/*
drbd_bitmap.c
This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
Copyright (C) 2004-2008, LINBIT Information Technologies GmbH.
Copyright (C) 2004-2008, Philipp Reisner <philipp.reisner@linbit.com>.
Copyright (C) 2004-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
drbd is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
drbd is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with drbd; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/bitops.h>
#include <linux/vmalloc.h>
#include <linux/string.h>
#include <linux/drbd.h>
#include <linux/slab.h>
#include <asm/kmap_types.h>
#include "drbd_int.h"
/* OPAQUE outside this file!
* interface defined in drbd_int.h
* convention:
* function name drbd_bm_... => used elsewhere, "public".
* function name bm_... => internal to implementation, "private".
*/
/*
* LIMITATIONS:
* We want to support >= peta byte of backend storage, while for now still using
* a granularity of one bit per 4KiB of storage.
* 1 << 50 bytes backend storage (1 PiB)
* 1 << (50 - 12) bits needed
* 38 --> we need u64 to index and count bits
* 1 << (38 - 3) bitmap bytes needed
* 35 --> we still need u64 to index and count bytes
* (that's 32 GiB of bitmap for 1 PiB storage)
* 1 << (35 - 2) 32bit longs needed
* 33 --> we'd even need u64 to index and count 32bit long words.
* 1 << (35 - 3) 64bit longs needed
* 32 --> we could get away with a 32bit unsigned int to index and count
* 64bit long words, but I rather stay with unsigned long for now.
* We probably should neither count nor point to bytes or long words
* directly, but either by bitnumber, or by page index and offset.
* 1 << (35 - 12)
* 22 --> we need that much 4KiB pages of bitmap.
* 1 << (22 + 3) --> on a 64bit arch,
* we need 32 MiB to store the array of page pointers.
*
* Because I'm lazy, and because the resulting patch was too large, too ugly
* and still incomplete, on 32bit we still "only" support 16 TiB (minus some),
* (1 << 32) bits * 4k storage.
*
* bitmap storage and IO:
* Bitmap is stored little endian on disk, and is kept little endian in
* core memory. Currently we still hold the full bitmap in core as long
* as we are "attached" to a local disk, which at 32 GiB for 1PiB storage
* seems excessive.
*
* We plan to reduce the amount of in-core bitmap pages by paging them in
* and out against their on-disk location as necessary, but need to make
* sure we don't cause too much meta data IO, and must not deadlock in
* tight memory situations. This needs some more work.
*/
/*
* NOTE
* Access to the *bm_pages is protected by bm_lock.
* It is safe to read the other members within the lock.
*
* drbd_bm_set_bits is called from bio_endio callbacks,
* We may be called with irq already disabled,
* so we need spin_lock_irqsave().
* And we need the kmap_atomic.
*/
struct drbd_bitmap {
struct page **bm_pages;
spinlock_t bm_lock;
/* see LIMITATIONS: above */
unsigned long bm_set; /* nr of set bits; THINK maybe atomic_t? */
unsigned long bm_bits;
size_t bm_words;
size_t bm_number_of_pages;
sector_t bm_dev_capacity;
struct mutex bm_change; /* serializes resize operations */
wait_queue_head_t bm_io_wait; /* used to serialize IO of single pages */
enum bm_flag bm_flags;
/* debugging aid, in case we are still racy somewhere */
char *bm_why;
struct task_struct *bm_task;
};
#define bm_print_lock_info(m) __bm_print_lock_info(m, __func__)
static void __bm_print_lock_info(struct drbd_conf *mdev, const char *func)
{
struct drbd_bitmap *b = mdev->bitmap;
if (!__ratelimit(&drbd_ratelimit_state))
return;
dev_err(DEV, "FIXME %s in %s, bitmap locked for '%s' by %s\n",
drbd_task_to_thread_name(mdev->tconn, current),
func, b->bm_why ?: "?",
drbd_task_to_thread_name(mdev->tconn, b->bm_task));
}
void drbd_bm_lock(struct drbd_conf *mdev, char *why, enum bm_flag flags)
{
struct drbd_bitmap *b = mdev->bitmap;
int trylock_failed;
if (!b) {
dev_err(DEV, "FIXME no bitmap in drbd_bm_lock!?\n");
return;
}
trylock_failed = !mutex_trylock(&b->bm_change);
if (trylock_failed) {
dev_warn(DEV, "%s going to '%s' but bitmap already locked for '%s' by %s\n",
drbd_task_to_thread_name(mdev->tconn, current),
why, b->bm_why ?: "?",
drbd_task_to_thread_name(mdev->tconn, b->bm_task));
mutex_lock(&b->bm_change);
}
if (BM_LOCKED_MASK & b->bm_flags)
dev_err(DEV, "FIXME bitmap already locked in bm_lock\n");
b->bm_flags |= flags & BM_LOCKED_MASK;
b->bm_why = why;
b->bm_task = current;
}
void drbd_bm_unlock(struct drbd_conf *mdev)
{
struct drbd_bitmap *b = mdev->bitmap;
if (!b) {
dev_err(DEV, "FIXME no bitmap in drbd_bm_unlock!?\n");
return;
}
if (!(BM_LOCKED_MASK & mdev->bitmap->bm_flags))
dev_err(DEV, "FIXME bitmap not locked in bm_unlock\n");
b->bm_flags &= ~BM_LOCKED_MASK;
b->bm_why = NULL;
b->bm_task = NULL;
mutex_unlock(&b->bm_change);
}
/* we store some "meta" info about our pages in page->private */
/* at a granularity of 4k storage per bitmap bit:
* one peta byte storage: 1<<50 byte, 1<<38 * 4k storage blocks
* 1<<38 bits,
* 1<<23 4k bitmap pages.
* Use 24 bits as page index, covers 2 peta byte storage
* at a granularity of 4k per bit.
* Used to report the failed page idx on io error from the endio handlers.
*/
#define BM_PAGE_IDX_MASK ((1UL<<24)-1)
/* this page is currently read in, or written back */
#define BM_PAGE_IO_LOCK 31
/* if there has been an IO error for this page */
#define BM_PAGE_IO_ERROR 30
/* this is to be able to intelligently skip disk IO,
* set if bits have been set since last IO. */
#define BM_PAGE_NEED_WRITEOUT 29
/* to mark for lazy writeout once syncer cleared all clearable bits,
* we if bits have been cleared since last IO. */
#define BM_PAGE_LAZY_WRITEOUT 28
/* pages marked with this "HINT" will be considered for writeout
* on activity log transactions */
#define BM_PAGE_HINT_WRITEOUT 27
/* store_page_idx uses non-atomic assignment. It is only used directly after
* allocating the page. All other bm_set_page_* and bm_clear_page_* need to
* use atomic bit manipulation, as set_out_of_sync (and therefore bitmap
* changes) may happen from various contexts, and wait_on_bit/wake_up_bit
* requires it all to be atomic as well. */
static void bm_store_page_idx(struct page *page, unsigned long idx)
{
BUG_ON(0 != (idx & ~BM_PAGE_IDX_MASK));
set_page_private(page, idx);
}
static unsigned long bm_page_to_idx(struct page *page)
{
return page_private(page) & BM_PAGE_IDX_MASK;
}
/* As is very unlikely that the same page is under IO from more than one
* context, we can get away with a bit per page and one wait queue per bitmap.
