;
}
EXPORT_SYMBOL(ore_get_rw_state);

/* Allocate an io_state for all the devices in the comps array
 *
 * This version of io_state allocation is used mostly by create/remove
 * and trunc where we currently need all the devices. The only wastful
 * bit is the read/write_attributes with no IO. Those sites should
 * be converted to use ore_get_rw_state() with length=0
 */
int  ore_get_io_state(struct ore_layout *layout, struct ore_components *oc,
                      struct ore_io_state **pios)
{
        return _ore_get_io_state(layout, oc, oc->numdevs, 0, 0, pios);
}
EXPORT_SYMBOL(ore_get_io_state);

void ore_put_io_state(struct ore_io_state *ios)
{
        if (ios) {
                unsigned i;

                for (i = 0; i < ios->numdevs; i++) {
                        struct ore_per_dev_state *per_dev = &ios->per_dev[i];

                        if (per_dev->or)
                                osd_end_request(per_dev->or);
                        if (per_dev->bio)
                                bio_put(per_dev->bio);
                }

                _ore_free_raid_stuff(ios);
                kfree(ios);
        }
}
EXPORT_SYMBOL(ore_put_io_state);

static void _sync_done(struct ore_io_state *ios, void *p)
{
        struct completion *waiting = p;

        complete(waiting);
}

static void _last_io(struct kref *kref)
{
        struct ore_io_state *ios = container_of(
                                        kref, struct ore_io_state, kref);

        ios->done(ios, ios->private);
}

static void _done_io(struct osd_request *or, void *p)
{
        struct ore_io_state *ios = p;

        kref_put(&ios->kref, _last_io);
}

int ore_io_execute(struct ore_io_state *ios)
{
        DECLARE_COMPLETION_ONSTACK(wait);
        bool sync = (ios->done == NULL);
        int i, ret;

        if (sync) {
                ios->done = _sync_done;
                ios->private = &wait;
        }

        for (i = 0; i < ios->numdevs; i++) {
                struct osd_request *or = ios->per_dev[i].or;
                if (unlikely(!or))
                        continue;

                ret = osd_finalize_request(or, 0, _ios_cred(ios, i), NULL);
                if (unlikely(ret)) {
                        ORE_DBGMSG("Failed to osd_finalize_request() => %d\n",
                                     ret);
                        return ret;
                }
        }

        kref_init(&ios->kref);

        for (i = 0; i < ios->numdevs; i++) {
                struct osd_request *or = ios->per_dev[i].or;
                if (unlikely(!or))
                        continue;

                kref_get(&ios->kref);
                osd_execute_request_async(or, _done_io, ios);
        }

        kref_put(&ios->kref, _last_io);
        ret = 0;

        if (sync) {
                wait_for_completion(&wait);
                ret = ore_check_io(ios, NULL);
        }
        return ret;
}

static void _clear_bio(struct bio *bio)
{
        struct bio_vec *bv;
        unsigned i;

        bio_for_each_segment_all(bv, bio, i) {
                unsigned this_count = bv->bv_len;

                if (likely(PAGE_SIZE == this_count))
                        clear_highpage(bv->bv_page);
                else
                        zero_user(bv->bv_page, bv->bv_offset, this_count);
        }
}

int ore_check_io(struct ore_io_state *ios, ore_on_dev_error on_dev_error)
{
        enum osd_err_priority acumulated_osd_err = 0;
        int acumulated_lin_err = 0;
        int i;

        for (i = 0; i < ios->numdevs; i++) {
                struct osd_sense_info osi;
                struct ore_per_dev_state *per_dev = &ios->per_dev[i];
                struct osd_request *or = per_dev->or;
                int ret;

                if (unlikely(!or))
                        continue;

                ret = osd_req_decode_sense(or, &osi);
                if (likely(!ret))
                        continue;

                if ((OSD_ERR_PRI_CLEAR_PAGES == osi.osd_err_pri) &&
                    per_dev->bio) {
                        /* start read offset passed endof file.
                         * Note: if we do not have bio it means read-attributes
                         * In this case we should return error to caller.
                         */
                        _clear_bio(per_dev->bio);
                        ORE_DBGMSG("start read offset passed end of file "
                                "offset=0x%llx, length=0x%llx\n",
                                _LLU(per_dev->offset),
                                _LLU(per_dev->length));

