diff options
Diffstat (limited to 'drivers/block/drbd/drbd_bitmap.c')
| -rw-r--r-- | drivers/block/drbd/drbd_bitmap.c | 1648 |
1 files changed, 1648 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c new file mode 100644 index 000000000..434c77dcc --- /dev/null +++ b/drivers/block/drbd/drbd_bitmap.c @@ -0,0 +1,1648 @@ +/* + 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. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#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_device *device, const char *func) +{ + struct drbd_bitmap *b = device->bitmap; + if (!__ratelimit(&drbd_ratelimit_state)) + return; + drbd_err(device, "FIXME %s[%d] in %s, bitmap locked for '%s' by %s[%d]\n", + current->comm, task_pid_nr(current), + func, b->bm_why ?: "?", + b->bm_task->comm, task_pid_nr(b->bm_task)); +} + +void drbd_bm_lock(struct drbd_device *device, char *why, enum bm_flag flags) +{ + struct drbd_bitmap *b = device->bitmap; + int trylock_failed; + + if (!b) { + drbd_err(device, "FIXME no bitmap in drbd_bm_lock!?\n"); + return; + } + + trylock_failed = !mutex_trylock(&b->bm_change); + + if (trylock_failed) { + drbd_warn(device, "%s[%d] going to '%s' but bitmap already locked for '%s' by %s[%d]\n", + current->comm, task_pid_nr(current), + why, b->bm_why ?: "?", + b->bm_task->comm, task_pid_nr(b->bm_task)); + mutex_lock(&b->bm_change); + } + if (BM_LOCKED_MASK & b->bm_flags) + drbd_err(device, "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_device *device) +{ + struct drbd_bitmap *b = device->bitmap; + if (!b) { + drbd_err(device, "FIXME no bitmap in drbd_bm_unlock!?\n"); + return; + } + + if (!(BM_LOCKED_MASK & device->bitmap->bm_flags)) + drbd_err(device, "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_device *device, int page_nr) +{ + struct drbd_bitmap *b = device->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_device *device, int page_nr) +{ + struct drbd_bitmap *b = device->bitmap; + void *addr = &page_private(b->bm_pages[page_nr]); + clear_bit_unlock(BM_PAGE_IO_LOCK, addr); + wake_up(&device->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 + * @device: 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_device *device, int page_nr) +{ + struct page *page; + if (page_nr >= device->bitmap->bm_number_of_pages) { + drbd_warn(device, "BAD: page_nr: %u, number_of_pages: %u\n", + page_nr, (int)device->bitmap->bm_number_of_pages); + return; + } + page = device->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_device*, but for the debug macros I like to have the device 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]) { + pr_alert("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 | __GFP_NOWARN); + 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 device->bitmap. + */ +int drbd_bm_init(struct drbd_device *device) +{ + struct drbd_bitmap *b = device->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); + + device->bitmap = b; + + return 0; +} + +sector_t drbd_bm_capacity(struct drbd_device *device) +{ + if (!expect(device->bitmap)) + return 0; + return device->bitmap->bm_dev_capacity; +} + +/* called on driver unload. TODO: call when a device is destroyed. + */ +void drbd_bm_cleanup(struct drbd_device *device) +{ + if (!expect(device->bitmap)) + return; + bm_free_pages(device->bitmap->bm_pages, device->bitmap->bm_number_of_pages); + bm_vk_free(device->bitmap->bm_pages, (BM_P_VMALLOCED & device->bitmap->bm_flags)); + kfree(device->bitmap); + device->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) { + pr_alert("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) { + pr_alert("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_device *device, sector_t capacity, int set_new_bits) +{ + struct drbd_bitmap *b = device->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(device, "resize", BM_LOCKED_MASK); + + drbd_info(device, "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(device)) { + u64 bits_on_disk = drbd_md_on_disk_bits(device->ldev); + put_ldev(device); + if (bits > bits_on_disk) { + drbd_info(device, "bits = %lu\n", bits); + drbd_info(device, "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(device, b->bm_pages != NULL); + npages = b->bm_pages; + } else { + if (drbd_insert_fault(device, 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); + drbd_info(device, "resync bitmap: bits=%lu words=%lu pages=%lu\n", bits, words, want); + + out: + drbd_bm_unlock(device); + 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_device *device) +{ + struct drbd_bitmap *b = device->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_device *device) +{ + unsigned long s; + /* if I don't have a disk, I don't know about out-of-sync status */ + if (!get_ldev_if_state(device, D_NEGOTIATING)) + return 0; + s = _drbd_bm_total_weight(device); + put_ldev(device); + return s; +} + +size_t drbd_bm_words(struct drbd_device *device) +{ + struct drbd_bitmap *b = device->bitmap; + if (!expect(b)) + return 0; + if (!expect(b->bm_pages)) + return 0; + + return b->bm_words; +} + +unsigned long drbd_bm_bits(struct drbd_device *device) +{ + struct drbd_bitmap *b = device->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_device *device, size_t offset, size_t