933 lines
27 KiB
C
933 lines
27 KiB
C
/*
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* Hierarchical Bitmap Data Type
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*
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* Copyright Red Hat, Inc., 2012
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*
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* Author: Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or
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* later. See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "qemu/hbitmap.h"
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#include "qemu/host-utils.h"
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#include "trace.h"
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#include "crypto/hash.h"
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/* HBitmaps provides an array of bits. The bits are stored as usual in an
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* array of unsigned longs, but HBitmap is also optimized to provide fast
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* iteration over set bits; going from one bit to the next is O(logB n)
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* worst case, with B = sizeof(long) * CHAR_BIT: the result is low enough
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* that the number of levels is in fact fixed.
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*
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* In order to do this, it stacks multiple bitmaps with progressively coarser
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* granularity; in all levels except the last, bit N is set iff the N-th
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* unsigned long is nonzero in the immediately next level. When iteration
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* completes on the last level it can examine the 2nd-last level to quickly
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* skip entire words, and even do so recursively to skip blocks of 64 words or
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* powers thereof (32 on 32-bit machines).
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*
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* Given an index in the bitmap, it can be split in group of bits like
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* this (for the 64-bit case):
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*
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* bits 0-57 => word in the last bitmap | bits 58-63 => bit in the word
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* bits 0-51 => word in the 2nd-last bitmap | bits 52-57 => bit in the word
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* bits 0-45 => word in the 3rd-last bitmap | bits 46-51 => bit in the word
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*
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* So it is easy to move up simply by shifting the index right by
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* log2(BITS_PER_LONG) bits. To move down, you shift the index left
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* similarly, and add the word index within the group. Iteration uses
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* ffs (find first set bit) to find the next word to examine; this
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* operation can be done in constant time in most current architectures.
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*
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* Setting or clearing a range of m bits on all levels, the work to perform
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* is O(m + m/W + m/W^2 + ...), which is O(m) like on a regular bitmap.
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*
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* When iterating on a bitmap, each bit (on any level) is only visited
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* once. Hence, The total cost of visiting a bitmap with m bits in it is
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* the number of bits that are set in all bitmaps. Unless the bitmap is
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* extremely sparse, this is also O(m + m/W + m/W^2 + ...), so the amortized
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* cost of advancing from one bit to the next is usually constant (worst case
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* O(logB n) as in the non-amortized complexity).
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*/
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struct HBitmap {
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/*
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* Size of the bitmap, as requested in hbitmap_alloc or in hbitmap_truncate.
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*/
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uint64_t orig_size;
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/* Number of total bits in the bottom level. */
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uint64_t size;
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/* Number of set bits in the bottom level. */
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uint64_t count;
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/* A scaling factor. Given a granularity of G, each bit in the bitmap will
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* will actually represent a group of 2^G elements. Each operation on a
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* range of bits first rounds the bits to determine which group they land
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* in, and then affect the entire page; iteration will only visit the first
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* bit of each group. Here is an example of operations in a size-16,
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* granularity-1 HBitmap:
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*
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* initial state 00000000
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* set(start=0, count=9) 11111000 (iter: 0, 2, 4, 6, 8)
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* reset(start=1, count=3) 00111000 (iter: 4, 6, 8)
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* set(start=9, count=2) 00111100 (iter: 4, 6, 8, 10)
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* reset(start=5, count=5) 00000000
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*
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* From an implementation point of view, when setting or resetting bits,
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* the bitmap will scale bit numbers right by this amount of bits. When
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* iterating, the bitmap will scale bit numbers left by this amount of
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* bits.
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*/
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int granularity;
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/* A meta dirty bitmap to track the dirtiness of bits in this HBitmap. */
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HBitmap *meta;
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/* A number of progressively less coarse bitmaps (i.e. level 0 is the
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* coarsest). Each bit in level N represents a word in level N+1 that
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* has a set bit, except the last level where each bit represents the
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* actual bitmap.
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*
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* Note that all bitmaps have the same number of levels. Even a 1-bit
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* bitmap will still allocate HBITMAP_LEVELS arrays.
