1 // SPDX-License-Identifier: GPL-2.0-or-later
5 This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
7 Copyright (C) 2004-2008, LINBIT Information Technologies GmbH.
8 Copyright (C) 2004-2008, Philipp Reisner <philipp.reisner@linbit.com>.
9 Copyright (C) 2004-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 #include <linux/bitmap.h>
16 #include <linux/vmalloc.h>
17 #include <linux/string.h>
18 #include <linux/drbd.h>
19 #include <linux/slab.h>
20 #include <linux/highmem.h>
25 /* OPAQUE outside this file!
26 * interface defined in drbd_int.h
29 * function name drbd_bm_... => used elsewhere, "public".
30 * function name bm_... => internal to implementation, "private".
36 * We want to support >= peta byte of backend storage, while for now still using
37 * a granularity of one bit per 4KiB of storage.
38 * 1 << 50 bytes backend storage (1 PiB)
39 * 1 << (50 - 12) bits needed
40 * 38 --> we need u64 to index and count bits
41 * 1 << (38 - 3) bitmap bytes needed
42 * 35 --> we still need u64 to index and count bytes
43 * (that's 32 GiB of bitmap for 1 PiB storage)
44 * 1 << (35 - 2) 32bit longs needed
45 * 33 --> we'd even need u64 to index and count 32bit long words.
46 * 1 << (35 - 3) 64bit longs needed
47 * 32 --> we could get away with a 32bit unsigned int to index and count
48 * 64bit long words, but I rather stay with unsigned long for now.
49 * We probably should neither count nor point to bytes or long words
50 * directly, but either by bitnumber, or by page index and offset.
52 * 22 --> we need that much 4KiB pages of bitmap.
53 * 1 << (22 + 3) --> on a 64bit arch,
54 * we need 32 MiB to store the array of page pointers.
56 * Because I'm lazy, and because the resulting patch was too large, too ugly
57 * and still incomplete, on 32bit we still "only" support 16 TiB (minus some),
58 * (1 << 32) bits * 4k storage.
61 * bitmap storage and IO:
62 * Bitmap is stored little endian on disk, and is kept little endian in
63 * core memory. Currently we still hold the full bitmap in core as long
64 * as we are "attached" to a local disk, which at 32 GiB for 1PiB storage
67 * We plan to reduce the amount of in-core bitmap pages by paging them in
68 * and out against their on-disk location as necessary, but need to make
69 * sure we don't cause too much meta data IO, and must not deadlock in
70 * tight memory situations. This needs some more work.
75 * Access to the *bm_pages is protected by bm_lock.
76 * It is safe to read the other members within the lock.
78 * drbd_bm_set_bits is called from bio_endio callbacks,
79 * We may be called with irq already disabled,
80 * so we need spin_lock_irqsave().
81 * And we need the kmap_atomic.
84 struct page **bm_pages;
87 /* exclusively to be used by __al_write_transaction(),
88 * drbd_bm_mark_for_writeout() and
89 * and drbd_bm_write_hinted() -> bm_rw() called from there.
91 unsigned int n_bitmap_hints;
92 unsigned int al_bitmap_hints[AL_UPDATES_PER_TRANSACTION];
94 /* see LIMITATIONS: above */
96 unsigned long bm_set; /* nr of set bits; THINK maybe atomic_t? */
97 unsigned long bm_bits;
99 size_t bm_number_of_pages;
100 sector_t bm_dev_capacity;
101 struct mutex bm_change; /* serializes resize operations */
103 wait_queue_head_t bm_io_wait; /* used to serialize IO of single pages */
105 enum bm_flag bm_flags;
107 /* debugging aid, in case we are still racy somewhere */
109 struct task_struct *bm_task;
112 #define bm_print_lock_info(m) __bm_print_lock_info(m, __func__)
113 static void __bm_print_lock_info(struct drbd_device *device, const char *func)
115 struct drbd_bitmap *b = device->bitmap;
116 if (!__ratelimit(&drbd_ratelimit_state))
118 drbd_err(device, "FIXME %s[%d] in %s, bitmap locked for '%s' by %s[%d]\n",
119 current->comm, task_pid_nr(current),
120 func, b->bm_why ?: "?",
121 b->bm_task->comm, task_pid_nr(b->bm_task));
124 void drbd_bm_lock(struct drbd_device *device, char *why, enum bm_flag flags)
126 struct drbd_bitmap *b = device->bitmap;
130 drbd_err(device, "FIXME no bitmap in drbd_bm_lock!?\n");
134 trylock_failed = !mutex_trylock(&b->bm_change);
136 if (trylock_failed) {
137 drbd_warn(device, "%s[%d] going to '%s' but bitmap already locked for '%s' by %s[%d]\n",
138 current->comm, task_pid_nr(current),
139 why, b->bm_why ?: "?",
140 b->bm_task->comm, task_pid_nr(b->bm_task));
141 mutex_lock(&b->bm_change);
143 if (BM_LOCKED_MASK & b->bm_flags)
144 drbd_err(device, "FIXME bitmap already locked in bm_lock\n");
145 b->bm_flags |= flags & BM_LOCKED_MASK;
148 b->bm_task = current;
151 void drbd_bm_unlock(struct drbd_device *device)
153 struct drbd_bitmap *b = device->bitmap;
155 drbd_err(device, "FIXME no bitmap in drbd_bm_unlock!?\n");
159 if (!(BM_LOCKED_MASK & device->bitmap->bm_flags))
160 drbd_err(device, "FIXME bitmap not locked in bm_unlock\n");
162 b->bm_flags &= ~BM_LOCKED_MASK;
165 mutex_unlock(&b->bm_change);
168 /* we store some "meta" info about our pages in page->private */
169 /* at a granularity of 4k storage per bitmap bit:
170 * one peta byte storage: 1<<50 byte, 1<<38 * 4k storage blocks
172 * 1<<23 4k bitmap pages.
173 * Use 24 bits as page index, covers 2 peta byte storage
174 * at a granularity of 4k per bit.
175 * Used to report the failed page idx on io error from the endio handlers.
177 #define BM_PAGE_IDX_MASK ((1UL<<24)-1)
178 /* this page is currently read in, or written back */
179 #define BM_PAGE_IO_LOCK 31
180 /* if there has been an IO error for this page */
181 #define BM_PAGE_IO_ERROR 30
182 /* this is to be able to intelligently skip disk IO,
183 * set if bits have been set since last IO. */
184 #define BM_PAGE_NEED_WRITEOUT 29
185 /* to mark for lazy writeout once syncer cleared all clearable bits,
186 * we if bits have been cleared since last IO. */
187 #define BM_PAGE_LAZY_WRITEOUT 28
188 /* pages marked with this "HINT" will be considered for writeout
189 * on activity log transactions */
190 #define BM_PAGE_HINT_WRITEOUT 27
192 /* store_page_idx uses non-atomic assignment. It is only used directly after
193 * allocating the page. All other bm_set_page_* and bm_clear_page_* need to
194 * use atomic bit manipulation, as set_out_of_sync (and therefore bitmap
195 * changes) may happen from various contexts, and wait_on_bit/wake_up_bit
196 * requires it all to be atomic as well. */
197 static void bm_store_page_idx(struct page *page, unsigned long idx)
199 BUG_ON(0 != (idx & ~BM_PAGE_IDX_MASK));
200 set_page_private(page, idx);
203 static unsigned long bm_page_to_idx(struct page *page)
205 return page_private(page) & BM_PAGE_IDX_MASK;
208 /* As is very unlikely that the same page is under IO from more than one
209 * context, we can get away with a bit per page and one wait queue per bitmap.
