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Subject[PATCH 03/12] DRBD: bitmap
Date
DRBD maintains a dirty bitmap in case it has to run without peer node or
without local disk. Writes to the on disk dirty bitmap are minimized by the
activity log (=AL). Each time an extent is evicted from the AL the part of
the bitmap no longer covered by the AL is written to disk.

---
diff -uNrp linux-2.6.29-rc8/drivers/block/drbd/drbd_bitmap.c linux-2.6.29-rc8-drbd/drivers/block/drbd/drbd_bitmap.c
--- linux-2.6.29-rc8/drivers/block/drbd/drbd_bitmap.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.29-rc8-drbd/drivers/block/drbd/drbd_bitmap.c 2009-03-23 11:25:50.336173000 +0100
@@ -0,0 +1,1266 @@
+/*
+-*- linux-c -*-
+ drbd_bitmap.c
+ Kernel module for 2.6.x Kernels
+
+ 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 "drbd_int.h"
+
+/* OPAQUE outside this file!
+ * interface defined in drbd_int.h
+
+ * convetion:
+ * function name drbd_bm_... => used elsewhere, "public".
+ * function name bm_... => internal to implementation, "private".
+
+ * Note that since find_first_bit returns int, at the current granularity of
+ * the bitmap (4KB per byte), this implementation "only" supports up to
+ * 1<<(32+12) == 16 TB...
+ */
+
+/*
+ * 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;
+ /* WARNING unsigned long bm_fo and friends:
+ * 32bit number of bit offset is just enough for 512 MB bitmap.
+ * it will blow up if we make the bitmap bigger...
+ * not that it makes much sense to have a bitmap that large,
+ * rather change the granularity to 16k or 64k or something.
+ * (that implies other problems, however...)
+ */
+ unsigned long bm_fo; /* next offset for drbd_bm_find_next */
+ 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 semaphore bm_change; /* serializes resize operations */
+
+ atomic_t bm_async_io;
+ wait_queue_head_t bm_io_wait;
+
+ unsigned long bm_flags;
+
+ /* debugging aid, in case we are still racy somewhere */
+ char *bm_why;
+ struct task_struct *bm_task;
+};
+
+/* definition of bits in bm_flags */
+#define BM_LOCKED 0
+#define BM_MD_IO_ERROR (BITS_PER_LONG-1) /* 31? 63? */
+
+static inline int bm_is_locked(struct drbd_bitmap *b)
+{
+ return test_bit(BM_LOCKED, &b->bm_flags);
+}
+
+#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 (!DRBD_ratelimit(5*HZ, 5))
+ return;
+ ERR("FIXME %s in %s, bitmap locked for '%s' by %s\n",
+ current == mdev->receiver.task ? "receiver" :
+ current == mdev->asender.task ? "asender" :
+ current == mdev->worker.task ? "worker" : current->comm,
+ func, b->bm_why ?: "?",
+ b->bm_task == mdev->receiver.task ? "receiver" :
+ b->bm_task == mdev->asender.task ? "asender" :
+ b->bm_task == mdev->worker.task ? "worker" : "?");
+}
+
+void drbd_bm_lock(struct drbd_conf *mdev, char *why)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+ int trylock_failed;
+
+ if (!b) {
+ ERR("FIXME no bitmap in drbd_bm_lock!?\n");
+ return;
+ }
+
+ trylock_failed = down_trylock(&b->bm_change);
+
+ if (trylock_failed) {
+ DBG("%s going to '%s' but bitmap already locked for '%s' by %s\n",
+ current == mdev->receiver.task ? "receiver" :
+ current == mdev->asender.task ? "asender" :
+ current == mdev->worker.task ? "worker" : "?",
+ why, b->bm_why ?: "?",
+ b->bm_task == mdev->receiver.task ? "receiver" :
+ b->bm_task == mdev->asender.task ? "asender" :
+ b->bm_task == mdev->worker.task ? "worker" : "?");
+ down(&b->bm_change);
+ }
+ if (__test_and_set_bit(BM_LOCKED, &b->bm_flags))
+ ERR("FIXME bitmap already locked in bm_lock\n");
+
+ b->bm_why = why;
+ b->bm_task = current;
+}
+
