fs/zfs/range_tree.c

	range_tree.c revision bf16b11e8deb633dd6c4296d46e92399d1582df4
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Copyright (c) 2013, 2014 by Delphix. All rights reserved.
 */

#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/dmu.h>
#include <sys/dnode.h>
#include <sys/zio.h>
#include <sys/range_tree.h>

static kmem_cache_t *range_seg_cache;

void
range_tree_init(void)
{
    ASSERT(range_seg_cache == NULL);
    range_seg_cache = kmem_cache_create("range_seg_cache",
        sizeof (range_seg_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
}

void
range_tree_fini(void)
{
    kmem_cache_destroy(range_seg_cache);
    range_seg_cache = NULL;
}

void
range_tree_stat_verify(range_tree_t *rt)
{
    range_seg_t *rs;
    uint64_t hist[RANGE_TREE_HISTOGRAM_SIZE] = { 0 };
    int i;

    for (rs = avl_first(&rt->rt_root); rs != NULL;
        rs = AVL_NEXT(&rt->rt_root, rs)) {
        uint64_t size = rs->rs_end - rs->rs_start;
        int idx = highbit64(size) - 1;

        hist[idx]++;
        ASSERT3U(hist[idx], !=, 0);
    }

    for (i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++) {
        if (hist[i] != rt->rt_histogram[i]) {
            zfs_dbgmsg("i=%d, hist=%p, hist=%llu, rt_hist=%llu",
                i, hist, hist[i], rt->rt_histogram[i]);
        }
        VERIFY3U(hist[i], ==, rt->rt_histogram[i]);
    }
}

static void
range_tree_stat_incr(range_tree_t *rt, range_seg_t *rs)
{
    uint64_t size = rs->rs_end - rs->rs_start;
    int idx = highbit64(size) - 1;

    ASSERT3U(idx, <,
        sizeof (rt->rt_histogram) / sizeof (*rt->rt_histogram));

    ASSERT(MUTEX_HELD(rt->rt_lock));
    rt->rt_histogram[idx]++;
    ASSERT3U(rt->rt_histogram[idx], !=, 0);
}

static void
range_tree_stat_decr(range_tree_t *rt, range_seg_t *rs)
{
    uint64_t size = rs->rs_end - rs->rs_start;
    int idx = highbit64(size) - 1;

    ASSERT3U(idx, <,
        sizeof (rt->rt_histogram) / sizeof (*rt->rt_histogram));

    ASSERT(MUTEX_HELD(rt->rt_lock));
    ASSERT3U(rt->rt_histogram[idx], !=, 0);
    rt->rt_histogram[idx]--;
}

/*
 * NOTE: caller is responsible for all locking.
 */
static int
range_tree_seg_compare(const void *x1, const void *x2)
{
    const range_seg_t *r1 = x1;
    const range_seg_t *r2 = x2;

    if (r1->rs_start < r2->rs_start) {
        if (r1->rs_end > r2->rs_start)
            return (0);
        return (-1);
    }
    if (r1->rs_start > r2->rs_start) {
        if (r1->rs_start < r2->rs_end)
            return (0);
        return (1);
    }
    return (0);
}

range_tree_t *
range_tree_create(range_tree_ops_t *ops, void *arg, kmutex_t *lp)
{
    range_tree_t *rt;

    rt = kmem_zalloc(sizeof (range_tree_t), KM_SLEEP);

    avl_create(&rt->rt_root, range_tree_seg_compare,
        sizeof (range_seg_t), offsetof(range_seg_t, rs_node));

    rt->rt_lock = lp;
    rt->rt_ops = ops;
    rt->rt_arg = arg;

    if (rt->rt_ops != NULL)
        rt->rt_ops->rtop_create(rt, rt->rt_arg);

    return (rt);
}

void
range_tree_destroy(range_tree_t *rt)
{
    VERIFY0(rt->rt_space);

    if (rt->rt_ops != NULL)
        rt->rt_ops->rtop_destroy(rt, rt->rt_arg);

    avl_destroy(&rt->rt_root);
    kmem_free(rt, sizeof (*rt));
}

void
range_tree_add(void *arg, uint64_t start, uint64_t size)
{
    range_tree_t *rt = arg;
    avl_index_t where;
    range_seg_t rsearch, *rs_before, *rs_after, *rs;
    uint64_t end = start + size;
    boolean_t merge_before, merge_after;