211 static void bm_page_lock_io(struct drbd_device *device, int page_nr)
213 struct drbd_bitmap *b = device->bitmap;
214 void *addr = &page_private(b->bm_pages[page_nr]);
215 wait_event(b->bm_io_wait, !test_and_set_bit(BM_PAGE_IO_LOCK, addr));
218 static void bm_page_unlock_io(struct drbd_device *device, int page_nr)
220 struct drbd_bitmap *b = device->bitmap;
221 void *addr = &page_private(b->bm_pages[page_nr]);
222 clear_bit_unlock(BM_PAGE_IO_LOCK, addr);
223 wake_up(&device->bitmap->bm_io_wait);
226 /* set _before_ submit_io, so it may be reset due to being changed
227 * while this page is in flight... will get submitted later again */
228 static void bm_set_page_unchanged(struct page *page)
231 clear_bit(BM_PAGE_NEED_WRITEOUT, &page_private(page));
232 clear_bit(BM_PAGE_LAZY_WRITEOUT, &page_private(page));
235 static void bm_set_page_need_writeout(struct page *page)
237 set_bit(BM_PAGE_NEED_WRITEOUT, &page_private(page));
240 void drbd_bm_reset_al_hints(struct drbd_device *device)
242 device->bitmap->n_bitmap_hints = 0;
246 * drbd_bm_mark_for_writeout() - mark a page with a "hint" to be considered for writeout
247 * @device: DRBD device.
248 * @page_nr: the bitmap page to mark with the "hint" flag
250 * From within an activity log transaction, we mark a few pages with these
251 * hints, then call drbd_bm_write_hinted(), which will only write out changed
252 * pages which are flagged with this mark.
254 void drbd_bm_mark_for_writeout(struct drbd_device *device, int page_nr)
256 struct drbd_bitmap *b = device->bitmap;
258 if (page_nr >= device->bitmap->bm_number_of_pages) {
259 drbd_warn(device, "BAD: page_nr: %u, number_of_pages: %u\n",
260 page_nr, (int)device->bitmap->bm_number_of_pages);
263 page = device->bitmap->bm_pages[page_nr];
264 BUG_ON(b->n_bitmap_hints >= ARRAY_SIZE(b->al_bitmap_hints));
265 if (!test_and_set_bit(BM_PAGE_HINT_WRITEOUT, &page_private(page)))
266 b->al_bitmap_hints[b->n_bitmap_hints++] = page_nr;
269 static int bm_test_page_unchanged(struct page *page)
271 volatile const unsigned long *addr = &page_private(page);
272 return (*addr & ((1UL<<BM_PAGE_NEED_WRITEOUT)|(1UL<<BM_PAGE_LAZY_WRITEOUT))) == 0;
275 static void bm_set_page_io_err(struct page *page)
277 set_bit(BM_PAGE_IO_ERROR, &page_private(page));
280 static void bm_clear_page_io_err(struct page *page)
282 clear_bit(BM_PAGE_IO_ERROR, &page_private(page));
285 static void bm_set_page_lazy_writeout(struct page *page)
287 set_bit(BM_PAGE_LAZY_WRITEOUT, &page_private(page));
290 static int bm_test_page_lazy_writeout(struct page *page)
292 return test_bit(BM_PAGE_LAZY_WRITEOUT, &page_private(page));
295 /* on a 32bit box, this would allow for exactly (2<<38) bits. */
296 static unsigned int bm_word_to_page_idx(struct drbd_bitmap *b, unsigned long long_nr)
298 /* page_nr = (word*sizeof(long)) >> PAGE_SHIFT; */
299 unsigned int page_nr = long_nr >> (PAGE_SHIFT - LN2_BPL + 3);
300 BUG_ON(page_nr >= b->bm_number_of_pages);
304 static unsigned int bm_bit_to_page_idx(struct drbd_bitmap *b, u64 bitnr)
306 /* page_nr = (bitnr/8) >> PAGE_SHIFT; */
307 unsigned int page_nr = bitnr >> (PAGE_SHIFT + 3);
308 BUG_ON(page_nr >= b->bm_number_of_pages);
312 static unsigned long *__bm_map_pidx(struct drbd_bitmap *b, unsigned int idx)
314 struct page *page = b->bm_pages[idx];
315 return (unsigned long *) kmap_atomic(page);
318 static unsigned long *bm_map_pidx(struct drbd_bitmap *b, unsigned int idx)
320 return __bm_map_pidx(b, idx);
323 static void __bm_unmap(unsigned long *p_addr)
325 kunmap_atomic(p_addr);
328 static void bm_unmap(unsigned long *p_addr)
330 return __bm_unmap(p_addr);
333 /* long word offset of _bitmap_ sector */
334 #define S2W(s) ((s)<<(BM_EXT_SHIFT-BM_BLOCK_SHIFT-LN2_BPL))
335 /* word offset from start of bitmap to word number _in_page_
336 * modulo longs per page
337 #define MLPP(X) ((X) % (PAGE_SIZE/sizeof(long))
338 hm, well, Philipp thinks gcc might not optimize the % into & (... - 1)
341 #define MLPP(X) ((X) & ((PAGE_SIZE/sizeof(long))-1))
343 /* Long words per page */
344 #define LWPP (PAGE_SIZE/sizeof(long))
347 * actually most functions herein should take a struct drbd_bitmap*, not a
348 * struct drbd_device*, but for the debug macros I like to have the device around
349 * to be able to report device specific.
353 static void bm_free_pages(struct page **pages, unsigned long number)
359 for (i = 0; i < number; i++) {
361 pr_alert("bm_free_pages tried to free a NULL pointer; i=%lu n=%lu\n",
365 __free_page(pages[i]);
370 static inline void bm_vk_free(void *ptr)
376 * "have" and "want" are NUMBER OF PAGES.
378 static struct page **bm_realloc_pages(struct drbd_bitmap *b, unsigned long want)
380 struct page **old_pages = b->bm_pages;
381 struct page **new_pages, *page;
382 unsigned int i, bytes;
383 unsigned long have = b->bm_number_of_pages;
385 BUG_ON(have == 0 && old_pages != NULL);
386 BUG_ON(have != 0 && old_pages == NULL);
391 /* Trying kmalloc first, falling back to vmalloc.
