dm-space-map-common.c

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/*
 * Copyright (C) 2011 Red Hat, Inc.
 *
 * This file is released under the GPL.
 */

#include "dm-space-map-common.h"
#include "dm-transaction-manager.h"

#include <linux/bitops.h>
#include <linux/device-mapper.h>

#define DM_MSG_PREFIX "space map common"

/*----------------------------------------------------------------*/

/*
 * Index validator.
 */
#define INDEX_CSUM_XOR 160478

static void index_prepare_for_write(struct dm_block_validator *v,
                    struct dm_block *b,
                    size_t block_size)
{
    struct disk_metadata_index *mi_le = dm_block_data(b);

    mi_le->blocknr = cpu_to_le64(dm_block_location(b));
    mi_le->csum = cpu_to_le32(dm_bm_checksum(&mi_le->padding,
                         block_size - sizeof(__le32),
                         INDEX_CSUM_XOR));
}

static int index_check(struct dm_block_validator *v,
               struct dm_block *b,
               size_t block_size)
{
    struct disk_metadata_index *mi_le = dm_block_data(b);
    __le32 csum_disk;

    if (dm_block_location(b) != le64_to_cpu(mi_le->blocknr)) {
        DMERR("index_check failed blocknr %llu wanted %llu",
              le64_to_cpu(mi_le->blocknr), dm_block_location(b));
        return -ENOTBLK;
    }

    csum_disk = cpu_to_le32(dm_bm_checksum(&mi_le->padding,
                           block_size - sizeof(__le32),
                           INDEX_CSUM_XOR));
    if (csum_disk != mi_le->csum) {
        DMERR("index_check failed csum %u wanted %u",
              le32_to_cpu(csum_disk), le32_to_cpu(mi_le->csum));
        return -EILSEQ;
    }

    return 0;
}

static struct dm_block_validator index_validator = {
    .name = "index",
    .prepare_for_write = index_prepare_for_write,
    .check = index_check
};

/*----------------------------------------------------------------*/

/*
 * Bitmap validator
 */
#define BITMAP_CSUM_XOR 240779

static void bitmap_prepare_for_write(struct dm_block_validator *v,
                     struct dm_block *b,
                     size_t block_size)
{
    struct disk_bitmap_header *disk_header = dm_block_data(b);

    disk_header->blocknr = cpu_to_le64(dm_block_location(b));
    disk_header->csum = cpu_to_le32(dm_bm_checksum(&disk_header->not_used,
                               block_size - sizeof(__le32),
                               BITMAP_CSUM_XOR));
}

static int bitmap_check(struct dm_block_validator *v,
            struct dm_block *b,
            size_t block_size)
{
    struct disk_bitmap_header *disk_header = dm_block_data(b);
    __le32 csum_disk;

    if (dm_block_location(b) != le64_to_cpu(disk_header->blocknr)) {
        DMERR("bitmap check failed blocknr %llu wanted %llu",
              le64_to_cpu(disk_header->blocknr), dm_block_location(b));
        return -ENOTBLK;
    }

    csum_disk = cpu_to_le32(dm_bm_checksum(&disk_header->not_used,
                           block_size - sizeof(__le32),
                           BITMAP_CSUM_XOR));
    if (csum_disk != disk_header->csum) {
        DMERR("bitmap check failed csum %u wanted %u",
              le32_to_cpu(csum_disk), le32_to_cpu(disk_header->csum));
        return -EILSEQ;
    }

    return 0;
}

static struct dm_block_validator dm_sm_bitmap_validator = {
    .name = "sm_bitmap",
    .prepare_for_write = bitmap_prepare_for_write,
    .check = bitmap_check
};

/*----------------------------------------------------------------*/

#define ENTRIES_PER_WORD 32
#define ENTRIES_SHIFT   5

static void *dm_bitmap_data(struct dm_block *b)
{
    return dm_block_data(b) + sizeof(struct disk_bitmap_header);
}

