usb: gadget: core: allow everybody to read sysfs attributes

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / exofs / ore_raid.c

/*
 * Copyright (C) 2011
 * Boaz Harrosh <bharrosh@panasas.com>
 *
 * This file is part of the objects raid engine (ore).
 *
 * It is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * You should have received a copy of the GNU General Public License
 * along with "ore". If not, write to the Free Software Foundation, Inc:
 *      "Free Software Foundation <info@fsf.org>"
 */

#include <linux/gfp.h>
#include <linux/async_tx.h>

#include "ore_raid.h"

#undef ORE_DBGMSG2
#define ORE_DBGMSG2 ORE_DBGMSG

struct page *_raid_page_alloc(void)
{
        return alloc_page(GFP_KERNEL);
}

void _raid_page_free(struct page *p)
{
        __free_page(p);
}

/* This struct is forward declare in ore_io_state, but is private to here.
 * It is put on ios->sp2d for RAID5/6 writes only. See _gen_xor_unit.
 *
 * __stripe_pages_2d is a 2d array of pages, and it is also a corner turn.
 * Ascending page index access is sp2d(p-minor, c-major). But storage is
 * sp2d[p-minor][c-major], so it can be properlly presented to the async-xor
 * API.
 */
struct __stripe_pages_2d {
        /* Cache some hot path repeated calculations */
        unsigned parity;
        unsigned data_devs;
        unsigned pages_in_unit;

        bool needed ;

        /* Array size is pages_in_unit (layout->stripe_unit / PAGE_SIZE) */
        struct __1_page_stripe {
                bool alloc;
                unsigned write_count;
                struct async_submit_ctl submit;
                struct dma_async_tx_descriptor *tx;

                /* The size of this array is data_devs + parity */
                struct page **pages;
                struct page **scribble;
                /* bool array, size of this array is data_devs */
                char *page_is_read;
        } _1p_stripes[];
};

/* This can get bigger then a page. So support multiple page allocations
 * _sp2d_free should be called even if _sp2d_alloc fails (by returning
 * none-zero).
 */
static int _sp2d_alloc(unsigned pages_in_unit, unsigned group_width,
                       unsigned parity, struct __stripe_pages_2d **psp2d)
{
        struct __stripe_pages_2d *sp2d;
        unsigned data_devs = group_width - parity;
        struct _alloc_all_bytes {
                struct __alloc_stripe_pages_2d {
                        struct __stripe_pages_2d sp2d;
                        struct __1_page_stripe _1p_stripes[pages_in_unit];
                } __asp2d;
                struct __alloc_1p_arrays {
                        struct page *pages[group_width];
                        struct page *scribble[group_width];
                        char page_is_read[data_devs];
                } __a1pa[pages_in_unit];
        } *_aab;
        struct __alloc_1p_arrays *__a1pa;
        struct __alloc_1p_arrays *__a1pa_end;
        const unsigned sizeof__a1pa = sizeof(_aab->__a1pa[0]);
        unsigned num_a1pa, alloc_size, i;

        /* FIXME: check these numbers in ore_verify_layout */
        BUG_ON(sizeof(_aab->__asp2d) > PAGE_SIZE);
        BUG_ON(sizeof__a1pa > PAGE_SIZE);

        if (sizeof(*_aab) > PAGE_SIZE) {
                num_a1pa = (PAGE_SIZE - sizeof(_aab->__asp2d)) / sizeof__a1pa;
                alloc_size = sizeof(_aab->__asp2d) + sizeof__a1pa * num_a1pa;
        } else {
                num_a1pa = pages_in_unit;
                alloc_size = sizeof(*_aab);
        }

        _aab = kzalloc(alloc_size, GFP_KERNEL);
        if (unlikely(!_aab)) {
                ORE_DBGMSG("!! Failed to alloc sp2d size=%d\n", alloc_size);
                return -ENOMEM;
        }

        sp2d = &_aab->__asp2d.sp2d;
        *psp2d = sp2d; /* From here Just call _sp2d_free */

        __a1pa = _aab->__a1pa;
        __a1pa_end = __a1pa + num_a1pa;

        for (i = 0; i < pages_in_unit; ++i) {
                if (unlikely(__a1pa >= __a1pa_end)) {
                        num_a1pa = min_t(unsigned, PAGE_SIZE / sizeof__a1pa,
                                                        pages_in_unit - i);