                        continue; /* we recovered */
                }

                if (on_dev_error) {
                        u64 residual = ios->reading ?
                                        or->in.residual : or->out.residual;
                        u64 offset = (ios->offset + ios->length) - residual;
                        unsigned dev = per_dev->dev - ios->oc->first_dev;
                        struct ore_dev *od = ios->oc->ods[dev];

                        on_dev_error(ios, od, dev, osi.osd_err_pri,
                                     offset, residual);
                }
                if (osi.osd_err_pri >= acumulated_osd_err) {
                        acumulated_osd_err = osi.osd_err_pri;
                        acumulated_lin_err = ret;
                }
        }

        return acumulated_lin_err;
}
EXPORT_SYMBOL(ore_check_io);

/*
 * L - logical offset into the file
 *
 * D - number of Data devices
 *      D = group_width - parity
 *
 * U - The number of bytes in a stripe within a group
 *      U =  stripe_unit * D
 *
 * T - The number of bytes striped within a group of component objects
 *     (before advancing to the next group)
 *      T = U * group_depth
 *
 * S - The number of bytes striped across all component objects
 *     before the pattern repeats
 *      S = T * group_count
 *
 * M - The "major" (i.e., across all components) cycle number
 *      M = L / S
 *
 * G - Counts the groups from the beginning of the major cycle
 *      G = (L - (M * S)) / T   [or (L % S) / T]
 *
 * H - The byte offset within the group
 *      H = (L - (M * S)) % T   [or (L % S) % T]
 *
 * N - The "minor" (i.e., across the group) stripe number
 *      N = H / U
 *
 * C - The component index coresponding to L
 *
 *      C = (H - (N * U)) / stripe_unit + G * D
 *      [or (L % U) / stripe_unit + G * D]
 *
 * O - The component offset coresponding to L
 *      O = L % stripe_unit + N * stripe_unit + M * group_depth * stripe_unit
 *
 * LCMdP – Parity cycle: Lowest Common Multiple of group_width, parity
 *          divide by parity
 *      LCMdP = lcm(group_width, parity) / parity
 *
 * R - The parity Rotation stripe
 *     (Note parity cycle always starts at a group's boundary)
 *      R = N % LCMdP
 *
 * I = the first parity device index
 *      I = (group_width + group_width - R*parity - parity) % group_width
 *
 * Craid - The component index Rotated
 *      Craid = (group_width + C - R*parity) % group_width
 *      (We add the group_width to avoid negative numbers modulo math)
 */
void ore_calc_stripe_info(struct ore_layout *layout, u64 file_offset,
                          u64 length, struct ore_striping_info *si)
{
        u32     stripe_unit = layout->stripe_unit;
        u32     group_width = layout->group_width;
        u64     group_depth = layout->group_depth;
        u32     parity      = layout->parity;

        u32     D = group_width - parity;
        u32     U = D * stripe_unit;
        u64     T = U * group_depth;
        u64     S = T * layout->group_count;
        u64     M = div64_u64(file_offset, S);

        /*
        G = (L - (M * S)) / T
        H = (L - (M * S)) % T
        */
        u64     LmodS = file_offset - M * S;
        u32     G = div64_u64(LmodS, T);
        u64     H = LmodS - G * T;

        u32     N = div_u64(H, U);
        u32     Nlast;

        /* "H - (N * U)" is just "H % U" so it's bound to u32 */
        u32     C = (u32)(H - (N * U)) / stripe_unit + G * group_width;
        u32 first_dev = C - C % group_width;

        div_u64_rem(file_offset, stripe_unit, &si->unit_off);

        si->obj_offset = si->unit_off + (N * stripe_unit) +
                                  (M * group_depth * stripe_unit);
        si->cur_comp = C - first_dev;
        si->cur_pg = si->unit_off / PAGE_SIZE;

        if (parity) {
                u32 LCMdP = lcm(group_width, parity) / parity;
                /* R     = N % LCMdP; */
                u32 RxP   = (N % LCMdP) * parity;

                si->par_dev = (group_width + group_width - parity - RxP) %
                              group_width + first_dev;
                si->dev = (group_width + group_width + C - RxP) %
                          group_width + first_dev;
                si->bytes_in_stripe = U;
                si->first_stripe_start = M * S + G * T + N * U;
        } else {
                /* Make the math correct see _prepare_one_group */
                si->par_dev = group_width;
                si->dev = C;
        }

        si->dev *= layout->mirrors_p1;
        si->par_dev *= layout->mirrors_p1;
        si->offset = file_offset;
        si->length = T - H;
        if (si->length > length)
                si->length = length;