392 * GFP_NOIO, as this is called while drbd IO is "suspended",
393 * and during resize or attach on diskless Primary,
394 * we must not block on IO to ourselves.
395 * Context is receiver thread or dmsetup. */
396 bytes = sizeof(struct page *)*want;
397 new_pages = kzalloc(bytes, GFP_NOIO | __GFP_NOWARN);
399 new_pages = __vmalloc(bytes,
400 GFP_NOIO | __GFP_ZERO,
407 for (i = 0; i < have; i++)
408 new_pages[i] = old_pages[i];
409 for (; i < want; i++) {
410 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
412 bm_free_pages(new_pages + have, i - have);
413 bm_vk_free(new_pages);
416 /* we want to know which page it is
417 * from the endio handlers */
418 bm_store_page_idx(page, i);
422 for (i = 0; i < want; i++)
423 new_pages[i] = old_pages[i];
424 /* NOT HERE, we are outside the spinlock!
425 bm_free_pages(old_pages + want, have - want);
433 * allocates the drbd_bitmap and stores it in device->bitmap.
435 int drbd_bm_init(struct drbd_device *device)
437 struct drbd_bitmap *b = device->bitmap;
439 b = kzalloc(sizeof(struct drbd_bitmap), GFP_KERNEL);
442 spin_lock_init(&b->bm_lock);
443 mutex_init(&b->bm_change);
444 init_waitqueue_head(&b->bm_io_wait);
451 sector_t drbd_bm_capacity(struct drbd_device *device)
453 if (!expect(device->bitmap))
455 return device->bitmap->bm_dev_capacity;
458 /* called on driver unload. TODO: call when a device is destroyed.
460 void drbd_bm_cleanup(struct drbd_device *device)
462 if (!expect(device->bitmap))
464 bm_free_pages(device->bitmap->bm_pages, device->bitmap->bm_number_of_pages);
465 bm_vk_free(device->bitmap->bm_pages);
466 kfree(device->bitmap);
467 device->bitmap = NULL;
471 * since (b->bm_bits % BITS_PER_LONG) != 0,
472 * this masks out the remaining bits.
473 * Returns the number of bits cleared.
475 #ifndef BITS_PER_PAGE
476 #define BITS_PER_PAGE (1UL << (PAGE_SHIFT + 3))
477 #define BITS_PER_PAGE_MASK (BITS_PER_PAGE - 1)
479 # if BITS_PER_PAGE != (1UL << (PAGE_SHIFT + 3))
480 # error "ambiguous BITS_PER_PAGE"
483 #define BITS_PER_LONG_MASK (BITS_PER_LONG - 1)
484 static int bm_clear_surplus(struct drbd_bitmap *b)
487 unsigned long *p_addr, *bm;
491 /* number of bits modulo bits per page */
492 tmp = (b->bm_bits & BITS_PER_PAGE_MASK);
493 /* mask the used bits of the word containing the last bit */
494 mask = (1UL << (tmp & BITS_PER_LONG_MASK)) -1;
495 /* bitmap is always stored little endian,
496 * on disk and in core memory alike */
497 mask = cpu_to_lel(mask);
499 p_addr = bm_map_pidx(b, b->bm_number_of_pages - 1);
500 bm = p_addr + (tmp/BITS_PER_LONG);
502 /* If mask != 0, we are not exactly aligned, so bm now points
503 * to the long containing the last bit.
504 * If mask == 0, bm already points to the word immediately
505 * after the last (long word aligned) bit. */
506 cleared = hweight_long(*bm & ~mask);
511 if (BITS_PER_LONG == 32 && ((bm - p_addr) & 1) == 1) {
512 /* on a 32bit arch, we may need to zero out
513 * a padding long to align with a 64bit remote */
514 cleared += hweight_long(*bm);
521 static void bm_set_surplus(struct drbd_bitmap *b)
524 unsigned long *p_addr, *bm;
527 /* number of bits modulo bits per page */
528 tmp = (b->bm_bits & BITS_PER_PAGE_MASK);
529 /* mask the used bits of the word containing the last bit */
530 mask = (1UL << (tmp & BITS_PER_LONG_MASK)) -1;
531 /* bitmap is always stored little endian,
532 * on disk and in core memory alike */
533 mask = cpu_to_lel(mask);
535 p_addr = bm_map_pidx(b, b->bm_number_of_pages - 1);
536 bm = p_addr + (tmp/BITS_PER_LONG);
538 /* If mask != 0, we are not exactly aligned, so bm now points
539 * to the long containing the last bit.
540 * If mask == 0, bm already points to the word immediately
541 * after the last (long word aligned) bit. */
546 if (BITS_PER_LONG == 32 && ((bm - p_addr) & 1) == 1) {
547 /* on a 32bit arch, we may need to zero out
548 * a padding long to align with a 64bit remote */
554 /* you better not modify the bitmap while this is running,
555 * or its results will be stale */
556 static unsigned long bm_count_bits(struct drbd_bitmap *b)
558 unsigned long *p_addr;
559 unsigned long bits = 0;
560 unsigned long mask = (1UL << (b->bm_bits & BITS_PER_LONG_MASK)) -1;
563 /* all but last page */
564 for (idx = 0; idx < b->bm_number_of_pages - 1; idx++) {
565 p_addr = __bm_map_pidx(b, idx);
566 bits += bitmap_weight(p_addr, BITS_PER_PAGE);
570 /* last (or only) page */
571 last_word = ((b->bm_bits - 1) & BITS_PER_PAGE_MASK) >> LN2_BPL;
572 p_addr = __bm_map_pidx(b, idx);
573 bits += bitmap_weight(p_addr, last_word * BITS_PER_LONG);
574 p_addr[last_word] &= cpu_to_lel(mask);
575 bits += hweight_long(p_addr[last_word]);
576 /* 32bit arch, may have an unused padding long */
577 if (BITS_PER_LONG == 32 && (last_word & 1) == 0)
578 p_addr[last_word+1] = 0;
583 /* offset and len in long words.*/
584 static void bm_memset(struct drbd_bitmap *b, size_t offset, int c, size_t len)
586 unsigned long *p_addr, *bm;
592 if (end > b->bm_words) {
593 pr_alert("bm_memset end > bm_words\n");
597 while (offset < end) {
598 do_now = min_t(size_t, ALIGN(offset + 1, LWPP), end) - offset;
599 idx = bm_word_to_page_idx(b, offset);
600 p_addr = bm_map_pidx(b, idx);
601 bm = p_addr + MLPP(offset);
602 if (bm+do_now > p_addr + LWPP) {
603 pr_alert("BUG BUG BUG! p_addr:%p bm:%p do_now:%d\n",
604 p_addr, bm, (int)do_now);
606 memset(bm, c, do_now * sizeof(long));
608 bm_set_page_need_writeout(b->bm_pages[idx]);
613 /* For the layout, see comment above drbd_md_set_sector_offsets(). */
614 static u64 drbd_md_on_disk_bits(struct drbd_backing_dev *ldev)
617 if (ldev->md.al_offset == 8)
618 bitmap_sectors = ldev->md.md_size_sect - ldev->md.bm_offset;
620 bitmap_sectors = ldev->md.al_offset - ldev->md.bm_offset;
621 return bitmap_sectors << (9 + 3);
625 * make sure the bitmap has enough room for the attached storage,
626 * if necessary, resize.
