[mirror_zfs.git] / module / zfs / space_map.c

/*
 * 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.
 */

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

static kmem_cache_t *space_seg_cache;

void
space_map_init(void)
{
        ASSERT(space_seg_cache == NULL);
        space_seg_cache = kmem_cache_create("space_seg_cache",
            sizeof (space_seg_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
}

void
space_map_fini(void)
{
        kmem_cache_destroy(space_seg_cache);
        space_seg_cache = NULL;
}

/*
 * Space map routines.
 * NOTE: caller is responsible for all locking.
 */
static int
space_map_seg_compare(const void *x1, const void *x2)
{
        const space_seg_t *s1 = x1;
        const space_seg_t *s2 = x2;

        if (s1->ss_start < s2->ss_start) {
                if (s1->ss_end > s2->ss_start)
                        return (0);
                return (-1);
        }
        if (s1->ss_start > s2->ss_start) {
                if (s1->ss_start < s2->ss_end)
                        return (0);
                return (1);
        }
        return (0);
}

void
space_map_create(space_map_t *sm, uint64_t start, uint64_t size, uint8_t shift,
        kmutex_t *lp)
{
        bzero(sm, sizeof (*sm));

        cv_init(&sm->sm_load_cv, NULL, CV_DEFAULT, NULL);

        avl_create(&sm->sm_root, space_map_seg_compare,
            sizeof (space_seg_t), offsetof(struct space_seg, ss_node));

        sm->sm_start = start;
        sm->sm_size = size;
        sm->sm_shift = shift;
        sm->sm_lock = lp;
}

void
space_map_destroy(space_map_t *sm)
{
        ASSERT(!sm->sm_loaded && !sm->sm_loading);
        VERIFY3U(sm->sm_space, ==, 0);
        avl_destroy(&sm->sm_root);
        cv_destroy(&sm->sm_load_cv);
}

void
space_map_add(space_map_t *sm, uint64_t start, uint64_t size)
{
        avl_index_t where;
        space_seg_t ssearch, *ss_before, *ss_after, *ss;
        uint64_t end = start + size;
        int merge_before, merge_after;

        ASSERT(MUTEX_HELD(sm->sm_lock));
        VERIFY(size != 0);
        VERIFY3U(start, >=, sm->sm_start);
        VERIFY3U(end, <=, sm->sm_start + sm->sm_size);
        VERIFY(sm->sm_space + size <= sm->sm_size);
        VERIFY(P2PHASE(start, 1ULL << sm->sm_shift) == 0);
        VERIFY(P2PHASE(size, 1ULL << sm->sm_shift) == 0);

        ssearch.ss_start = start;
        ssearch.ss_end = end;
        ss = avl_find(&sm->sm_root, &ssearch, &where);

        if (ss != NULL && ss->ss_start <= start && ss->ss_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(ss == NULL);

        ss_before = avl_nearest(&sm->sm_root, where, AVL_BEFORE);
        ss_after = avl_nearest(&sm->sm_root, where, AVL_AFTER);

        merge_before = (ss_before != NULL && ss_before->ss_end == start);
        merge_after = (ss_after != NULL && ss_after->ss_start == end);

        if (merge_before && merge_after) {
                avl_remove(&sm->sm_root, ss_before);
                if (sm->sm_pp_root) {
                        avl_remove(sm->sm_pp_root, ss_before);
                        avl_remove(sm->sm_pp_root, ss_after);
                }
                ss_after->ss_start = ss_before->ss_start;
                kmem_cache_free(space_seg_cache, ss_before);
                ss = ss_after;
        } else if (merge_before) {
                ss_before->ss_end = end;
                if (sm->sm_pp_root)
                        avl_remove(sm->sm_pp_root, ss_before);
                ss = ss_before;
        } else if (merge_after) {
                ss_after->ss_start = start;
                if (sm->sm_pp_root)
                        avl_remove(sm->sm_pp_root, ss_after);
                ss = ss_after;
        } else {
                ss = kmem_cache_alloc(space_seg_cache, KM_PUSHPAGE);
                ss->ss_start = start;
                ss->ss_end = end;
                avl_insert(&sm->sm_root, ss, where);
        }

        if (sm->sm_pp_root)
                avl_add(sm->sm_pp_root, ss);

        sm->sm_space += size;
}

void
space_map_remove(space_map_t *sm, uint64_t start, uint64_t size)
{
        avl_index_t where;
        space_seg_t ssearch, *ss, *newseg;
        uint64_t end = start + size;
        int left_over, right_over;