*/
static void bm_page_lock_io(struct drbd_conf *mdev, int page_nr)
{
struct drbd_bitmap *b = mdev->bitmap;
void *addr = &page_private(b->bm_pages[page_nr]);
wait_event(b->bm_io_wait, !test_and_set_bit(BM_PAGE_IO_LOCK, addr));
}
static void bm_page_unlock_io(struct drbd_conf *mdev, int page_nr)
{
struct drbd_bitmap *b = mdev->bitmap;
void *addr = &page_private(b->bm_pages[page_nr]);
clear_bit_unlock(BM_PAGE_IO_LOCK, addr);
wake_up(&mdev->bitmap->bm_io_wait);
}
/* set _before_ submit_io, so it may be reset due to being changed
* while this page is in flight... will get submitted later again */
static void bm_set_page_unchanged(struct page *page)
{
/* use cmpxchg? */
clear_bit(BM_PAGE_NEED_WRITEOUT, &page_private(page));
clear_bit(BM_PAGE_LAZY_WRITEOUT, &page_private(page));
}
static void bm_set_page_need_writeout(struct page *page)
{
set_bit(BM_PAGE_NEED_WRITEOUT, &page_private(page));
}
/**
* drbd_bm_mark_for_writeout() - mark a page with a "hint" to be considered for writeout
* @mdev: DRBD device.
* @page_nr: the bitmap page to mark with the "hint" flag
*
* From within an activity log transaction, we mark a few pages with these
* hints, then call drbd_bm_write_hinted(), which will only write out changed
* pages which are flagged with this mark.
*/
void drbd_bm_mark_for_writeout(struct drbd_conf *mdev, int page_nr)
{
struct page *page;
if (page_nr >= mdev->bitmap->bm_number_of_pages) {
dev_warn(DEV, "BAD: page_nr: %u, number_of_pages: %u\n",
page_nr, (int)mdev->bitmap->bm_number_of_pages);
return;
}
page = mdev->bitmap->bm_pages[page_nr];
set_bit(BM_PAGE_HINT_WRITEOUT, &page_private(page));
}
static int bm_test_page_unchanged(struct page *page)
{
volatile const unsigned long *addr = &page_private(page);
return (*addr & ((1UL<<BM_PAGE_NEED_WRITEOUT)|(1UL<<BM_PAGE_LAZY_WRITEOUT))) == 0;
}
static void bm_set_page_io_err(struct page *page)
{
set_bit(BM_PAGE_IO_ERROR, &page_private(page));
}
static void bm_clear_page_io_err(struct page *page)
{
clear_bit(BM_PAGE_IO_ERROR, &page_private(page));
}
static void bm_set_page_lazy_writeout(struct page *page)
{
set_bit(BM_PAGE_LAZY_WRITEOUT, &page_private(page));
}
static int bm_test_page_lazy_writeout(struct page *page)
{
return test_bit(BM_PAGE_LAZY_WRITEOUT, &page_private(page));
}
/* on a 32bit box, this would allow for exactly (2<<38) bits. */
static unsigned int bm_word_to_page_idx(struct drbd_bitmap *b, unsigned long long_nr)
{
/* page_nr = (word*sizeof(long)) >> PAGE_SHIFT; */
unsigned int page_nr = long_nr >> (PAGE_SHIFT - LN2_BPL + 3);
BUG_ON(page_nr >= b->bm_number_of_pages);
return page_nr;
}
static unsigned int bm_bit_to_page_idx(struct drbd_bitmap *b, u64 bitnr)
{
/* page_nr = (bitnr/8) >> PAGE_SHIFT; */
unsigned int page_nr = bitnr >> (PAGE_SHIFT + 3);
BUG_ON(page_nr >= b->bm_number_of_pages);
return page_nr;
}
static unsigned long *__bm_map_pidx(struct drbd_bitmap *b, unsigned int idx)
{
struct page *page = b->bm_pages[idx];
return (unsigned long *) kmap_atomic(page);
}
static unsigned long *bm_map_pidx(struct drbd_bitmap *b, unsigned int idx)
{
return __bm_map_pidx(b, idx);
}
static void __bm_unmap(unsigned long *p_addr)
{
kunmap_atomic(p_addr);
};
static void bm_unmap(unsigned long *p_addr)
{
return __bm_unmap(p_addr);
}
/* long word offset of _bitmap_ sector */
#define S2W(s) ((s)<<(BM_EXT_SHIFT-BM_BLOCK_SHIFT-LN2_BPL))
/* word offset from start of bitmap to word number _in_page_
* modulo longs per page
#define MLPP(X) ((X) % (PAGE_SIZE/sizeof(long))
hm, well, Philipp thinks gcc might not optimize the % into & (... - 1)
so do it explicitly:
*/
#define MLPP(X) ((X) & ((PAGE_SIZE/sizeof(long))-1))
/* Long words per page */
#define LWPP (PAGE_SIZE/sizeof(long))
/*
* actually most functions herein should take a struct drbd_bitmap*, not a
* struct drbd_conf*, but for the debug macros I like to have the mdev around
* to be able to report device specific.
*/
static void bm_free_pages(struct page **pages, unsigned long number)
{
unsigned long i;
if (!pages)
return;
for (i = 0; i < number; i++) {
if (!pages[i]) {
printk(KERN_ALERT "drbd: bm_free_pages tried to free "
"a NULL pointer; i=%lu n=%lu\n",
i, number);
continue;
}
__free_page(pages[i]);
pages[i] = NULL;
}
}
static void bm_vk_free(void *ptr, int v)
{
if (v)
vfree(ptr);
else
kfree(ptr);
}
/*
* "have" and "want" are NUMBER OF PAGES.
*/
static struct page **bm_realloc_pages(struct drbd_bitmap *b, unsigned long want)
{
struct page **old_pages = b->bm_pages;
struct page **new_pages, *page;
unsigned int i, bytes, vmalloced = 0;
unsigned long have = b->bm_number_of_pages;
BUG_ON(have == 0 && old_pages != NULL);
BUG_ON(have != 0 && old_pages == NULL);
if (have == want)
return old_pages;
/* Trying kmalloc first, falling back to vmalloc.
* GFP_NOIO, as this is called while drbd IO is "suspended",
* and during resize or attach on diskless Primary,
* we must not block on IO to ourselves.
* Context is receiver thread or dmsetup. */
bytes = sizeof(struct page *)*want;
new_pages = kzalloc(bytes, GFP_NOIO);
if (!new_pages) {
new_pages = __vmalloc(bytes,
GFP_NOIO | __GFP_HIGHMEM | __GFP_ZERO,
PAGE_KERNEL);
if (!new_pages)
return NULL;
vmalloced = 1;
}
if (want >= have) {
for (i = 0; i < have; i++)
new_pages[i] = old_pages[i];
for (; i < want; i++) {
page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
if (!page) {
bm_free_pages(new_pages + have, i - have);
bm_vk_free(new_pages, vmalloced);
return NULL;
}
/* we want to know which page it is
* from the endio handlers */
bm_store_page_idx(page, i);
new_pages[i] = page;
}
} else {
for (i = 0; i < want; i++)
new_pages[i] = old_pages[i];
/* NOT HERE, we are outside the spinlock!
bm_free_pages(old_pages + want, have - want);
*/
}
if (vmalloced)
b->bm_flags |= BM_P_VMALLOCED;
else
b->bm_flags &= ~BM_P_VMALLOCED;
return new_pages;
}
/*
* called on driver init only. TODO call when a device is created.