                        __a1pa = kzalloc(num_a1pa * sizeof__a1pa, GFP_KERNEL);
                        if (unlikely(!__a1pa)) {
                                ORE_DBGMSG("!! Failed to _alloc_1p_arrays=%d\n",
                                           num_a1pa);
                                return -ENOMEM;
                        }
                        __a1pa_end = __a1pa + num_a1pa;
                        /* First *pages is marked for kfree of the buffer */
                        sp2d->_1p_stripes[i].alloc = true;
                }

                sp2d->_1p_stripes[i].pages = __a1pa->pages;
                sp2d->_1p_stripes[i].scribble = __a1pa->scribble ;
                sp2d->_1p_stripes[i].page_is_read = __a1pa->page_is_read;
                ++__a1pa;
        }

        sp2d->parity = parity;
        sp2d->data_devs = data_devs;
        sp2d->pages_in_unit = pages_in_unit;
        return 0;
}

static void _sp2d_reset(struct __stripe_pages_2d *sp2d,
                        const struct _ore_r4w_op *r4w, void *priv)
{
        unsigned data_devs = sp2d->data_devs;
        unsigned group_width = data_devs + sp2d->parity;
        unsigned p;

        if (!sp2d->needed)
                return;

        for (p = 0; p < sp2d->pages_in_unit; p++) {
                struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

                if (_1ps->write_count < group_width) {
                        unsigned c;

                        for (c = 0; c < data_devs; c++)
                                if (_1ps->page_is_read[c]) {
                                        struct page *page = _1ps->pages[c];

                                        r4w->put_page(priv, page);
                                        _1ps->page_is_read[c] = false;
                                }
                }

                memset(_1ps->pages, 0, group_width * sizeof(*_1ps->pages));
                _1ps->write_count = 0;
                _1ps->tx = NULL;
        }

        sp2d->needed = false;
}

static void _sp2d_free(struct __stripe_pages_2d *sp2d)
{
        unsigned i;

        if (!sp2d)
                return;

        for (i = 0; i < sp2d->pages_in_unit; ++i) {
                if (sp2d->_1p_stripes[i].alloc)
                        kfree(sp2d->_1p_stripes[i].pages);
        }

        kfree(sp2d);
}

static unsigned _sp2d_min_pg(struct __stripe_pages_2d *sp2d)
{
        unsigned p;

        for (p = 0; p < sp2d->pages_in_unit; p++) {
                struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

                if (_1ps->write_count)
                        return p;
        }

        return ~0;
}

static unsigned _sp2d_max_pg(struct __stripe_pages_2d *sp2d)
{
        unsigned p;

        for (p = sp2d->pages_in_unit - 1; p >= 0; --p) {
                struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

                if (_1ps->write_count)
                        return p;
        }

        return ~0;
}

static void _gen_xor_unit(struct __stripe_pages_2d *sp2d)
{
        unsigned p;
        for (p = 0; p < sp2d->pages_in_unit; p++) {
                struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

                if (!_1ps->write_count)
                        continue;

                init_async_submit(&_1ps->submit,
                        ASYNC_TX_XOR_ZERO_DST | ASYNC_TX_ACK,
                        NULL,
                        NULL, NULL,
                        (addr_conv_t *)_1ps->scribble);

                /* TODO: raid6 */
                _1ps->tx = async_xor(_1ps->pages[sp2d->data_devs], _1ps->pages,
                                     0, sp2d->data_devs, PAGE_SIZE,
                                     &_1ps->submit);
        }

        for (p = 0; p < sp2d->pages_in_unit; p++) {
                struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
                /* NOTE: We wait for HW synchronously (I don't have such HW
                 * to test with.) Is parallelism needed with today's multi
                 * cores?
                 */
                async_tx_issue_pending(_1ps->tx);
        }
}

void _ore_add_stripe_page(struct __stripe_pages_2d *sp2d,
                       struct ore_striping_info *si, struct page *page)
{
        struct __1_page_stripe *_1ps;

        sp2d->needed = true;

        _1ps = &sp2d->_1p_stripes[si->cur_pg];
        _1ps->pages[si->cur_comp] = page;
        ++_1ps->write_count;

        si->cur_pg = (si->cur_pg + 1) % sp2d->pages_in_unit;
        /* si->cur_comp is advanced outside at main loop */
}

void _ore_add_sg_seg(struct ore_per_dev_state *per_dev, unsigned cur_len,
                     bool not_last)
{
        struct osd_sg_entry *sge;

        ORE_DBGMSG("dev=%d cur_len=0x%x not_last=%d cur_sg=%d "
                     "offset=0x%llx length=0x%x last_sgs_total=0x%x\n",
                     per_dev->dev, cur_len, not_last, per_dev->cur_sg,
                     _LLU(per_dev->offset), per_dev->length,
                     per_dev->last_sgs_total);

        if (!per_dev->cur_sg) {
                sge = per_dev->sglist;