number, + unsigned long *buffer) +{ + struct drbd_bitmap *b = device->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_device *device, size_t offset, size_t number, + unsigned long *buffer) +{ + struct drbd_bitmap *b = device->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)) + drbd_err(device, "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_device *device) +{ + struct drbd_bitmap *b = device->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_device *device) +{ + struct drbd_bitmap *b = device->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); +} + +static void drbd_bm_aio_ctx_destroy(struct kref *kref) +{ + struct drbd_bm_aio_ctx *ctx = container_of(kref, struct drbd_bm_aio_ctx, kref); + unsigned long flags; + + spin_lock_irqsave(&ctx->device->resource->req_lock, flags); + list_del(&ctx->list); + spin_unlock_irqrestore(&ctx->device->resource->req_lock, flags); + put_ldev(ctx->device); + kfree(ctx); +} + +/* bv_page may be a copy, or may be the original */ +static void drbd_bm_endio(struct bio *bio, int error) +{ + struct drbd_bm_aio_ctx *ctx = bio->bi_private; + struct drbd_device *device = ctx->device; + struct drbd_bitmap *b = device->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])) + drbd_warn(device, "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)) + drbd_err(device, "IO ERROR %d on bitmap page idx %u\n", + error, idx); + } else { + bm_clear_page_io_err(b->bm_pages[idx]); + dynamic_drbd_dbg(device, "bitmap page idx %u completed\n", idx); + } + + bm_page_unlock_io(device, 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(&device->misc_wait); + kref_put(&ctx->kref, &drbd_bm_aio_ctx_destroy); + } +} + +static void bm_page_io_async(struct drbd_bm_aio_ctx *ctx, int page_nr) __must_hold(local) +{ + struct bio *bio = bio_alloc_drbd(GFP_NOIO); + struct drbd_device *device = ctx->device; + struct drbd_bitmap *b = device->bitmap; + struct page *page; + unsigned int len; + unsigned int rw = (ctx->flags & BM_AIO_READ) ? READ : WRITE; + + sector_t on_disk_sector = + device->ldev->md.md_offset + device->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(device->ldev) - on_disk_sector + 1)<<9); + + /* serialize IO on this page */ + bm_page_lock_io(device, 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 = device->ldev->md_bdev; + bio->bi_iter.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 = drbd_bm_endio; + + if (drbd_insert_fault(device, (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, &device->rs_sect_ev); + } +} + +/* + * bm_rw: read/write the whole bitmap from/to its on disk location. + */ +static int bm_rw(struct drbd_device *device, const unsigned int flags, unsigned lazy_writeout_upper_idx) __must_hold(local) +{ + struct drbd_bm_aio_ctx *ctx; + struct drbd_bitmap *b = device->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 drbd_bm_aio_ctx), GFP_NOIO); + if (!ctx) + return -ENOMEM; + + *ctx = (struct drbd_bm_aio_ctx) { + .device = device, + .start_jif = jiffies, + .in_flight = ATOMIC_INIT(1), + .done = 0, + .flags = flags, + .error = 0, + .kref = { ATOMIC_INIT(2) }, + }; + + if (!get_ldev_if_state(device, D_ATTACHING)) { /* put is in drbd_bm_aio_ctx_destroy() */ + drbd_err(device, "ASSERT FAILED: get_ldev_if_state() == 1 in bm_rw()\n"); + kfree(ctx); + return -ENODEV; + } + /* Here D_ATTACHING is sufficient since drbd_bm_read() is called only from + drbd_adm_attach(), after device->ldev was assigned. */ + + if (0 == (ctx->flags & ~BM_AIO_READ)) + WARN_ON(!(BM_LOCKED_MASK & b->bm_flags)); + + spin_lock_irq(&device->resource->req_lock); + list_add_tail(&ctx->list, &device->pending_bitmap_io); + spin_unlock_irq(&device->resource->req_lock); + + 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 (!(flags & BM_AIO_READ)) { + if ((flags & BM_AIO_WRITE_HINTED) && + !test_and_clear_bit(BM_PAGE_HINT_WRITEOUT, + &page_private(b->bm_pages[i]))) + continue; + + if (!(flags & BM_AIO_WRITE_ALL_PAGES) && + bm_test_page_unchanged(b->bm_pages[i])) { + dynamic_drbd_dbg(device, "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_drbd_dbg(device, "skipped bm lazy write for idx %u\n", i); + continue; + } + } + atomic_inc(&ctx->in_flight); + bm_page_io_async(ctx, i); + ++count; + cond_resched(); + } + + /* + * We initialize ctx->in_flight to one to make sure drbd_bm_endio + * 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(device, device->ldev, &ctx->done); + else + kref_put(&ctx->kref, &drbd_bm_aio_ctx_destroy); + + /* summary for global bitmap IO */ + if (flags == 0) + drbd_info(device, "bitmap %s of %u pages took %lu jiffies\n", + (flags & BM_AIO_READ) ? "READ" : "WRITE", + count, jiffies - now); + + if (ctx->error) { + drbd_alert(device, "we had at least one MD IO ERROR during bitmap IO\n"); + drbd_chk_io_error(device, 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 (flags & BM_AIO_READ) { + b->bm_set = bm_count_bits(b); + drbd_info(device, "recounting of set bits took additional %lu jiffies\n", + jiffies - now); + } + now = b->bm_set; + + if ((flags & ~BM_AIO_READ) == 0) + drbd_info(device, "%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, &drbd_bm_aio_ctx_destroy); + return err; +} + +/** + * drbd_bm_read() - Read the whole