+void drbd_bm_unlock(struct drbd_conf *mdev)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+ if (!b) {
+ ERR("FIXME no bitmap in drbd_bm_unlock!?\n");
+ return;
+ }
+
+ if (!__test_and_clear_bit(BM_LOCKED, &mdev->bitmap->bm_flags))
+ ERR("FIXME bitmap not locked in bm_unlock\n");
+
+ b->bm_why = NULL;
+ b->bm_task = NULL;
+ up(&b->bm_change);
+}
+
+#define bm_end_info(ignored...) ((void)(0))
+
+#if 0
+#define catch_oob_access_start() do { \
+ do { \
+ if ((bm-p_addr) >= PAGE_SIZE/sizeof(long)) { \
+ printk(KERN_ALERT "drbd_bitmap.c:%u %s: p_addr:%p bm:%p %d\n", \
+ __LINE__ , __func__ , p_addr, bm, (bm-p_addr)); \
+ break; \
+ }
+#define catch_oob_access_end() \
+ } while (0); } while (0)
+#else
+#define catch_oob_access_start() do {
+#define catch_oob_access_end() } while (0)
+#endif
+
+/* word offset to long pointer */
+STATIC unsigned long *bm_map_paddr(struct drbd_bitmap *b, unsigned long offset)
+{
+ struct page *page;
+ unsigned long page_nr;
+
+ /* page_nr = (word*sizeof(long)) >> PAGE_SHIFT; */
+ page_nr = offset >> (PAGE_SHIFT - LN2_BPL + 3);
+ BUG_ON(page_nr >= b->bm_number_of_pages);
+ page = b->bm_pages[page_nr];
+
+ return (unsigned long *) kmap_atomic(page, KM_IRQ1);
+}
+
+STATIC void bm_unmap(unsigned long *p_addr)
+{
+ kunmap_atomic(p_addr, KM_IRQ1);
+};
+
+/* long word offset of _bitmap_ sector */
+#define S2W(s) ((s)<<(BM_EXT_SIZE_B-BM_BLOCK_SIZE_B-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 optimze 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;
+ }
+}
+
+/*
+ * "have" and "want" are NUMBER OF PAGES.
+ */
+STATIC struct page **bm_realloc_pages(struct page **old_pages,
+ unsigned long have,
+ unsigned long want)
+{
+ struct page **new_pages, *page;
+ unsigned int i, bytes;
+
+ BUG_ON(have == 0 && old_pages != NULL);
+ BUG_ON(have != 0 && old_pages == NULL);
+
+ if (have == want)
+ return old_pages;
+
+ /* To use kmalloc here is ok, as long as we support 4TB at max...
+ * otherwise this might become bigger than 128KB, which is
+ * the maximum for kmalloc.
+ *
+ * no, it is not: on 64bit boxes, sizeof(void*) == 8,
+ * 128MB bitmap @ 4K pages -> 256K of page pointers.
+ * ==> use vmalloc for now again.
+ * then again, we could do something like
+ * if (nr_pages > watermark) vmalloc else kmalloc :*> ...
+ * or do cascading page arrays:
+ * one page for the page array of the page array,
+ * those pages for the real bitmap pages.
+ * there we could even add some optimization members,
+ * so we won't need to kmap_atomic in bm_find_next_bit just to see
+ * that the page has no bits set ...
+ * or we can try a "huge" page ;-)
+ */
+ bytes = sizeof(struct page *)*want;
+ new_pages = vmalloc(bytes);
+ if (!new_pages)
+ return NULL;
+
+ memset(new_pages, 0, bytes);
+ if (want >= have) {
+ for (i = 0; i < have; i++)
+ new_pages[i] = old_pages[i];
+ for (; i < want; i++) {
+ page = alloc_page(GFP_HIGHUSER);
+ if (!page) {
+ bm_free_pages(new_pages + have, i - have);
+ vfree(new_pages);
+ return NULL;
+ }
+ 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);
+ */
+ }
+
+ 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);
+ init_MUTEX(&b->bm_change);
+ init_waitqueue_head(&b->bm_io_wait);
+
+ mdev->bitmap = b;
+
+ return 0;
+}
+
+sector_t drbd_bm_capacity(struct drbd_conf *mdev)
+{
+ ERR_IF(!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)
+{
+ ERR_IF (!mdev->bitmap) return;
+ bm_free_pages(mdev->bitmap->bm_pages, mdev->bitmap->bm_number_of_pages);
+ vfree(mdev->bitmap->bm_pages);
+ kfree(mdev->bitmap);
+ mdev->bitmap = NULL;
+}
+
+/*
+ * since (b->bm_bits % BITS_PER_LONG) != 0,
+ * this masks out the remaining bits.