    ASSERT(MUTEX_HELD(rt->rt_lock));
    VERIFY(size != 0);

    rsearch.rs_start = start;
    rsearch.rs_end = end;
    rs = avl_find(&rt->rt_root, &rsearch, &where);

    if (rs != NULL && rs->rs_start <= start && rs->rs_end >= end) {
        zfs_panic_recover("zfs: allocating allocated segment"
            "(offset=%llu size=%llu)\n",
            (longlong_t)start, (longlong_t)size);
        return;
    }

    /* Make sure we don't overlap with either of our neighbors */
    VERIFY(rs == NULL);

    rs_before = avl_nearest(&rt->rt_root, where, AVL_BEFORE);
    rs_after = avl_nearest(&rt->rt_root, where, AVL_AFTER);

    merge_before = (rs_before != NULL && rs_before->rs_end == start);
    merge_after = (rs_after != NULL && rs_after->rs_start == end);

    if (merge_before && merge_after) {
        avl_remove(&rt->rt_root, rs_before);
        if (rt->rt_ops != NULL) {
            rt->rt_ops->rtop_remove(rt, rs_before, rt->rt_arg);
            rt->rt_ops->rtop_remove(rt, rs_after, rt->rt_arg);
        }

        range_tree_stat_decr(rt, rs_before);
        range_tree_stat_decr(rt, rs_after);

        rs_after->rs_start = rs_before->rs_start;
        kmem_cache_free(range_seg_cache, rs_before);
        rs = rs_after;
    } else if (merge_before) {
        if (rt->rt_ops != NULL)
            rt->rt_ops->rtop_remove(rt, rs_before, rt->rt_arg);

        range_tree_stat_decr(rt, rs_before);

        rs_before->rs_end = end;
        rs = rs_before;
    } else if (merge_after) {
        if (rt->rt_ops != NULL)
            rt->rt_ops->rtop_remove(rt, rs_after, rt->rt_arg);

        range_tree_stat_decr(rt, rs_after);

        rs_after->rs_start = start;
        rs = rs_after;
    } else {
        rs = kmem_cache_alloc(range_seg_cache, KM_SLEEP);
        rs->rs_start = start;
        rs->rs_end = end;
        avl_insert(&rt->rt_root, rs, where);
    }

    if (rt->rt_ops != NULL)
        rt->rt_ops->rtop_add(rt, rs, rt->rt_arg);

    range_tree_stat_incr(rt, rs);
    rt->rt_space += size;
}

void
range_tree_remove(void *arg, uint64_t start, uint64_t size)
{
    range_tree_t *rt = arg;
    avl_index_t where;
    range_seg_t rsearch, *rs, *newseg;
    uint64_t end = start + size;
    boolean_t left_over, right_over;

    ASSERT(MUTEX_HELD(rt->rt_lock));
    VERIFY3U(size, !=, 0);
    VERIFY3U(size, <=, rt->rt_space);

    rsearch.rs_start = start;
    rsearch.rs_end = end;
    rs = avl_find(&rt->rt_root, &rsearch, &where);

    /* Make sure we completely overlap with someone */
    if (rs == NULL) {
        zfs_panic_recover("zfs: freeing free segment "
            "(offset=%llu size=%llu)",
            (longlong_t)start, (longlong_t)size);
        return;
    }
    VERIFY3U(rs->rs_start, <=, start);
    VERIFY3U(rs->rs_end, >=, end);

    left_over = (rs->rs_start != start);
    right_over = (rs->rs_end != end);

    range_tree_stat_decr(rt, rs);

    if (rt->rt_ops != NULL)
        rt->rt_ops->rtop_remove(rt, rs, rt->rt_arg);

    if (left_over && right_over) {
        newseg = kmem_cache_alloc(range_seg_cache, KM_SLEEP);
        newseg->rs_start = end;
        newseg->rs_end = rs->rs_end;
        range_tree_stat_incr(rt, newseg);

        rs->rs_end = start;