                /* First time we prepare two entries */
                if (per_dev->length) {
                        ++per_dev->cur_sg;
                        sge->offset = per_dev->offset;
                        sge->len = per_dev->length;
                } else {
                        /* Here the parity is the first unit of this object.
                         * This happens every time we reach a parity device on
                         * the same stripe as the per_dev->offset. We need to
                         * just skip this unit.
                         */
                        per_dev->offset += cur_len;
                        return;
                }
        } else {
                /* finalize the last one */
                sge = &per_dev->sglist[per_dev->cur_sg - 1];
                sge->len = per_dev->length - per_dev->last_sgs_total;
        }

        if (not_last) {
                /* Partly prepare the next one */
                struct osd_sg_entry *next_sge = sge + 1;

                ++per_dev->cur_sg;
                next_sge->offset = sge->offset + sge->len + cur_len;
                /* Save cur len so we know how mutch was added next time */
                per_dev->last_sgs_total = per_dev->length;
                next_sge->len = 0;
        } else if (!sge->len) {
                /* Optimize for when the last unit is a parity */
                --per_dev->cur_sg;
        }
}

static int _alloc_read_4_write(struct ore_io_state *ios)
{
        struct ore_layout *layout = ios->layout;
        int ret;
        /* We want to only read those pages not in cache so worst case
         * is a stripe populated with every other page
         */
        unsigned sgs_per_dev = ios->sp2d->pages_in_unit + 2;

        ret = _ore_get_io_state(layout, ios->oc,
                                layout->group_width * layout->mirrors_p1,
                                sgs_per_dev, 0, &ios->ios_read_4_write);
        return ret;
}

/* @si contains info of the to-be-inserted page. Update of @si should be
 * maintained by caller. Specificaly si->dev, si->obj_offset, ...
 */
static int _add_to_read_4_write(struct ore_io_state *ios,
                                struct ore_striping_info *si, struct page *page)
{
        struct request_queue *q;
        struct ore_per_dev_state *per_dev;
        struct ore_io_state *read_ios;
        unsigned first_dev = si->dev - (si->dev %
                          (ios->layout->group_width * ios->layout->mirrors_p1));
        unsigned comp = si->dev - first_dev;
        unsigned added_len;

        if (!ios->ios_read_4_write) {
                int ret = _alloc_read_4_write(ios);

                if (unlikely(ret))
                        return ret;
        }

        read_ios = ios->ios_read_4_write;
        read_ios->numdevs = ios->layout->group_width * ios->layout->mirrors_p1;

        per_dev = &read_ios->per_dev[comp];
        if (!per_dev->length) {
                per_dev->bio = bio_kmalloc(GFP_KERNEL,
                                           ios->sp2d->pages_in_unit);
                if (unlikely(!per_dev->bio)) {
                        ORE_DBGMSG("Failed to allocate BIO size=%u\n",
                                     ios->sp2d->pages_in_unit);
                        return -ENOMEM;
                }
                per_dev->offset = si->obj_offset;
                per_dev->dev = si->dev;
        } else if (si->obj_offset != (per_dev->offset + per_dev->length)) {
                u64 gap = si->obj_offset - (per_dev->offset + per_dev->length);

                _ore_add_sg_seg(per_dev, gap, true);
        }
        q = osd_request_queue(ore_comp_dev(read_ios->oc, per_dev->dev));
        added_len = bio_add_pc_page(q, per_dev->bio, page, PAGE_SIZE, 0);
        if (unlikely(added_len != PAGE_SIZE)) {
                ORE_DBGMSG("Failed to bio_add_pc_page bi_vcnt=%d\n",
                              per_dev->bio->bi_vcnt);
                return -ENOMEM;
        }

        per_dev->length += PAGE_SIZE;
        return 0;
}

static void _mark_read4write_pages_uptodate(struct ore_io_state *ios, int ret)
{
        struct bio_vec *bv;
        unsigned i, d;

        /* loop on all devices all pages */
        for (d = 0; d < ios->numdevs; d++) {
                struct bio *bio = ios->per_dev[d].bio;

                if (!bio)
                        continue;

                __bio_for_each_segment(bv, bio, i, 0) {
                        struct page *page = bv->bv_page;

                        SetPageUptodate(page);
                        if (PageError(page))
                                ClearPageError(page);
                }
        }
}