+ * Rerturns the number of bits cleared.
+ */
+STATIC int bm_clear_surplus(struct drbd_bitmap *b)
+{
+ const unsigned long mask = (1UL << (b->bm_bits & (BITS_PER_LONG-1))) - 1;
+ size_t w = b->bm_bits >> LN2_BPL;
+ int cleared = 0;
+ unsigned long *p_addr, *bm;
+
+ p_addr = bm_map_paddr(b, w);
+ bm = p_addr + MLPP(w);
+ if (w < b->bm_words) {
+ catch_oob_access_start();
+ cleared = hweight_long(*bm & ~mask);
+ *bm &= mask;
+ catch_oob_access_end();
+ w++; bm++;
+ }
+
+ if (w < b->bm_words) {
+ catch_oob_access_start();
+ cleared += hweight_long(*bm);
+ *bm = 0;
+ catch_oob_access_end();
+ }
+ bm_unmap(p_addr);
+ return cleared;
+}
+
+STATIC void bm_set_surplus(struct drbd_bitmap *b)
+{
+ const unsigned long mask = (1UL << (b->bm_bits & (BITS_PER_LONG-1))) - 1;
+ size_t w = b->bm_bits >> LN2_BPL;
+ unsigned long *p_addr, *bm;
+
+ p_addr = bm_map_paddr(b, w);
+ bm = p_addr + MLPP(w);
+ if (w < b->bm_words) {
+ catch_oob_access_start();
+ *bm |= ~mask;
+ bm++; w++;
+ catch_oob_access_end();
+ }
+
+ if (w < b->bm_words) {
+ catch_oob_access_start();
+ *bm = ~(0UL);
+ catch_oob_access_end();
+ }
+ bm_unmap(p_addr);
+}
+
+STATIC unsigned long __bm_count_bits(struct drbd_bitmap *b, const int swap_endian)
+{
+ unsigned long *p_addr, *bm, offset = 0;
+ unsigned long bits = 0;
+ unsigned long i, do_now;
+
+ while (offset < b->bm_words) {
+ i = do_now = min_t(size_t, b->bm_words-offset, LWPP);
+ p_addr = bm_map_paddr(b, offset);
+ bm = p_addr + MLPP(offset);
+ while (i--) {
+ catch_oob_access_start();
+#ifndef __LITTLE_ENDIAN
+ if (swap_endian)
+ *bm = lel_to_cpu(*bm);
+#endif
+ bits += hweight_long(*bm++);
+ catch_oob_access_end();
+ }
+ bm_unmap(p_addr);
+ offset += do_now;
+ }
+
+ return bits;
+}
+
+static inline unsigned long bm_count_bits(struct drbd_bitmap *b)
+{
+ return __bm_count_bits(b, 0);
+}
+
+static inline unsigned long bm_count_bits_swap_endian(struct drbd_bitmap *b)
+{
+ return __bm_count_bits(b, 1);
+}
+
+void _drbd_bm_recount_bits(struct drbd_conf *mdev, char *file, int line)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+ unsigned long flags, bits;
+
+ ERR_IF(!b) return;
+
+ /* IMO this should be inside drbd_bm_lock/unlock.
+ * Unfortunately it is used outside of the locks.
+ * And I'm not yet sure where we need to place the
+ * lock/unlock correctly.
+ */
+
+ spin_lock_irqsave(&b->bm_lock, flags);
+ bits = bm_count_bits(b);
+ if (bits != b->bm_set) {
+ ERR("bm_set was %lu, corrected to %lu. %s:%d\n",
+ b->bm_set, bits, file, line);
+ b->bm_set = bits;
+ }
+ spin_unlock_irqrestore(&b->bm_lock, flags);
+}
+
+/* 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;
+ size_t do_now, end;
+
+#define BM_SECTORS_PER_BIT (BM_BLOCK_SIZE/512)
+
+ 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;
+ p_addr = bm_map_paddr(b, offset);
+ bm = p_addr + MLPP(offset);
+ catch_oob_access_start();
+ 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);
+ break; /* breaks to after catch_oob_access_end() only! */
+ }
+ memset(bm, c, do_now * sizeof(long));
+ catch_oob_access_end();
+ bm_unmap(p_addr);
+ offset += do_now;
+ }
+}
+
+/*
+ * make sure the bitmap has enough room for the attached storage,
+ * if neccessary, 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 initiallized to all bits set.