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*/
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unsigned long *levels[HBITMAP_LEVELS];
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/* The length of each levels[] array. */
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uint64_t sizes[HBITMAP_LEVELS];
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};
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/* Advance hbi to the next nonzero word and return it. hbi->pos
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* is updated. Returns zero if we reach the end of the bitmap.
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*/
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static unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi)
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{
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size_t pos = hbi->pos;
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const HBitmap *hb = hbi->hb;
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unsigned i = HBITMAP_LEVELS - 1;
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unsigned long cur;
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do {
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i--;
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pos >>= BITS_PER_LEVEL;
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cur = hbi->cur[i] & hb->levels[i][pos];
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} while (cur == 0);
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/* Check for end of iteration. We always use fewer than BITS_PER_LONG
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* bits in the level 0 bitmap; thus we can repurpose the most significant
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* bit as a sentinel. The sentinel is set in hbitmap_alloc and ensures
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* that the above loop ends even without an explicit check on i.
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*/
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if (i == 0 && cur == (1UL << (BITS_PER_LONG - 1))) {
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return 0;
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}
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for (; i < HBITMAP_LEVELS - 1; i++) {
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/* Shift back pos to the left, matching the right shifts above.
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* The index of this word's least significant set bit provides
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* the low-order bits.
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*/
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assert(cur);
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pos = (pos << BITS_PER_LEVEL) + ctzl(cur);
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hbi->cur[i] = cur & (cur - 1);
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/* Set up next level for iteration. */
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cur = hb->levels[i + 1][pos];
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}
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hbi->pos = pos;
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trace_hbitmap_iter_skip_words(hbi->hb, hbi, pos, cur);
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assert(cur);
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return cur;
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}
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int64_t hbitmap_iter_next(HBitmapIter *hbi)
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{
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unsigned long cur = hbi->cur[HBITMAP_LEVELS - 1] &
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hbi->hb->levels[HBITMAP_LEVELS - 1][hbi->pos];
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int64_t item;
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if (cur == 0) {
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cur = hbitmap_iter_skip_words(hbi);
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if (cur == 0) {
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return -1;
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}
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}
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/* The next call will resume work from the next bit. */
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hbi->cur[HBITMAP_LEVELS - 1] = cur & (cur - 1);
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item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + ctzl(cur);
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return item << hbi->granularity;
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}
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void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first)
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{
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unsigned i, bit;
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uint64_t pos;
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hbi->hb = hb;
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pos = first >> hb->granularity;
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assert(pos < hb->size);
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hbi->pos = pos >> BITS_PER_LEVEL;
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hbi->granularity = hb->granularity;
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for (i = HBITMAP_LEVELS; i-- > 0; ) {
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bit = pos & (BITS_PER_LONG - 1);
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pos >>= BITS_PER_LEVEL;
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/* Drop bits representing items before first. */
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hbi->cur[i] = hb->levels[i][pos] & ~((1UL << bit) - 1);
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/* We have already added level i+1, so the lowest set bit has
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* been processed. Clear it.
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*/
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if (i != HBITMAP_LEVELS - 1) {
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hbi->cur[i] &= ~(1UL << bit);
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}
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}
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}
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int64_t hbitmap_next_dirty(const HBitmap *hb, int64_t start, int64_t count)
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{
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HBitmapIter hbi;
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int64_t first_dirty_off;
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uint64_t end;
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assert(start >= 0 && count >= 0);
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if (start >= hb->orig_size || count == 0) {
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return -1;
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}
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end = count > hb->orig_size - start ? hb->orig_size : start + count;
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hbitmap_iter_init(&hbi, hb, start);
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first_dirty_off = hbitmap_iter_next(&hbi);
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if (first_dirty_off < 0 || first_dirty_off >= end) {
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return -1;
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}
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return MAX(start, first_dirty_off);
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}
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int64_t hbitmap_next_zero(const HBitmap *hb, int64_t start, int64_t count)
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{
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size_t pos = (start >> hb->granularity) >> BITS_PER_LEVEL;
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unsigned long *last_lev = hb->levels[HBITMAP_LEVELS - 1];
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unsigned long cur = last_lev[pos];
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unsigned start_bit_offset;
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uint64_t end_bit, sz;
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int64_t res;
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assert(start >= 0 && count >= 0);
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if (start >= hb->orig_size || count == 0) {
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return -1;
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}
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end_bit = count > hb->orig_size - start ?