/* read_4_write is hacked to read the start of the first stripe and/or
 * the end of the last stripe. If needed, with an sg-gap at each device/page.
 * It is assumed to be called after the to_be_written pages of the first stripe
 * are populating ios->sp2d[][]
 *
 * NOTE: We call ios->r4w->lock_fn for all pages needed for parity calculations
 * These pages are held at sp2d[p].pages[c] but with
 * sp2d[p].page_is_read[c] = true. At _sp2d_reset these pages are
 * ios->r4w->lock_fn(). The ios->r4w->lock_fn might signal that the page is
 * @uptodate=true, so we don't need to read it, only unlock, after IO.
 *
 * TODO: The read_4_write should calc a need_to_read_pages_count, if bigger then
 * to-be-written count, we should consider the xor-in-place mode.
 * need_to_read_pages_count is the actual number of pages not present in cache.
 * maybe "devs_in_group - ios->sp2d[p].write_count" is a good enough
 * approximation? In this mode the read pages are put in the empty places of
 * ios->sp2d[p][*], xor is calculated the same way. These pages are
 * allocated/freed and don't go through cache
 */
static int _read_4_write(struct ore_io_state *ios)
{
        struct ore_io_state *ios_read;
        struct ore_striping_info read_si;
        struct __stripe_pages_2d *sp2d = ios->sp2d;
        u64 offset = ios->si.first_stripe_start;
        u64 last_stripe_end;
        unsigned bytes_in_stripe = ios->si.bytes_in_stripe;
        unsigned i, c, p, min_p = sp2d->pages_in_unit, max_p = -1;
        int ret;

        if (offset == ios->offset) /* Go to start collect $200 */
                goto read_last_stripe;

        min_p = _sp2d_min_pg(sp2d);
        max_p = _sp2d_max_pg(sp2d);

        for (c = 0; ; c++) {
                ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
                read_si.obj_offset += min_p * PAGE_SIZE;
                offset += min_p * PAGE_SIZE;
                for (p = min_p; p <= max_p; p++) {
                        struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
                        struct page **pp = &_1ps->pages[c];
                        bool uptodate;

                        if (*pp)
                                /* to-be-written pages start here */
                                goto read_last_stripe;

                        *pp = ios->r4w->get_page(ios->private, offset,
                                                 &uptodate);
                        if (unlikely(!*pp))
                                return -ENOMEM;

                        if (!uptodate)
                                _add_to_read_4_write(ios, &read_si, *pp);

                        /* Mark read-pages to be cache_released */
                        _1ps->page_is_read[c] = true;
                        read_si.obj_offset += PAGE_SIZE;
                        offset += PAGE_SIZE;
                }
                offset += (sp2d->pages_in_unit - p) * PAGE_SIZE;
        }

read_last_stripe:
        offset = ios->offset + (ios->length + PAGE_SIZE - 1) /
                                PAGE_SIZE * PAGE_SIZE;
        last_stripe_end = div_u64(offset + bytes_in_stripe - 1, bytes_in_stripe)
                                 * bytes_in_stripe;
        if (offset == last_stripe_end) /* Optimize for the aligned case */
                goto read_it;

        ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
        p = read_si.unit_off / PAGE_SIZE;
        c = _dev_order(ios->layout->group_width * ios->layout->mirrors_p1,
                       ios->layout->mirrors_p1, read_si.par_dev, read_si.dev);

        BUG_ON(ios->si.first_stripe_start + bytes_in_stripe != last_stripe_end);
        /* unaligned IO must be within a single stripe */

        if (min_p == sp2d->pages_in_unit) {
                /* Didn't do it yet */
                min_p = _sp2d_min_pg(sp2d);
                max_p = _sp2d_max_pg(sp2d);
        }

        while (offset < last_stripe_end) {
                struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

                if ((min_p <= p) && (p <= max_p)) {
                        struct page *page;
                        bool uptodate;

                        BUG_ON(_1ps->pages[c]);
                        page = ios->r4w->get_page(ios->private, offset,
                                                  &uptodate);
                        if (unlikely(!page))
                                return -ENOMEM;

                        _1ps->pages[c] = page;
                        /* Mark read-pages to be cache_released */
                        _1ps->page_is_read[c] = true;
                        if (!uptodate)
                                _add_to_read_4_write(ios, &read_si, page);
                }

                offset += PAGE_SIZE;
                if (p == (sp2d->pages_in_unit - 1)) {
                        ++c;
                        p = 0;
                        ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
                } else {
                        read_si.obj_offset += PAGE_SIZE;
                        ++p;
                }
        }

read_it:
        ios_read = ios->ios_read_4_write;
        if (!ios_read)
                return 0;

        /* FIXME: Ugly to signal _sbi_read_mirror that we have bio(s). Change
         * to check for per_dev->bio
         */
        ios_read->pages = ios->pages;