+ */
+int drbd_bm_resize(struct drbd_conf *mdev, sector_t capacity)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+ unsigned long bits, words, owords, obits, *p_addr, *bm;
+ unsigned long want, have, onpages; /* number of pages */
+ struct page **npages, **opages = NULL;
+ int err = 0, growing;
+
+ ERR_IF(!b) return -ENOMEM;
+
+ drbd_bm_lock(mdev, "resize");
+
+ INFO("drbd_bm_resize called with capacity == %llu\n",
+ (unsigned long long)capacity);
+
+ if (capacity == b->bm_dev_capacity)
+ goto out;
+
+ 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_fo =
+ 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);
+ vfree(opages);
+ 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 (inc_local(mdev)) {
+ D_ASSERT((u64)bits <= (((u64)mdev->bc->md.md_size_sect-MD_BM_OFFSET) << 12));
+ dec_local(mdev);
+ }
+
+ /* one extra long to catch off by one errors */
+ want = ALIGN((words+1)*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
+ npages = bm_realloc_pages(b->bm_pages, have, 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)
+ 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) {
+ bm_memset(b, owords, 0xff, words-owords);
+ b->bm_set += bits - obits;
+ }
+
+ if (want < have) {
+ /* implicit: (opages != NULL) && (opages != npages) */
+ bm_free_pages(opages + want, have - want);
+ }
+
+ p_addr = bm_map_paddr(b, words);
+ bm = p_addr + MLPP(words);
+ catch_oob_access_start();
+ *bm = DRBD_MAGIC;
+ catch_oob_access_end();
+ bm_unmap(p_addr);
+
+ (void)bm_clear_surplus(b);
+ if (!growing)
+ b->bm_set = bm_count_bits(b);
+
+ bm_end_info(mdev, __func__);
+ spin_unlock_irq(&b->bm_lock);
+ if (opages != npages)
+ vfree(opages);
+ INFO("resync bitmap: bits=%lu words=%lu\n", bits, words);
+
+ 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 I don't have a disk, I don't know about out-of-sync status */
+ if (!inc_local_if_state(mdev, Negotiating))
+ return 0;
+
+ ERR_IF(!b) return 0;
+ ERR_IF(!b->bm_pages) return 0;
+
+ spin_lock_irqsave(&b->bm_lock, flags);
+ s = b->bm_set;
+ spin_unlock_irqrestore(&b->bm_lock, flags);
+
+ dec_local(mdev);
+
+ return s;
+}
+
+size_t drbd_bm_words(struct drbd_conf *mdev)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+ ERR_IF(!b) return 0;
+ ERR_IF(!b->bm_pages) return 0;
+
+ return b->bm_words;
+}
+
+unsigned long drbd_bm_bits(struct drbd_conf *mdev)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+ ERR_IF(!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;
+ size_t end, do_now;
+
+ end = offset + number;
+
+ ERR_IF(!b) return;
+ ERR_IF(!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;
+ p_addr = bm_map_paddr(b, offset);
+ bm = p_addr + MLPP(offset);
+ offset += do_now;
+ while (do_now--) {
+ catch_oob_access_start();
+ bits = hweight_long(*bm);
+ word = *bm | lel_to_cpu(*buffer++);
+ *bm++ = word;
+ b->bm_set += hweight_long(word) - bits;
+ catch_oob_access_end();
+ }
+ bm_unmap(p_addr);
+ }
+ /* 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);
+ bm_end_info(mdev, __func__);
+ }
+ 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;
+
+ ERR_IF(!b) return;
+ ERR_IF(!b->bm_pages) return;
+
+ spin_lock_irq(&b->bm_lock);
+ if ((offset >= b->bm_words) ||
+ (end > b->bm_words) ||
+ (number <= 0))
+ ERR("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_paddr(b, offset);
+ bm = p_addr + MLPP(offset);
+ offset += do_now;
+ while (do_now--) {
+ catch_oob_access_start();
+ *buffer++ = cpu_to_lel(*bm++);
+ catch_oob_access_end();
+ }
+ 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;
+ ERR_IF(!b) return;
+ ERR_IF(!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;
+ ERR_IF(!b) return;
+ ERR_IF(!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);
+}
+
+static void bm_async_io_complete(struct bio *bio, int error)
+{
+ struct drbd_bitmap *b = bio->bi_private;
+ int uptodate = bio_flagged(bio, BIO_UPTODATE);
+
+
+ /* strange behaviour 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 (error) {
+ /* doh. what now?