627 * called whenever we may have changed the device size.
628 * returns -ENOMEM if we could not allocate enough memory, 0 on success.
629 * In case this is actually a resize, we copy the old bitmap into the new one.
630 * Otherwise, the bitmap is initialized to all bits set.
632 int drbd_bm_resize(struct drbd_device *device, sector_t capacity, int set_new_bits)
634 struct drbd_bitmap *b = device->bitmap;
635 unsigned long bits, words, owords, obits;
636 unsigned long want, have, onpages; /* number of pages */
637 struct page **npages, **opages = NULL;
644 drbd_bm_lock(device, "resize", BM_LOCKED_MASK);
646 drbd_info(device, "drbd_bm_resize called with capacity == %llu\n",
647 (unsigned long long)capacity);
649 if (capacity == b->bm_dev_capacity)
653 spin_lock_irq(&b->bm_lock);
654 opages = b->bm_pages;
655 onpages = b->bm_number_of_pages;
656 owords = b->bm_words;
658 b->bm_number_of_pages =
662 b->bm_dev_capacity = 0;
663 spin_unlock_irq(&b->bm_lock);
664 bm_free_pages(opages, onpages);
668 bits = BM_SECT_TO_BIT(ALIGN(capacity, BM_SECT_PER_BIT));
671 words = ALIGN(bits,BITS_PER_LONG) >> LN2_BPL;
672 a 32bit host could present the wrong number of words
675 words = ALIGN(bits, 64) >> LN2_BPL;
677 if (get_ldev(device)) {
678 u64 bits_on_disk = drbd_md_on_disk_bits(device->ldev);
680 if (bits > bits_on_disk) {
681 drbd_info(device, "bits = %lu\n", bits);
682 drbd_info(device, "bits_on_disk = %llu\n", bits_on_disk);
688 want = ALIGN(words*sizeof(long), PAGE_SIZE) >> PAGE_SHIFT;
689 have = b->bm_number_of_pages;
691 D_ASSERT(device, b->bm_pages != NULL);
692 npages = b->bm_pages;
694 if (drbd_insert_fault(device, DRBD_FAULT_BM_ALLOC))
697 npages = bm_realloc_pages(b, want);
705 spin_lock_irq(&b->bm_lock);
706 opages = b->bm_pages;
707 owords = b->bm_words;
710 growing = bits > obits;
711 if (opages && growing && set_new_bits)
714 b->bm_pages = npages;
715 b->bm_number_of_pages = want;
718 b->bm_dev_capacity = capacity;
722 bm_memset(b, owords, 0xff, words-owords);
723 b->bm_set += bits - obits;
725 bm_memset(b, owords, 0x00, words-owords);
730 /* implicit: (opages != NULL) && (opages != npages) */
731 bm_free_pages(opages + want, have - want);
734 (void)bm_clear_surplus(b);
736 spin_unlock_irq(&b->bm_lock);
737 if (opages != npages)
740 b->bm_set = bm_count_bits(b);
741 drbd_info(device, "resync bitmap: bits=%lu words=%lu pages=%lu\n", bits, words, want);
744 drbd_bm_unlock(device);
749 * if not protected by other means, return value may be out of date when
750 * leaving this function...
751 * we still need to lock it, since it is important that this returns
752 * bm_set == 0 precisely.
754 * maybe bm_set should be atomic_t ?
756 unsigned long _drbd_bm_total_weight(struct drbd_device *device)
758 struct drbd_bitmap *b = device->bitmap;
764 if (!expect(b->bm_pages))
767 spin_lock_irqsave(&b->bm_lock, flags);
769 spin_unlock_irqrestore(&b->bm_lock, flags);
774 unsigned long drbd_bm_total_weight(struct drbd_device *device)
777 /* if I don't have a disk, I don't know about out-of-sync status */
778 if (!get_ldev_if_state(device, D_NEGOTIATING))
780 s = _drbd_bm_total_weight(device);
785 size_t drbd_bm_words(struct drbd_device *device)
787 struct drbd_bitmap *b = device->bitmap;
790 if (!expect(b->bm_pages))
796 unsigned long drbd_bm_bits(struct drbd_device *device)
798 struct drbd_bitmap *b = device->bitmap;
805 /* merge number words from buffer into the bitmap starting at offset.
806 * buffer[i] is expected to be little endian unsigned long.
807 * bitmap must be locked by drbd_bm_lock.
808 * currently only used from receive_bitmap.
810 void drbd_bm_merge_lel(struct drbd_device *device, size_t offset, size_t number,
811 unsigned long *buffer)
813 struct drbd_bitmap *b = device->bitmap;
814 unsigned long *p_addr, *bm;
815 unsigned long word, bits;
819 end = offset + number;
823 if (!expect(b->bm_pages))
827 WARN_ON(offset >= b->bm_words);
828 WARN_ON(end > b->bm_words);
830 spin_lock_irq(&b->bm_lock);
831 while (offset < end) {
832 do_now = min_t(size_t, ALIGN(offset+1, LWPP), end) - offset;
833 idx = bm_word_to_page_idx(b, offset);
834 p_addr = bm_map_pidx(b, idx);
835 bm = p_addr + MLPP(offset);
838 bits = hweight_long(*bm);
839 word = *bm | *buffer++;
841 b->bm_set += hweight_long(word) - bits;
844 bm_set_page_need_writeout(b->bm_pages[idx]);
846 /* with 32bit <-> 64bit cross-platform connect
847 * this is only correct for current usage,
848 * where we _know_ that we are 64 bit aligned,
849 * and know that this function is used in this way, too...
851 if (end == b->bm_words)
852 b->bm_set -= bm_clear_surplus(b);
853 spin_unlock_irq(&b->bm_lock);
856 /* copy number words from the bitmap starting at offset into the buffer.
857 * buffer[i] will be little endian unsigned long.
