/* * 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, 2015 by Delphix. All rights reserved. */ #include <sys/zfs_context.h> #include <sys/range_tree.h> #include <sys/space_reftree.h> /* * Space reference trees. * * A range tree is a collection of integers. Every integer is either * in the tree, or it's not. A space 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 range tree. * This representation comes in handy when computing the union or * intersection of multiple space maps. For example, the union of * N range trees is the subset of the reference tree with refcnt >= 1. * The intersection of N range trees is the subset with refcnt >= N. * * [It's very much like a Fourier transform. Unions and intersections * are hard to perform in the 'range tree domain', so we convert the trees * 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_reftree_compare(const void *x1, const void *x2) { const space_ref_t *sr1 = (const space_ref_t *)x1; const space_ref_t *sr2 = (const space_ref_t *)x2; int cmp = AVL_CMP(sr1->sr_offset, sr2->sr_offset); if (likely(cmp)) return (cmp); return (AVL_PCMP(sr1, sr2)); } void space_reftree_create(avl_tree_t *t) { avl_create(t, space_reftree_compare, sizeof (space_ref_t), offsetof(space_ref_t, sr_node)); } void space_reftree_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_reftree_add_node(avl_tree_t *t, uint64_t offset, int64_t refcnt) { space_ref_t *sr; sr = kmem_alloc(sizeof (*sr), KM_SLEEP); sr->sr_offset = offset; sr->sr_refcnt = refcnt; avl_add(t, sr); } void space_reftree_add_seg(avl_tree_t *t, uint64_t start, uint64_t end, int64_t refcnt) { space_reftree_add_node(t, start, refcnt); space_reftree_add_node(t, end, -refcnt); } /* * Convert (or add) a range tree into a reference tree. */ void space_reftree_add_map(avl_tree_t *t, range_tree_t *rt, int64_t refcnt) { range_seg_t *rs; for (rs = avl_first(&rt->rt_root); rs; rs = AVL_NEXT(&rt->rt_root, rs)) space_reftree_add_seg(t, rs->rs_start, rs->rs_end, refcnt); } /* * Convert a reference tree into a range tree. The range tree will contain * all members of the reference tree for which refcnt >= minref. */ void space_reftree_generate_map(avl_tree_t *t, range_tree_t *rt, int64_t minref) { uint64_t start = -1ULL; int64_t refcnt = 0; space_ref_t *sr; range_tree_vacate(rt, 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) range_tree_add(rt, start, end - start); start = -1ULL; } } } ASSERT(refcnt == 0); ASSERT(start == -1ULL); }