* allocates the drbd_bitmap, and stores it in mdev->bitmap.
*/
int drbd_bm_init(struct drbd_conf *mdev)
{
struct drbd_bitmap *b = mdev->bitmap;
WARN_ON(b != NULL);
b = kzalloc(sizeof(struct drbd_bitmap), GFP_KERNEL);
if (!b)
return -ENOMEM;
spin_lock_init(&b->bm_lock);
mutex_init(&b->bm_change);
init_waitqueue_head(&b->bm_io_wait);
mdev->bitmap = b;
return 0;
}
sector_t drbd_bm_capacity(struct drbd_conf *mdev)
{
if (!expect(mdev->bitmap))
return 0;
return mdev->bitmap->bm_dev_capacity;
}
/* called on driver unload. TODO: call when a device is destroyed.
*/
void drbd_bm_cleanup(struct drbd_conf *mdev)
{
if (!expect(mdev->bitmap))
return;
bm_free_pages(mdev->bitmap->bm_pages, mdev->bitmap->bm_number_of_pages);
bm_vk_free(mdev->bitmap->bm_pages, (BM_P_VMALLOCED & mdev->bitmap->bm_flags));
kfree(mdev->bitmap);
mdev->bitmap = NULL;
}
/*
* since (b->bm_bits % BITS_PER_LONG) != 0,
* this masks out the remaining bits.
* Returns the number of bits cleared.
*/
#define BITS_PER_PAGE (1UL << (PAGE_SHIFT + 3))
#define BITS_PER_PAGE_MASK (BITS_PER_PAGE - 1)
#define BITS_PER_LONG_MASK (BITS_PER_LONG - 1)
static int bm_clear_surplus(struct drbd_bitmap *b)
{
unsigned long mask;
unsigned long *p_addr, *bm;
int tmp;
int cleared = 0;
/* number of bits modulo bits per page */
tmp = (b->bm_bits & BITS_PER_PAGE_MASK);
/* mask the used bits of the word containing the last bit */
mask = (1UL << (tmp & BITS_PER_LONG_MASK)) -1;
/* bitmap is always stored little endian,
* on disk and in core memory alike */
mask = cpu_to_lel(mask);
p_addr = bm_map_pidx(b, b->bm_number_of_pages - 1);
bm = p_addr + (tmp/BITS_PER_LONG);
if (mask) {
/* If mask != 0, we are not exactly aligned, so bm now points
* to the long containing the last bit.
* If mask == 0, bm already points to the word immediately
* after the last (long word aligned) bit. */
cleared = hweight_long(*bm & ~mask);
*bm &= mask;
bm++;
}
if (BITS_PER_LONG == 32 && ((bm - p_addr) & 1) == 1) {
/* on a 32bit arch, we may need to zero out
* a padding long to align with a 64bit remote */
cleared += hweight_long(*bm);
*bm = 0;
}
bm_unmap(p_addr);
return cleared;
}
static void bm_set_surplus(struct drbd_bitmap *b)
{
unsigned long mask;
unsigned long *p_addr, *bm;
int tmp;
/* number of bits modulo bits per page */
tmp = (b->bm_bits & BITS_PER_PAGE_MASK);
/* mask the used bits of the word containing the last bit */
mask = (1UL << (tmp & BITS_PER_LONG_MASK)) -1;
/* bitmap is always stored little endian,
* on disk and in core memory alike */
mask = cpu_to_lel(mask);
p_addr = bm_map_pidx(b, b->bm_number_of_pages - 1);
bm = p_addr + (tmp/BITS_PER_LONG);
if (mask) {
/* If mask != 0, we are not exactly aligned, so bm now points
* to the long containing the last bit.
* If mask == 0, bm already points to the word immediately
* after the last (long word aligned) bit. */
*bm |= ~mask;
bm++;
}
if (BITS_PER_LONG == 32 && ((bm - p_addr) & 1) == 1) {
/* on a 32bit arch, we may need to zero out
* a padding long to align with a 64bit remote */
*bm = ~0UL;
}
bm_unmap(p_addr);
}
/* you better not modify the bitmap while this is running,
* or its results will be stale */
static unsigned long bm_count_bits(struct drbd_bitmap *b)
{
unsigned long *p_addr;
unsigned long bits = 0;
unsigned long mask = (1UL << (b->bm_bits & BITS_PER_LONG_MASK)) -1;
int idx, i, last_word;
/* all but last page */
for (idx = 0; idx < b->bm_number_of_pages - 1; idx++) {
p_addr = __bm_map_pidx(b, idx);
for (i = 0; i < LWPP; i++)
bits += hweight_long(p_addr[i]);
__bm_unmap(p_addr);
cond_resched();
}
/* last (or only) page */
last_word = ((b->bm_bits - 1) & BITS_PER_PAGE_MASK) >> LN2_BPL;
p_addr = __bm_map_pidx(b, idx);
for (i = 0; i < last_word; i++)
bits += hweight_long(p_addr[i]);
p_addr[last_word] &= cpu_to_lel(mask);
bits += hweight_long(p_addr[last_word]);
/* 32bit arch, may have an unused padding long */
if (BITS_PER_LONG == 32 && (last_word & 1) == 0)
p_addr[last_word+1] = 0;
__bm_unmap(p_addr);
return bits;
}
/* offset and len in long words.*/
static void bm_memset(struct drbd_bitmap *b, size_t offset, int c, size_t len)
{
unsigned long *p_addr, *bm;
unsigned int idx;
size_t do_now, end;
end = offset + len;
if (end > b->bm_words) {
printk(KERN_ALERT "drbd: bm_memset end > bm_words\n");
return;
}
while (offset < end) {
do_now = min_t(size_t, ALIGN(offset + 1, LWPP), end) - offset;
idx = bm_word_to_page_idx(b, offset);
p_addr = bm_map_pidx(b, idx);
bm = p_addr + MLPP(offset);
if (bm+do_now > p_addr + LWPP) {
printk(KERN_ALERT "drbd: BUG BUG BUG! p_addr:%p bm:%p do_now:%d\n",
p_addr, bm, (int)do_now);
} else
memset(bm, c, do_now * sizeof(long));
bm_unmap(p_addr);
bm_set_page_need_writeout(b->bm_pages[idx]);
offset += do_now;
}
}
/* For the layout, see comment above drbd_md_set_sector_offsets(). */
static u64 drbd_md_on_disk_bits(struct drbd_backing_dev *ldev)
{
u64 bitmap_sectors;
if (ldev->md.al_offset == 8)
bitmap_sectors = ldev->md.md_size_sect - ldev->md.bm_offset;
else
bitmap_sectors = ldev->md.al_offset - ldev->md.bm_offset;
return bitmap_sectors << (9 + 3);
}
/*
* make sure the bitmap has enough room for the attached storage,
* if necessary, resize.
* called whenever we may have changed the device size.
* returns -ENOMEM if we could not allocate enough memory, 0 on success.
* In case this is actually a resize, we copy the old bitmap into the new one.
* Otherwise, the bitmap is initialized to all bits set.
