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drbd: store in-core bitmap little endian, regardless of architecture
Our on-disk bitmap is a little endian bitstream. Up to now, we have stored the in-core copy of that in native endian, applying byte order conversion when necessary. Instead, keep the bitmap pages little endian, as they are read from disk, and use the generic_*_le_bit family of functions. Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Lars Ellenberg
Philipp Reisner
parent
7777a8ba1f
commit
95a0f10cdd
@ -30,6 +30,7 @@
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#include <asm/kmap_types.h>
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#include "drbd_int.h"
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/* OPAQUE outside this file!
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* interface defined in drbd_int.h
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@ -154,6 +155,14 @@ void drbd_bm_unlock(struct drbd_conf *mdev)
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mutex_unlock(&b->bm_change);
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}
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static unsigned int bm_bit_to_page_idx(struct drbd_bitmap *b, u64 bitnr)
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{
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/* page_nr = (bitnr/8) >> PAGE_SHIFT; */
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unsigned int page_nr = bitnr >> (PAGE_SHIFT + 3);
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BUG_ON(page_nr >= b->bm_number_of_pages);
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return page_nr;
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}
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/* word offset to long pointer */
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static unsigned long *__bm_map_paddr(struct drbd_bitmap *b, unsigned long offset, const enum km_type km)
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{
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@ -168,6 +177,17 @@ static unsigned long *__bm_map_paddr(struct drbd_bitmap *b, unsigned long offset
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return (unsigned long *) kmap_atomic(page, km);
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}
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static unsigned long *__bm_map_pidx(struct drbd_bitmap *b, unsigned int idx, const enum km_type km)
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{
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struct page *page = b->bm_pages[idx];
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return (unsigned long *) kmap_atomic(page, km);
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}
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static unsigned long *bm_map_pidx(struct drbd_bitmap *b, unsigned int idx)
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{
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return __bm_map_pidx(b, idx, KM_IRQ1);
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}
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static unsigned long * bm_map_paddr(struct drbd_bitmap *b, unsigned long offset)
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{
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return __bm_map_paddr(b, offset, KM_IRQ1);
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@ -329,22 +349,42 @@ void drbd_bm_cleanup(struct drbd_conf *mdev)
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* this masks out the remaining bits.
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* Returns the number of bits cleared.
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*/
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#define BITS_PER_PAGE (1UL << (PAGE_SHIFT + 3))
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#define BITS_PER_PAGE_MASK (BITS_PER_PAGE - 1)
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#define BITS_PER_LONG_MASK (BITS_PER_LONG - 1)
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static int bm_clear_surplus(struct drbd_bitmap *b)
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{
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const unsigned long mask = (1UL << (b->bm_bits & (BITS_PER_LONG-1))) - 1;
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size_t w = b->bm_bits >> LN2_BPL;
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int cleared = 0;
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unsigned long mask;
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unsigned long *p_addr, *bm;
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int tmp;
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int cleared = 0;
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p_addr = bm_map_paddr(b, w);
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bm = p_addr + MLPP(w);
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if (w < b->bm_words) {
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/* number of bits modulo bits per page */
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tmp = (b->bm_bits & BITS_PER_PAGE_MASK);
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/* mask the used bits of the word containing the last bit */
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mask = (1UL << (tmp & BITS_PER_LONG_MASK)) -1;
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/* bitmap is always stored little endian,
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* on disk and in core memory alike */
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mask = cpu_to_lel(mask);
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/* because of the "extra long to catch oob access" we allocate in
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* drbd_bm_resize, bm_number_of_pages -1 is not necessarily the page
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* containing the last _relevant_ bitmap word */
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p_addr = bm_map_pidx(b, bm_bit_to_page_idx(b, b->bm_bits - 1));
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bm = p_addr + (tmp/BITS_PER_LONG);
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if (mask) {
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/* If mask != 0, we are not exactly aligned, so bm now points
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* to the long containing the last bit.