+ * for now, set all bits, and flag MD_IO_ERROR */
+ __set_bit(BM_MD_IO_ERROR, &b->bm_flags);
+ }
+ if (atomic_dec_and_test(&b->bm_async_io))
+ wake_up(&b->bm_io_wait);
+
+ bio_put(bio);
+}
+
+STATIC void bm_page_io_async(struct drbd_conf *mdev, struct drbd_bitmap *b, int page_nr, int rw) __must_hold(local)
+{
+ /* we are process context. we always get a bio */
+ struct bio *bio = bio_alloc(GFP_KERNEL, 1);
+ unsigned int len;
+ sector_t on_disk_sector =
+ mdev->bc->md.md_offset + mdev->bc->md.bm_offset;
+ on_disk_sector += ((sector_t)page_nr) << (PAGE_SHIFT-9);
+
+ /* this might happen with very small
+ * flexible external meta data device */
+ len = min_t(unsigned int, PAGE_SIZE,
+ (drbd_md_last_sector(mdev->bc) - on_disk_sector + 1)<<9);
+
+ bio->bi_bdev = mdev->bc->md_bdev;
+ bio->bi_sector = on_disk_sector;
+ bio_add_page(bio, b->bm_pages[page_nr], len, 0);
+ bio->bi_private = b;
+ bio->bi_end_io = bm_async_io_complete;
+
+ if (FAULT_ACTIVE(mdev, (rw & WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD)) {
+ bio->bi_rw |= rw;
+ bio_endio(bio, -EIO);
+ } else {
+ submit_bio(rw, bio);
+ }
+}
+
+# if defined(__LITTLE_ENDIAN)
+ /* nothing to do, on disk == in memory */
+# define bm_cpu_to_lel(x) ((void)0)
+# else
+void bm_cpu_to_lel(struct drbd_bitmap *b)
+{
+ /* need to cpu_to_lel all the pages ...
+ * this may be optimized by using
+ * cpu_to_lel(-1) == -1 and cpu_to_lel(0) == 0;
+ * the following is still not optimal, but better than nothing */
+ if (b->bm_set == 0) {
+ /* no page at all; avoid swap if all is 0 */
+ i = b->bm_number_of_pages;
+ } else if (b->bm_set == b->bm_bits) {
+ /* only the last page */
+ i = b->bm_number_of_pages - 1;
+ } else {
+ /* all pages */
+ i = 0;
+ }
+ for (; i < b->bm_number_of_pages; i++) {
+ unsigned long *bm;
+ /* if you'd want to use kmap_atomic, you'd have to disable irq! */
+ p_addr = kmap(b->bm_pages[i]);
+ for (bm = p_addr; bm < p_addr + PAGE_SIZE/sizeof(long); bm++)
+ *bm = cpu_to_lel(*bm);
+ kunmap(p_addr);
+ }
+}
+# endif
+/* lel_to_cpu == cpu_to_lel */
+# define bm_lel_to_cpu(x) bm_cpu_to_lel(x)
+
+/*
+ * bm_rw: read/write the whole bitmap from/to its on disk location.