*/
int drbd_bm_resize(struct drbd_conf *mdev, sector_t capacity, int set_new_bits)
{
struct drbd_bitmap *b = mdev->bitmap;
unsigned long bits, words, owords, obits;
unsigned long want, have, onpages; /* number of pages */
struct page **npages, **opages = NULL;
int err = 0, growing;
int opages_vmalloced;
if (!expect(b))
return -ENOMEM;
drbd_bm_lock(mdev, "resize", BM_LOCKED_MASK);
dev_info(DEV, "drbd_bm_resize called with capacity == %llu\n",
(unsigned long long)capacity);
if (capacity == b->bm_dev_capacity)
goto out;
opages_vmalloced = (BM_P_VMALLOCED & b->bm_flags);
if (capacity == 0) {
spin_lock_irq(&b->bm_lock);
opages = b->bm_pages;
onpages = b->bm_number_of_pages;
owords = b->bm_words;
b->bm_pages = NULL;
b->bm_number_of_pages =
b->bm_set =
b->bm_bits =
b->bm_words =
b->bm_dev_capacity = 0;
spin_unlock_irq(&b->bm_lock);
bm_free_pages(opages, onpages);
bm_vk_free(opages, opages_vmalloced);
goto out;
}
bits = BM_SECT_TO_BIT(ALIGN(capacity, BM_SECT_PER_BIT));
/* if we would use
words = ALIGN(bits,BITS_PER_LONG) >> LN2_BPL;
a 32bit host could present the wrong number of words
to a 64bit host.
*/
words = ALIGN(bits, 64) >> LN2_BPL;
if (get_ldev(mdev)) {
u64 bits_on_disk = drbd_md_on_disk_bits(mdev->ldev);
put_ldev(mdev);
if (bits > bits_on_disk) {
dev_info(DEV, "bits = %lu\n", bits);
dev_info(DEV, "bits_on_disk = %llu\n", bits_on_disk);
err = -ENOSPC;
goto out;
}
}
want = ALIGN(words*sizeof(long), PAGE_SIZE) >> PAGE_SHIFT;
have = b->bm_number_of_pages;
if (want == have) {
D_ASSERT(b->bm_pages != NULL);
npages = b->bm_pages;
} else {
if (drbd_insert_fault(mdev, DRBD_FAULT_BM_ALLOC))
npages = NULL;
else
npages = bm_realloc_pages(b, want);
}
if (!npages) {
err = -ENOMEM;
goto out;
}
spin_lock_irq(&b->bm_lock);
opages = b->bm_pages;
owords = b->bm_words;
obits = b->bm_bits;
growing = bits > obits;
if (opages && growing && set_new_bits)
bm_set_surplus(b);
b->bm_pages = npages;
b->bm_number_of_pages = want;
b->bm_bits = bits;
b->bm_words = words;
b->bm_dev_capacity = capacity;
if (growing) {
if (set_new_bits) {
bm_memset(b, owords, 0xff, words-owords);
b->bm_set += bits - obits;
} else
bm_memset(b, owords, 0x00, words-owords);
}
if (want < have) {
/* implicit: (opages != NULL) && (opages != npages) */
bm_free_pages(opages + want, have - want);
}
(void)bm_clear_surplus(b);
spin_unlock_irq(&b->bm_lock);
if (opages != npages)
bm_vk_free(opages, opages_vmalloced);
if (!growing)
b->bm_set = bm_count_bits(b);
dev_info(DEV, "resync bitmap: bits=%lu words=%lu pages=%lu\n", bits, words, want);
out:
drbd_bm_unlock(mdev);
return err;
}
/* inherently racy:
* if not protected by other means, return value may be out of date when
* leaving this function...
* we still need to lock it, since it is important that this returns
* bm_set == 0 precisely.
*
* maybe bm_set should be atomic_t ?
*/
unsigned long _drbd_bm_total_weight(struct drbd_conf *mdev)
{
struct drbd_bitmap *b = mdev->bitmap;
unsigned long s;
unsigned long flags;
if (!expect(b))
return 0;
if (!expect(b->bm_pages))
return 0;
spin_lock_irqsave(&b->bm_lock, flags);
s = b->bm_set;
spin_unlock_irqrestore(&b->bm_lock, flags);
return s;
}
unsigned long drbd_bm_total_weight(struct drbd_conf *mdev)
{
unsigned long s;
/* if I don't have a disk, I don't know about out-of-sync status */
if (!get_ldev_if_state(mdev, D_NEGOTIATING))
return 0;
s = _drbd_bm_total_weight(mdev);
put_ldev(mdev);
return s;
}
size_t drbd_bm_words(struct drbd_conf *mdev)
{
struct drbd_bitmap *b = mdev->bitmap;
if (!expect(b))
return 0;
if (!expect(b->bm_pages))
return 0;
return b->bm_words;
}
unsigned long drbd_bm_bits(struct drbd_conf *mdev)
{
struct drbd_bitmap *b = mdev->bitmap;
if (!expect(b))
return 0;
return b->bm_bits;
}
/* merge number words from buffer into the bitmap starting at offset.
* buffer[i] is expected to be little endian unsigned long.
* bitmap must be locked by drbd_bm_lock.
* currently only used from receive_bitmap.
*/
void drbd_bm_merge_lel(struct drbd_conf *mdev, size_t offset, size_t number,
unsigned long *buffer)
{
struct drbd_bitmap *b = mdev->bitmap;
unsigned long *p_addr, *bm;
unsigned long word, bits;
unsigned int idx;
size_t end, do_now;
end = offset + number;
if (!expect(b))
return;
if (!expect(b->bm_pages))
return;
if (number == 0)
return;
WARN_ON(offset >= b->bm_words);
WARN_ON(end > b->bm_words);
spin_lock_irq(&b->bm_lock);
while (offset < end) {
do_now = min_t(size_t, ALIGN(offset+1, LWPP), end) - offset;
idx = bm_word_to_page_idx(b, offset);
p_addr = bm_map_pidx(b, idx);
bm = p_addr + MLPP(offset);
offset += do_now;
while (do_now--) {
bits = hweight_long(*bm);
word = *bm | *buffer++;
*bm++ = word;
b->bm_set += hweight_long(word) - bits;
}
bm_unmap(p_addr);
bm_set_page_need_writeout(b->bm_pages[idx]);
}
/* with 32bit <-> 64bit cross-platform connect
* this is only correct for current usage,
* where we _know_ that we are 64 bit aligned,
* and know that this function is used in this way, too...
*/
if (end == b->bm_words)
b->bm_set -= bm_clear_surplus(b);
spin_unlock_irq(&b->bm_lock);
}
/* copy number words from the bitmap starting at offset into the buffer.
* buffer[i] will be little endian unsigned long.
