freebsd-dev/sbin/hastd/activemap.c
Mikolaj Golub 47f1eb5c4b Fix a typo in comments.
Approved by:	pjd (mentor)
MFC after:	3 days
2011-04-10 15:11:19 +00:00

692 lines
17 KiB
C

/*-
* Copyright (c) 2009-2010 The FreeBSD Foundation
* All rights reserved.
*
* This software was developed by Pawel Jakub Dawidek under sponsorship from
* the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h> /* powerof2() */
#include <sys/queue.h>
#include <assert.h>
#include <bitstring.h>
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <activemap.h>
#define ACTIVEMAP_MAGIC 0xac71e4
struct activemap {
int am_magic; /* Magic value. */
off_t am_mediasize; /* Media size in bytes. */
uint32_t am_extentsize; /* Extent size in bytes,
must be power of 2. */
uint8_t am_extentshift;/* 2 ^ extentbits == extentsize */
int am_nextents; /* Number of extents. */
size_t am_mapsize; /* Bitmap size in bytes. */
uint16_t *am_memtab; /* An array that holds number of pending
writes per extent. */
bitstr_t *am_diskmap; /* On-disk bitmap of dirty extents. */
bitstr_t *am_memmap; /* In-memory bitmap of dirty extents. */
size_t am_diskmapsize; /* Map size rounded up to sector size. */
uint64_t am_ndirty; /* Number of dirty regions. */
bitstr_t *am_syncmap; /* Bitmap of extents to sync. */
off_t am_syncoff; /* Next synchronization offset. */
TAILQ_HEAD(skeepdirty, keepdirty) am_keepdirty; /* List of extents that
we keep dirty to reduce bitmap
updates. */
int am_nkeepdirty; /* Number of am_keepdirty elements. */
int am_nkeepdirty_limit; /* Maximum number of am_keepdirty
elements. */
};
struct keepdirty {
int kd_extent;
TAILQ_ENTRY(keepdirty) kd_next;
};
/*
* Helper function taken from sys/systm.h to calculate extentshift.
*/
static uint32_t
bitcount32(uint32_t x)
{
x = (x & 0x55555555) + ((x & 0xaaaaaaaa) >> 1);
x = (x & 0x33333333) + ((x & 0xcccccccc) >> 2);
x = (x + (x >> 4)) & 0x0f0f0f0f;
x = (x + (x >> 8));
x = (x + (x >> 16)) & 0x000000ff;
return (x);
}
static __inline int
off2ext(const struct activemap *amp, off_t offset)
{
int extent;
assert(offset >= 0 && offset < amp->am_mediasize);
extent = (offset >> amp->am_extentshift);
assert(extent >= 0 && extent < amp->am_nextents);
return (extent);
}
static __inline off_t
ext2off(const struct activemap *amp, int extent)
{
off_t offset;
assert(extent >= 0 && extent < amp->am_nextents);
offset = ((off_t)extent << amp->am_extentshift);
assert(offset >= 0 && offset < amp->am_mediasize);
return (offset);
}
/*
* Function calculates number of requests needed to synchronize the given
* extent.
*/
static __inline int
ext2reqs(const struct activemap *amp, int ext)
{
off_t left;
if (ext < amp->am_nextents - 1)
return (((amp->am_extentsize - 1) / MAXPHYS) + 1);
assert(ext == amp->am_nextents - 1);
left = amp->am_mediasize % amp->am_extentsize;
if (left == 0)
left = amp->am_extentsize;
return (((left - 1) / MAXPHYS) + 1);
}
/*
* Initialize activemap structure and allocate memory for internal needs.
* Function returns 0 on success and -1 if any of the allocations failed.