+ */
+STATIC int bm_rw(struct drbd_conf *mdev, int rw) __must_hold(local)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+ /* sector_t sector; */
+ int bm_words, num_pages, i;
+ unsigned long now;
+ char ppb[10];
+ int err = 0;
+
+ WARN_ON(!bm_is_locked(b));
+
+ /* no spinlock here, the drbd_bm_lock should be enough! */
+
+ bm_words = drbd_bm_words(mdev);
+ num_pages = (bm_words*sizeof(long) + PAGE_SIZE-1) >> PAGE_SHIFT;
+
+ /* on disk bitmap is little endian */
+ if (rw == WRITE)
+ bm_cpu_to_lel(b);
+
+ now = jiffies;
+ atomic_set(&b->bm_async_io, num_pages);
+ __clear_bit(BM_MD_IO_ERROR, &b->bm_flags);
+
+ /* let the layers below us try to merge these bios... */
+ for (i = 0; i < num_pages; i++)
+ bm_page_io_async(mdev, b, i, rw);
+
+ drbd_blk_run_queue(bdev_get_queue(mdev->bc->md_bdev));
+ wait_event(b->bm_io_wait, atomic_read(&b->bm_async_io) == 0);
+
+ MTRACE(TraceTypeMDIO, TraceLvlSummary,
+ INFO("%s of bitmap took %lu jiffies\n",
+ rw == READ ? "reading" : "writing", jiffies - now);
+ );
+
+ if (test_bit(BM_MD_IO_ERROR, &b->bm_flags)) {
+ ALERT("we had at least one MD IO ERROR during bitmap IO\n");
+ drbd_chk_io_error(mdev, 1, TRUE);
+ drbd_io_error(mdev, TRUE);
+ err = -EIO;
+ }
+
+ now = jiffies;
+ if (rw == WRITE) {
+ /* swap back endianness */
+ bm_lel_to_cpu(b);
+ /* flush bitmap to stable storage */
+ drbd_md_flush(mdev);
+ } else /* rw == READ */ {
+ /* just read, if neccessary adjust endianness */
+ b->bm_set = bm_count_bits_swap_endian(b);
+ INFO("recounting of set bits took additional %lu jiffies\n",
+ jiffies - now);
+ }
+ now = b->bm_set;
+
+ INFO("%s (%lu bits) marked out-of-sync by on disk bit-map.\n",
+ ppsize(ppb, now << (BM_BLOCK_SIZE_B-10)), now);
+
+ return err;
+}
+
+/**
+ * drbd_bm_read: Read the whole bitmap from its on disk location.
+ *
+ * currently only called from "drbd_nl_disk_conf"
+ */
+int drbd_bm_read(struct drbd_conf *mdev) __must_hold(local)
+{
+ return bm_rw(mdev, READ);
+}
+
+/**
+ * drbd_bm_write: Write the whole bitmap to its on disk location.
+ *
+ * called at various occasions.
+ */
+int drbd_bm_write(struct drbd_conf *mdev) __must_hold(local)
+{
+ return bm_rw(mdev, WRITE);
+}
+
+/**
+ * drbd_bm_write_sect: Writes a 512 byte piece of the bitmap to its
+ * on disk location. On disk bitmap is little endian.
+ *
+ * @enr: The _sector_ offset from the start of the bitmap.
+ *
+ */
+int drbd_bm_write_sect(struct drbd_conf *mdev, unsigned long enr) __must_hold(local)
+{
+ sector_t on_disk_sector = enr + mdev->bc->md.md_offset
+ + mdev->bc->md.bm_offset;
+ int bm_words, num_words, offset;
+ int err = 0;
+
+ mutex_lock(&mdev->md_io_mutex);
+ bm_words = drbd_bm_words(mdev);
+ offset = S2W(enr); /* word offset into bitmap */
+ num_words = min(S2W(1), bm_words - offset);
+ if (num_words < S2W(1))
+ memset(page_address(mdev->md_io_page), 0, MD_HARDSECT);
+ drbd_bm_get_lel(mdev, offset, num_words,
+ page_address(mdev->md_io_page));
+ if (!drbd_md_sync_page_io(mdev, mdev->bc, on_disk_sector, WRITE)) {
+ int i;
+ err = -EIO;
+ ERR("IO ERROR writing bitmap sector %lu "
+ "(meta-disk sector %llus)\n",
+ enr, (unsigned long long)on_disk_sector);
+ drbd_chk_io_error(mdev, 1, TRUE);
+ drbd_io_error(mdev, TRUE);
+ for (i = 0; i < AL_EXT_PER_BM_SECT; i++)
+ drbd_bm_ALe_set_all(mdev, enr*AL_EXT_PER_BM_SECT+i);
+ }
+ mdev->bm_writ_cnt++;
+ mutex_unlock(&mdev->md_io_mutex);
+ return err;
+}
+
+void drbd_bm_reset_find(struct drbd_conf *mdev)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+
+ ERR_IF(!b) return;
+
+ spin_lock_irq(&b->bm_lock);
+ if (bm_is_locked(b))
+ bm_print_lock_info(mdev);
+ b->bm_fo = 0;
+ spin_unlock_irq(&b->bm_lock);
+
+}
+
+/* NOTE
+ * find_first_bit returns int, we return unsigned long.