*/
void drbd_bm_get_lel(struct drbd_conf *mdev, size_t offset, size_t number,
unsigned long *buffer)
{
struct drbd_bitmap *b = mdev->bitmap;
unsigned long *p_addr, *bm;
size_t end, do_now;
end = offset + number;
if (!expect(b))
return;
if (!expect(b->bm_pages))
return;
spin_lock_irq(&b->bm_lock);
if ((offset >= b->bm_words) ||
(end > b->bm_words) ||
(number <= 0))
dev_err(DEV, "offset=%lu number=%lu bm_words=%lu\n",
(unsigned long) offset,
(unsigned long) number,
(unsigned long) b->bm_words);
else {
while (offset < end) {
do_now = min_t(size_t, ALIGN(offset+1, LWPP), end) - offset;
p_addr = bm_map_pidx(b, bm_word_to_page_idx(b, offset));
bm = p_addr + MLPP(offset);
offset += do_now;
while (do_now--)
*buffer++ = *bm++;
bm_unmap(p_addr);
}
}
spin_unlock_irq(&b->bm_lock);
}
/* set all bits in the bitmap */
void drbd_bm_set_all(struct drbd_conf *mdev)
{
struct drbd_bitmap *b = mdev->bitmap;
if (!expect(b))
return;
if (!expect(b->bm_pages))
return;
spin_lock_irq(&b->bm_lock);
bm_memset(b, 0, 0xff, b->bm_words);
(void)bm_clear_surplus(b);
b->bm_set = b->bm_bits;
spin_unlock_irq(&b->bm_lock);
}
/* clear all bits in the bitmap */
void drbd_bm_clear_all(struct drbd_conf *mdev)
{
struct drbd_bitmap *b = mdev->bitmap;
if (!expect(b))
return;
if (!expect(b->bm_pages))
return;
spin_lock_irq(&b->bm_lock);
bm_memset(b, 0, 0, b->bm_words);
b->bm_set = 0;
spin_unlock_irq(&b->bm_lock);
}
struct bm_aio_ctx {
struct drbd_conf *mdev;
atomic_t in_flight;
unsigned int done;
unsigned flags;
#define BM_AIO_COPY_PAGES 1
#define BM_AIO_WRITE_HINTED 2
#define BM_WRITE_ALL_PAGES 4
int error;
struct kref kref;
};
static void bm_aio_ctx_destroy(struct kref *kref)
{
struct bm_aio_ctx *ctx = container_of(kref, struct bm_aio_ctx, kref);
put_ldev(ctx->mdev);
kfree(ctx);
}
/* bv_page may be a copy, or may be the original */
static void bm_async_io_complete(struct bio *bio, int error)
{
struct bm_aio_ctx *ctx = bio->bi_private;
struct drbd_conf *mdev = ctx->mdev;
struct drbd_bitmap *b = mdev->bitmap;
unsigned int idx = bm_page_to_idx(bio->bi_io_vec[0].bv_page);
int uptodate = bio_flagged(bio, BIO_UPTODATE);
/* strange behavior of some lower level drivers...
* fail the request by clearing the uptodate flag,
* but do not return any error?!
* do we want to WARN() on this? */
if (!error && !uptodate)
error = -EIO;
if ((ctx->flags & BM_AIO_COPY_PAGES) == 0 &&
!bm_test_page_unchanged(b->bm_pages[idx]))
dev_warn(DEV, "bitmap page idx %u changed during IO!\n", idx);
if (error) {
/* ctx error will hold the completed-last non-zero error code,
* in case error codes differ. */
ctx->error = error;
bm_set_page_io_err(b->bm_pages[idx]);
/* Not identical to on disk version of it.
* Is BM_PAGE_IO_ERROR enough? */
if (__ratelimit(&drbd_ratelimit_state))
dev_err(DEV, "IO ERROR %d on bitmap page idx %u\n",
error, idx);
} else {
bm_clear_page_io_err(b->bm_pages[idx]);
dynamic_dev_dbg(DEV, "bitmap page idx %u completed\n", idx);
}
bm_page_unlock_io(mdev, idx);
if (ctx->flags & BM_AIO_COPY_PAGES)
mempool_free(bio->bi_io_vec[0].bv_page, drbd_md_io_page_pool);
bio_put(bio);
if (atomic_dec_and_test(&ctx->in_flight)) {
ctx->done = 1;
wake_up(&mdev->misc_wait);
kref_put(&ctx->kref, &bm_aio_ctx_destroy);
}
}
static void bm_page_io_async(struct bm_aio_ctx *ctx, int page_nr, int rw) __must_hold(local)
{
struct bio *bio = bio_alloc_drbd(GFP_NOIO);
struct drbd_conf *mdev = ctx->mdev;
struct drbd_bitmap *b = mdev->bitmap;
struct page *page;
unsigned int len;
sector_t on_disk_sector =
mdev->ldev->md.md_offset + mdev->ldev->md.bm_offset;
on_disk_sector += ((sector_t)page_nr) << (PAGE_SHIFT-9);
/* this might happen with very small
* flexible external meta data device,
* or with PAGE_SIZE > 4k */
len = min_t(unsigned int, PAGE_SIZE,
(drbd_md_last_sector(mdev->ldev) - on_disk_sector + 1)<<9);
/* serialize IO on this page */
bm_page_lock_io(mdev, page_nr);
/* before memcpy and submit,
* so it can be redirtied any time */
bm_set_page_unchanged(b->bm_pages[page_nr]);
if (ctx->flags & BM_AIO_COPY_PAGES) {
page = mempool_alloc(drbd_md_io_page_pool, __GFP_HIGHMEM|__GFP_WAIT);
copy_highpage(page, b->bm_pages[page_nr]);
bm_store_page_idx(page, page_nr);
} else
page = b->bm_pages[page_nr];
bio->bi_bdev = mdev->ldev->md_bdev;
bio->bi_sector = on_disk_sector;
/* bio_add_page of a single page to an empty bio will always succeed,
* according to api. Do we want to assert that? */
bio_add_page(bio, page, len, 0);
bio->bi_private = ctx;
bio->bi_end_io = bm_async_io_complete;
if (drbd_insert_fault(mdev, (rw & WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD)) {
bio->bi_rw |= rw;
bio_endio(bio, -EIO);
} else {
submit_bio(rw, bio);
/* this should not count as user activity and cause the
* resync to throttle -- see drbd_rs_should_slow_down(). */
atomic_add(len >> 9, &mdev->rs_sect_ev);
}
}
/*
* bm_rw: read/write the whole bitmap from/to its on disk location.
*/
static int bm_rw(struct drbd_conf *mdev, int rw, unsigned flags, unsigned lazy_writeout_upper_idx) __must_hold(local)
{
struct bm_aio_ctx *ctx;
struct drbd_bitmap *b = mdev->bitmap;
int num_pages, i, count = 0;
unsigned long now;
char ppb[10];
int err = 0;
/*
* We are protected against bitmap disappearing/resizing by holding an
* ldev reference (caller must have called get_ldev()).
* For read/write, we are protected against changes to the bitmap by
* the bitmap lock (see drbd_bitmap_io).
* For lazy writeout, we don't care for ongoing changes to the bitmap,
* as we submit copies of pages anyways.