        ASSERT(MUTEX_HELD(sm->sm_lock));
        VERIFY(size != 0);
        VERIFY(P2PHASE(start, 1ULL << sm->sm_shift) == 0);
        VERIFY(P2PHASE(size, 1ULL << sm->sm_shift) == 0);

        ssearch.ss_start = start;
        ssearch.ss_end = end;
        ss = avl_find(&sm->sm_root, &ssearch, &where);

        /* Make sure we completely overlap with someone */
        if (ss == NULL) {
                zfs_panic_recover("zfs: freeing free segment "
                    "(offset=%llu size=%llu)",
                    (longlong_t)start, (longlong_t)size);
                return;
        }
        VERIFY3U(ss->ss_start, <=, start);
        VERIFY3U(ss->ss_end, >=, end);
        VERIFY(sm->sm_space - size <= sm->sm_size);

        left_over = (ss->ss_start != start);
        right_over = (ss->ss_end != end);

        if (sm->sm_pp_root)
                avl_remove(sm->sm_pp_root, ss);

        if (left_over && right_over) {
                newseg = kmem_cache_alloc(space_seg_cache, KM_PUSHPAGE);
                newseg->ss_start = end;
                newseg->ss_end = ss->ss_end;
                ss->ss_end = start;
                avl_insert_here(&sm->sm_root, newseg, ss, AVL_AFTER);
                if (sm->sm_pp_root)
                        avl_add(sm->sm_pp_root, newseg);
        } else if (left_over) {
                ss->ss_end = start;
        } else if (right_over) {
                ss->ss_start = end;
        } else {
                avl_remove(&sm->sm_root, ss);
                kmem_cache_free(space_seg_cache, ss);
                ss = NULL;
        }

        if (sm->sm_pp_root && ss != NULL)
                avl_add(sm->sm_pp_root, ss);

        sm->sm_space -= size;
}

boolean_t
space_map_contains(space_map_t *sm, uint64_t start, uint64_t size)
{
        avl_index_t where;
        space_seg_t ssearch, *ss;
        uint64_t end = start + size;

        ASSERT(MUTEX_HELD(sm->sm_lock));
        VERIFY(size != 0);
        VERIFY(P2PHASE(start, 1ULL << sm->sm_shift) == 0);
        VERIFY(P2PHASE(size, 1ULL << sm->sm_shift) == 0);

        ssearch.ss_start = start;
        ssearch.ss_end = end;
        ss = avl_find(&sm->sm_root, &ssearch, &where);

        return (ss != NULL && ss->ss_start <= start && ss->ss_end >= end);
}

void
space_map_vacate(space_map_t *sm, space_map_func_t *func, space_map_t *mdest)
{
        space_seg_t *ss;
        void *cookie = NULL;

        ASSERT(MUTEX_HELD(sm->sm_lock));

        while ((ss = avl_destroy_nodes(&sm->sm_root, &cookie)) != NULL) {
                if (func != NULL)
                        func(mdest, ss->ss_start, ss->ss_end - ss->ss_start);
                kmem_cache_free(space_seg_cache, ss);
        }
        sm->sm_space = 0;
}

void
space_map_walk(space_map_t *sm, space_map_func_t *func, space_map_t *mdest)
{
        space_seg_t *ss;

        ASSERT(MUTEX_HELD(sm->sm_lock));

        for (ss = avl_first(&sm->sm_root); ss; ss = AVL_NEXT(&sm->sm_root, ss))
                func(mdest, ss->ss_start, ss->ss_end - ss->ss_start);
}