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hb->size :
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((start + count - 1) >> hb->granularity) + 1;
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sz = (end_bit + BITS_PER_LONG - 1) >> BITS_PER_LEVEL;
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/* There may be some zero bits in @cur before @start. We are not interested
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* in them, let's set them.
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*/
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start_bit_offset = (start >> hb->granularity) & (BITS_PER_LONG - 1);
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cur |= (1UL << start_bit_offset) - 1;
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assert((start >> hb->granularity) < hb->size);
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if (cur == (unsigned long)-1) {
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do {
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pos++;
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} while (pos < sz && last_lev[pos] == (unsigned long)-1);
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if (pos >= sz) {
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return -1;
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}
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cur = last_lev[pos];
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}
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res = (pos << BITS_PER_LEVEL) + ctol(cur);
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if (res >= end_bit) {
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return -1;
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}
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res = res << hb->granularity;
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if (res < start) {
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assert(((start - res) >> hb->granularity) == 0);
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return start;
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}
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return res;
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}
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bool hbitmap_next_dirty_area(const HBitmap *hb, int64_t start, int64_t end,
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int64_t max_dirty_count,
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int64_t *dirty_start, int64_t *dirty_count)
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{
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int64_t next_zero;
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assert(start >= 0 && end >= 0 && max_dirty_count > 0);
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end = MIN(end, hb->orig_size);
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if (start >= end) {
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return false;
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}
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start = hbitmap_next_dirty(hb, start, end - start);
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if (start < 0) {
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return false;
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}
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end = start + MIN(end - start, max_dirty_count);
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next_zero = hbitmap_next_zero(hb, start, end - start);
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if (next_zero >= 0) {
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end = next_zero;
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}
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*dirty_start = start;
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*dirty_count = end - start;
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return true;
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}
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bool hbitmap_empty(const HBitmap *hb)
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{
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return hb->count == 0;
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}
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int hbitmap_granularity(const HBitmap *hb)
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{
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return hb->granularity;
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}
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uint64_t hbitmap_count(const HBitmap *hb)
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{
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return hb->count << hb->granularity;
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}
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/**
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* hbitmap_iter_next_word:
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* @hbi: HBitmapIter to operate on.
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* @p_cur: Location where to store the next non-zero word.
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*
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* Return the index of the next nonzero word that is set in @hbi's
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* associated HBitmap, and set *p_cur to the content of that word
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* (bits before the index that was passed to hbitmap_iter_init are
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* trimmed on the first call). Return -1, and set *p_cur to zero,
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* if all remaining words are zero.
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*/
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static size_t hbitmap_iter_next_word(HBitmapIter *hbi, unsigned long *p_cur)
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{
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unsigned long cur = hbi->cur[HBITMAP_LEVELS - 1];
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if (cur == 0) {
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cur = hbitmap_iter_skip_words(hbi);
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if (cur == 0) {
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*p_cur = 0;
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return -1;
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}
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}
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/* The next call will resume work from the next word. */
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hbi->cur[HBITMAP_LEVELS - 1] = 0;
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*p_cur = cur;
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return hbi->pos;
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}
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/* Count the number of set bits between start and end, not accounting for
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* the granularity. Also an example of how to use hbitmap_iter_next_word.
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*/
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static uint64_t hb_count_between(HBitmap *hb, uint64_t start, uint64_t last)
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{
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HBitmapIter hbi;
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uint64_t count = 0;
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uint64_t end = last + 1;
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unsigned long cur;
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size_t pos;
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hbitmap_iter_init(&hbi, hb, start << hb->granularity);
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for (;;) {
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pos = hbitmap_iter_next_word(&hbi, &cur);
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if (pos >= (end >> BITS_PER_LEVEL)) {
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break;
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}
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count += ctpopl(cur);
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}
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if (pos == (end >> BITS_PER_LEVEL)) {
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/* Drop bits representing the END-th and subsequent items. */
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int bit = end & (BITS_PER_LONG - 1);
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cur &= (1UL << bit) - 1;
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count += ctpopl(cur);
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}
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return count;
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}
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/* Setting starts at the last layer and propagates up if an element
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* changes.