        Nlast = div_u64(H + si->length + U - 1, U);
        si->maxdevUnits = Nlast - N;

        si->M = M;
}
EXPORT_SYMBOL(ore_calc_stripe_info);

int _ore_add_stripe_unit(struct ore_io_state *ios,  unsigned *cur_pg,
                         unsigned pgbase, struct page **pages,
                         struct ore_per_dev_state *per_dev, int cur_len)
{
        unsigned pg = *cur_pg;
        struct request_queue *q =
                        osd_request_queue(_ios_od(ios, per_dev->dev));
        unsigned len = cur_len;
        int ret;

        if (per_dev->bio == NULL) {
                unsigned bio_size;

                if (!ios->reading) {
                        bio_size = ios->si.maxdevUnits;
                } else {
                        bio_size = (ios->si.maxdevUnits + 1) *
                             (ios->layout->group_width - ios->layout->parity) /
                             ios->layout->group_width;
                }
                bio_size *= (ios->layout->stripe_unit / PAGE_SIZE);

                per_dev->bio = bio_kmalloc(GFP_KERNEL, bio_size);
                if (unlikely(!per_dev->bio)) {
                        ORE_DBGMSG("Failed to allocate BIO size=%u\n",
                                     bio_size);
                        ret = -ENOMEM;
                        goto out;
                }
        }

        while (cur_len > 0) {
                unsigned pglen = min_t(unsigned, PAGE_SIZE - pgbase, cur_len);
                unsigned added_len;

                cur_len -= pglen;

                added_len = bio_add_pc_page(q, per_dev->bio, pages[pg],
                                            pglen, pgbase);
                if (unlikely(pglen != added_len)) {
                        /* If bi_vcnt == bi_max then this is a SW BUG */
                        ORE_DBGMSG("Failed bio_add_pc_page bi_vcnt=0x%x "
                                   "bi_max=0x%x BIO_MAX=0x%x cur_len=0x%x\n",
                                   per_dev->bio->bi_vcnt,
                                   per_dev->bio->bi_max_vecs,
                                   BIO_MAX_PAGES_KMALLOC, cur_len);
                        ret = -ENOMEM;
                        goto out;
                }
                _add_stripe_page(ios->sp2d, &ios->si, pages[pg]);

                pgbase = 0;
                ++pg;
        }
        BUG_ON(cur_len);

        per_dev->length += len;
        *cur_pg = pg;
        ret = 0;
out:    /* we fail the complete unit on an error eg don't advance
         * per_dev->length and cur_pg. This means that we might have a bigger
         * bio than the CDB requested length (per_dev->length). That's fine
         * only the oposite is fatal.
         */
        return ret;
}

static int _add_parity_units(struct ore_io_state *ios,
                             struct ore_striping_info *si,
                             unsigned dev, unsigned first_dev,
                             unsigned mirrors_p1, unsigned devs_in_group,
                             unsigned cur_len)
{
        unsigned do_parity;
        int ret = 0;

        for (do_parity = ios->layout->parity; do_parity; --do_parity) {
                struct ore_per_dev_state *per_dev;

                per_dev = &ios->per_dev[dev - first_dev];
                if (!per_dev->length && !per_dev->offset) {
                        /* Only/always the parity unit of the first
                         * stripe will be empty. So this is a chance to
                         * initialize the per_dev info.
                         */
                        per_dev->dev = dev;
                        per_dev->offset = si->obj_offset - si->unit_off;
                }

                ret = _ore_add_parity_unit(ios, si, per_dev, cur_len,
                                           do_parity == 1);
                if (unlikely(ret))
                                break;