*/
int
activemap_init(struct activemap **ampp, uint64_t mediasize, uint32_t extentsize,
uint32_t sectorsize, uint32_t keepdirty)
{
struct activemap *amp;
assert(ampp != NULL);
assert(mediasize > 0);
assert(extentsize > 0);
assert(powerof2(extentsize));
assert(sectorsize > 0);
assert(powerof2(sectorsize));
assert(keepdirty > 0);
amp = malloc(sizeof(*amp));
if (amp == NULL)
return (-1);
amp->am_mediasize = mediasize;
amp->am_nkeepdirty_limit = keepdirty;
amp->am_extentsize = extentsize;
amp->am_extentshift = bitcount32(extentsize - 1);
amp->am_nextents = ((mediasize - 1) / extentsize) + 1;
amp->am_mapsize = sizeof(bitstr_t) * bitstr_size(amp->am_nextents);
amp->am_diskmapsize = roundup2(amp->am_mapsize, sectorsize);
amp->am_ndirty = 0;
amp->am_syncoff = -2;
TAILQ_INIT(&amp->am_keepdirty);
amp->am_nkeepdirty = 0;
amp->am_memtab = calloc(amp->am_nextents, sizeof(amp->am_memtab[0]));
amp->am_diskmap = calloc(1, amp->am_diskmapsize);
amp->am_memmap = bit_alloc(amp->am_nextents);
amp->am_syncmap = bit_alloc(amp->am_nextents);
/*
* Check to see if any of the allocations above failed.
*/
if (amp->am_memtab == NULL || amp->am_diskmap == NULL ||
amp->am_memmap == NULL || amp->am_syncmap == NULL) {
if (amp->am_memtab != NULL)
free(amp->am_memtab);
if (amp->am_diskmap != NULL)
free(amp->am_diskmap);
if (amp->am_memmap != NULL)
free(amp->am_memmap);
if (amp->am_syncmap != NULL)
free(amp->am_syncmap);
amp->am_magic = 0;
free(amp);
errno = ENOMEM;
return (-1);
}
amp->am_magic = ACTIVEMAP_MAGIC;
*ampp = amp;
return (0);
}
static struct keepdirty *
keepdirty_find(struct activemap *amp, int extent)
{
struct keepdirty *kd;
TAILQ_FOREACH(kd, &amp->am_keepdirty, kd_next) {
if (kd->kd_extent == extent)
break;
}
return (kd);
}
static void
keepdirty_add(struct activemap *amp, int extent)
{
struct keepdirty *kd;
kd = keepdirty_find(amp, extent);
if (kd != NULL) {
/*
* Only move element at the begining.
*/
TAILQ_REMOVE(&amp->am_keepdirty, kd, kd_next);
TAILQ_INSERT_HEAD(&amp->am_keepdirty, kd, kd_next);
return;
}
/*
* Add new element, but first remove the most unused one if
* we have too many.
*/
if (amp->am_nkeepdirty >= amp->am_nkeepdirty_limit) {
kd = TAILQ_LAST(&amp->am_keepdirty, skeepdirty);
assert(kd != NULL);
TAILQ_REMOVE(&amp->am_keepdirty, kd, kd_next);
amp->am_nkeepdirty--;
assert(amp->am_nkeepdirty > 0);
}
if (kd == NULL)
kd = malloc(sizeof(*kd));
/* We can ignore allocation failure. */
if (kd != NULL) {
kd->kd_extent = extent;
amp->am_nkeepdirty++;
TAILQ_INSERT_HEAD(&amp->am_keepdirty, kd, kd_next);
}
}
static void
keepdirty_fill(struct activemap *amp)
{
struct keepdirty *kd;
TAILQ_FOREACH(kd, &amp->am_keepdirty, kd_next)
bit_set(amp->am_diskmap, kd->kd_extent);
}
static void
keepdirty_free(struct activemap *amp)
{
struct keepdirty *kd;
while ((kd = TAILQ_FIRST(&amp->am_keepdirty)) != NULL) {
TAILQ_REMOVE(&amp->am_keepdirty, kd, kd_next);
amp->am_nkeepdirty--;
free(kd);
}
assert(amp->am_nkeepdirty == 0);
}
/*
* Function frees resources allocated by activemap_init() function.