#define WORD_MASK_HIGH 0xAAAAAAAAAAAAAAAAULL

static unsigned bitmap_word_used(void *addr, unsigned b)
{
    __le64 *words_le = addr;
    __le64 *w_le = words_le + (b >> ENTRIES_SHIFT);

    uint64_t bits = le64_to_cpu(*w_le);
    uint64_t mask = (bits + WORD_MASK_HIGH + 1) & WORD_MASK_HIGH;

    return !(~bits & mask);
}

static unsigned sm_lookup_bitmap(void *addr, unsigned b)
{
    __le64 *words_le = addr;
    __le64 *w_le = words_le + (b >> ENTRIES_SHIFT);
    unsigned hi, lo;

    b = (b & (ENTRIES_PER_WORD - 1)) << 1;
    hi = !!test_bit_le(b, (void *) w_le);
    lo = !!test_bit_le(b + 1, (void *) w_le);
    return (hi << 1) | lo;
}

static void sm_set_bitmap(void *addr, unsigned b, unsigned val)
{
    __le64 *words_le = addr;
    __le64 *w_le = words_le + (b >> ENTRIES_SHIFT);

    b = (b & (ENTRIES_PER_WORD - 1)) << 1;

    if (val & 2)
        __set_bit_le(b, (void *) w_le);
    else
        __clear_bit_le(b, (void *) w_le);

    if (val & 1)
        __set_bit_le(b + 1, (void *) w_le);
    else
        __clear_bit_le(b + 1, (void *) w_le);
}

static int sm_find_free(void *addr, unsigned begin, unsigned end,
            unsigned *result)
{
    while (begin < end) {
        if (!(begin & (ENTRIES_PER_WORD - 1)) &&
            bitmap_word_used(addr, begin)) {
            begin += ENTRIES_PER_WORD;
            continue;
        }

        if (!sm_lookup_bitmap(addr, begin)) {
            *result = begin;
            return 0;
        }

        begin++;
    }

    return -ENOSPC;
}

/*----------------------------------------------------------------*/

static int sm_ll_init(struct ll_disk *ll, struct dm_transaction_manager *tm)
{
    ll->tm = tm;

    ll->bitmap_info.tm = tm;
    ll->bitmap_info.levels = 1;

    /*
     * Because the new bitmap blocks are created via a shadow
     * operation, the old entry has already had its reference count
     * decremented and we don't need the btree to do any bookkeeping.
     */
    ll->bitmap_info.value_type.size = sizeof(struct disk_index_entry);
    ll->bitmap_info.value_type.inc = NULL;
    ll->bitmap_info.value_type.dec = NULL;
    ll->bitmap_info.value_type.equal = NULL;

    ll->ref_count_info.tm = tm;
    ll->ref_count_info.levels = 1;
    ll->ref_count_info.value_type.size = sizeof(uint32_t);
    ll->ref_count_info.value_type.inc = NULL;
    ll->ref_count_info.value_type.dec = NULL;
    ll->ref_count_info.value_type.equal = NULL;

    ll->block_size = dm_bm_block_size(dm_tm_get_bm(tm));

    if (ll->block_size > (1 << 30)) {
        DMERR("block size too big to hold bitmaps");
        return -EINVAL;
    }

    ll->entries_per_block = (ll->block_size - sizeof(struct disk_bitmap_header)) *
        ENTRIES_PER_BYTE;
    ll->nr_blocks = 0;
    ll->bitmap_root = 0;
    ll->ref_count_root = 0;
    ll->bitmap_index_changed = false;

    return 0;
}

int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks)
{
    int r;
    dm_block_t i, nr_blocks, nr_indexes;
    unsigned old_blocks, blocks;

    nr_blocks = ll->nr_blocks + extra_blocks;
    old_blocks = dm_sector_div_up(ll->nr_blocks, ll->entries_per_block);
    blocks = dm_sector_div_up(nr_blocks, ll->entries_per_block);

    nr_indexes = dm_sector_div_up(nr_blocks, ll->entries_per_block);
    if (nr_indexes > ll->max_entries(ll)) {
        DMERR("space map too large");
        return -EINVAL;
    }

    for (i = old_blocks; i < blocks; i++) {
        struct dm_block *b;
        struct disk_index_entry idx;

        r = dm_tm_new_block(ll->tm, &dm_sm_bitmap_validator, &b);
        if (r < 0)
            return r;
        idx.blocknr = cpu_to_le64(dm_block_location(b));

        r = dm_tm_unlock(ll->tm, b);
        if (r < 0)
            return r;