859 void drbd_bm_get_lel(struct drbd_device *device, size_t offset, size_t number,
860 unsigned long *buffer)
862 struct drbd_bitmap *b = device->bitmap;
863 unsigned long *p_addr, *bm;
866 end = offset + number;
870 if (!expect(b->bm_pages))
873 spin_lock_irq(&b->bm_lock);
874 if ((offset >= b->bm_words) ||
875 (end > b->bm_words) ||
877 drbd_err(device, "offset=%lu number=%lu bm_words=%lu\n",
878 (unsigned long) offset,
879 (unsigned long) number,
880 (unsigned long) b->bm_words);
882 while (offset < end) {
883 do_now = min_t(size_t, ALIGN(offset+1, LWPP), end) - offset;
884 p_addr = bm_map_pidx(b, bm_word_to_page_idx(b, offset));
885 bm = p_addr + MLPP(offset);
892 spin_unlock_irq(&b->bm_lock);
895 /* set all bits in the bitmap */
896 void drbd_bm_set_all(struct drbd_device *device)
898 struct drbd_bitmap *b = device->bitmap;
901 if (!expect(b->bm_pages))
904 spin_lock_irq(&b->bm_lock);
905 bm_memset(b, 0, 0xff, b->bm_words);
906 (void)bm_clear_surplus(b);
907 b->bm_set = b->bm_bits;
908 spin_unlock_irq(&b->bm_lock);
911 /* clear all bits in the bitmap */
912 void drbd_bm_clear_all(struct drbd_device *device)
914 struct drbd_bitmap *b = device->bitmap;
917 if (!expect(b->bm_pages))
920 spin_lock_irq(&b->bm_lock);
921 bm_memset(b, 0, 0, b->bm_words);
923 spin_unlock_irq(&b->bm_lock);
926 static void drbd_bm_aio_ctx_destroy(struct kref *kref)
928 struct drbd_bm_aio_ctx *ctx = container_of(kref, struct drbd_bm_aio_ctx, kref);
931 spin_lock_irqsave(&ctx->device->resource->req_lock, flags);
932 list_del(&ctx->list);
933 spin_unlock_irqrestore(&ctx->device->resource->req_lock, flags);
934 put_ldev(ctx->device);
938 /* bv_page may be a copy, or may be the original */
939 static void drbd_bm_endio(struct bio *bio)
941 struct drbd_bm_aio_ctx *ctx = bio->bi_private;
942 struct drbd_device *device = ctx->device;
943 struct drbd_bitmap *b = device->bitmap;
944 unsigned int idx = bm_page_to_idx(bio_first_page_all(bio));
946 if ((ctx->flags & BM_AIO_COPY_PAGES) == 0 &&
947 !bm_test_page_unchanged(b->bm_pages[idx]))
948 drbd_warn(device, "bitmap page idx %u changed during IO!\n", idx);
950 if (bio->bi_status) {
951 /* ctx error will hold the completed-last non-zero error code,
952 * in case error codes differ. */
953 ctx->error = blk_status_to_errno(bio->bi_status);
954 bm_set_page_io_err(b->bm_pages[idx]);
955 /* Not identical to on disk version of it.
956 * Is BM_PAGE_IO_ERROR enough? */
957 if (__ratelimit(&drbd_ratelimit_state))
958 drbd_err(device, "IO ERROR %d on bitmap page idx %u\n",
959 bio->bi_status, idx);
961 bm_clear_page_io_err(b->bm_pages[idx]);
962 dynamic_drbd_dbg(device, "bitmap page idx %u completed\n", idx);
965 bm_page_unlock_io(device, idx);
967 if (ctx->flags & BM_AIO_COPY_PAGES)
968 mempool_free(bio->bi_io_vec[0].bv_page, &drbd_md_io_page_pool);
972 if (atomic_dec_and_test(&ctx->in_flight)) {
974 wake_up(&device->misc_wait);
975 kref_put(&ctx->kref, &drbd_bm_aio_ctx_destroy);
979 static void bm_page_io_async(struct drbd_bm_aio_ctx *ctx, int page_nr) __must_hold(local)
981 struct bio *bio = bio_alloc_drbd(GFP_NOIO);
982 struct drbd_device *device = ctx->device;
983 struct drbd_bitmap *b = device->bitmap;
986 unsigned int op = (ctx->flags & BM_AIO_READ) ? REQ_OP_READ : REQ_OP_WRITE;
988 sector_t on_disk_sector =
989 device->ldev->md.md_offset + device->ldev->md.bm_offset;
990 on_disk_sector += ((sector_t)page_nr) << (PAGE_SHIFT-9);
992 /* this might happen with very small
993 * flexible external meta data device,
994 * or with PAGE_SIZE > 4k */
995 len = min_t(unsigned int, PAGE_SIZE,
996 (drbd_md_last_sector(device->ldev) - on_disk_sector + 1)<<9);
998 /* serialize IO on this page */
999 bm_page_lock_io(device, page_nr);
1000 /* before memcpy and submit,
1001 * so it can be redirtied any time */
1002 bm_set_page_unchanged(b->bm_pages[page_nr]);
1004 if (ctx->flags & BM_AIO_COPY_PAGES) {
1005 page = mempool_alloc(&drbd_md_io_page_pool,
1006 GFP_NOIO | __GFP_HIGHMEM);
1007 copy_highpage(page, b->bm_pages[page_nr]);
1008 bm_store_page_idx(page, page_nr);
1010 page = b->bm_pages[page_nr];
1011 bio_set_dev(bio, device->ldev->md_bdev);
1012 bio->bi_iter.bi_sector = on_disk_sector;
1013 /* bio_add_page of a single page to an empty bio will always succeed,
1014 * according to api. Do we want to assert that? */
1015 bio_add_page(bio, page, len, 0);
1016 bio->bi_private = ctx;
1017 bio->bi_end_io = drbd_bm_endio;
1018 bio_set_op_attrs(bio, op, 0);
1020 if (drbd_insert_fault(device, (op == REQ_OP_WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD)) {
1024 /* this should not count as user activity and cause the
1025 * resync to throttle -- see drbd_rs_should_slow_down(). */
1026 atomic_add(len >> 9, &device->rs_sect_ev);
1031 * bm_rw: read/write the whole bitmap from/to its on disk location.
1033 static int bm_rw(struct drbd_device *device, const unsigned int flags, unsigned lazy_writeout_upper_idx) __must_hold(local)
1035 struct drbd_bm_aio_ctx *ctx;
1036 struct drbd_bitmap *b = device->bitmap;
1037 unsigned int num_pages, i, count = 0;
1043 * We are protected against bitmap disappearing/resizing by holding an
1044 * ldev reference (caller must have called get_ldev()).
1045 * For read/write, we are protected against changes to the bitmap by
1046 * the bitmap lock (see drbd_bitmap_io).
1047 * For lazy writeout, we don't care for ongoing changes to the bitmap,
1048 * as we submit copies of pages anyways.