*/
void
activemap_free(struct activemap *amp)
{
assert(amp->am_magic == ACTIVEMAP_MAGIC);
amp->am_magic = 0;
keepdirty_free(amp);
free(amp->am_memtab);
free(amp->am_diskmap);
free(amp->am_memmap);
free(amp->am_syncmap);
}
/*
* Function should be called before we handle write requests. It updates
* internal structures and returns true if on-disk metadata should be updated.
*/
bool
activemap_write_start(struct activemap *amp, off_t offset, off_t length)
{
bool modified;
off_t end;
int ext;
assert(amp->am_magic == ACTIVEMAP_MAGIC);
assert(length > 0);
modified = false;
end = offset + length - 1;
for (ext = off2ext(amp, offset); ext <= off2ext(amp, end); ext++) {
/*
* If the number of pending writes is increased from 0,
* we have to mark the extent as dirty also in on-disk bitmap.
* By returning true we inform the caller that on-disk bitmap
* was modified and has to be flushed to disk.
*/
if (amp->am_memtab[ext]++ == 0) {
assert(!bit_test(amp->am_memmap, ext));
bit_set(amp->am_memmap, ext);
amp->am_ndirty++;
modified = true;
}
keepdirty_add(amp, ext);
}
return (modified);
}
/*
* Function should be called after receiving write confirmation. It updates
* internal structures and returns true if on-disk metadata should be updated.
*/
bool
activemap_write_complete(struct activemap *amp, off_t offset, off_t length)
{
bool modified;
off_t end;
int ext;
assert(amp->am_magic == ACTIVEMAP_MAGIC);
assert(length > 0);
modified = false;
end = offset + length - 1;
for (ext = off2ext(amp, offset); ext <= off2ext(amp, end); ext++) {
/*
* If the number of pending writes goes down to 0, we have to
* mark the extent as clean also in on-disk bitmap.
* By returning true we inform the caller that on-disk bitmap
* was modified and has to be flushed to disk.
*/
assert(amp->am_memtab[ext] > 0);
assert(bit_test(amp->am_memmap, ext));
if (--amp->am_memtab[ext] == 0) {
bit_clear(amp->am_memmap, ext);
amp->am_ndirty--;
modified = true;
}
}
return (modified);
}
/*
* Function should be called after finishing synchronization of one extent.
* It returns true if on-disk metadata should be updated.
*/
bool
activemap_extent_complete(struct activemap *amp, int extent)
{
bool modified;
int reqs;
assert(amp->am_magic == ACTIVEMAP_MAGIC);
assert(extent >= 0 && extent < amp->am_nextents);
modified = false;
reqs = ext2reqs(amp, extent);
assert(amp->am_memtab[extent] >= reqs);
amp->am_memtab[extent] -= reqs;
assert(bit_test(amp->am_memmap, extent));
if (amp->am_memtab[extent] == 0) {
bit_clear(amp->am_memmap, extent);
amp->am_ndirty--;
modified = true;
}
return (modified);
}
/*
* Function returns number of dirty regions.
*/
uint64_t
activemap_ndirty(const struct activemap *amp)
{
assert(amp->am_magic == ACTIVEMAP_MAGIC);
return (amp->am_ndirty);
}
/*
* Function compare on-disk bitmap and in-memory bitmap and returns true if
* they differ and should be flushed to the disk.
*/
bool
activemap_differ(const struct activemap *amp)
{
assert(amp->am_magic == ACTIVEMAP_MAGIC);
return (memcmp(amp->am_diskmap, amp->am_memmap,
amp->am_mapsize) != 0);
}
/*
* Function returns number of bytes used by bitmap.
*/
size_t
activemap_size(const struct activemap *amp)
{
assert(amp->am_magic == ACTIVEMAP_MAGIC);
return (amp->am_mapsize);
}
/*
* Function returns number of bytes needed for storing on-disk bitmap.