*/
ctx = kmalloc(sizeof(struct bm_aio_ctx), GFP_NOIO);
if (!ctx)
return -ENOMEM;
*ctx = (struct bm_aio_ctx) {
.mdev = mdev,
.in_flight = ATOMIC_INIT(1),
.done = 0,
.flags = flags,
.error = 0,
.kref = { ATOMIC_INIT(2) },
};
if (!get_ldev_if_state(mdev, D_ATTACHING)) { /* put is in bm_aio_ctx_destroy() */
dev_err(DEV, "ASSERT FAILED: get_ldev_if_state() == 1 in bm_rw()\n");
kfree(ctx);
return -ENODEV;
}
if (!ctx->flags)
WARN_ON(!(BM_LOCKED_MASK & b->bm_flags));
num_pages = b->bm_number_of_pages;
now = jiffies;
/* let the layers below us try to merge these bios... */
for (i = 0; i < num_pages; i++) {
/* ignore completely unchanged pages */
if (lazy_writeout_upper_idx && i == lazy_writeout_upper_idx)
break;
if (rw & WRITE) {
if ((flags & BM_AIO_WRITE_HINTED) &&
!test_and_clear_bit(BM_PAGE_HINT_WRITEOUT,
&page_private(b->bm_pages[i])))
continue;
if (!(flags & BM_WRITE_ALL_PAGES) &&
bm_test_page_unchanged(b->bm_pages[i])) {
dynamic_dev_dbg(DEV, "skipped bm write for idx %u\n", i);
continue;
}
/* during lazy writeout,
* ignore those pages not marked for lazy writeout. */
if (lazy_writeout_upper_idx &&
!bm_test_page_lazy_writeout(b->bm_pages[i])) {
dynamic_dev_dbg(DEV, "skipped bm lazy write for idx %u\n", i);
continue;
}
}
atomic_inc(&ctx->in_flight);
bm_page_io_async(ctx, i, rw);
++count;
cond_resched();
}
/*
* We initialize ctx->in_flight to one to make sure bm_async_io_complete
* will not set ctx->done early, and decrement / test it here. If there
* are still some bios in flight, we need to wait for them here.
* If all IO is done already (or nothing had been submitted), there is
* no need to wait. Still, we need to put the kref associated with the
* "in_flight reached zero, all done" event.
*/
if (!atomic_dec_and_test(&ctx->in_flight))
wait_until_done_or_force_detached(mdev, mdev->ldev, &ctx->done);
else
kref_put(&ctx->kref, &bm_aio_ctx_destroy);
/* summary for global bitmap IO */
if (flags == 0)
dev_info(DEV, "bitmap %s of %u pages took %lu jiffies\n",
rw == WRITE ? "WRITE" : "READ",
count, jiffies - now);
if (ctx->error) {
dev_alert(DEV, "we had at least one MD IO ERROR during bitmap IO\n");
drbd_chk_io_error(mdev, 1, DRBD_META_IO_ERROR);
err = -EIO; /* ctx->error ? */
}
if (atomic_read(&ctx->in_flight))
err = -EIO; /* Disk timeout/force-detach during IO... */
now = jiffies;
if (rw == WRITE) {
drbd_md_flush(mdev);
} else /* rw == READ */ {
b->bm_set = bm_count_bits(b);
dev_info(DEV, "recounting of set bits took additional %lu jiffies\n",
jiffies - now);
}
now = b->bm_set;
if (flags == 0)
dev_info(DEV, "%s (%lu bits) marked out-of-sync by on disk bit-map.\n",
ppsize(ppb, now << (BM_BLOCK_SHIFT-10)), now);
kref_put(&ctx->kref, &bm_aio_ctx_destroy);
return err;
}
/**
* drbd_bm_read() - Read the whole bitmap from its on disk location.
* @mdev: DRBD device.
*/
int drbd_bm_read(struct drbd_conf *mdev) __must_hold(local)
{
return bm_rw(mdev, READ, 0, 0);
}
/**
* drbd_bm_write() - Write the whole bitmap to its on disk location.
* @mdev: DRBD device.
*
* Will only write pages that have changed since last IO.
*/
int drbd_bm_write(struct drbd_conf *mdev) __must_hold(local)
{
return bm_rw(mdev, WRITE, 0, 0);
}
/**
* drbd_bm_write_all() - Write the whole bitmap to its on disk location.
* @mdev: DRBD device.
*
* Will write all pages.
*/
int drbd_bm_write_all(struct drbd_conf *mdev) __must_hold(local)
{
return bm_rw(mdev, WRITE, BM_WRITE_ALL_PAGES, 0);
}
/**
* drbd_bm_lazy_write_out() - Write bitmap pages 0 to @upper_idx-1, if they have changed.
* @mdev: DRBD device.
* @upper_idx: 0: write all changed pages; +ve: page index to stop scanning for changed pages
*/
int drbd_bm_write_lazy(struct drbd_conf *mdev, unsigned upper_idx) __must_hold(local)
{
return bm_rw(mdev, WRITE, BM_AIO_COPY_PAGES, upper_idx);
}
/**
* drbd_bm_write_copy_pages() - Write the whole bitmap to its on disk location.
* @mdev: DRBD device.
*
* Will only write pages that have changed since last IO.
* In contrast to drbd_bm_write(), this will copy the bitmap pages
* to temporary writeout pages. It is intended to trigger a full write-out
* while still allowing the bitmap to change, for example if a resync or online
* verify is aborted due to a failed peer disk, while local IO continues, or
* pending resync acks are still being processed.
*/
int drbd_bm_write_copy_pages(struct drbd_conf *mdev) __must_hold(local)
{
return bm_rw(mdev, WRITE, BM_AIO_COPY_PAGES, 0);
}
/**
* drbd_bm_write_hinted() - Write bitmap pages with "hint" marks, if they have changed.
* @mdev: DRBD device.
*/
int drbd_bm_write_hinted(struct drbd_conf *mdev) __must_hold(local)
{
return bm_rw(mdev, WRITE, BM_AIO_WRITE_HINTED | BM_AIO_COPY_PAGES, 0);
}
/**
* drbd_bm_write_page() - Writes a PAGE_SIZE aligned piece of bitmap
* @mdev: DRBD device.
* @idx: bitmap page index
*
* We don't want to special case on logical_block_size of the backend device,
* so we submit PAGE_SIZE aligned pieces.
* Note that on "most" systems, PAGE_SIZE is 4k.
*
* In case this becomes an issue on systems with larger PAGE_SIZE,
* we may want to change this again to write 4k aligned 4k pieces.
*/
int drbd_bm_write_page(struct drbd_conf *mdev, unsigned int idx) __must_hold(local)
{
struct bm_aio_ctx *ctx;
int err;
if (bm_test_page_unchanged(mdev->bitmap->bm_pages[idx])) {
dynamic_dev_dbg(DEV, "skipped bm page write for idx %u\n", idx);
return 0;
}
ctx = kmalloc(sizeof(struct bm_aio_ctx), GFP_NOIO);
if (!ctx)
return -ENOMEM;
*ctx = (struct bm_aio_ctx) {
.mdev = mdev,
.in_flight = ATOMIC_INIT(1),
.done = 0,
.flags = BM_AIO_COPY_PAGES,
.error = 0,
.kref = { ATOMIC_INIT(2) },
};
if (!get_ldev_if_state(mdev, D_ATTACHING)) { /* put is in bm_aio_ctx_destroy() */
dev_err(DEV, "ASSERT FAILED: get_ldev_if_state() == 1 in drbd_bm_write_page()\n");
kfree(ctx);
return -ENODEV;
}
bm_page_io_async(ctx, idx, WRITE_SYNC);
wait_until_done_or_force_detached(mdev, mdev->ldev, &ctx->done);
if (ctx->error)
drbd_chk_io_error(mdev, 1, DRBD_META_IO_ERROR);
/* that causes us to detach, so the in memory bitmap will be
* gone in a moment as well. */
mdev->bm_writ_cnt++;
err = atomic_read(&ctx->in_flight) ? -EIO : ctx->error;
kref_put(&ctx->kref, &bm_aio_ctx_destroy);
return err;
}
/* NOTE
* find_first_bit returns int, we return unsigned long.