                if (do_parity != 1) {
                        dev = ((dev + mirrors_p1) % devs_in_group) + first_dev;
                        si->cur_comp = (si->cur_comp + 1) %
                                                       ios->layout->group_width;
                }
        }

        return ret;
}

static int _prepare_for_striping(struct ore_io_state *ios)
{
        struct ore_striping_info *si = &ios->si;
        unsigned stripe_unit = ios->layout->stripe_unit;
        unsigned mirrors_p1 = ios->layout->mirrors_p1;
        unsigned group_width = ios->layout->group_width;
        unsigned devs_in_group = group_width * mirrors_p1;
        unsigned dev = si->dev;
        unsigned first_dev = dev - (dev % devs_in_group);
        unsigned cur_pg = ios->pages_consumed;
        u64 length = ios->length;
        int ret = 0;

        if (!ios->pages) {
                ios->numdevs = ios->layout->mirrors_p1;
                return 0;
        }

        BUG_ON(length > si->length);

        while (length) {
                struct ore_per_dev_state *per_dev =
                                                &ios->per_dev[dev - first_dev];
                unsigned cur_len, page_off = 0;

                if (!per_dev->length && !per_dev->offset) {
                        /* First time initialize the per_dev info. */
                        per_dev->dev = dev;
                        if (dev == si->dev) {
                                WARN_ON(dev == si->par_dev);
                                per_dev->offset = si->obj_offset;
                                cur_len = stripe_unit - si->unit_off;
                                page_off = si->unit_off & ~PAGE_MASK;
                                BUG_ON(page_off && (page_off != ios->pgbase));
                        } else {
                                per_dev->offset = si->obj_offset - si->unit_off;
                                cur_len = stripe_unit;
                        }
                } else {
                        cur_len = stripe_unit;
                }
                if (cur_len >= length)
                        cur_len = length;

                ret = _ore_add_stripe_unit(ios, &cur_pg, page_off, ios->pages,
                                           per_dev, cur_len);
                if (unlikely(ret))
                        goto out;

                length -= cur_len;

                dev = ((dev + mirrors_p1) % devs_in_group) + first_dev;
                si->cur_comp = (si->cur_comp + 1) % group_width;
                if (unlikely((dev == si->par_dev) || (!length && ios->sp2d))) {
                        if (!length && ios->sp2d) {
                                /* If we are writing and this is the very last
                                 * stripe. then operate on parity dev.
                                 */
                                dev = si->par_dev;
                                /* If last stripe operate on parity comp */
                                si->cur_comp = group_width - ios->layout->parity;
                        }

                        /* In writes cur_len just means if it's the
                         * last one. See _ore_add_parity_unit.
                         */
                        ret = _add_parity_units(ios, si, dev, first_dev,
                                                mirrors_p1, devs_in_group,
                                                ios->sp2d ? length : cur_len);
                        if (unlikely(ret))
                                        goto out;

                        /* Rotate next par_dev backwards with wraping */
                        si->par_dev = (devs_in_group + si->par_dev -
                                       ios->layout->parity * mirrors_p1) %
                                      devs_in_group + first_dev;
                        /* Next stripe, start fresh */
                        si->cur_comp = 0;
                        si->cur_pg = 0;
                        si->obj_offset += cur_len;
                        si->unit_off = 0;
                }
        }
out:
        ios->numdevs = devs_in_group;
        ios->pages_consumed = cur_pg;
        return ret;
}

int ore_create(struct ore_io_state *ios)
{
        int i, ret;

        for (i = 0; i < ios->oc->numdevs; i++) {
                struct osd_request *or;

                or = osd_start_request(_ios_od(ios, i), GFP_KERNEL);
                if (unlikely(!or)) {
                        ORE_ERR("%s: osd_start_request failed\n", __func__);
                        ret = -ENOMEM;
                        goto out;
                }
                ios->per_dev[i].or = or;
                ios->numdevs++;

                osd_req_create_object(or, _ios_obj(ios, i));
        }
        ret = ore_io_execute(ios);

out:
        return ret;
}
EXPORT_SYMBOL(ore_create);