1051 ctx = kmalloc(sizeof(struct drbd_bm_aio_ctx), GFP_NOIO);
1055 *ctx = (struct drbd_bm_aio_ctx) {
1057 .start_jif = jiffies,
1058 .in_flight = ATOMIC_INIT(1),
1062 .kref = KREF_INIT(2),
1065 if (!get_ldev_if_state(device, D_ATTACHING)) { /* put is in drbd_bm_aio_ctx_destroy() */
1066 drbd_err(device, "ASSERT FAILED: get_ldev_if_state() == 1 in bm_rw()\n");
1070 /* Here D_ATTACHING is sufficient since drbd_bm_read() is called only from
1071 drbd_adm_attach(), after device->ldev was assigned. */
1073 if (0 == (ctx->flags & ~BM_AIO_READ))
1074 WARN_ON(!(BM_LOCKED_MASK & b->bm_flags));
1076 spin_lock_irq(&device->resource->req_lock);
1077 list_add_tail(&ctx->list, &device->pending_bitmap_io);
1078 spin_unlock_irq(&device->resource->req_lock);
1080 num_pages = b->bm_number_of_pages;
1084 /* let the layers below us try to merge these bios... */
1086 if (flags & BM_AIO_READ) {
1087 for (i = 0; i < num_pages; i++) {
1088 atomic_inc(&ctx->in_flight);
1089 bm_page_io_async(ctx, i);
1093 } else if (flags & BM_AIO_WRITE_HINTED) {
1094 /* ASSERT: BM_AIO_WRITE_ALL_PAGES is not set. */
1096 for (hint = 0; hint < b->n_bitmap_hints; hint++) {
1097 i = b->al_bitmap_hints[hint];
1098 if (i >= num_pages) /* == -1U: no hint here. */
1100 /* Several AL-extents may point to the same page. */
1101 if (!test_and_clear_bit(BM_PAGE_HINT_WRITEOUT,
1102 &page_private(b->bm_pages[i])))
1104 /* Has it even changed? */
1105 if (bm_test_page_unchanged(b->bm_pages[i]))
1107 atomic_inc(&ctx->in_flight);
1108 bm_page_io_async(ctx, i);
1112 for (i = 0; i < num_pages; i++) {
1113 /* ignore completely unchanged pages */
1114 if (lazy_writeout_upper_idx && i == lazy_writeout_upper_idx)
1116 if (!(flags & BM_AIO_WRITE_ALL_PAGES) &&
1117 bm_test_page_unchanged(b->bm_pages[i])) {
1118 dynamic_drbd_dbg(device, "skipped bm write for idx %u\n", i);
1121 /* during lazy writeout,
1122 * ignore those pages not marked for lazy writeout. */
1123 if (lazy_writeout_upper_idx &&
1124 !bm_test_page_lazy_writeout(b->bm_pages[i])) {
1125 dynamic_drbd_dbg(device, "skipped bm lazy write for idx %u\n", i);
1128 atomic_inc(&ctx->in_flight);
1129 bm_page_io_async(ctx, i);
1136 * We initialize ctx->in_flight to one to make sure drbd_bm_endio
1137 * will not set ctx->done early, and decrement / test it here. If there
1138 * are still some bios in flight, we need to wait for them here.
1139 * If all IO is done already (or nothing had been submitted), there is
1140 * no need to wait. Still, we need to put the kref associated with the
1141 * "in_flight reached zero, all done" event.
1143 if (!atomic_dec_and_test(&ctx->in_flight))
1144 wait_until_done_or_force_detached(device, device->ldev, &ctx->done);
1146 kref_put(&ctx->kref, &drbd_bm_aio_ctx_destroy);
1148 /* summary for global bitmap IO */
1150 unsigned int ms = jiffies_to_msecs(jiffies - now);
1152 drbd_info(device, "bitmap %s of %u pages took %u ms\n",
1153 (flags & BM_AIO_READ) ? "READ" : "WRITE",
1159 drbd_alert(device, "we had at least one MD IO ERROR during bitmap IO\n");
1160 drbd_chk_io_error(device, 1, DRBD_META_IO_ERROR);
1161 err = -EIO; /* ctx->error ? */
1164 if (atomic_read(&ctx->in_flight))
1165 err = -EIO; /* Disk timeout/force-detach during IO... */
1168 if (flags & BM_AIO_READ) {
1169 b->bm_set = bm_count_bits(b);
1170 drbd_info(device, "recounting of set bits took additional %lu jiffies\n",
1175 if ((flags & ~BM_AIO_READ) == 0)
1176 drbd_info(device, "%s (%lu bits) marked out-of-sync by on disk bit-map.\n",
1177 ppsize(ppb, now << (BM_BLOCK_SHIFT-10)), now);
1179 kref_put(&ctx->kref, &drbd_bm_aio_ctx_destroy);
1184 * drbd_bm_read() - Read the whole bitmap from its on disk location.
1185 * @device: DRBD device.
1187 int drbd_bm_read(struct drbd_device *device) __must_hold(local)
1189 return bm_rw(device, BM_AIO_READ, 0);
1193 * drbd_bm_write() - Write the whole bitmap to its on disk location.
1194 * @device: DRBD device.
1196 * Will only write pages that have changed since last IO.
1198 int drbd_bm_write(struct drbd_device *device) __must_hold(local)
1200 return bm_rw(device, 0, 0);
1204 * drbd_bm_write_all() - Write the whole bitmap to its on disk location.
1205 * @device: DRBD device.
1207 * Will write all pages.
1209 int drbd_bm_write_all(struct drbd_device *device) __must_hold(local)
1211 return bm_rw(device, BM_AIO_WRITE_ALL_PAGES, 0);
1215 * drbd_bm_write_lazy() - Write bitmap pages 0 to @upper_idx-1, if they have changed.
1216 * @device: DRBD device.
1217 * @upper_idx: 0: write all changed pages; +ve: page index to stop scanning for changed pages
1219 int drbd_bm_write_lazy(struct drbd_device *device, unsigned upper_idx) __must_hold(local)
1221 return bm_rw(device, BM_AIO_COPY_PAGES, upper_idx);
1225 * drbd_bm_write_copy_pages() - Write the whole bitmap to its on disk location.
1226 * @device: DRBD device.
1228 * Will only write pages that have changed since last IO.
1229 * In contrast to drbd_bm_write(), this will copy the bitmap pages
1230 * to temporary writeout pages. It is intended to trigger a full write-out
1231 * while still allowing the bitmap to change, for example if a resync or online
1232 * verify is aborted due to a failed peer disk, while local IO continues, or
1233 * pending resync acks are still being processed.
1235 int drbd_bm_write_copy_pages(struct drbd_device *device) __must_hold(local)
1237 return bm_rw(device, BM_AIO_COPY_PAGES, 0);
1241 * drbd_bm_write_hinted() - Write bitmap pages with "hint" marks, if they have changed.
1242 * @device: DRBD device.
1244 int drbd_bm_write_hinted(struct drbd_device *device) __must_hold(local)
1246 return bm_rw(device, BM_AIO_WRITE_HINTED | BM_AIO_COPY_PAGES, 0);
1250 * find_first_bit returns int, we return unsigned long.
1251 * For this to work on 32bit arch with bitnumbers > (1<<32),
1252 * we'd need to return u64, and get a whole lot of other places
1253 * fixed where we still use unsigned long.
1255 * this returns a bit number, NOT a sector!
