bytemark/flexnbd-c
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Stopped NBD writes from committing all-zero blocks to disc (tentative, needs

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further testing).
This commit is contained in:
Matthew Bloch
2012-05-18 13:24:35 +01:00
parent 0432fef8f5
commit ca53d6f270
5 changed files with 194 additions and 40 deletions
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40
bitset.h
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@@ -1,19 +1,25 @@
#ifndef __BITSET_H
#define __BITSET_H
#include <inttypes.h>
#include <string.h>
static inline char char_with_bit_set(int num) {
return 1<<(num%8);
}
static inline char char_with_bit_set(int num) { return 1<<(num%8); }
static inline int bit_is_set(char* b, int idx) {
return (b[idx/8] & char_with_bit_set(idx)) != 0;
}
static inline int bit_is_clear(char* b, int idx) {
return !bit_is_set(b, idx);
}
static inline int bit_has_value(char* b, int idx, int value) {
if (value)
return bit_is_set(b, idx);
else
return bit_is_clear(b, idx);
}
static inline void bit_set(char* b, int idx) {
b[idx/8] &= char_with_bit_set(idx);
b[idx/8] |= char_with_bit_set(idx);
}
static inline void bit_clear(char* b, int idx) {
b[idx/8] &= ~char_with_bit_set(idx);
@@ -35,5 +41,31 @@ static inline void bit_clear_range(char* b, int from, int len) {
bit_clear(b, from++);
}
static inline int bit_run_count(char* b, int from, int len) {
int count;
int first_value = bit_is_set(b, from);
for (count=0; len > 0 && bit_has_value(b, from+count, first_value); count++, len--)
;
/* FIXME: debug this later */
/*for (; (from+count) % 64 != 0 && len > 0; len--)
if (bit_has_value(b, from+count, first_value))
count++;
else
return count;
for (; len >= 64; len-=64) {
if (*((uint64_t*)(b + ((from+count)/8))) == UINT64_MAX)
count += 64;
else
break;
}
for (; len > 0; len--)
if (bit_is_set(b, from+count))
count++;*/
return count;
}
#endif