        idx.nr_free = cpu_to_le32(ll->entries_per_block);
        idx.none_free_before = 0;

        r = ll->save_ie(ll, i, &idx);
        if (r < 0)
            return r;
    }

    ll->nr_blocks = nr_blocks;
    return 0;
}

int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result)
{
    int r;
    dm_block_t index = b;
    struct disk_index_entry ie_disk;
    struct dm_block *blk;

    b = do_div(index, ll->entries_per_block);
    r = ll->load_ie(ll, index, &ie_disk);
    if (r < 0)
        return r;

    r = dm_tm_read_lock(ll->tm, le64_to_cpu(ie_disk.blocknr),
                &dm_sm_bitmap_validator, &blk);
    if (r < 0)
        return r;

    *result = sm_lookup_bitmap(dm_bitmap_data(blk), b);

    return dm_tm_unlock(ll->tm, blk);
}

int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result)
{
    __le32 le_rc;
    int r = sm_ll_lookup_bitmap(ll, b, result);

    if (r)
        return r;

    if (*result != 3)
        return r;

    r = dm_btree_lookup(&ll->ref_count_info, ll->ref_count_root, &b, &le_rc);
    if (r < 0)
        return r;

    *result = le32_to_cpu(le_rc);

    return r;
}

int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
              dm_block_t end, dm_block_t *result)
{
    int r;
    struct disk_index_entry ie_disk;
    dm_block_t i, index_begin = begin;
    dm_block_t index_end = dm_sector_div_up(end, ll->entries_per_block);

    /*
     * FIXME: Use shifts
     */
    begin = do_div(index_begin, ll->entries_per_block);
    end = do_div(end, ll->entries_per_block);

    for (i = index_begin; i < index_end; i++, begin = 0) {
        struct dm_block *blk;
        unsigned position;
        uint32_t bit_end;

        r = ll->load_ie(ll, i, &ie_disk);
        if (r < 0)
            return r;

        if (le32_to_cpu(ie_disk.nr_free) == 0)
            continue;

        r = dm_tm_read_lock(ll->tm, le64_to_cpu(ie_disk.blocknr),
                    &dm_sm_bitmap_validator, &blk);
        if (r < 0)
            return r;

        bit_end = (i == index_end - 1) ?  end : ll->entries_per_block;

        r = sm_find_free(dm_bitmap_data(blk),
                 max_t(unsigned, begin, le32_to_cpu(ie_disk.none_free_before)),
                 bit_end, &position);
        if (r == -ENOSPC) {
            /*
             * This might happen because we started searching
             * part way through the bitmap.
             */
            dm_tm_unlock(ll->tm, blk);
            continue;

        } else if (r < 0) {
            dm_tm_unlock(ll->tm, blk);
            return r;
        }

        r = dm_tm_unlock(ll->tm, blk);
        if (r < 0)
            return r;

        *result = i * ll->entries_per_block + (dm_block_t) position;
        return 0;
    }

    return -ENOSPC;
}

int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
         uint32_t ref_count, enum allocation_event *ev)
{
    int r;
    uint32_t bit, old;
    struct dm_block *nb;
    dm_block_t index = b;
    struct disk_index_entry ie_disk;
    void *bm_le;
    int inc;

    bit = do_div(index, ll->entries_per_block);
    r = ll->load_ie(ll, index, &ie_disk);
    if (r < 0)
        return r;

    r = dm_tm_shadow_block(ll->tm, le64_to_cpu(ie_disk.blocknr),
                   &dm_sm_bitmap_validator, &nb, &inc);
    if (r < 0) {
        DMERR("dm_tm_shadow_block() failed");
        return r;
    }
    ie_disk.blocknr = cpu_to_le64(dm_block_location(nb));

    bm_le = dm_bitmap_data(nb);
    old = sm_lookup_bitmap(bm_le, bit);

    if (ref_count <= 2) {
        sm_set_bitmap(bm_le, bit, ref_count);

        r = dm_tm_unlock(ll->tm, nb);
        if (r < 0)
            return r;

        if (old > 2) {
            r = dm_btree_remove(&ll->ref_count_info,
                        ll->ref_count_root,
                        &b, &ll->ref_count_root);
            if (r)
                return r;
        }