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* If mask == 0, bm already points to the word immediately
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* after the last (long word aligned) bit. */
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cleared = hweight_long(*bm & ~mask);
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*bm &= mask;
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w++; bm++;
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bm++;
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}
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if (w < b->bm_words) {
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if (BITS_PER_LONG == 32 && ((bm - p_addr) & 1) == 1) {
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/* on a 32bit arch, we may need to zero out
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* a padding long to align with a 64bit remote */
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cleared += hweight_long(*bm);
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*bm = 0;
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}
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@ -354,24 +394,41 @@ static int bm_clear_surplus(struct drbd_bitmap *b)
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static void bm_set_surplus(struct drbd_bitmap *b)
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{
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const unsigned long mask = (1UL << (b->bm_bits & (BITS_PER_LONG-1))) - 1;
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size_t w = b->bm_bits >> LN2_BPL;
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unsigned long mask;
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unsigned long *p_addr, *bm;
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int tmp;
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p_addr = bm_map_paddr(b, w);
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bm = p_addr + MLPP(w);
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if (w < b->bm_words) {
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/* number of bits modulo bits per page */
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tmp = (b->bm_bits & BITS_PER_PAGE_MASK);
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/* mask the used bits of the word containing the last bit */
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mask = (1UL << (tmp & BITS_PER_LONG_MASK)) -1;
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/* bitmap is always stored little endian,
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* on disk and in core memory alike */
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mask = cpu_to_lel(mask);
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/* because of the "extra long to catch oob access" we allocate in
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* drbd_bm_resize, bm_number_of_pages -1 is not necessarily the page
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* containing the last _relevant_ bitmap word */
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p_addr = bm_map_pidx(b, bm_bit_to_page_idx(b, b->bm_bits - 1));
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bm = p_addr + (tmp/BITS_PER_LONG);
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if (mask) {
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/* If mask != 0, we are not exactly aligned, so bm now points
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* to the long containing the last bit.
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* If mask == 0, bm already points to the word immediately
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* after the last (long word aligned) bit. */
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*bm |= ~mask;
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bm++; w++;
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bm++;
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}
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if (w < b->bm_words) {
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*bm = ~(0UL);
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if (BITS_PER_LONG == 32 && ((bm - p_addr) & 1) == 1) {
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/* on a 32bit arch, we may need to zero out
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* a padding long to align with a 64bit remote */
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*bm = ~0UL;
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}
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bm_unmap(p_addr);
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}
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static unsigned long __bm_count_bits(struct drbd_bitmap *b, const int swap_endian)
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static unsigned long bm_count_bits(struct drbd_bitmap *b)
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{
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unsigned long *p_addr, *bm, offset = 0;
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unsigned long bits = 0;
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@ -389,10 +446,6 @@ static unsigned long __bm_count_bits(struct drbd_bitmap *b, const int swap_endia
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p_addr = __bm_map_paddr(b, offset, KM_USER0);
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bm = p_addr + MLPP(offset);
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while (i--) {
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#ifndef __LITTLE_ENDIAN
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if (swap_endian)
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*bm = lel_to_cpu(*bm);
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#endif
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bits += hweight_long(*bm++);
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}
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offset += do_now;
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@ -415,16 +468,6 @@ static unsigned long __bm_count_bits(struct drbd_bitmap *b, const int swap_endia
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return bits;
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}
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static unsigned long bm_count_bits(struct drbd_bitmap *b)
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{
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return __bm_count_bits(b, 0);
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}
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static unsigned long bm_count_bits_swap_endian(struct drbd_bitmap *b)
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{
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return __bm_count_bits(b, 1);
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}
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/* offset and len in long words.*/
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static void bm_memset(struct drbd_bitmap *b, size_t offset, int c, size_t len)
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{
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@ -662,7 +705,7 @@ void drbd_bm_merge_lel(struct drbd_conf *mdev, size_t offset, size_t number,
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offset += do_now;
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while (do_now--) {
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bits = hweight_long(*bm);
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word = *bm | lel_to_cpu(*buffer++);
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word = *bm | *buffer++;
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*bm++ = word;
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b->bm_set += hweight_long(word) - bits;
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}
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@ -709,7 +752,7 @@ void drbd_bm_get_lel(struct drbd_conf *mdev, size_t offset, size_t number,
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bm = p_addr + MLPP(offset);
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offset += do_now;
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while (do_now--)
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*buffer++ = cpu_to_lel(*bm++);
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*buffer++ = *bm++;
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bm_unmap(p_addr);
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}
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}
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@ -795,39 +838,6 @@ static void bm_page_io_async(struct drbd_conf *mdev, struct drbd_bitmap *b, int
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}
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}
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# if defined(__LITTLE_ENDIAN)
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/* nothing to do, on disk == in memory */
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# define bm_cpu_to_lel(x) ((void)0)
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# else
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static void bm_cpu_to_lel(struct drbd_bitmap *b)
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{
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/* need to cpu_to_lel all the pages ...