        avl_insert_here(&rt->rt_root, newseg, rs, AVL_AFTER);
        if (rt->rt_ops != NULL)
            rt->rt_ops->rtop_add(rt, newseg, rt->rt_arg);
    } else if (left_over) {
        rs->rs_end = start;
    } else if (right_over) {
        rs->rs_start = end;
    } else {
        avl_remove(&rt->rt_root, rs);
        kmem_cache_free(range_seg_cache, rs);
        rs = NULL;
    }

    if (rs != NULL) {
        range_tree_stat_incr(rt, rs);

        if (rt->rt_ops != NULL)
            rt->rt_ops->rtop_add(rt, rs, rt->rt_arg);
    }

    rt->rt_space -= size;
}

static range_seg_t *
range_tree_find_impl(range_tree_t *rt, uint64_t start, uint64_t size)
{
    avl_index_t where;
    range_seg_t rsearch;
    uint64_t end = start + size;

    ASSERT(MUTEX_HELD(rt->rt_lock));
    VERIFY(size != 0);

    rsearch.rs_start = start;
    rsearch.rs_end = end;
    return (avl_find(&rt->rt_root, &rsearch, &where));
}

static range_seg_t *
range_tree_find(range_tree_t *rt, uint64_t start, uint64_t size)
{
    range_seg_t *rs = range_tree_find_impl(rt, start, size);
    if (rs != NULL && rs->rs_start <= start && rs->rs_end >= start + size)
        return (rs);
    return (NULL);
}

void
range_tree_verify(range_tree_t *rt, uint64_t off, uint64_t size)
{
    range_seg_t *rs;

    mutex_enter(rt->rt_lock);
    rs = range_tree_find(rt, off, size);
    if (rs != NULL)
        panic("freeing free block; rs=%p", (void *)rs);
    mutex_exit(rt->rt_lock);
}

boolean_t
range_tree_contains(range_tree_t *rt, uint64_t start, uint64_t size)
{
    return (range_tree_find(rt, start, size) != NULL);
}

/*
 * Ensure that this range is not in the tree, regardless of whether
 * it is currently in the tree.
 */
void
range_tree_clear(range_tree_t *rt, uint64_t start, uint64_t size)
{
    range_seg_t *rs;

    while ((rs = range_tree_find_impl(rt, start, size)) != NULL) {
        uint64_t free_start = MAX(rs->rs_start, start);
        uint64_t free_end = MIN(rs->rs_end, start + size);
        range_tree_remove(rt, free_start, free_end - free_start);
    }
}

void
range_tree_swap(range_tree_t **rtsrc, range_tree_t **rtdst)
{
    range_tree_t *rt;

    ASSERT(MUTEX_HELD((*rtsrc)->rt_lock));
    ASSERT0(range_tree_space(*rtdst));
    ASSERT0(avl_numnodes(&(*rtdst)->rt_root));

    rt = *rtsrc;
    *rtsrc = *rtdst;
    *rtdst = rt;
}

void
range_tree_vacate(range_tree_t *rt, range_tree_func_t *func, void *arg)
{
    range_seg_t *rs;
    void *cookie = NULL;

    ASSERT(MUTEX_HELD(rt->rt_lock));

    if (rt->rt_ops != NULL)
        rt->rt_ops->rtop_vacate(rt, rt->rt_arg);

    while ((rs = avl_destroy_nodes(&rt->rt_root, &cookie)) != NULL) {
        if (func != NULL)
            func(arg, rs->rs_start, rs->rs_end - rs->rs_start);
        kmem_cache_free(range_seg_cache, rs);
    }

    bzero(rt->rt_histogram, sizeof (rt->rt_histogram));
    rt->rt_space = 0;
}

void
range_tree_walk(range_tree_t *rt, range_tree_func_t *func, void *arg)
{
    range_seg_t *rs;

    ASSERT(MUTEX_HELD(rt->rt_lock));

    for (rs = avl_first(&rt->rt_root); rs; rs = AVL_NEXT(&rt->rt_root, rs))
        func(arg, rs->rs_start, rs->rs_end - rs->rs_start);
}

uint64_t
range_tree_space(range_tree_t *rt)
{
    return (rt->rt_space);
}