/*
 * Wait for any in-progress space_map_load() to complete.
 */
void
space_map_load_wait(space_map_t *sm)
{
        ASSERT(MUTEX_HELD(sm->sm_lock));

        while (sm->sm_loading) {
                ASSERT(!sm->sm_loaded);
                cv_wait(&sm->sm_load_cv, sm->sm_lock);
        }
}

/*
 * Note: space_map_load() will drop sm_lock across dmu_read() calls.
 * The caller must be OK with this.
 */
int
space_map_load(space_map_t *sm, space_map_ops_t *ops, uint8_t maptype,
        space_map_obj_t *smo, objset_t *os)
{
        uint64_t *entry, *entry_map, *entry_map_end;
        uint64_t bufsize, size, offset, end, space;
        uint64_t mapstart = sm->sm_start;
        int error = 0;

        ASSERT(MUTEX_HELD(sm->sm_lock));
        ASSERT(!sm->sm_loaded);
        ASSERT(!sm->sm_loading);

        sm->sm_loading = B_TRUE;
        end = smo->smo_objsize;
        space = smo->smo_alloc;

        ASSERT(sm->sm_ops == NULL);
        VERIFY3U(sm->sm_space, ==, 0);

        if (maptype == SM_FREE) {
                space_map_add(sm, sm->sm_start, sm->sm_size);
                space = sm->sm_size - space;
        }

        bufsize = 1ULL << SPACE_MAP_BLOCKSHIFT;
        entry_map = zio_buf_alloc(bufsize);

        mutex_exit(sm->sm_lock);
        if (end > bufsize)
                dmu_prefetch(os, smo->smo_object, bufsize, end - bufsize);
        mutex_enter(sm->sm_lock);

        for (offset = 0; offset < end; offset += bufsize) {
                size = MIN(end - offset, bufsize);
                VERIFY(P2PHASE(size, sizeof (uint64_t)) == 0);
                VERIFY(size != 0);

                dprintf("object=%llu  offset=%llx  size=%llx\n",
                    smo->smo_object, offset, size);

                mutex_exit(sm->sm_lock);
                error = dmu_read(os, smo->smo_object, offset, size, entry_map,
                    DMU_READ_PREFETCH);
                mutex_enter(sm->sm_lock);
                if (error != 0)
                        break;

                entry_map_end = entry_map + (size / sizeof (uint64_t));
                for (entry = entry_map; entry < entry_map_end; entry++) {
                        uint64_t e = *entry;

                        if (SM_DEBUG_DECODE(e))         /* Skip debug entries */
                                continue;

                        (SM_TYPE_DECODE(e) == maptype ?
                            space_map_add : space_map_remove)(sm,
                            (SM_OFFSET_DECODE(e) << sm->sm_shift) + mapstart,
                            SM_RUN_DECODE(e) << sm->sm_shift);
                }
        }

        if (error == 0) {
                VERIFY3U(sm->sm_space, ==, space);

                sm->sm_loaded = B_TRUE;
                sm->sm_ops = ops;
                if (ops != NULL)
                        ops->smop_load(sm);
        } else {
                space_map_vacate(sm, NULL, NULL);
        }

        zio_buf_free(entry_map, bufsize);

        sm->sm_loading = B_FALSE;

        cv_broadcast(&sm->sm_load_cv);

        return (error);
}

void
space_map_unload(space_map_t *sm)
{
        ASSERT(MUTEX_HELD(sm->sm_lock));

        if (sm->sm_loaded && sm->sm_ops != NULL)
                sm->sm_ops->smop_unload(sm);

        sm->sm_loaded = B_FALSE;
        sm->sm_ops = NULL;

        space_map_vacate(sm, NULL, NULL);
}

uint64_t
space_map_maxsize(space_map_t *sm)
{
        ASSERT(sm->sm_ops != NULL);
        return (sm->sm_ops->smop_max(sm));
}

uint64_t
space_map_alloc(space_map_t *sm, uint64_t size)
{
        uint64_t start;

        start = sm->sm_ops->smop_alloc(sm, size);
        if (start != -1ULL)
                space_map_remove(sm, start, size);
        return (start);
}

void
space_map_claim(space_map_t *sm, uint64_t start, uint64_t size)
{
        sm->sm_ops->smop_claim(sm, start, size);
        space_map_remove(sm, start, size);
}

void
space_map_free(space_map_t *sm, uint64_t start, uint64_t size)
{
        space_map_add(sm, start, size);
        sm->sm_ops->smop_free(sm, start, size);
}