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* this may be optimized by using
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* cpu_to_lel(-1) == -1 and cpu_to_lel(0) == 0;
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* the following is still not optimal, but better than nothing */
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unsigned int i;
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unsigned long *p_addr, *bm;
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if (b->bm_set == 0) {
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/* no page at all; avoid swap if all is 0 */
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i = b->bm_number_of_pages;
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} else if (b->bm_set == b->bm_bits) {
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/* only the last page */
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i = b->bm_number_of_pages - 1;
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} else {
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/* all pages */
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i = 0;
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}
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for (; i < b->bm_number_of_pages; i++) {
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p_addr = kmap_atomic(b->bm_pages[i], KM_USER0);
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for (bm = p_addr; bm < p_addr + PAGE_SIZE/sizeof(long); bm++)
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*bm = cpu_to_lel(*bm);
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kunmap_atomic(p_addr, KM_USER0);
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}
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}
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# endif
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/* lel_to_cpu == cpu_to_lel */
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# define bm_lel_to_cpu(x) bm_cpu_to_lel(x)
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/*
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* bm_rw: read/write the whole bitmap from/to its on disk location.
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*/
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@ -847,10 +857,6 @@ static int bm_rw(struct drbd_conf *mdev, int rw) __must_hold(local)
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bm_words = drbd_bm_words(mdev);
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num_pages = (bm_words*sizeof(long) + PAGE_SIZE-1) >> PAGE_SHIFT;
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/* on disk bitmap is little endian */
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if (rw == WRITE)
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bm_cpu_to_lel(b);
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now = jiffies;
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atomic_set(&b->bm_async_io, num_pages);
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__clear_bit(BM_MD_IO_ERROR, &b->bm_flags);
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@ -869,13 +875,9 @@ static int bm_rw(struct drbd_conf *mdev, int rw) __must_hold(local)
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now = jiffies;
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if (rw == WRITE) {
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/* swap back endianness */
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bm_lel_to_cpu(b);
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/* flush bitmap to stable storage */
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drbd_md_flush(mdev);
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} else /* rw == READ */ {
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/* just read, if necessary adjust endianness */
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b->bm_set = bm_count_bits_swap_endian(b);
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b->bm_set = bm_count_bits(b);
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dev_info(DEV, "recounting of set bits took additional %lu jiffies\n",
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jiffies - now);
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}
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@ -969,9 +971,9 @@ static unsigned long __bm_find_next(struct drbd_conf *mdev, unsigned long bm_fo,
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p_addr = __bm_map_paddr(b, offset, km);
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if (find_zero_bit)
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i = find_next_zero_bit(p_addr, PAGE_SIZE*8, bm_fo & BPP_MASK);
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i = generic_find_next_zero_le_bit(p_addr, PAGE_SIZE*8, bm_fo & BPP_MASK);
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else
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i = find_next_bit(p_addr, PAGE_SIZE*8, bm_fo & BPP_MASK);
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i = generic_find_next_le_bit(p_addr, PAGE_SIZE*8, bm_fo & BPP_MASK);
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__bm_unmap(p_addr, km);
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if (i < PAGE_SIZE*8) {
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@ -1064,9 +1066,9 @@ static int __bm_change_bits_to(struct drbd_conf *mdev, const unsigned long s,
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last_page_nr = page_nr;
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}
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if (val)
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c += (0 == __test_and_set_bit(bitnr & BPP_MASK, p_addr));
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c += (0 == generic___test_and_set_le_bit(bitnr & BPP_MASK, p_addr));
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else
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c -= (0 != __test_and_clear_bit(bitnr & BPP_MASK, p_addr));
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c -= (0 != generic___test_and_clear_le_bit(bitnr & BPP_MASK, p_addr));
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}
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if (p_addr)
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__bm_unmap(p_addr, km);
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@ -1211,7 +1213,7 @@ int drbd_bm_test_bit(struct drbd_conf *mdev, const unsigned long bitnr)
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if (bitnr < b->bm_bits) {
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unsigned long offset = bitnr>>LN2_BPL;
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p_addr = bm_map_paddr(b, offset);
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i = test_bit(bitnr & BPP_MASK, p_addr) ? 1 : 0;
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i = generic_test_le_bit(bitnr & BPP_MASK, p_addr) ? 1 : 0;
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bm_unmap(p_addr);
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} else if (bitnr == b->bm_bits) {
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i = -1;
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@ -1255,7 +1257,7 @@ int drbd_bm_count_bits(struct drbd_conf *mdev, const unsigned long s, const unsi
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ERR_IF (bitnr >= b->bm_bits) {
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dev_err(DEV, "bitnr=%lu bm_bits=%lu\n", bitnr, b->bm_bits);
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} else {
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c += (0 != test_bit(bitnr - (page_nr << (PAGE_SHIFT+3)), p_addr));
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c += (0 != generic_test_le_bit(bitnr - (page_nr << (PAGE_SHIFT+3)), p_addr));
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}
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}
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if (p_addr)
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