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*/
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static inline bool hb_set_elem(unsigned long *elem, uint64_t start, uint64_t last)
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{
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unsigned long mask;
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unsigned long old;
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assert((last >> BITS_PER_LEVEL) == (start >> BITS_PER_LEVEL));
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assert(start <= last);
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mask = 2UL << (last & (BITS_PER_LONG - 1));
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mask -= 1UL << (start & (BITS_PER_LONG - 1));
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old = *elem;
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*elem |= mask;
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return old != *elem;
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}
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/* The recursive workhorse (the depth is limited to HBITMAP_LEVELS)...
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* Returns true if at least one bit is changed. */
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static bool hb_set_between(HBitmap *hb, int level, uint64_t start,
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uint64_t last)
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{
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size_t pos = start >> BITS_PER_LEVEL;
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size_t lastpos = last >> BITS_PER_LEVEL;
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bool changed = false;
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size_t i;
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i = pos;
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if (i < lastpos) {
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uint64_t next = (start | (BITS_PER_LONG - 1)) + 1;
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changed |= hb_set_elem(&hb->levels[level][i], start, next - 1);
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for (;;) {
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start = next;
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next += BITS_PER_LONG;
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if (++i == lastpos) {
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break;
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}
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changed |= (hb->levels[level][i] == 0);
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hb->levels[level][i] = ~0UL;
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}
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}
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changed |= hb_set_elem(&hb->levels[level][i], start, last);
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/* If there was any change in this layer, we may have to update
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* the one above.
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*/
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if (level > 0 && changed) {
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hb_set_between(hb, level - 1, pos, lastpos);
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}
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return changed;
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}
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void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t count)
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{
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/* Compute range in the last layer. */
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uint64_t first, n;
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uint64_t last = start + count - 1;
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if (count == 0) {
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return;
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}
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trace_hbitmap_set(hb, start, count,
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start >> hb->granularity, last >> hb->granularity);
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first = start >> hb->granularity;
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last >>= hb->granularity;
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assert(last < hb->size);
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n = last - first + 1;
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hb->count += n - hb_count_between(hb, first, last);
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if (hb_set_between(hb, HBITMAP_LEVELS - 1, first, last) &&
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hb->meta) {
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hbitmap_set(hb->meta, start, count);
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}
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}
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/* Resetting works the other way round: propagate up if the new
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* value is zero.
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*/
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static inline bool hb_reset_elem(unsigned long *elem, uint64_t start, uint64_t last)
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{
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unsigned long mask;
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bool blanked;
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assert((last >> BITS_PER_LEVEL) == (start >> BITS_PER_LEVEL));
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assert(start <= last);
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mask = 2UL << (last & (BITS_PER_LONG - 1));
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mask -= 1UL << (start & (BITS_PER_LONG - 1));
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blanked = *elem != 0 && ((*elem & ~mask) == 0);
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*elem &= ~mask;
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return blanked;
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}
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/* The recursive workhorse (the depth is limited to HBITMAP_LEVELS)...
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* Returns true if at least one bit is changed. */
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static bool hb_reset_between(HBitmap *hb, int level, uint64_t start,
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uint64_t last)
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{
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size_t pos = start >> BITS_PER_LEVEL;
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size_t lastpos = last >> BITS_PER_LEVEL;
|
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bool changed = false;
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size_t i;
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i = pos;
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if (i < lastpos) {
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uint64_t next = (start | (BITS_PER_LONG - 1)) + 1;
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|
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/* Here we need a more complex test than when setting bits. Even if
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* something was changed, we must not blank bits in the upper level
|
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* unless the lower-level word became entirely zero. So, remove pos
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* from the upper-level range if bits remain set.