int ore_remove(struct ore_io_state *ios)
{
        int i, ret;

        for (i = 0; i < ios->oc->numdevs; i++) {
                struct osd_request *or;

                or = osd_start_request(_ios_od(ios, i), GFP_KERNEL);
                if (unlikely(!or)) {
                        ORE_ERR("%s: osd_start_request failed\n", __func__);
                        ret = -ENOMEM;
                        goto out;
                }
                ios->per_dev[i].or = or;
                ios->numdevs++;

                osd_req_remove_object(or, _ios_obj(ios, i));
        }
        ret = ore_io_execute(ios);

out:
        return ret;
}
EXPORT_SYMBOL(ore_remove);

static int _write_mirror(struct ore_io_state *ios, int cur_comp)
{
        struct ore_per_dev_state *master_dev = &ios->per_dev[cur_comp];
        unsigned dev = ios->per_dev[cur_comp].dev;
        unsigned last_comp = cur_comp + ios->layout->mirrors_p1;
        int ret = 0;

        if (ios->pages && !master_dev->length)
                return 0; /* Just an empty slot */

        for (; cur_comp < last_comp; ++cur_comp, ++dev) {
                struct ore_per_dev_state *per_dev = &ios->per_dev[cur_comp];
                struct osd_request *or;

                or = osd_start_request(_ios_od(ios, dev), GFP_KERNEL);
                if (unlikely(!or)) {
                        ORE_ERR("%s: osd_start_request failed\n", __func__);
                        ret = -ENOMEM;
                        goto out;
                }
                per_dev->or = or;

                if (ios->pages) {
                        struct bio *bio;

                        if (per_dev != master_dev) {
                                bio = bio_clone_kmalloc(master_dev->bio,
                                                        GFP_KERNEL);
                                if (unlikely(!bio)) {
                                        ORE_DBGMSG(
                                              "Failed to allocate BIO size=%u\n",
                                              master_dev->bio->bi_max_vecs);
                                        ret = -ENOMEM;
                                        goto out;
                                }

                                bio->bi_bdev = NULL;
                                bio->bi_next = NULL;
                                per_dev->offset = master_dev->offset;
                                per_dev->length = master_dev->length;
                                per_dev->bio =  bio;
                                per_dev->dev = dev;
                        } else {
                                bio = master_dev->bio;
                                /* FIXME: bio_set_dir() */
                                bio->bi_rw |= REQ_WRITE;
                        }

                        osd_req_write(or, _ios_obj(ios, cur_comp),
                                      per_dev->offset, bio, per_dev->length);
                        ORE_DBGMSG("write(0x%llx) offset=0x%llx "
                                      "length=0x%llx dev=%d\n",
                                     _LLU(_ios_obj(ios, cur_comp)->id),
                                     _LLU(per_dev->offset),
                                     _LLU(per_dev->length), dev);
                } else if (ios->kern_buff) {
                        per_dev->offset = ios->si.obj_offset;
                        per_dev->dev = ios->si.dev + dev;

                        /* no cross device without page array */
                        BUG_ON((ios->layout->group_width > 1) &&
                               (ios->si.unit_off + ios->length >
                                ios->layout->stripe_unit));

                        ret = osd_req_write_kern(or, _ios_obj(ios, cur_comp),
                                                 per_dev->offset,
                                                 ios->kern_buff, ios->length);
                        if (unlikely(ret))
                                goto out;
                        ORE_DBGMSG2("write_kern(0x%llx) offset=0x%llx "
                                      "length=0x%llx dev=%d\n",
                                     _LLU(_ios_obj(ios, cur_comp)->id),
                                     _LLU(per_dev->offset),
                                     _LLU(ios->length), per_dev->dev);
                } else {
                        osd_req_set_attributes(or, _ios_obj(ios, cur_comp));
                        ORE_DBGMSG2("obj(0x%llx) set_attributes=%d dev=%d\n",
                                     _LLU(_ios_obj(ios, cur_comp)->id),
                                     ios->out_attr_len, dev);
                }

                if (ios->out_attr)
                        osd_req_add_set_attr_list(or, ios->out_attr,
                                                  ios->out_attr_len);