/*
 * Note: space_map_sync() will drop sm_lock across dmu_write() calls.
 */
void
space_map_sync(space_map_t *sm, uint8_t maptype,
        space_map_obj_t *smo, objset_t *os, dmu_tx_t *tx)
{
        spa_t *spa = dmu_objset_spa(os);
        void *cookie = NULL;
        space_seg_t *ss;
        uint64_t bufsize, start, size, run_len, delta, sm_space;
        uint64_t *entry, *entry_map, *entry_map_end;

        ASSERT(MUTEX_HELD(sm->sm_lock));

        if (sm->sm_space == 0)
                return;

        dprintf("object %4llu, txg %llu, pass %d, %c, count %lu, space %llx\n",
            smo->smo_object, dmu_tx_get_txg(tx), spa_sync_pass(spa),
            maptype == SM_ALLOC ? 'A' : 'F', avl_numnodes(&sm->sm_root),
            sm->sm_space);

        if (maptype == SM_ALLOC)
                smo->smo_alloc += sm->sm_space;
        else
                smo->smo_alloc -= sm->sm_space;

        bufsize = (8 + avl_numnodes(&sm->sm_root)) * sizeof (uint64_t);
        bufsize = MIN(bufsize, 1ULL << SPACE_MAP_BLOCKSHIFT);
        entry_map = zio_buf_alloc(bufsize);
        entry_map_end = entry_map + (bufsize / sizeof (uint64_t));
        entry = entry_map;

        *entry++ = SM_DEBUG_ENCODE(1) |
            SM_DEBUG_ACTION_ENCODE(maptype) |
            SM_DEBUG_SYNCPASS_ENCODE(spa_sync_pass(spa)) |
            SM_DEBUG_TXG_ENCODE(dmu_tx_get_txg(tx));

        delta = 0;
        sm_space = sm->sm_space;
        while ((ss = avl_destroy_nodes(&sm->sm_root, &cookie)) != NULL) {
                size = ss->ss_end - ss->ss_start;
                start = (ss->ss_start - sm->sm_start) >> sm->sm_shift;

                delta += size;
                size >>= sm->sm_shift;

                while (size) {
                        run_len = MIN(size, SM_RUN_MAX);

                        if (entry == entry_map_end) {
                                mutex_exit(sm->sm_lock);
                                dmu_write(os, smo->smo_object, smo->smo_objsize,
                                    bufsize, entry_map, tx);
                                mutex_enter(sm->sm_lock);
                                smo->smo_objsize += bufsize;
                                entry = entry_map;
                        }

                        *entry++ = SM_OFFSET_ENCODE(start) |
                            SM_TYPE_ENCODE(maptype) |
                            SM_RUN_ENCODE(run_len);

                        start += run_len;
                        size -= run_len;
                }
                kmem_cache_free(space_seg_cache, ss);
        }

        if (entry != entry_map) {
                size = (entry - entry_map) * sizeof (uint64_t);
                mutex_exit(sm->sm_lock);
                dmu_write(os, smo->smo_object, smo->smo_objsize,
                    size, entry_map, tx);
                mutex_enter(sm->sm_lock);
                smo->smo_objsize += size;
        }

        /*
         * Ensure that the space_map's accounting wasn't changed
         * while we were in the middle of writing it out.
         */
        VERIFY3U(sm->sm_space, ==, sm_space);

        zio_buf_free(entry_map, bufsize);

        sm->sm_space -= delta;
        VERIFY3U(sm->sm_space, ==, 0);
}

void
space_map_truncate(space_map_obj_t *smo, objset_t *os, dmu_tx_t *tx)
{
        VERIFY(dmu_free_range(os, smo->smo_object, 0, -1ULL, tx) == 0);