bitmap from its on disk location. + * @device: DRBD device. + */ +int drbd_bm_read(struct drbd_device *device) __must_hold(local) +{ + return bm_rw(device, BM_AIO_READ, 0); +} + +/** + * drbd_bm_write() - Write the whole bitmap to its on disk location. + * @device: DRBD device. + * + * Will only write pages that have changed since last IO. + */ +int drbd_bm_write(struct drbd_device *device) __must_hold(local) +{ + return bm_rw(device, 0, 0); +} + +/** + * drbd_bm_write_all() - Write the whole bitmap to its on disk location. + * @device: DRBD device. + * + * Will write all pages. + */ +int drbd_bm_write_all(struct drbd_device *device) __must_hold(local) +{ + return bm_rw(device, BM_AIO_WRITE_ALL_PAGES, 0); +} + +/** + * drbd_bm_write_lazy() - Write bitmap pages 0 to @upper_idx-1, if they have changed. + * @device: 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_device *device, unsigned upper_idx) __must_hold(local) +{ + return bm_rw(device, BM_AIO_COPY_PAGES, upper_idx); +} + +/** + * drbd_bm_write_copy_pages() - Write the whole bitmap to its on disk location. + * @device: 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_device *device) __must_hold(local) +{ + return bm_rw(device, BM_AIO_COPY_PAGES, 0); +} + +/** + * drbd_bm_write_hinted() - Write bitmap pages with "hint" marks, if they have changed. + * @device: DRBD device. + */ +int drbd_bm_write_hinted(struct drbd_device *device) __must_hold(local) +{ + return bm_rw(device, BM_AIO_WRITE_HINTED | BM_AIO_COPY_PAGES, 0); +} + +/* 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_device *device, unsigned long bm_fo, + const int find_zero_bit) +{ + struct drbd_bitmap *b = device->bitmap; + unsigned long *p_addr; + unsigned long bit_offset; + unsigned i; + + + if (bm_fo > b->bm_bits) { + drbd_err(device, "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_device *device, + unsigned long bm_fo, const int find_zero_bit) +{ + struct drbd_bitmap *b = device->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(device); + + i = __bm_find_next(device, bm_fo, find_zero_bit); + + spin_unlock_irq(&b->bm_lock); + return i; +} + +unsigned long drbd_bm_find_next(struct drbd_device *device, unsigned long bm_fo) +{ + return bm_find_next(device, bm_fo, 0); +} + +#if 0 +/* not yet needed for anything. */ +unsigned long drbd_bm_find_next_zero(struct drbd_device *device, unsigned long bm_fo) +{ + return bm_find_next(device, bm_fo, 1); +} +#endif + +/* does not spin_lock_irqsave. + * you must take drbd_bm_lock() first */ +unsigned long _drbd_bm_find_next(struct drbd_device *device, unsigned long bm_fo) +{ + /* WARN_ON(!(BM_DONT_SET & device->b->bm_flags)); */ + return __bm_find_next(device, bm_fo, 0); +} + +unsigned long _drbd_bm_find_next_zero(struct drbd_device *device, unsigned long bm_fo) +{ + /* WARN_ON(!(BM_DONT_SET & device->b->bm_flags)); */ + return __bm_find_next(device, 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_device *device, const unsigned long s, + unsigned long e, int val) +{ + struct drbd_bitmap *b = device->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) { + drbd_err(device, "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_device *device, const unsigned long s, + const unsigned long e, int val) +{ + unsigned long flags; + struct drbd_bitmap *b = device->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(device); + + c = __bm_change_bits_to(device, 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_device *device, const unsigned long s, const unsigned long e) +{ + return bm_change_bits_to(device, s, e, 1); +} + +/* returns number of bits changed 1 -> 0 */ +int drbd_bm_clear_bits(struct drbd_device *device, const unsigned long s, const unsigned long e) +{ + return -bm_change_bits_to(device, 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_device *device, 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 = device->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(device, 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(device, 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(device->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(device->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(device, 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_device *device, const unsigned long bitnr) +{ + unsigned long flags; + struct drbd_bitmap *b = device->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(device); + 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) */ + drbd_err(device, "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_device *device, const unsigned long s, const unsigned long e) +{ + unsigned long flags; + struct drbd_bitmap *b = device->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(device); + 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 + drbd_err(device, "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_device *device, unsigned long enr) +{ + struct drbd_bitmap *b = device->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(device); + + 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 { + drbd_err(device, "start offset (%d) too large in drbd_bm_e_weight\n", s); + } + spin_unlock_irqrestore(&b->bm_lock, flags); + return count; +} |