* For this to work on 32bit arch with bitnumbers > (1<<32),
* we'd need to return u64, and get a whole lot of other places
* fixed where we still use unsigned long.
*
* this returns a bit number, NOT a sector!
*/
static unsigned long __bm_find_next(struct drbd_conf *mdev, unsigned long bm_fo,
const int find_zero_bit)
{
struct drbd_bitmap *b = mdev->bitmap;
unsigned long *p_addr;
unsigned long bit_offset;
unsigned i;
if (bm_fo > b->bm_bits) {
dev_err(DEV, "bm_fo=%lu bm_bits=%lu\n", bm_fo, b->bm_bits);
bm_fo = DRBD_END_OF_BITMAP;
} else {
while (bm_fo < b->bm_bits) {
/* bit offset of the first bit in the page */
bit_offset = bm_fo & ~BITS_PER_PAGE_MASK;
p_addr = __bm_map_pidx(b, bm_bit_to_page_idx(b, bm_fo));
if (find_zero_bit)
i = find_next_zero_bit_le(p_addr,
PAGE_SIZE*8, bm_fo & BITS_PER_PAGE_MASK);
else
i = find_next_bit_le(p_addr,
PAGE_SIZE*8, bm_fo & BITS_PER_PAGE_MASK);
__bm_unmap(p_addr);
if (i < PAGE_SIZE*8) {
bm_fo = bit_offset + i;
if (bm_fo >= b->bm_bits)
break;
goto found;
}
bm_fo = bit_offset + PAGE_SIZE*8;
}
bm_fo = DRBD_END_OF_BITMAP;
}
found:
return bm_fo;
}
static unsigned long bm_find_next(struct drbd_conf *mdev,
unsigned long bm_fo, const int find_zero_bit)
{
struct drbd_bitmap *b = mdev->bitmap;
unsigned long i = DRBD_END_OF_BITMAP;
if (!expect(b))
return i;
if (!expect(b->bm_pages))
return i;
spin_lock_irq(&b->bm_lock);
if (BM_DONT_TEST & b->bm_flags)
bm_print_lock_info(mdev);
i = __bm_find_next(mdev, bm_fo, find_zero_bit);
spin_unlock_irq(&b->bm_lock);
return i;
}
unsigned long drbd_bm_find_next(struct drbd_conf *mdev, unsigned long bm_fo)
{
return bm_find_next(mdev, bm_fo, 0);
}
#if 0
/* not yet needed for anything. */
unsigned long drbd_bm_find_next_zero(struct drbd_conf *mdev, unsigned long bm_fo)
{
return bm_find_next(mdev, bm_fo, 1);
}
#endif
/* does not spin_lock_irqsave.
* you must take drbd_bm_lock() first */
unsigned long _drbd_bm_find_next(struct drbd_conf *mdev, unsigned long bm_fo)
{
/* WARN_ON(!(BM_DONT_SET & mdev->b->bm_flags)); */
return __bm_find_next(mdev, bm_fo, 0);
}
unsigned long _drbd_bm_find_next_zero(struct drbd_conf *mdev, unsigned long bm_fo)
{
/* WARN_ON(!(BM_DONT_SET & mdev->b->bm_flags)); */
return __bm_find_next(mdev, bm_fo, 1);
}
/* returns number of bits actually changed.
* for val != 0, we change 0 -> 1, return code positive
* for val == 0, we change 1 -> 0, return code negative
* wants bitnr, not sector.
* expected to be called for only a few bits (e - s about BITS_PER_LONG).
* Must hold bitmap lock already. */
static int __bm_change_bits_to(struct drbd_conf *mdev, const unsigned long s,
unsigned long e, int val)
{
struct drbd_bitmap *b = mdev->bitmap;
unsigned long *p_addr = NULL;
unsigned long bitnr;
unsigned int last_page_nr = -1U;
int c = 0;
int changed_total = 0;
if (e >= b->bm_bits) {
dev_err(DEV, "ASSERT FAILED: bit_s=%lu bit_e=%lu bm_bits=%lu\n",
s, e, b->bm_bits);
e = b->bm_bits ? b->bm_bits -1 : 0;
}
for (bitnr = s; bitnr <= e; bitnr++) {
unsigned int page_nr = bm_bit_to_page_idx(b, bitnr);
if (page_nr != last_page_nr) {
if (p_addr)
__bm_unmap(p_addr);
if (c < 0)
bm_set_page_lazy_writeout(b->bm_pages[last_page_nr]);
else if (c > 0)
bm_set_page_need_writeout(b->bm_pages[last_page_nr]);
changed_total += c;
c = 0;
p_addr = __bm_map_pidx(b, page_nr);
last_page_nr = page_nr;
}
if (val)
c += (0 == __test_and_set_bit_le(bitnr & BITS_PER_PAGE_MASK, p_addr));
else
c -= (0 != __test_and_clear_bit_le(bitnr & BITS_PER_PAGE_MASK, p_addr));
}
if (p_addr)
__bm_unmap(p_addr);
if (c < 0)
bm_set_page_lazy_writeout(b->bm_pages[last_page_nr]);
else if (c > 0)
bm_set_page_need_writeout(b->bm_pages[last_page_nr]);
changed_total += c;
b->bm_set += changed_total;
return changed_total;
}
/* returns number of bits actually changed.
* for val != 0, we change 0 -> 1, return code positive
* for val == 0, we change 1 -> 0, return code negative
* wants bitnr, not sector */
static int bm_change_bits_to(struct drbd_conf *mdev, const unsigned long s,
const unsigned long e, int val)
{
unsigned long flags;
struct drbd_bitmap *b = mdev->bitmap;
int c = 0;
if (!expect(b))
return 1;
if (!expect(b->bm_pages))
return 0;
spin_lock_irqsave(&b->bm_lock, flags);
if ((val ? BM_DONT_SET : BM_DONT_CLEAR) & b->bm_flags)
bm_print_lock_info(mdev);
c = __bm_change_bits_to(mdev, s, e, val);
spin_unlock_irqrestore(&b->bm_lock, flags);
return c;
}
/* returns number of bits changed 0 -> 1 */
int drbd_bm_set_bits(struct drbd_conf *mdev, const unsigned long s, const unsigned long e)
{
return bm_change_bits_to(mdev, s, e, 1);
}
/* returns number of bits changed 1 -> 0 */
int drbd_bm_clear_bits(struct drbd_conf *mdev, const unsigned long s, const unsigned long e)
{
return -bm_change_bits_to(mdev, s, e, 0);
}
/* sets all bits in full words,
* from first_word up to, but not including, last_word */
static inline void bm_set_full_words_within_one_page(struct drbd_bitmap *b,
int page_nr, int first_word, int last_word)
{
int i;
int bits;
int changed = 0;
unsigned long *paddr = kmap_atomic(b->bm_pages[page_nr]);
for (i = first_word; i < last_word; i++) {
bits = hweight_long(paddr[i]);
paddr[i] = ~0UL;
changed += BITS_PER_LONG - bits;
}
kunmap_atomic(paddr);
if (changed) {
/* We only need lazy writeout, the information is still in the
* remote bitmap as well, and is reconstructed during the next
* bitmap exchange, if lost locally due to a crash. */
bm_set_page_lazy_writeout(b->bm_pages[page_nr]);
b->bm_set += changed;
}
}
/* Same thing as drbd_bm_set_bits,
* but more efficient for a large bit range.