        smo->smo_objsize = 0;
        smo->smo_alloc = 0;
}

/*
 * Space map reference trees.
 *
 * A space map is a collection of integers.  Every integer is either
 * in the map, or it's not.  A space map reference tree generalizes
 * the idea: it allows its members to have arbitrary reference counts,
 * as opposed to the implicit reference count of 0 or 1 in a space map.
 * This representation comes in handy when computing the union or
 * intersection of multiple space maps.  For example, the union of
 * N space maps is the subset of the reference tree with refcnt >= 1.
 * The intersection of N space maps is the subset with refcnt >= N.
 *
 * [It's very much like a Fourier transform.  Unions and intersections
 * are hard to perform in the 'space map domain', so we convert the maps
 * into the 'reference count domain', where it's trivial, then invert.]
 *
 * vdev_dtl_reassess() uses computations of this form to determine
 * DTL_MISSING and DTL_OUTAGE for interior vdevs -- e.g. a RAID-Z vdev
 * has an outage wherever refcnt >= vdev_nparity + 1, and a mirror vdev
 * has an outage wherever refcnt >= vdev_children.
 */
static int
space_map_ref_compare(const void *x1, const void *x2)
{
        const space_ref_t *sr1 = x1;
        const space_ref_t *sr2 = x2;

        if (sr1->sr_offset < sr2->sr_offset)
                return (-1);
        if (sr1->sr_offset > sr2->sr_offset)
                return (1);

        if (sr1 < sr2)
                return (-1);
        if (sr1 > sr2)
                return (1);

        return (0);
}

void
space_map_ref_create(avl_tree_t *t)
{
        avl_create(t, space_map_ref_compare,
            sizeof (space_ref_t), offsetof(space_ref_t, sr_node));
}

void
space_map_ref_destroy(avl_tree_t *t)
{
        space_ref_t *sr;
        void *cookie = NULL;

        while ((sr = avl_destroy_nodes(t, &cookie)) != NULL)
                kmem_free(sr, sizeof (*sr));

        avl_destroy(t);
}

static void
space_map_ref_add_node(avl_tree_t *t, uint64_t offset, int64_t refcnt)
{
        space_ref_t *sr;

        sr = kmem_alloc(sizeof (*sr), KM_PUSHPAGE);
        sr->sr_offset = offset;
        sr->sr_refcnt = refcnt;

        avl_add(t, sr);
}

void
space_map_ref_add_seg(avl_tree_t *t, uint64_t start, uint64_t end,
        int64_t refcnt)
{
        space_map_ref_add_node(t, start, refcnt);
        space_map_ref_add_node(t, end, -refcnt);
}

/*
 * Convert (or add) a space map into a reference tree.
 */
void
space_map_ref_add_map(avl_tree_t *t, space_map_t *sm, int64_t refcnt)
{
        space_seg_t *ss;

        ASSERT(MUTEX_HELD(sm->sm_lock));

        for (ss = avl_first(&sm->sm_root); ss; ss = AVL_NEXT(&sm->sm_root, ss))
                space_map_ref_add_seg(t, ss->ss_start, ss->ss_end, refcnt);
}

/*
 * Convert a reference tree into a space map.  The space map will contain
 * all members of the reference tree for which refcnt >= minref.
 */
void
space_map_ref_generate_map(avl_tree_t *t, space_map_t *sm, int64_t minref)
{
        uint64_t start = -1ULL;
        int64_t refcnt = 0;
        space_ref_t *sr;

        ASSERT(MUTEX_HELD(sm->sm_lock));

        space_map_vacate(sm, NULL, NULL);

        for (sr = avl_first(t); sr != NULL; sr = AVL_NEXT(t, sr)) {
                refcnt += sr->sr_refcnt;
                if (refcnt >= minref) {
                        if (start == -1ULL) {
                                start = sr->sr_offset;
                        }
                } else {
                        if (start != -1ULL) {
                                uint64_t end = sr->sr_offset;
                                ASSERT(start <= end);
                                if (end > start)
                                        space_map_add(sm, start, end - start);
                                start = -1ULL;
                        }
                }
        }
        ASSERT(refcnt == 0);
        ASSERT(start == -1ULL);
}