+ * should not make much difference anyways, but ...
+ *
+ * this returns a bit number, NOT a sector!
+ */
+#define BPP_MASK ((1UL << (PAGE_SHIFT+3)) - 1)
+unsigned long drbd_bm_find_next(struct drbd_conf *mdev)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+ unsigned long i = -1UL;
+ unsigned long *p_addr;
+ unsigned long bit_offset; /* bit offset of the mapped page. */
+
+ ERR_IF(!b) return i;
+ ERR_IF(!b->bm_pages) return i;
+
+ spin_lock_irq(&b->bm_lock);
+ if (bm_is_locked(b))
+ bm_print_lock_info(mdev);
+ if (b->bm_fo > b->bm_bits) {
+ ERR("bm_fo=%lu bm_bits=%lu\n", b->bm_fo, b->bm_bits);
+ } else {
+ while (b->bm_fo < b->bm_bits) {
+ unsigned long offset;
+ bit_offset = b->bm_fo & ~BPP_MASK; /* bit offset of the page */
+ offset = bit_offset >> LN2_BPL; /* word offset of the page */
+ p_addr = bm_map_paddr(b, offset);
+ i = find_next_bit(p_addr, PAGE_SIZE*8, b->bm_fo & BPP_MASK);
+ bm_unmap(p_addr);
+ if (i < PAGE_SIZE*8) {
+ i = bit_offset + i;
+ if (i >= b->bm_bits)
+ break;
+ b->bm_fo = i+1;
+ goto found;
+ }
+ b->bm_fo = bit_offset + PAGE_SIZE*8;
+ }
+ i = -1UL;
+ b->bm_fo = b->bm_bits;
+ /* Set bm_fo to after bitmap, such that
+ * subsequent calls always return -1
+ */
+ }
+ found:
+ spin_unlock_irq(&b->bm_lock);
+ return i;
+}
+
+void drbd_bm_set_find(struct drbd_conf *mdev, unsigned long i)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+
+ spin_lock_irq(&b->bm_lock);
+
+ b->bm_fo = min_t(unsigned long, i, b->bm_bits);
+
+ spin_unlock_irq(&b->bm_lock);
+}
+
+int drbd_bm_rs_done(struct drbd_conf *mdev)
+{
+ D_ASSERT(mdev->bitmap);
+ return mdev->bitmap->bm_fo >= mdev->bitmap->bm_bits;
+}
+
+/* returns number of bits actually changed.
+ * for val != 0, we change 0 -> 1, return code positiv
+ * 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;
+ unsigned long *p_addr = NULL;
+ unsigned long bitnr;
+ unsigned long last_page_nr = -1UL;
+ int c = 0;
+
+ ERR_IF(!b) return 1;
+ ERR_IF(!b->bm_pages) return 0;
+
+ spin_lock_irqsave(&b->bm_lock, flags);
+ if (bm_is_locked(b))
+ bm_print_lock_info(mdev);
+ for (bitnr = s; bitnr <= e; bitnr++) {
+ ERR_IF (bitnr >= b->bm_bits) {
+ ERR("bitnr=%lu bm_bits=%lu\n", bitnr, b->bm_bits);
+ } else {
+ unsigned long offset = bitnr>>LN2_BPL;
+ unsigned long page_nr = offset >> (PAGE_SHIFT - LN2_BPL + 3);
+ if (page_nr != last_page_nr) {
+ if (p_addr)
+ bm_unmap(p_addr);
+ p_addr = bm_map_paddr(b, offset);
+ last_page_nr = page_nr;
+ }
+ if (val)
+ c += (0 == __test_and_set_bit(bitnr & BPP_MASK, p_addr));
+ else
+ c -= (0 != __test_and_clear_bit(bitnr & BPP_MASK, p_addr));
+ }
+ }
+ if (p_addr)
+ bm_unmap(p_addr);
+ b->bm_set += c;
+ 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);
+}
+
+/* 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;
+
+ ERR_IF(!b) return 0;
+ ERR_IF(!b->bm_pages) return 0;
+
+ spin_lock_irqsave(&b->bm_lock, flags);