    } else {
        __le32 le_rc = cpu_to_le32(ref_count);

        sm_set_bitmap(bm_le, bit, 3);
        r = dm_tm_unlock(ll->tm, nb);
        if (r < 0)
            return r;

        __dm_bless_for_disk(&le_rc);
        r = dm_btree_insert(&ll->ref_count_info, ll->ref_count_root,
                    &b, &le_rc, &ll->ref_count_root);
        if (r < 0) {
            DMERR("ref count insert failed");
            return r;
        }
    }

    if (ref_count && !old) {
        *ev = SM_ALLOC;
        ll->nr_allocated++;
        le32_add_cpu(&ie_disk.nr_free, -1);
        if (le32_to_cpu(ie_disk.none_free_before) == bit)
            ie_disk.none_free_before = cpu_to_le32(bit + 1);

    } else if (old && !ref_count) {
        *ev = SM_FREE;
        ll->nr_allocated--;
        le32_add_cpu(&ie_disk.nr_free, 1);
        ie_disk.none_free_before = cpu_to_le32(min(le32_to_cpu(ie_disk.none_free_before), bit));
    }

    return ll->save_ie(ll, index, &ie_disk);
}

int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
{
    int r;
    uint32_t rc;

    r = sm_ll_lookup(ll, b, &rc);
    if (r)
        return r;

    return sm_ll_insert(ll, b, rc + 1, ev);
}

int sm_ll_dec(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
{
    int r;
    uint32_t rc;

    r = sm_ll_lookup(ll, b, &rc);
    if (r)
        return r;

    if (!rc)
        return -EINVAL;

    return sm_ll_insert(ll, b, rc - 1, ev);
}

int sm_ll_commit(struct ll_disk *ll)
{
    int r = 0;

    if (ll->bitmap_index_changed) {
        r = ll->commit(ll);
        if (!r)
            ll->bitmap_index_changed = false;
    }

    return r;
}

/*----------------------------------------------------------------*/

static int metadata_ll_load_ie(struct ll_disk *ll, dm_block_t index,
                   struct disk_index_entry *ie)
{
    memcpy(ie, ll->mi_le.index + index, sizeof(*ie));
    return 0;
}

static int metadata_ll_save_ie(struct ll_disk *ll, dm_block_t index,
                   struct disk_index_entry *ie)
{
    ll->bitmap_index_changed = true;
    memcpy(ll->mi_le.index + index, ie, sizeof(*ie));
    return 0;
}

static int metadata_ll_init_index(struct ll_disk *ll)
{
    int r;
    struct dm_block *b;

    r = dm_tm_new_block(ll->tm, &index_validator, &b);
    if (r < 0)
        return r;

    memcpy(dm_block_data(b), &ll->mi_le, sizeof(ll->mi_le));
    ll->bitmap_root = dm_block_location(b);

    return dm_tm_unlock(ll->tm, b);
}

static int metadata_ll_open(struct ll_disk *ll)
{
    int r;
    struct dm_block *block;

    r = dm_tm_read_lock(ll->tm, ll->bitmap_root,
                &index_validator, &block);
    if (r)
        return r;

    memcpy(&ll->mi_le, dm_block_data(block), sizeof(ll->mi_le));
    return dm_tm_unlock(ll->tm, block);
}

static dm_block_t metadata_ll_max_entries(struct ll_disk *ll)
{
    return MAX_METADATA_BITMAPS;
}

static int metadata_ll_commit(struct ll_disk *ll)
{
    int r, inc;
    struct dm_block *b;

    r = dm_tm_shadow_block(ll->tm, ll->bitmap_root, &index_validator, &b, &inc);
    if (r)
        return r;

    memcpy(dm_block_data(b), &ll->mi_le, sizeof(ll->mi_le));
    ll->bitmap_root = dm_block_location(b);

    return dm_tm_unlock(ll->tm, b);
}

int sm_ll_new_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm)
{
    int r;

    r = sm_ll_init(ll, tm);
    if (r < 0)
        return r;

    ll->load_ie = metadata_ll_load_ie;
    ll->save_ie = metadata_ll_save_ie;
    ll->init_index = metadata_ll_init_index;
    ll->open_index = metadata_ll_open;
    ll->max_entries = metadata_ll_max_entries;
    ll->commit = metadata_ll_commit;