                if (ios->in_attr)
                        osd_req_add_get_attr_list(or, ios->in_attr,
                                                  ios->in_attr_len);
        }

out:
        return ret;
}

int ore_write(struct ore_io_state *ios)
{
        int i;
        int ret;

        if (unlikely(ios->sp2d && !ios->r4w)) {
                /* A library is attempting a RAID-write without providing
                 * a pages lock interface.
                 */
                WARN_ON_ONCE(1);
                return -ENOTSUPP;
        }

        ret = _prepare_for_striping(ios);
        if (unlikely(ret))
                return ret;

        for (i = 0; i < ios->numdevs; i += ios->layout->mirrors_p1) {
                ret = _write_mirror(ios, i);
                if (unlikely(ret))
                        return ret;
        }

        ret = ore_io_execute(ios);
        return ret;
}
EXPORT_SYMBOL(ore_write);

int _ore_read_mirror(struct ore_io_state *ios, unsigned cur_comp)
{
        struct osd_request *or;
        struct ore_per_dev_state *per_dev = &ios->per_dev[cur_comp];
        struct osd_obj_id *obj = _ios_obj(ios, cur_comp);
        unsigned first_dev = (unsigned)obj->id;

        if (ios->pages && !per_dev->length)
                return 0; /* Just an empty slot */

        first_dev = per_dev->dev + first_dev % ios->layout->mirrors_p1;
        or = osd_start_request(_ios_od(ios, first_dev), GFP_KERNEL);
        if (unlikely(!or)) {
                ORE_ERR("%s: osd_start_request failed\n", __func__);
                return -ENOMEM;
        }
        per_dev->or = or;

        if (ios->pages) {
                if (per_dev->cur_sg) {
                        /* finalize the last sg_entry */
                        _ore_add_sg_seg(per_dev, 0, false);
                        if (unlikely(!per_dev->cur_sg))
                                return 0; /* Skip parity only device */

                        osd_req_read_sg(or, obj, per_dev->bio,
                                        per_dev->sglist, per_dev->cur_sg);
                } else {
                        /* The no raid case */
                        osd_req_read(or, obj, per_dev->offset,
                                     per_dev->bio, per_dev->length);
                }

                ORE_DBGMSG("read(0x%llx) offset=0x%llx length=0x%llx"
                             " dev=%d sg_len=%d\n", _LLU(obj->id),
                             _LLU(per_dev->offset), _LLU(per_dev->length),
                             first_dev, per_dev->cur_sg);
        } else {
                BUG_ON(ios->kern_buff);

                osd_req_get_attributes(or, obj);
                ORE_DBGMSG2("obj(0x%llx) get_attributes=%d dev=%d\n",
                              _LLU(obj->id),
                              ios->in_attr_len, first_dev);
        }
        if (ios->out_attr)
                osd_req_add_set_attr_list(or, ios->out_attr, ios->out_attr_len);

        if (ios->in_attr)
                osd_req_add_get_attr_list(or, ios->in_attr, ios->in_attr_len);

        return 0;
}

int ore_read(struct ore_io_state *ios)
{
        int i;
        int ret;

        ret = _prepare_for_striping(ios);
        if (unlikely(ret))
                return ret;

        for (i = 0; i < ios->numdevs; i += ios->layout->mirrors_p1) {
                ret = _ore_read_mirror(ios, i);
                if (unlikely(ret))
                        return ret;
        }

        ret = ore_io_execute(ios);
        return ret;
}
EXPORT_SYMBOL(ore_read);

int extract_attr_from_ios(struct ore_io_state *ios, struct osd_attr *attr)
{
        struct osd_attr cur_attr = {.attr_page = 0}; /* start with zeros */
        void *iter = NULL;
        int nelem;

        do {
                nelem = 1;
                osd_req_decode_get_attr_list(ios->per_dev[0].or,
                                             &cur_attr, &nelem, &iter);
                if ((cur_attr.attr_page == attr->attr_page) &&
                    (cur_attr.attr_id == attr->attr_id)) {
                        attr->len = cur_attr.len;
                        attr->val_ptr = cur_attr.val_ptr;
                        return 0;
                }
        } while (iter);