* This is the same as activemap_size(), but rounded up to sector size.
*/
size_t
activemap_ondisk_size(const struct activemap *amp)
{
assert(amp->am_magic == ACTIVEMAP_MAGIC);
return (amp->am_diskmapsize);
}
/*
* Function copies the given buffer read from disk to the internal bitmap.
*/
void
activemap_copyin(struct activemap *amp, const unsigned char *buf, size_t size)
{
int ext;
assert(amp->am_magic == ACTIVEMAP_MAGIC);
assert(size >= amp->am_mapsize);
memcpy(amp->am_diskmap, buf, amp->am_mapsize);
memcpy(amp->am_memmap, buf, amp->am_mapsize);
memcpy(amp->am_syncmap, buf, amp->am_mapsize);
bit_ffs(amp->am_memmap, amp->am_nextents, &ext);
if (ext == -1) {
/* There are no dirty extents, so we can leave now. */
return;
}
/*
* Set synchronization offset to the first dirty extent.
*/
activemap_sync_rewind(amp);
/*
* We have dirty extents and we want them to stay that way until
* we synchronize, so we set number of pending writes to number
* of requests needed to synchronize one extent.
*/
amp->am_ndirty = 0;
for (; ext < amp->am_nextents; ext++) {
if (bit_test(amp->am_memmap, ext)) {
amp->am_memtab[ext] = ext2reqs(amp, ext);
amp->am_ndirty++;
}
}
}
/*
* Function merges the given bitmap with existing one.
*/
void
activemap_merge(struct activemap *amp, const unsigned char *buf, size_t size)
{
bitstr_t *remmap = __DECONST(bitstr_t *, buf);
int ext;
assert(amp->am_magic == ACTIVEMAP_MAGIC);
assert(size >= amp->am_mapsize);
bit_ffs(remmap, amp->am_nextents, &ext);
if (ext == -1) {
/* There are no dirty extents, so we can leave now. */
return;
}
/*
* We have dirty extents and we want them to stay that way until
* we synchronize, so we set number of pending writes to number
* of requests needed to synchronize one extent.
*/
for (; ext < amp->am_nextents; ext++) {
/* Local extent already dirty. */
if (bit_test(amp->am_syncmap, ext))
continue;
/* Remote extent isn't dirty. */
if (!bit_test(remmap, ext))
continue;
bit_set(amp->am_syncmap, ext);
bit_set(amp->am_memmap, ext);
bit_set(amp->am_diskmap, ext);
if (amp->am_memtab[ext] == 0)
amp->am_ndirty++;
amp->am_memtab[ext] = ext2reqs(amp, ext);
}
/*
* Set synchronization offset to the first dirty extent.
*/
activemap_sync_rewind(amp);
}
/*
* Function returns pointer to internal bitmap that should be written to disk.
*/
const unsigned char *
activemap_bitmap(struct activemap *amp, size_t *sizep)
{
assert(amp->am_magic == ACTIVEMAP_MAGIC);
if (sizep != NULL)
*sizep = amp->am_diskmapsize;
memcpy(amp->am_diskmap, amp->am_memmap, amp->am_mapsize);
keepdirty_fill(amp);
return ((const unsigned char *)amp->am_diskmap);
}
/*
* Function calculates size needed to store bitmap on disk.
*/
size_t
activemap_calc_ondisk_size(uint64_t mediasize, uint32_t extentsize,
uint32_t sectorsize)
{
uint64_t nextents, mapsize;
assert(mediasize > 0);
assert(extentsize > 0);
assert(powerof2(extentsize));
assert(sectorsize > 0);
assert(powerof2(sectorsize));
nextents = ((mediasize - 1) / extentsize) + 1;
mapsize = sizeof(bitstr_t) * bitstr_size(nextents);
return (roundup2(mapsize, sectorsize));
}
/*
* Set synchronization offset to the first dirty extent.