* You must first drbd_bm_lock().
* Can be called to set the whole bitmap in one go.
* Sets bits from s to e _inclusive_. */
void _drbd_bm_set_bits(struct drbd_conf *mdev, const unsigned long s, const unsigned long e)
{
/* First set_bit from the first bit (s)
* up to the next long boundary (sl),
* then assign full words up to the last long boundary (el),
* then set_bit up to and including the last bit (e).
*
* Do not use memset, because we must account for changes,
* so we need to loop over the words with hweight() anyways.
*/
struct drbd_bitmap *b = mdev->bitmap;
unsigned long sl = ALIGN(s,BITS_PER_LONG);
unsigned long el = (e+1) & ~((unsigned long)BITS_PER_LONG-1);
int first_page;
int last_page;
int page_nr;
int first_word;
int last_word;
if (e - s <= 3*BITS_PER_LONG) {
/* don't bother; el and sl may even be wrong. */
spin_lock_irq(&b->bm_lock);
__bm_change_bits_to(mdev, s, e, 1);
spin_unlock_irq(&b->bm_lock);
return;
}
/* difference is large enough that we can trust sl and el */
spin_lock_irq(&b->bm_lock);
/* bits filling the current long */
if (sl)
__bm_change_bits_to(mdev, s, sl-1, 1);
first_page = sl >> (3 + PAGE_SHIFT);
last_page = el >> (3 + PAGE_SHIFT);
/* MLPP: modulo longs per page */
/* LWPP: long words per page */
first_word = MLPP(sl >> LN2_BPL);
last_word = LWPP;
/* first and full pages, unless first page == last page */
for (page_nr = first_page; page_nr < last_page; page_nr++) {
bm_set_full_words_within_one_page(mdev->bitmap, page_nr, first_word, last_word);
spin_unlock_irq(&b->bm_lock);
cond_resched();
first_word = 0;
spin_lock_irq(&b->bm_lock);
}
/* last page (respectively only page, for first page == last page) */
last_word = MLPP(el >> LN2_BPL);
/* consider bitmap->bm_bits = 32768, bitmap->bm_number_of_pages = 1. (or multiples).
* ==> e = 32767, el = 32768, last_page = 2,
* and now last_word = 0.
* We do not want to touch last_page in this case,
* as we did not allocate it, it is not present in bitmap->bm_pages.
*/
if (last_word)
bm_set_full_words_within_one_page(mdev->bitmap, last_page, first_word, last_word);
/* possibly trailing bits.
* example: (e & 63) == 63, el will be e+1.
* if that even was the very last bit,
* it would trigger an assert in __bm_change_bits_to()
*/
if (el <= e)
__bm_change_bits_to(mdev, el, e, 1);
spin_unlock_irq(&b->bm_lock);
}
/* returns bit state
* wants bitnr, NOT sector.
* inherently racy... area needs to be locked by means of {al,rs}_lru
* 1 ... bit set
* 0 ... bit not set
* -1 ... first out of bounds access, stop testing for bits!
*/
int drbd_bm_test_bit(struct drbd_conf *mdev, const unsigned long bitnr)
{
unsigned long flags;
struct drbd_bitmap *b = mdev->bitmap;
unsigned long *p_addr;
int i;
if (!expect(b))
return 0;
if (!expect(b->bm_pages))
return 0;
spin_lock_irqsave(&b->bm_lock, flags);
if (BM_DONT_TEST & b->bm_flags)
bm_print_lock_info(mdev);
if (bitnr < b->bm_bits) {
p_addr = bm_map_pidx(b, bm_bit_to_page_idx(b, bitnr));
i = test_bit_le(bitnr & BITS_PER_PAGE_MASK, p_addr) ? 1 : 0;
bm_unmap(p_addr);
} else if (bitnr == b->bm_bits) {
i = -1;
} else { /* (bitnr > b->bm_bits) */
dev_err(DEV, "bitnr=%lu > bm_bits=%lu\n", bitnr, b->bm_bits);
i = 0;
}
spin_unlock_irqrestore(&b->bm_lock, flags);
return i;
}
/* returns number of bits set in the range [s, e] */
int drbd_bm_count_bits(struct drbd_conf *mdev, const unsigned long s, const unsigned long e)
{
unsigned long flags;
struct drbd_bitmap *b = mdev->bitmap;
unsigned long *p_addr = NULL;
unsigned long bitnr;
unsigned int page_nr = -1U;
int c = 0;
/* If this is called without a bitmap, that is a bug. But just to be
* robust in case we screwed up elsewhere, in that case pretend there
* was one dirty bit in the requested area, so we won't try to do a
* local read there (no bitmap probably implies no disk) */
if (!expect(b))
return 1;
if (!expect(b->bm_pages))
return 1;
spin_lock_irqsave(&b->bm_lock, flags);
if (BM_DONT_TEST & b->bm_flags)
bm_print_lock_info(mdev);
for (bitnr = s; bitnr <= e; bitnr++) {
unsigned int idx = bm_bit_to_page_idx(b, bitnr);
if (page_nr != idx) {
page_nr = idx;
if (p_addr)
bm_unmap(p_addr);
p_addr = bm_map_pidx(b, idx);
}
if (expect(bitnr < b->bm_bits))
c += (0 != test_bit_le(bitnr - (page_nr << (PAGE_SHIFT+3)), p_addr));
else
dev_err(DEV, "bitnr=%lu bm_bits=%lu\n", bitnr, b->bm_bits);
}
if (p_addr)
bm_unmap(p_addr);
spin_unlock_irqrestore(&b->bm_lock, flags);
return c;
}
/* inherently racy...
* return value may be already out-of-date when this function returns.
* but the general usage is that this is only use during a cstate when bits are
* only cleared, not set, and typically only care for the case when the return
* value is zero, or we already "locked" this "bitmap extent" by other means.
*
* enr is bm-extent number, since we chose to name one sector (512 bytes)
* worth of the bitmap a "bitmap extent".
*
* TODO
* I think since we use it like a reference count, we should use the real
* reference count of some bitmap extent element from some lru instead...
*
*/
int drbd_bm_e_weight(struct drbd_conf *mdev, unsigned long enr)
{
struct drbd_bitmap *b = mdev->bitmap;
int count, s, e;
unsigned long flags;
unsigned long *p_addr, *bm;
if (!expect(b))
return 0;
if (!expect(b->bm_pages))
return 0;
spin_lock_irqsave(&b->bm_lock, flags);
if (BM_DONT_TEST & b->bm_flags)
bm_print_lock_info(mdev);
s = S2W(enr);
e = min((size_t)S2W(enr+1), b->bm_words);
count = 0;
if (s < b->bm_words) {
int n = e-s;
p_addr = bm_map_pidx(b, bm_word_to_page_idx(b, s));
bm = p_addr + MLPP(s);
while (n--)
count += hweight_long(*bm++);
bm_unmap(p_addr);
} else {
dev_err(DEV, "start offset (%d) too large in drbd_bm_e_weight\n", s);
}
spin_unlock_irqrestore(&b->bm_lock, flags);
return count;
}