        /* Now read these devices */
        for (i = 0; i < ios_read->numdevs; i += ios_read->layout->mirrors_p1) {
                ret = _ore_read_mirror(ios_read, i);
                if (unlikely(ret))
                        return ret;
        }

        ret = ore_io_execute(ios_read); /* Synchronus execution */
        if (unlikely(ret)) {
                ORE_DBGMSG("!! ore_io_execute => %d\n", ret);
                return ret;
        }

        _mark_read4write_pages_uptodate(ios_read, ret);
        return 0;
}

/* In writes @cur_len means length left. .i.e cur_len==0 is the last parity U */
int _ore_add_parity_unit(struct ore_io_state *ios,
                            struct ore_striping_info *si,
                            struct ore_per_dev_state *per_dev,
                            unsigned cur_len)
{
        if (ios->reading) {
                BUG_ON(per_dev->cur_sg >= ios->sgs_per_dev);
                _ore_add_sg_seg(per_dev, cur_len, true);
        } else {
                struct __stripe_pages_2d *sp2d = ios->sp2d;
                struct page **pages = ios->parity_pages + ios->cur_par_page;
                unsigned num_pages;
                unsigned array_start = 0;
                unsigned i;
                int ret;

                si->cur_pg = _sp2d_min_pg(sp2d);
                num_pages  = _sp2d_max_pg(sp2d) + 1 - si->cur_pg;

                if (!cur_len) /* If last stripe operate on parity comp */
                        si->cur_comp = sp2d->data_devs;

                if (!per_dev->length) {
                        per_dev->offset += si->cur_pg * PAGE_SIZE;
                        /* If first stripe, Read in all read4write pages
                         * (if needed) before we calculate the first parity.
                         */
                        _read_4_write(ios);
                }

                for (i = 0; i < num_pages; i++) {
                        pages[i] = _raid_page_alloc();
                        if (unlikely(!pages[i]))
                                return -ENOMEM;

                        ++(ios->cur_par_page);
                }

                BUG_ON(si->cur_comp != sp2d->data_devs);
                BUG_ON(si->cur_pg + num_pages > sp2d->pages_in_unit);

                ret = _ore_add_stripe_unit(ios,  &array_start, 0, pages,
                                           per_dev, num_pages * PAGE_SIZE);
                if (unlikely(ret))
                        return ret;

                /* TODO: raid6 if (last_parity_dev) */
                _gen_xor_unit(sp2d);
                _sp2d_reset(sp2d, ios->r4w, ios->private);
        }
        return 0;
}

int _ore_post_alloc_raid_stuff(struct ore_io_state *ios)
{
        struct ore_layout *layout = ios->layout;

        if (ios->parity_pages) {
                unsigned pages_in_unit = layout->stripe_unit / PAGE_SIZE;
                unsigned stripe_size = ios->si.bytes_in_stripe;
                u64 last_stripe, first_stripe;

                if (_sp2d_alloc(pages_in_unit, layout->group_width,
                                layout->parity, &ios->sp2d)) {
                        return -ENOMEM;
                }

                BUG_ON(ios->offset % PAGE_SIZE);

                /* Round io down to last full strip */
                first_stripe = div_u64(ios->offset, stripe_size);
                last_stripe = div_u64(ios->offset + ios->length, stripe_size);

                /* If an IO spans more then a single stripe it must end at
                 * a stripe boundary. The reminder at the end is pushed into the
                 * next IO.
                 */
                if (last_stripe != first_stripe) {
                        ios->length = last_stripe * stripe_size - ios->offset;

                        BUG_ON(!ios->length);
                        ios->nr_pages = (ios->length + PAGE_SIZE - 1) /
                                        PAGE_SIZE;
                        ios->si.length = ios->length; /*make it consistent */
                }
        }
        return 0;
}

void _ore_free_raid_stuff(struct ore_io_state *ios)
{
        if (ios->sp2d) { /* writing and raid */
                unsigned i;

                for (i = 0; i < ios->cur_par_page; i++) {
                        struct page *page = ios->parity_pages[i];

                        if (page)
                                _raid_page_free(page);
                }
                if (ios->extra_part_alloc)
                        kfree(ios->parity_pages);
                /* If IO returned an error pages might need unlocking */
                _sp2d_reset(ios->sp2d, ios->r4w, ios->private);
                _sp2d_free(ios->sp2d);
        } else {
                /* Will only be set if raid reading && sglist is big */
                if (ios->extra_part_alloc)
                        kfree(ios->per_dev[0].sglist);
        }
        if (ios->ios_read_4_write)
                ore_put_io_state(ios->ios_read_4_write);
}