        return -EIO;
}
EXPORT_SYMBOL(extract_attr_from_ios);

static int _truncate_mirrors(struct ore_io_state *ios, unsigned cur_comp,
                             struct osd_attr *attr)
{
        int last_comp = cur_comp + ios->layout->mirrors_p1;

        for (; cur_comp < last_comp; ++cur_comp) {
                struct ore_per_dev_state *per_dev = &ios->per_dev[cur_comp];
                struct osd_request *or;

                or = osd_start_request(_ios_od(ios, cur_comp), GFP_KERNEL);
                if (unlikely(!or)) {
                        ORE_ERR("%s: osd_start_request failed\n", __func__);
                        return -ENOMEM;
                }
                per_dev->or = or;

                osd_req_set_attributes(or, _ios_obj(ios, cur_comp));
                osd_req_add_set_attr_list(or, attr, 1);
        }

        return 0;
}

struct _trunc_info {
        struct ore_striping_info si;
        u64 prev_group_obj_off;
        u64 next_group_obj_off;

        unsigned first_group_dev;
        unsigned nex_group_dev;
};

static void _calc_trunk_info(struct ore_layout *layout, u64 file_offset,
                             struct _trunc_info *ti)
{
        unsigned stripe_unit = layout->stripe_unit;

        ore_calc_stripe_info(layout, file_offset, 0, &ti->si);

        ti->prev_group_obj_off = ti->si.M * stripe_unit;
        ti->next_group_obj_off = ti->si.M ? (ti->si.M - 1) * stripe_unit : 0;

        ti->first_group_dev = ti->si.dev - (ti->si.dev % layout->group_width);
        ti->nex_group_dev = ti->first_group_dev + layout->group_width;
}

int ore_truncate(struct ore_layout *layout, struct ore_components *oc,
                   u64 size)
{
        struct ore_io_state *ios;
        struct exofs_trunc_attr {
                struct osd_attr attr;
                __be64 newsize;
        } *size_attrs;
        struct _trunc_info ti;
        int i, ret;

        ret = ore_get_io_state(layout, oc, &ios);
        if (unlikely(ret))
                return ret;

        _calc_trunk_info(ios->layout, size, &ti);

        size_attrs = kcalloc(ios->oc->numdevs, sizeof(*size_attrs),
                             GFP_KERNEL);
        if (unlikely(!size_attrs)) {
                ret = -ENOMEM;
                goto out;
        }

        ios->numdevs = ios->oc->numdevs;

        for (i = 0; i < ios->numdevs; ++i) {
                struct exofs_trunc_attr *size_attr = &size_attrs[i];
                u64 obj_size;

                if (i < ti.first_group_dev)
                        obj_size = ti.prev_group_obj_off;
                else if (i >= ti.nex_group_dev)
                        obj_size = ti.next_group_obj_off;
                else if (i < ti.si.dev) /* dev within this group */
                        obj_size = ti.si.obj_offset +
                                      ios->layout->stripe_unit - ti.si.unit_off;
                else if (i == ti.si.dev)
                        obj_size = ti.si.obj_offset;
                else /* i > ti.dev */
                        obj_size = ti.si.obj_offset - ti.si.unit_off;

                size_attr->newsize = cpu_to_be64(obj_size);
                size_attr->attr = g_attr_logical_length;
                size_attr->attr.val_ptr = &size_attr->newsize;

                ORE_DBGMSG2("trunc(0x%llx) obj_offset=0x%llx dev=%d\n",
                             _LLU(oc->comps->obj.id), _LLU(obj_size), i);
                ret = _truncate_mirrors(ios, i * ios->layout->mirrors_p1,
                                        &size_attr->attr);
                if (unlikely(ret))
                        goto out;
        }
        ret = ore_io_execute(ios);

out:
        kfree(size_attrs);
        ore_put_io_state(ios);
        return ret;
}
EXPORT_SYMBOL(ore_truncate);

const struct osd_attr g_attr_logical_length = ATTR_DEF(
        OSD_APAGE_OBJECT_INFORMATION, OSD_ATTR_OI_LOGICAL_LENGTH, 8);
EXPORT_SYMBOL(g_attr_logical_length);