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*/
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if (hb_reset_elem(&hb->levels[level][i], start, next - 1)) {
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changed = true;
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} else {
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pos++;
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}
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for (;;) {
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start = next;
|
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next += BITS_PER_LONG;
|
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if (++i == lastpos) {
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break;
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}
|
|
changed |= (hb->levels[level][i] != 0);
|
|
hb->levels[level][i] = 0UL;
|
|
}
|
|
}
|
|
|
|
/* Same as above, this time for lastpos. */
|
|
if (hb_reset_elem(&hb->levels[level][i], start, last)) {
|
|
changed = true;
|
|
} else {
|
|
lastpos--;
|
|
}
|
|
|
|
if (level > 0 && changed) {
|
|
hb_reset_between(hb, level - 1, pos, lastpos);
|
|
}
|
|
|
|
return changed;
|
|
|
|
}
|
|
|
|
void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count)
|
|
{
|
|
/* Compute range in the last layer. */
|
|
uint64_t first;
|
|
uint64_t last = start + count - 1;
|
|
uint64_t gran = 1ULL << hb->granularity;
|
|
|
|
if (count == 0) {
|
|
return;
|
|
}
|
|
|
|
assert(QEMU_IS_ALIGNED(start, gran));
|
|
assert(QEMU_IS_ALIGNED(count, gran) || (start + count == hb->orig_size));
|
|
|
|
trace_hbitmap_reset(hb, start, count,
|
|
start >> hb->granularity, last >> hb->granularity);
|
|
|
|
first = start >> hb->granularity;
|
|
last >>= hb->granularity;
|
|
assert(last < hb->size);
|
|
|
|
hb->count -= hb_count_between(hb, first, last);
|
|
if (hb_reset_between(hb, HBITMAP_LEVELS - 1, first, last) &&
|
|
hb->meta) {
|
|
hbitmap_set(hb->meta, start, count);
|
|
}
|
|
}
|
|
|
|
void hbitmap_reset_all(HBitmap *hb)
|
|
{
|
|
unsigned int i;
|
|
|
|
/* Same as hbitmap_alloc() except for memset() instead of malloc() */
|
|
for (i = HBITMAP_LEVELS; --i >= 1; ) {
|
|
memset(hb->levels[i], 0, hb->sizes[i] * sizeof(unsigned long));
|
|
}
|
|
|
|
hb->levels[0][0] = 1UL << (BITS_PER_LONG - 1);
|
|
hb->count = 0;
|
|
}
|
|
|
|
bool hbitmap_is_serializable(const HBitmap *hb)
|
|
{
|
|
/* Every serialized chunk must be aligned to 64 bits so that endianness
|
|
* requirements can be fulfilled on both 64 bit and 32 bit hosts.
|
|
* We have hbitmap_serialization_align() which converts this
|
|
* alignment requirement from bitmap bits to items covered (e.g. sectors).
|
|
* That value is:
|
|
* 64 << hb->granularity
|
|
* Since this value must not exceed UINT64_MAX, hb->granularity must be
|
|
* less than 58 (== 64 - 6, where 6 is ld(64), i.e. 1 << 6 == 64).
|
|
*
|
|
* In order for hbitmap_serialization_align() to always return a
|
|
* meaningful value, bitmaps that are to be serialized must have a
|
|
* granularity of less than 58. */
|
|
|
|
return hb->granularity < 58;
|
|
}
|
|
|
|
bool hbitmap_get(const HBitmap *hb, uint64_t item)
|
|
{
|
|
/* Compute position and bit in the last layer. */
|
|
uint64_t pos = item >> hb->granularity;
|
|
unsigned long bit = 1UL << (pos & (BITS_PER_LONG - 1));
|
|
assert(pos < hb->size);
|
|
|
|
return (hb->levels[HBITMAP_LEVELS - 1][pos >> BITS_PER_LEVEL] & bit) != 0;
|
|
}
|
|
|
|
uint64_t hbitmap_serialization_align(const HBitmap *hb)
|
|
{
|
|
assert(hbitmap_is_serializable(hb));
|
|
|
|
/* Require at least 64 bit granularity to be safe on both 64 bit and 32 bit
|
|
* hosts. */
|
|
return UINT64_C(64) << hb->granularity;
|
|
}
|
|
|
|
/* Start should be aligned to serialization granularity, chunk size should be
|
|
* aligned to serialization granularity too, except for last chunk.