    ll->nr_blocks = 0;
    ll->nr_allocated = 0;

    r = ll->init_index(ll);
    if (r < 0)
        return r;

    r = dm_btree_empty(&ll->ref_count_info, &ll->ref_count_root);
    if (r < 0)
        return r;

    return 0;
}

int sm_ll_open_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm,
            void *root_le, size_t len)
{
    int r;
    struct disk_sm_root *smr = root_le;

    if (len < sizeof(struct disk_sm_root)) {
        DMERR("sm_metadata root too small");
        return -ENOMEM;
    }

    r = sm_ll_init(ll, tm);
    if (r < 0)
        return r;

    ll->load_ie = metadata_ll_load_ie;
    ll->save_ie = metadata_ll_save_ie;
    ll->init_index = metadata_ll_init_index;
    ll->open_index = metadata_ll_open;
    ll->max_entries = metadata_ll_max_entries;
    ll->commit = metadata_ll_commit;

    ll->nr_blocks = le64_to_cpu(smr->nr_blocks);
    ll->nr_allocated = le64_to_cpu(smr->nr_allocated);
    ll->bitmap_root = le64_to_cpu(smr->bitmap_root);
    ll->ref_count_root = le64_to_cpu(smr->ref_count_root);

    return ll->open_index(ll);
}

/*----------------------------------------------------------------*/

static int disk_ll_load_ie(struct ll_disk *ll, dm_block_t index,
               struct disk_index_entry *ie)
{
    return dm_btree_lookup(&ll->bitmap_info, ll->bitmap_root, &index, ie);
}

static int disk_ll_save_ie(struct ll_disk *ll, dm_block_t index,
               struct disk_index_entry *ie)
{
    __dm_bless_for_disk(ie);
    return dm_btree_insert(&ll->bitmap_info, ll->bitmap_root,
                   &index, ie, &ll->bitmap_root);
}

static int disk_ll_init_index(struct ll_disk *ll)
{
    return dm_btree_empty(&ll->bitmap_info, &ll->bitmap_root);
}

static int disk_ll_open(struct ll_disk *ll)
{
    /* nothing to do */
    return 0;
}

static dm_block_t disk_ll_max_entries(struct ll_disk *ll)
{
    return -1ULL;
}

static int disk_ll_commit(struct ll_disk *ll)
{
    return 0;
}

int sm_ll_new_disk(struct ll_disk *ll, struct dm_transaction_manager *tm)
{
    int r;

    r = sm_ll_init(ll, tm);
    if (r < 0)
        return r;

    ll->load_ie = disk_ll_load_ie;
    ll->save_ie = disk_ll_save_ie;
    ll->init_index = disk_ll_init_index;
    ll->open_index = disk_ll_open;
    ll->max_entries = disk_ll_max_entries;
    ll->commit = disk_ll_commit;

    ll->nr_blocks = 0;
    ll->nr_allocated = 0;

    r = ll->init_index(ll);
    if (r < 0)
        return r;

    r = dm_btree_empty(&ll->ref_count_info, &ll->ref_count_root);
    if (r < 0)
        return r;

    return 0;
}

int sm_ll_open_disk(struct ll_disk *ll, struct dm_transaction_manager *tm,
            void *root_le, size_t len)
{
    int r;
    struct disk_sm_root *smr = root_le;

    if (len < sizeof(struct disk_sm_root)) {
        DMERR("sm_metadata root too small");
        return -ENOMEM;
    }

    r = sm_ll_init(ll, tm);
    if (r < 0)
        return r;

    ll->load_ie = disk_ll_load_ie;
    ll->save_ie = disk_ll_save_ie;
    ll->init_index = disk_ll_init_index;
    ll->open_index = disk_ll_open;
    ll->max_entries = disk_ll_max_entries;
    ll->commit = disk_ll_commit;

    ll->nr_blocks = le64_to_cpu(smr->nr_blocks);
    ll->nr_allocated = le64_to_cpu(smr->nr_allocated);
    ll->bitmap_root = le64_to_cpu(smr->bitmap_root);
    ll->ref_count_root = le64_to_cpu(smr->ref_count_root);

    return ll->open_index(ll);
}

/*----------------------------------------------------------------*/