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

#include <linux/list.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/device-mapper.h>

#define DM_MSG_PREFIX "space map disk"

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

/*
 * Space map interface.
 */
struct sm_disk {
    struct dm_space_map sm;

    struct ll_disk ll;
    struct ll_disk old_ll;

    dm_block_t begin;
    dm_block_t nr_allocated_this_transaction;
};

static void sm_disk_destroy(struct dm_space_map *sm)
{
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);

    kfree(smd);
}

static int sm_disk_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
{
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);

    return sm_ll_extend(&smd->ll, extra_blocks);
}

static int sm_disk_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
{
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
    *count = smd->old_ll.nr_blocks;

    return 0;
}

static int sm_disk_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
{
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
    *count = (smd->old_ll.nr_blocks - smd->old_ll.nr_allocated) - smd->nr_allocated_this_transaction;

    return 0;
}

static int sm_disk_get_count(struct dm_space_map *sm, dm_block_t b,
                 uint32_t *result)
{
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
    return sm_ll_lookup(&smd->ll, b, result);
}

static int sm_disk_count_is_more_than_one(struct dm_space_map *sm, dm_block_t b,
                      int *result)
{
    int r;
    uint32_t count;

    r = sm_disk_get_count(sm, b, &count);
    if (r)
        return r;

    return count > 1;
}

static int sm_disk_set_count(struct dm_space_map *sm, dm_block_t b,
                 uint32_t count)
{
    int r;
    uint32_t old_count;
    enum allocation_event ev;
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);

    r = sm_ll_insert(&smd->ll, b, count, &ev);
    if (!r) {
        switch (ev) {
        case SM_NONE:
            break;

        case SM_ALLOC:
            /*
             * This _must_ be free in the prior transaction
             * otherwise we've lost atomicity.
             */
            smd->nr_allocated_this_transaction++;
            break;

        case SM_FREE:
            /*
             * It's only free if it's also free in the last
             * transaction.
             */
            r = sm_ll_lookup(&smd->old_ll, b, &old_count);
            if (r)
                return r;

            if (!old_count)
                smd->nr_allocated_this_transaction--;
            break;
        }
    }

    return r;
}

static int sm_disk_inc_block(struct dm_space_map *sm, dm_block_t b)
{
    int r;
    enum allocation_event ev;
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);

    r = sm_ll_inc(&smd->ll, b, &ev);
    if (!r && (ev == SM_ALLOC))
        /*
         * This _must_ be free in the prior transaction
         * otherwise we've lost atomicity.
         */
        smd->nr_allocated_this_transaction++;

    return r;
}

static int sm_disk_dec_block(struct dm_space_map *sm, dm_block_t b)
{
    int r;
    uint32_t old_count;
    enum allocation_event ev;
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);

    r = sm_ll_dec(&smd->ll, b, &ev);
    if (!r && (ev == SM_FREE)) {
        /*
         * It's only free if it's also free in the last
         * transaction.
         */
        r = sm_ll_lookup(&smd->old_ll, b, &old_count);
        if (r)
            return r;

        if (!old_count)
            smd->nr_allocated_this_transaction--;
    }

    return r;
}

static int sm_disk_new_block(struct dm_space_map *sm, dm_block_t *b)
{
    int r;
    enum allocation_event ev;
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);

    /* FIXME: we should loop round a couple of times */
    r = sm_ll_find_free_block(&smd->old_ll, smd->begin, smd->old_ll.nr_blocks, b);
    if (r)
        return r;

    smd->begin = *b + 1;
    r = sm_ll_inc(&smd->ll, *b, &ev);
    if (!r) {
        BUG_ON(ev != SM_ALLOC);
        smd->nr_allocated_this_transaction++;
    }

    return r;
}

static int sm_disk_commit(struct dm_space_map *sm)
{
    int r;
    dm_block_t nr_free;
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);

    r = sm_disk_get_nr_free(sm, &nr_free);
    if (r)
        return r;

    r = sm_ll_commit(&smd->ll);
    if (r)
        return r;

    memcpy(&smd->old_ll, &smd->ll, sizeof(smd->old_ll));
    smd->begin = 0;
    smd->nr_allocated_this_transaction = 0;

    r = sm_disk_get_nr_free(sm, &nr_free);
    if (r)
        return r;

    return 0;
}

static int sm_disk_root_size(struct dm_space_map *sm, size_t *result)
{
    *result = sizeof(struct disk_sm_root);

    return 0;
}

static int sm_disk_copy_root(struct dm_space_map *sm, void *where_le, size_t max)
{
    struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
    struct disk_sm_root root_le;

    root_le.nr_blocks = cpu_to_le64(smd->ll.nr_blocks);
    root_le.nr_allocated = cpu_to_le64(smd->ll.nr_allocated);
    root_le.bitmap_root = cpu_to_le64(smd->ll.bitmap_root);
    root_le.ref_count_root = cpu_to_le64(smd->ll.ref_count_root);

    if (max < sizeof(root_le))
        return -ENOSPC;

    memcpy(where_le, &root_le, sizeof(root_le));

    return 0;
}

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

static struct dm_space_map ops = {
    .destroy = sm_disk_destroy,
    .extend = sm_disk_extend,
    .get_nr_blocks = sm_disk_get_nr_blocks,
    .get_nr_free = sm_disk_get_nr_free,
    .get_count = sm_disk_get_count,
    .count_is_more_than_one = sm_disk_count_is_more_than_one,
    .set_count = sm_disk_set_count,
    .inc_block = sm_disk_inc_block,
    .dec_block = sm_disk_dec_block,
    .new_block = sm_disk_new_block,
    .commit = sm_disk_commit,
    .root_size = sm_disk_root_size,
    .copy_root = sm_disk_copy_root
};

struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
                       dm_block_t nr_blocks)
{
    int r;
    struct sm_disk *smd;

    smd = kmalloc(sizeof(*smd), GFP_KERNEL);
    if (!smd)
        return ERR_PTR(-ENOMEM);

    smd->begin = 0;
    smd->nr_allocated_this_transaction = 0;
    memcpy(&smd->sm, &ops, sizeof(smd->sm));

    r = sm_ll_new_disk(&smd->ll, tm);
    if (r)
        goto bad;

    r = sm_ll_extend(&smd->ll, nr_blocks);
    if (r)
        goto bad;

    r = sm_disk_commit(&smd->sm);
    if (r)
        goto bad;

    return &smd->sm;

bad:
    kfree(smd);
    return ERR_PTR(r);
}
EXPORT_SYMBOL_GPL(dm_sm_disk_create);

struct dm_space_map *dm_sm_disk_open(struct dm_transaction_manager *tm,
                     void *root_le, size_t len)
{
    int r;
    struct sm_disk *smd;

    smd = kmalloc(sizeof(*smd), GFP_KERNEL);
    if (!smd)
        return ERR_PTR(-ENOMEM);

    smd->begin = 0;
    smd->nr_allocated_this_transaction = 0;
    memcpy(&smd->sm, &ops, sizeof(smd->sm));

    r = sm_ll_open_disk(&smd->ll, tm, root_le, len);
    if (r)
        goto bad;

    r = sm_disk_commit(&smd->sm);
    if (r)
        goto bad;

    return &smd->sm;

bad:
    kfree(smd);
    return ERR_PTR(r);
}
EXPORT_SYMBOL_GPL(dm_sm_disk_open);

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