|
|
*/
|
|
static void serialization_chunk(const HBitmap *hb,
|
|
uint64_t start, uint64_t count,
|
|
unsigned long **first_el, uint64_t *el_count)
|
|
{
|
|
uint64_t last = start + count - 1;
|
|
uint64_t gran = hbitmap_serialization_align(hb);
|
|
|
|
assert((start & (gran - 1)) == 0);
|
|
assert((last >> hb->granularity) < hb->size);
|
|
if ((last >> hb->granularity) != hb->size - 1) {
|
|
assert((count & (gran - 1)) == 0);
|
|
}
|
|
|
|
start = (start >> hb->granularity) >> BITS_PER_LEVEL;
|
|
last = (last >> hb->granularity) >> BITS_PER_LEVEL;
|
|
|
|
*first_el = &hb->levels[HBITMAP_LEVELS - 1][start];
|
|
*el_count = last - start + 1;
|
|
}
|
|
|
|
uint64_t hbitmap_serialization_size(const HBitmap *hb,
|
|
uint64_t start, uint64_t count)
|
|
{
|
|
uint64_t el_count;
|
|
unsigned long *cur;
|
|
|
|
if (!count) {
|
|
return 0;
|
|
}
|
|
serialization_chunk(hb, start, count, &cur, &el_count);
|
|
|
|
return el_count * sizeof(unsigned long);
|
|
}
|
|
|
|
void hbitmap_serialize_part(const HBitmap *hb, uint8_t *buf,
|
|
uint64_t start, uint64_t count)
|
|
{
|
|
uint64_t el_count;
|
|
unsigned long *cur, *end;
|
|
|
|
if (!count) {
|
|
return;
|
|
}
|
|
serialization_chunk(hb, start, count, &cur, &el_count);
|
|
end = cur + el_count;
|
|
|
|
while (cur != end) {
|
|
unsigned long el =
|
|
(BITS_PER_LONG == 32 ? cpu_to_le32(*cur) : cpu_to_le64(*cur));
|
|
|
|
memcpy(buf, &el, sizeof(el));
|
|
buf += sizeof(el);
|
|
cur++;
|
|
}
|
|
}
|
|
|
|
void hbitmap_deserialize_part(HBitmap *hb, uint8_t *buf,
|
|
uint64_t start, uint64_t count,
|
|
bool finish)
|
|
{
|
|
uint64_t el_count;
|
|
unsigned long *cur, *end;
|
|
|
|
if (!count) {
|
|
return;
|
|
}
|
|
serialization_chunk(hb, start, count, &cur, &el_count);
|
|
end = cur + el_count;
|
|
|
|
while (cur != end) {
|
|
memcpy(cur, buf, sizeof(*cur));
|
|
|
|
if (BITS_PER_LONG == 32) {
|
|
le32_to_cpus((uint32_t *)cur);
|
|
} else {
|
|
le64_to_cpus((uint64_t *)cur);
|
|
}
|
|
|
|
buf += sizeof(unsigned long);
|
|
cur++;
|
|
}
|
|
if (finish) {
|
|
hbitmap_deserialize_finish(hb);
|
|
}
|
|
}
|
|
|
|
void hbitmap_deserialize_zeroes(HBitmap *hb, uint64_t start, uint64_t count,
|
|
bool finish)
|
|
{
|
|
uint64_t el_count;
|
|
unsigned long *first;
|
|
|
|
if (!count) {
|
|
return;
|
|
}
|
|
serialization_chunk(hb, start, count, &first, &el_count);
|
|
|
|
memset(first, 0, el_count * sizeof(unsigned long));
|
|
if (finish) {
|
|
hbitmap_deserialize_finish(hb);
|
|
}
|
|
}
|
|
|
|
void hbitmap_deserialize_ones(HBitmap *hb, uint64_t start, uint64_t count,
|
|
bool finish)
|
|
{
|
|
uint64_t el_count;
|
|
unsigned long *first;
|
|
|
|
if (!count) {
|
|
return;
|
|
}
|
|
serialization_chunk(hb, start, count, &first, &el_count);
|
|
|
|
memset(first, 0xff, el_count * sizeof(unsigned long));