1257 static unsigned long __bm_find_next(struct drbd_device *device, unsigned long bm_fo,
1258 const int find_zero_bit)
1260 struct drbd_bitmap *b = device->bitmap;
1261 unsigned long *p_addr;
1262 unsigned long bit_offset;
1266 if (bm_fo > b->bm_bits) {
1267 drbd_err(device, "bm_fo=%lu bm_bits=%lu\n", bm_fo, b->bm_bits);
1268 bm_fo = DRBD_END_OF_BITMAP;
1270 while (bm_fo < b->bm_bits) {
1271 /* bit offset of the first bit in the page */
1272 bit_offset = bm_fo & ~BITS_PER_PAGE_MASK;
1273 p_addr = __bm_map_pidx(b, bm_bit_to_page_idx(b, bm_fo));
1276 i = find_next_zero_bit_le(p_addr,
1277 PAGE_SIZE*8, bm_fo & BITS_PER_PAGE_MASK);
1279 i = find_next_bit_le(p_addr,
1280 PAGE_SIZE*8, bm_fo & BITS_PER_PAGE_MASK);
1283 if (i < PAGE_SIZE*8) {
1284 bm_fo = bit_offset + i;
1285 if (bm_fo >= b->bm_bits)
1289 bm_fo = bit_offset + PAGE_SIZE*8;
1291 bm_fo = DRBD_END_OF_BITMAP;
1297 static unsigned long bm_find_next(struct drbd_device *device,
1298 unsigned long bm_fo, const int find_zero_bit)
1300 struct drbd_bitmap *b = device->bitmap;
1301 unsigned long i = DRBD_END_OF_BITMAP;
1305 if (!expect(b->bm_pages))
1308 spin_lock_irq(&b->bm_lock);
1309 if (BM_DONT_TEST & b->bm_flags)
1310 bm_print_lock_info(device);
1312 i = __bm_find_next(device, bm_fo, find_zero_bit);
1314 spin_unlock_irq(&b->bm_lock);
1318 unsigned long drbd_bm_find_next(struct drbd_device *device, unsigned long bm_fo)
1320 return bm_find_next(device, bm_fo, 0);
1324 /* not yet needed for anything. */
1325 unsigned long drbd_bm_find_next_zero(struct drbd_device *device, unsigned long bm_fo)
1327 return bm_find_next(device, bm_fo, 1);
1331 /* does not spin_lock_irqsave.
1332 * you must take drbd_bm_lock() first */
1333 unsigned long _drbd_bm_find_next(struct drbd_device *device, unsigned long bm_fo)
1335 /* WARN_ON(!(BM_DONT_SET & device->b->bm_flags)); */
1336 return __bm_find_next(device, bm_fo, 0);
1339 unsigned long _drbd_bm_find_next_zero(struct drbd_device *device, unsigned long bm_fo)
1341 /* WARN_ON(!(BM_DONT_SET & device->b->bm_flags)); */
1342 return __bm_find_next(device, bm_fo, 1);
1345 /* returns number of bits actually changed.
1346 * for val != 0, we change 0 -> 1, return code positive
1347 * for val == 0, we change 1 -> 0, return code negative
1348 * wants bitnr, not sector.
1349 * expected to be called for only a few bits (e - s about BITS_PER_LONG).
1350 * Must hold bitmap lock already. */
1351 static int __bm_change_bits_to(struct drbd_device *device, const unsigned long s,
1352 unsigned long e, int val)
1354 struct drbd_bitmap *b = device->bitmap;
1355 unsigned long *p_addr = NULL;
1356 unsigned long bitnr;
1357 unsigned int last_page_nr = -1U;
1359 int changed_total = 0;
1361 if (e >= b->bm_bits) {
1362 drbd_err(device, "ASSERT FAILED: bit_s=%lu bit_e=%lu bm_bits=%lu\n",
1364 e = b->bm_bits ? b->bm_bits -1 : 0;
1366 for (bitnr = s; bitnr <= e; bitnr++) {
1367 unsigned int page_nr = bm_bit_to_page_idx(b, bitnr);
1368 if (page_nr != last_page_nr) {
1372 bm_set_page_lazy_writeout(b->bm_pages[last_page_nr]);
1374 bm_set_page_need_writeout(b->bm_pages[last_page_nr]);
1377 p_addr = __bm_map_pidx(b, page_nr);
1378 last_page_nr = page_nr;
1381 c += (0 == __test_and_set_bit_le(bitnr & BITS_PER_PAGE_MASK, p_addr));
1383 c -= (0 != __test_and_clear_bit_le(bitnr & BITS_PER_PAGE_MASK, p_addr));
1388 bm_set_page_lazy_writeout(b->bm_pages[last_page_nr]);
1390 bm_set_page_need_writeout(b->bm_pages[last_page_nr]);
1392 b->bm_set += changed_total;
1393 return changed_total;
1396 /* returns number of bits actually changed.
1397 * for val != 0, we change 0 -> 1, return code positive
1398 * for val == 0, we change 1 -> 0, return code negative
1399 * wants bitnr, not sector */
1400 static int bm_change_bits_to(struct drbd_device *device, const unsigned long s,
1401 const unsigned long e, int val)
1403 unsigned long flags;
1404 struct drbd_bitmap *b = device->bitmap;
1409 if (!expect(b->bm_pages))
1412 spin_lock_irqsave(&b->bm_lock, flags);
1413 if ((val ? BM_DONT_SET : BM_DONT_CLEAR) & b->bm_flags)
1414 bm_print_lock_info(device);
1416 c = __bm_change_bits_to(device, s, e, val);
1418 spin_unlock_irqrestore(&b->bm_lock, flags);
1422 /* returns number of bits changed 0 -> 1 */
1423 int drbd_bm_set_bits(struct drbd_device *device, const unsigned long s, const unsigned long e)
1425 return bm_change_bits_to(device, s, e, 1);
1428 /* returns number of bits changed 1 -> 0 */
1429 int drbd_bm_clear_bits(struct drbd_device *device, const unsigned long s, const unsigned long e)
1431 return -bm_change_bits_to(device, s, e, 0);
1434 /* sets all bits in full words,
1435 * from first_word up to, but not including, last_word */
1436 static inline void bm_set_full_words_within_one_page(struct drbd_bitmap *b,
1437 int page_nr, int first_word, int last_word)
1442 unsigned long *paddr = kmap_atomic(b->bm_pages[page_nr]);
1444 /* I think it is more cache line friendly to hweight_long then set to ~0UL,
1445 * than to first bitmap_weight() all words, then bitmap_fill() all words */
1446 for (i = first_word; i < last_word; i++) {
1447 bits = hweight_long(paddr[i]);
1449 changed += BITS_PER_LONG - bits;
1451 kunmap_atomic(paddr);
1453 /* We only need lazy writeout, the information is still in the
1454 * remote bitmap as well, and is reconstructed during the next
1455 * bitmap exchange, if lost locally due to a crash. */
1456 bm_set_page_lazy_writeout(b->bm_pages[page_nr]);
1457 b->bm_set += changed;
1461 /* Same thing as drbd_bm_set_bits,
1462 * but more efficient for a large bit range.