*/
void
activemap_sync_rewind(struct activemap *amp)
{
int ext;
assert(amp->am_magic == ACTIVEMAP_MAGIC);
bit_ffs(amp->am_syncmap, amp->am_nextents, &ext);
if (ext == -1) {
/* There are no extents to synchronize. */
amp->am_syncoff = -2;
return;
}
/*
* Mark that we want to start synchronization from the begining.
*/
amp->am_syncoff = -1;
}
/*
* Return next offset of where we should synchronize.
*/
off_t
activemap_sync_offset(struct activemap *amp, off_t *lengthp, int *syncextp)
{
off_t syncoff, left;
int ext;
assert(amp->am_magic == ACTIVEMAP_MAGIC);
assert(lengthp != NULL);
assert(syncextp != NULL);
*syncextp = -1;
if (amp->am_syncoff == -2)
return (-1);
if (amp->am_syncoff >= 0 &&
(amp->am_syncoff + MAXPHYS >= amp->am_mediasize ||
off2ext(amp, amp->am_syncoff) !=
off2ext(amp, amp->am_syncoff + MAXPHYS))) {
/*
* We are about to change extent, so mark previous one as clean.
*/
ext = off2ext(amp, amp->am_syncoff);
bit_clear(amp->am_syncmap, ext);
*syncextp = ext;
amp->am_syncoff = -1;
}
if (amp->am_syncoff == -1) {
/*
* Let's find first extent to synchronize.
*/
bit_ffs(amp->am_syncmap, amp->am_nextents, &ext);
if (ext == -1) {
amp->am_syncoff = -2;
return (-1);
}
amp->am_syncoff = ext2off(amp, ext);
} else {
/*
* We don't change extent, so just increase offset.
*/
amp->am_syncoff += MAXPHYS;
if (amp->am_syncoff >= amp->am_mediasize) {
amp->am_syncoff = -2;
return (-1);
}
}
syncoff = amp->am_syncoff;
left = ext2off(amp, off2ext(amp, syncoff)) +
amp->am_extentsize - syncoff;
if (syncoff + left > amp->am_mediasize)
left = amp->am_mediasize - syncoff;
if (left > MAXPHYS)
left = MAXPHYS;
assert(left >= 0 && left <= MAXPHYS);
assert(syncoff >= 0 && syncoff < amp->am_mediasize);
assert(syncoff + left >= 0 && syncoff + left <= amp->am_mediasize);
*lengthp = left;
return (syncoff);
}
/*
* Mark extent(s) containing the given region for synchronization.
* Most likely one of the components is unavailable.
*/
bool
activemap_need_sync(struct activemap *amp, off_t offset, off_t length)
{
bool modified;
off_t end;
int ext;
assert(amp->am_magic == ACTIVEMAP_MAGIC);
modified = false;
end = offset + length - 1;
for (ext = off2ext(amp, offset); ext <= off2ext(amp, end); ext++) {
if (bit_test(amp->am_syncmap, ext)) {
/* Already marked for synchronization. */
assert(bit_test(amp->am_memmap, ext));
continue;
}
bit_set(amp->am_syncmap, ext);
if (!bit_test(amp->am_memmap, ext)) {
bit_set(amp->am_memmap, ext);
amp->am_ndirty++;
}
amp->am_memtab[ext] += ext2reqs(amp, ext);
modified = true;
}
return (modified);
}
void
activemap_dump(const struct activemap *amp)
{
int bit;
printf("M: ");
for (bit = 0; bit < amp->am_nextents; bit++)
printf("%d", bit_test(amp->am_memmap, bit) ? 1 : 0);
printf("\n");
printf("D: ");
for (bit = 0; bit < amp->am_nextents; bit++)
printf("%d", bit_test(amp->am_diskmap, bit) ? 1 : 0);
printf("\n");
printf("S: ");
for (bit = 0; bit < amp->am_nextents; bit++)
printf("%d", bit_test(amp->am_syncmap, bit) ? 1 : 0);
printf("\n");
}