|
|
if (finish) {
|
|
hbitmap_deserialize_finish(hb);
|
|
}
|
|
}
|
|
|
|
void hbitmap_deserialize_finish(HBitmap *bitmap)
|
|
{
|
|
int64_t i, size, prev_size;
|
|
int lev;
|
|
|
|
/* restore levels starting from penultimate to zero level, assuming
|
|
* that the last level is ok */
|
|
size = MAX((bitmap->size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
|
|
for (lev = HBITMAP_LEVELS - 1; lev-- > 0; ) {
|
|
prev_size = size;
|
|
size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
|
|
memset(bitmap->levels[lev], 0, size * sizeof(unsigned long));
|
|
|
|
for (i = 0; i < prev_size; ++i) {
|
|
if (bitmap->levels[lev + 1][i]) {
|
|
bitmap->levels[lev][i >> BITS_PER_LEVEL] |=
|
|
1UL << (i & (BITS_PER_LONG - 1));
|
|
}
|
|
}
|
|
}
|
|
|
|
bitmap->levels[0][0] |= 1UL << (BITS_PER_LONG - 1);
|
|
bitmap->count = hb_count_between(bitmap, 0, bitmap->size - 1);
|
|
}
|
|
|
|
void hbitmap_free(HBitmap *hb)
|
|
{
|
|
unsigned i;
|
|
assert(!hb->meta);
|
|
for (i = HBITMAP_LEVELS; i-- > 0; ) {
|
|
g_free(hb->levels[i]);
|
|
}
|
|
g_free(hb);
|
|
}
|
|
|
|
HBitmap *hbitmap_alloc(uint64_t size, int granularity)
|
|
{
|
|
HBitmap *hb = g_new0(struct HBitmap, 1);
|
|
unsigned i;
|
|
|
|
assert(size <= INT64_MAX);
|
|
hb->orig_size = size;
|
|
|
|
assert(granularity >= 0 && granularity < 64);
|
|
size = (size + (1ULL << granularity) - 1) >> granularity;
|
|
assert(size <= ((uint64_t)1 << HBITMAP_LOG_MAX_SIZE));
|
|
|
|
hb->size = size;
|
|
hb->granularity = granularity;
|
|
for (i = HBITMAP_LEVELS; i-- > 0; ) {
|
|
size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
|
|
hb->sizes[i] = size;
|
|
hb->levels[i] = g_new0(unsigned long, size);
|
|
}
|
|
|
|
/* We necessarily have free bits in level 0 due to the definition
|
|
* of HBITMAP_LEVELS, so use one for a sentinel. This speeds up
|
|
* hbitmap_iter_skip_words.
|
|
*/
|
|
assert(size == 1);
|
|
hb->levels[0][0] |= 1UL << (BITS_PER_LONG - 1);
|
|
return hb;
|
|
}
|
|
|
|
void hbitmap_truncate(HBitmap *hb, uint64_t size)
|
|
{
|
|
bool shrink;
|
|
unsigned i;
|
|
uint64_t num_elements = size;
|
|
uint64_t old;
|
|
|
|
assert(size <= INT64_MAX);
|
|
hb->orig_size = size;
|
|
|
|
/* Size comes in as logical elements, adjust for granularity. */
|
|
size = (size + (1ULL << hb->granularity) - 1) >> hb->granularity;
|
|
assert(size <= ((uint64_t)1 << HBITMAP_LOG_MAX_SIZE));
|
|
shrink = size < hb->size;
|
|
|
|
/* bit sizes are identical; nothing to do. */
|
|
if (size == hb->size) {
|
|
return;
|
|
}
|
|
|
|
/* If we're losing bits, let's clear those bits before we invalidate all of
|
|
* our invariants. This helps keep the bitcount consistent, and will prevent
|
|
* us from carrying around garbage bits beyond the end of the map.