+ if (bm_is_locked(b))
+ bm_print_lock_info(mdev);
+ if (bitnr < b->bm_bits) {
+ unsigned long offset = bitnr>>LN2_BPL;
+ p_addr = bm_map_paddr(b, offset);
+ i = test_bit(bitnr & BPP_MASK, p_addr) ? 1 : 0;
+ bm_unmap(p_addr);
+ } else if (bitnr == b->bm_bits) {
+ i = -1;
+ } else { /* (bitnr > b->bm_bits) */
+ ERR("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 */
+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, page_nr = -1;
+ unsigned long bitnr;
+ int c = 0;
+ size_t w;
+
+ /* 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) */
+ ERR_IF(!b) return 1;
+ ERR_IF(!b->bm_pages) return 1;
+
+ spin_lock_irqsave(&b->bm_lock, flags);
+ for (bitnr = s; bitnr <= e; bitnr++) {
+ w = bitnr >> LN2_BPL;
+ if (page_nr != w >> (PAGE_SHIFT - LN2_BPL + 3)) {
+ page_nr = w >> (PAGE_SHIFT - LN2_BPL + 3);
+ if (p_addr)
+ bm_unmap(p_addr);
+ p_addr = bm_map_paddr(b, w);
+ }
+ ERR_IF (bitnr >= b->bm_bits) {
+ ERR("bitnr=%lu bm_bits=%lu\n", bitnr, b->bm_bits);
+ } else {
+ c += (0 != test_bit(bitnr - (page_nr << (PAGE_SHIFT+3)), p_addr));
+ }
+ }
+ 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;
+
+ ERR_IF(!b) return 0;
+ ERR_IF(!b->bm_pages) return 0;
+
+ spin_lock_irqsave(&b->bm_lock, flags);
+ if (bm_is_locked(b))
+ 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_paddr(b, s);
+ bm = p_addr + MLPP(s);
+ while (n--) {
+ catch_oob_access_start();
+ count += hweight_long(*bm++);
+ catch_oob_access_end();
+ }
+ bm_unmap(p_addr);
+ } else {
+ ERR("start offset (%d) too large in drbd_bm_e_weight\n", s);
+ }
+ spin_unlock_irqrestore(&b->bm_lock, flags);
+ return count;
+}
+
+/* set all bits covered by the AL-extent al_enr */
+unsigned long drbd_bm_ALe_set_all(struct drbd_conf *mdev, unsigned long al_enr)
+{
+ struct drbd_bitmap *b = mdev->bitmap;
+ unsigned long *p_addr, *bm;
+ unsigned long weight;
+ int count, s, e, i, do_now;
+ ERR_IF(!b) return 0;
+ ERR_IF(!b->bm_pages) return 0;
+
+ spin_lock_irq(&b->bm_lock);
+ if (bm_is_locked(b))
+ bm_print_lock_info(mdev);
+ weight = b->bm_set;
+
+ s = al_enr * BM_WORDS_PER_AL_EXT;
+ e = min_t(size_t, s + BM_WORDS_PER_AL_EXT, b->bm_words);
+ /* assert that s and e are on the same page */
+ D_ASSERT((e-1) >> (PAGE_SHIFT - LN2_BPL + 3)
+ == s >> (PAGE_SHIFT - LN2_BPL + 3));
+ count = 0;
+ if (s < b->bm_words) {
+ i = do_now = e-s;
+ p_addr = bm_map_paddr(b, s);
+ bm = p_addr + MLPP(s);
+ while (i--) {
+ catch_oob_access_start();
+ count += hweight_long(*bm);
+ *bm = -1UL;
+ catch_oob_access_end();
+ bm++;
+ }
+ bm_unmap(p_addr);
+ b->bm_set += do_now*BITS_PER_LONG - count;
+ if (e == b->bm_words)
+ b->bm_set -= bm_clear_surplus(b);
+ } else {
+ ERR("start offset (%d) too large in drbd_bm_ALe_set_all\n", s);
+ }
+ weight = b->bm_set - weight;
+ spin_unlock_irq(&b->bm_lock);
+ return weight;
+}

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