1463 * You must first drbd_bm_lock().
1464 * Can be called to set the whole bitmap in one go.
1465 * Sets bits from s to e _inclusive_. */
1466 void _drbd_bm_set_bits(struct drbd_device *device, const unsigned long s, const unsigned long e)
1468 /* First set_bit from the first bit (s)
1469 * up to the next long boundary (sl),
1470 * then assign full words up to the last long boundary (el),
1471 * then set_bit up to and including the last bit (e).
1473 * Do not use memset, because we must account for changes,
1474 * so we need to loop over the words with hweight() anyways.
1476 struct drbd_bitmap *b = device->bitmap;
1477 unsigned long sl = ALIGN(s,BITS_PER_LONG);
1478 unsigned long el = (e+1) & ~((unsigned long)BITS_PER_LONG-1);
1485 if (e - s <= 3*BITS_PER_LONG) {
1486 /* don't bother; el and sl may even be wrong. */
1487 spin_lock_irq(&b->bm_lock);
1488 __bm_change_bits_to(device, s, e, 1);
1489 spin_unlock_irq(&b->bm_lock);
1493 /* difference is large enough that we can trust sl and el */
1495 spin_lock_irq(&b->bm_lock);
1497 /* bits filling the current long */
1499 __bm_change_bits_to(device, s, sl-1, 1);
1501 first_page = sl >> (3 + PAGE_SHIFT);
1502 last_page = el >> (3 + PAGE_SHIFT);
1504 /* MLPP: modulo longs per page */
1505 /* LWPP: long words per page */
1506 first_word = MLPP(sl >> LN2_BPL);
1509 /* first and full pages, unless first page == last page */
1510 for (page_nr = first_page; page_nr < last_page; page_nr++) {
1511 bm_set_full_words_within_one_page(device->bitmap, page_nr, first_word, last_word);
1512 spin_unlock_irq(&b->bm_lock);
1515 spin_lock_irq(&b->bm_lock);
1517 /* last page (respectively only page, for first page == last page) */
1518 last_word = MLPP(el >> LN2_BPL);
1520 /* consider bitmap->bm_bits = 32768, bitmap->bm_number_of_pages = 1. (or multiples).
1521 * ==> e = 32767, el = 32768, last_page = 2,
1522 * and now last_word = 0.
1523 * We do not want to touch last_page in this case,
1524 * as we did not allocate it, it is not present in bitmap->bm_pages.
1527 bm_set_full_words_within_one_page(device->bitmap, last_page, first_word, last_word);
1529 /* possibly trailing bits.
1530 * example: (e & 63) == 63, el will be e+1.
1531 * if that even was the very last bit,
1532 * it would trigger an assert in __bm_change_bits_to()
1535 __bm_change_bits_to(device, el, e, 1);
1536 spin_unlock_irq(&b->bm_lock);
1539 /* returns bit state
1540 * wants bitnr, NOT sector.
1541 * inherently racy... area needs to be locked by means of {al,rs}_lru
1544 * -1 ... first out of bounds access, stop testing for bits!
1546 int drbd_bm_test_bit(struct drbd_device *device, const unsigned long bitnr)
1548 unsigned long flags;
1549 struct drbd_bitmap *b = device->bitmap;
1550 unsigned long *p_addr;
1555 if (!expect(b->bm_pages))
1558 spin_lock_irqsave(&b->bm_lock, flags);
1559 if (BM_DONT_TEST & b->bm_flags)
1560 bm_print_lock_info(device);
1561 if (bitnr < b->bm_bits) {
1562 p_addr = bm_map_pidx(b, bm_bit_to_page_idx(b, bitnr));
1563 i = test_bit_le(bitnr & BITS_PER_PAGE_MASK, p_addr) ? 1 : 0;
1565 } else if (bitnr == b->bm_bits) {
1567 } else { /* (bitnr > b->bm_bits) */
1568 drbd_err(device, "bitnr=%lu > bm_bits=%lu\n", bitnr, b->bm_bits);
1572 spin_unlock_irqrestore(&b->bm_lock, flags);
1576 /* returns number of bits set in the range [s, e] */
1577 int drbd_bm_count_bits(struct drbd_device *device, const unsigned long s, const unsigned long e)
1579 unsigned long flags;
1580 struct drbd_bitmap *b = device->bitmap;
1581 unsigned long *p_addr = NULL;
1582 unsigned long bitnr;
1583 unsigned int page_nr = -1U;
1586 /* If this is called without a bitmap, that is a bug. But just to be
1587 * robust in case we screwed up elsewhere, in that case pretend there
1588 * was one dirty bit in the requested area, so we won't try to do a
1589 * local read there (no bitmap probably implies no disk) */
1592 if (!expect(b->bm_pages))
1595 spin_lock_irqsave(&b->bm_lock, flags);
1596 if (BM_DONT_TEST & b->bm_flags)
1597 bm_print_lock_info(device);
1598 for (bitnr = s; bitnr <= e; bitnr++) {
1599 unsigned int idx = bm_bit_to_page_idx(b, bitnr);
1600 if (page_nr != idx) {
1604 p_addr = bm_map_pidx(b, idx);
1606 if (expect(bitnr < b->bm_bits))
1607 c += (0 != test_bit_le(bitnr - (page_nr << (PAGE_SHIFT+3)), p_addr));
1609 drbd_err(device, "bitnr=%lu bm_bits=%lu\n", bitnr, b->bm_bits);
1613 spin_unlock_irqrestore(&b->bm_lock, flags);
1618 /* inherently racy...
1619 * return value may be already out-of-date when this function returns.
1620 * but the general usage is that this is only use during a cstate when bits are
1621 * only cleared, not set, and typically only care for the case when the return
1622 * value is zero, or we already "locked" this "bitmap extent" by other means.
1624 * enr is bm-extent number, since we chose to name one sector (512 bytes)
1625 * worth of the bitmap a "bitmap extent".
1628 * I think since we use it like a reference count, we should use the real
1629 * reference count of some bitmap extent element from some lru instead...
1632 int drbd_bm_e_weight(struct drbd_device *device, unsigned long enr)
1634 struct drbd_bitmap *b = device->bitmap;
1636 unsigned long flags;
1637 unsigned long *p_addr, *bm;
1641 if (!expect(b->bm_pages))
1644 spin_lock_irqsave(&b->bm_lock, flags);
1645 if (BM_DONT_TEST & b->bm_flags)
1646 bm_print_lock_info(device);
1649 e = min((size_t)S2W(enr+1), b->bm_words);
1651 if (s < b->bm_words) {
1653 p_addr = bm_map_pidx(b, bm_word_to_page_idx(b, s));
1654 bm = p_addr + MLPP(s);
1655 count += bitmap_weight(bm, n * BITS_PER_LONG);
1658 drbd_err(device, "start offset (%d) too large in drbd_bm_e_weight\n", s);
1660 spin_unlock_irqrestore(&b->bm_lock, flags);