|
|
*/
|
|
if (shrink) {
|
|
/* Don't clear partial granularity groups;
|
|
* start at the first full one. */
|
|
uint64_t start = ROUND_UP(num_elements, UINT64_C(1) << hb->granularity);
|
|
uint64_t fix_count = (hb->size << hb->granularity) - start;
|
|
|
|
assert(fix_count);
|
|
hbitmap_reset(hb, start, fix_count);
|
|
}
|
|
|
|
hb->size = size;
|
|
for (i = HBITMAP_LEVELS; i-- > 0; ) {
|
|
size = MAX(BITS_TO_LONGS(size), 1);
|
|
if (hb->sizes[i] == size) {
|
|
break;
|
|
}
|
|
old = hb->sizes[i];
|
|
hb->sizes[i] = size;
|
|
hb->levels[i] = g_realloc(hb->levels[i], size * sizeof(unsigned long));
|
|
if (!shrink) {
|
|
memset(&hb->levels[i][old], 0x00,
|
|
(size - old) * sizeof(*hb->levels[i]));
|
|
}
|
|
}
|
|
if (hb->meta) {
|
|
hbitmap_truncate(hb->meta, hb->size << hb->granularity);
|
|
}
|
|
}
|
|
|
|
bool hbitmap_can_merge(const HBitmap *a, const HBitmap *b)
|
|
{
|
|
return (a->orig_size == b->orig_size);
|
|
}
|
|
|
|
/**
|
|
* hbitmap_sparse_merge: performs dst = dst | src
|
|
* works with differing granularities.
|
|
* best used when src is sparsely populated.
|
|
*/
|
|
static void hbitmap_sparse_merge(HBitmap *dst, const HBitmap *src)
|
|
{
|
|
int64_t offset;
|
|
int64_t count;
|
|
|
|
for (offset = 0;
|
|
hbitmap_next_dirty_area(src, offset, src->orig_size, INT64_MAX,
|
|
&offset, &count);
|
|
offset += count)
|
|
{
|
|
hbitmap_set(dst, offset, count);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Given HBitmaps A and B, let R := A (BITOR) B.
|
|
* Bitmaps A and B will not be modified,
|
|
* except when bitmap R is an alias of A or B.
|
|
*
|
|
* @return true if the merge was successful,
|
|
* false if it was not attempted.
|
|
*/
|
|
bool hbitmap_merge(const HBitmap *a, const HBitmap *b, HBitmap *result)
|
|
{
|
|
int i;
|
|
uint64_t j;
|
|
|
|
if (!hbitmap_can_merge(a, b) || !hbitmap_can_merge(a, result)) {
|
|
return false;
|
|
}
|
|
assert(hbitmap_can_merge(b, result));
|
|
|
|
if ((!hbitmap_count(a) && result == b) ||
|
|
(!hbitmap_count(b) && result == a)) {
|
|
return true;
|
|
}
|
|
|
|
if (!hbitmap_count(a) && !hbitmap_count(b)) {
|
|
hbitmap_reset_all(result);
|
|
return true;
|
|
}
|
|
|
|
if (a->granularity != b->granularity) {
|
|
if ((a != result) && (b != result)) {
|
|
hbitmap_reset_all(result);
|
|
}
|
|
if (a != result) {
|
|
hbitmap_sparse_merge(result, a);
|
|
}
|
|
if (b != result) {
|
|
hbitmap_sparse_merge(result, b);
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/* This merge is O(size), as BITS_PER_LONG and HBITMAP_LEVELS are constant.
|
|
* It may be possible to improve running times for sparsely populated maps
|
|
* by using hbitmap_iter_next, but this is suboptimal for dense maps.
|
|
*/
|
|
assert(a->size == b->size);
|
|
for (i = HBITMAP_LEVELS - 1; i >= 0; i--) {
|
|
for (j = 0; j < a->sizes[i]; j++) {
|
|
result->levels[i][j] = a->levels[i][j] | b->levels[i][j];
|
|
}
|
|
}
|
|
|
|
/* Recompute the dirty count */
|
|
result->count = hb_count_between(result, 0, result->size - 1);
|
|
|
|
return true;
|
|
}
|
|
|
|
char *hbitmap_sha256(const HBitmap *bitmap, Error **errp)
|
|
{
|
|
size_t size = bitmap->sizes[HBITMAP_LEVELS - 1] * sizeof(unsigned long);
|
|
char *data = (char *)bitmap->levels[HBITMAP_LEVELS - 1];
|
|
char *hash = NULL;
|
|
qcrypto_hash_digest(QCRYPTO_HASH_ALG_SHA256, data, size, &hash, errp);
|
|
|
|
return hash;
|
|
}
|