f2fs: refactor __find_rev_next_{zero}_bit
This patch refactors __find_rev_next_{zero}_bit which was disabled previously
due to bugs.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Jaegeuk Kim
Родитель
67f8cf3cee
Коммит
f96999c35f
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@ -29,6 +29,21 @@ static struct kmem_cache *discard_entry_slab;
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static struct kmem_cache *sit_entry_set_slab;
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static struct kmem_cache *inmem_entry_slab;
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static unsigned long __reverse_ulong(unsigned char *str)
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{
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unsigned long tmp = 0;
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int shift = 24, idx = 0;
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#if BITS_PER_LONG == 64
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shift = 56;
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#endif
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while (shift >= 0) {
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tmp |= (unsigned long)str[idx++] << shift;
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shift -= BITS_PER_BYTE;
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}
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return tmp;
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}
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/*
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* __reverse_ffs is copied from include/asm-generic/bitops/__ffs.h since
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* MSB and LSB are reversed in a byte by f2fs_set_bit.
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@ -38,27 +53,31 @@ static inline unsigned long __reverse_ffs(unsigned long word)
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int num = 0;
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#if BITS_PER_LONG == 64
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if ((word & 0xffffffff) == 0) {
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if ((word & 0xffffffff00000000UL) == 0)
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num += 32;
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else
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word >>= 32;
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}
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#endif
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if ((word & 0xffff) == 0) {
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if ((word & 0xffff0000) == 0)
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num += 16;
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else
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word >>= 16;
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}
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if ((word & 0xff) == 0) {
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if ((word & 0xff00) == 0)
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num += 8;
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else
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word >>= 8;
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}
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if ((word & 0xf0) == 0)
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num += 4;
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else
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word >>= 4;
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if ((word & 0xc) == 0)
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num += 2;
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else
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word >>= 2;
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if ((word & 0x2) == 0)
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num += 1;
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return num;
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@ -68,26 +87,16 @@ static inline unsigned long __reverse_ffs(unsigned long word)
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* __find_rev_next(_zero)_bit is copied from lib/find_next_bit.c because
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* f2fs_set_bit makes MSB and LSB reversed in a byte.
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* Example:
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* LSB <--> MSB
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* f2fs_set_bit(0, bitmap) => 0000 0001
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* f2fs_set_bit(7, bitmap) => 1000 0000
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* MSB <--> LSB
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* f2fs_set_bit(0, bitmap) => 1000 0000
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* f2fs_set_bit(7, bitmap) => 0000 0001
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*/
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static unsigned long __find_rev_next_bit(const unsigned long *addr,
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unsigned long size, unsigned long offset)
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{
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while (!f2fs_test_bit(offset, (unsigned char *)addr))
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offset++;
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if (offset > size)
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offset = size;
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return offset;
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#if 0
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const unsigned long *p = addr + BIT_WORD(offset);
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unsigned long result = offset & ~(BITS_PER_LONG - 1);
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unsigned long tmp;
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unsigned long mask, submask;
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unsigned long quot, rest;
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if (offset >= size)
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return size;
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@ -97,14 +106,9 @@ static unsigned long __find_rev_next_bit(const unsigned long *addr,
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if (!offset)
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goto aligned;
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tmp = *(p++);
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quot = (offset >> 3) << 3;
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rest = offset & 0x7;
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mask = ~0UL << quot;
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submask = (unsigned char)(0xff << rest) >> rest;
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submask <<= quot;
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mask &= submask;
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tmp &= mask;
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tmp = __reverse_ulong((unsigned char *)p);
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tmp &= ~0UL >> offset;
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if (size < BITS_PER_LONG)
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goto found_first;
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if (tmp)
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@ -112,42 +116,34 @@ static unsigned long __find_rev_next_bit(const unsigned long *addr,
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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p++;
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aligned:
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while (size & ~(BITS_PER_LONG-1)) {
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tmp = *(p++);
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tmp = __reverse_ulong((unsigned char *)p);
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if (tmp)
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goto found_middle;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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p++;
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}
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if (!size)
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return result;
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tmp = *p;
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tmp = __reverse_ulong((unsigned char *)p);
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found_first:
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tmp &= (~0UL >> (BITS_PER_LONG - size));
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if (tmp == 0UL) /* Are any bits set? */
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tmp &= (~0UL << (BITS_PER_LONG - size));
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if (!tmp) /* Are any bits set? */
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return result + size; /* Nope. */
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found_middle:
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return result + __reverse_ffs(tmp);
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#endif
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}
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static unsigned long __find_rev_next_zero_bit(const unsigned long *addr,
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unsigned long size, unsigned long offset)
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{
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while (f2fs_test_bit(offset, (unsigned char *)addr))
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offset++;
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if (offset > size)
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offset = size;
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return offset;
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#if 0
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const unsigned long *p = addr + BIT_WORD(offset);
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unsigned long result = offset & ~(BITS_PER_LONG - 1);
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unsigned long tmp;
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unsigned long mask, submask;
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unsigned long quot, rest;
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if (offset >= size)
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return size;
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@ -157,40 +153,36 @@ static unsigned long __find_rev_next_zero_bit(const unsigned long *addr,
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if (!offset)
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goto aligned;
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tmp = *(p++);
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quot = (offset >> 3) << 3;
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rest = offset & 0x7;
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mask = ~(~0UL << quot);
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submask = (unsigned char)~((unsigned char)(0xff << rest) >> rest);
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submask <<= quot;
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mask += submask;
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tmp |= mask;
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tmp = __reverse_ulong((unsigned char *)p);
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tmp |= ~((~0UL << offset) >> offset);
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if (size < BITS_PER_LONG)
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goto found_first;
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if (~tmp)
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if (tmp != ~0UL)
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goto found_middle;
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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p++;
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aligned:
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while (size & ~(BITS_PER_LONG - 1)) {
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tmp = *(p++);
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if (~tmp)
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tmp = __reverse_ulong((unsigned char *)p);
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if (tmp != ~0UL)
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goto found_middle;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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p++;
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}
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if (!size)
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return result;
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tmp = *p;
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tmp = __reverse_ulong((unsigned char *)p);
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found_first:
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tmp |= ~0UL << size;
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if (tmp == ~0UL) /* Are any bits zero? */
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tmp |= ~(~0UL << (BITS_PER_LONG - size));
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if (tmp == ~0UL) /* Are any bits zero? */
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return result + size; /* Nope. */
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found_middle:
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return result + __reverse_ffz(tmp);
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#endif
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}
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void register_inmem_page(struct inode *inode, struct page *page)
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