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author | Jaegeuk Kim <jaegeuk@kernel.org> | 2015-10-20 22:17:19 (GMT) |
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committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2015-10-21 22:26:00 (GMT) |
commit | f96999c35f46fa9bce8a3a2812cd0a28fcde5903 (patch) | |
tree | a2e07780054b175cf2295f316a88607c46a05225 /fs | |
parent | 67f8cf3cee6f398d05de8333c04fea2ddb59c805 (diff) | |
download | linux-f96999c35f46fa9bce8a3a2812cd0a28fcde5903.tar.xz |
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>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/f2fs/segment.c | 106 |
1 files changed, 49 insertions, 57 deletions
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index f37c212..7835e41 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -29,6 +29,21 @@ static struct kmem_cache *discard_entry_slab; static struct kmem_cache *sit_entry_set_slab; static struct kmem_cache *inmem_entry_slab; +static unsigned long __reverse_ulong(unsigned char *str) +{ + unsigned long tmp = 0; + int shift = 24, idx = 0; + +#if BITS_PER_LONG == 64 + shift = 56; +#endif + while (shift >= 0) { + tmp |= (unsigned long)str[idx++] << shift; + shift -= BITS_PER_BYTE; + } + return tmp; +} + /* * __reverse_ffs is copied from include/asm-generic/bitops/__ffs.h since * MSB and LSB are reversed in a byte by f2fs_set_bit. @@ -38,27 +53,31 @@ static inline unsigned long __reverse_ffs(unsigned long word) int num = 0; #if BITS_PER_LONG == 64 - if ((word & 0xffffffff) == 0) { + if ((word & 0xffffffff00000000UL) == 0) num += 32; + else word >>= 32; - } #endif - if ((word & 0xffff) == 0) { + if ((word & 0xffff0000) == 0) num += 16; + else word >>= 16; - } - if ((word & 0xff) == 0) { + + if ((word & 0xff00) == 0) num += 8; + else word >>= 8; - } + if ((word & 0xf0) == 0) num += 4; else word >>= 4; + if ((word & 0xc) == 0) num += 2; else word >>= 2; + if ((word & 0x2) == 0) num += 1; return num; @@ -68,26 +87,16 @@ static inline unsigned long __reverse_ffs(unsigned long word) * __find_rev_next(_zero)_bit is copied from lib/find_next_bit.c because * f2fs_set_bit makes MSB and LSB reversed in a byte. * Example: - * LSB <--> MSB - * f2fs_set_bit(0, bitmap) => 0000 0001 - * f2fs_set_bit(7, bitmap) => 1000 0000 + * MSB <--> LSB + * f2fs_set_bit(0, bitmap) => 1000 0000 + * f2fs_set_bit(7, bitmap) => 0000 0001 */ static unsigned long __find_rev_next_bit(const unsigned long *addr, unsigned long size, unsigned long offset) { - while (!f2fs_test_bit(offset, (unsigned char *)addr)) - offset++; - - if (offset > size) - offset = size; - - return offset; -#if 0 const unsigned long *p = addr + BIT_WORD(offset); unsigned long result = offset & ~(BITS_PER_LONG - 1); unsigned long tmp; - unsigned long mask, submask; - unsigned long quot, rest; if (offset >= size) return size; @@ -97,14 +106,9 @@ static unsigned long __find_rev_next_bit(const unsigned long *addr, if (!offset) goto aligned; - tmp = *(p++); - quot = (offset >> 3) << 3; - rest = offset & 0x7; - mask = ~0UL << quot; - submask = (unsigned char)(0xff << rest) >> rest; - submask <<= quot; - mask &= submask; - tmp &= mask; + tmp = __reverse_ulong((unsigned char *)p); + tmp &= ~0UL >> offset; + if (size < BITS_PER_LONG) goto found_first; if (tmp) @@ -112,42 +116,34 @@ static unsigned long __find_rev_next_bit(const unsigned long *addr, size -= BITS_PER_LONG; result += BITS_PER_LONG; + p++; aligned: while (size & ~(BITS_PER_LONG-1)) { - tmp = *(p++); + tmp = __reverse_ulong((unsigned char *)p); if (tmp) goto found_middle; result += BITS_PER_LONG; size -= BITS_PER_LONG; + p++; } if (!size) return result; - tmp = *p; + + tmp = __reverse_ulong((unsigned char *)p); found_first: - tmp &= (~0UL >> (BITS_PER_LONG - size)); - if (tmp == 0UL) /* Are any bits set? */ + tmp &= (~0UL << (BITS_PER_LONG - size)); + if (!tmp) /* Are any bits set? */ return result + size; /* Nope. */ found_middle: return result + __reverse_ffs(tmp); -#endif } static unsigned long __find_rev_next_zero_bit(const unsigned long *addr, unsigned long size, unsigned long offset) { - while (f2fs_test_bit(offset, (unsigned char *)addr)) - offset++; - - if (offset > size) - offset = size; - - return offset; -#if 0 const unsigned long *p = addr + BIT_WORD(offset); unsigned long result = offset & ~(BITS_PER_LONG - 1); unsigned long tmp; - unsigned long mask, submask; - unsigned long quot, rest; if (offset >= size) return size; @@ -157,40 +153,36 @@ static unsigned long __find_rev_next_zero_bit(const unsigned long *addr, if (!offset) goto aligned; - tmp = *(p++); - quot = (offset >> 3) << 3; - rest = offset & 0x7; - mask = ~(~0UL << quot); - submask = (unsigned char)~((unsigned char)(0xff << rest) >> rest); - submask <<= quot; - mask += submask; - tmp |= mask; + tmp = __reverse_ulong((unsigned char *)p); + tmp |= ~((~0UL << offset) >> offset); + if (size < BITS_PER_LONG) goto found_first; - if (~tmp) + if (tmp != ~0UL) goto found_middle; size -= BITS_PER_LONG; result += BITS_PER_LONG; + p++; aligned: while (size & ~(BITS_PER_LONG - 1)) { - tmp = *(p++); - if (~tmp) + tmp = __reverse_ulong((unsigned char *)p); + if (tmp != ~0UL) goto found_middle; result += BITS_PER_LONG; size -= BITS_PER_LONG; + p++; } if (!size) return result; - tmp = *p; + tmp = __reverse_ulong((unsigned char *)p); found_first: - tmp |= ~0UL << size; - if (tmp == ~0UL) /* Are any bits zero? */ + tmp |= ~(~0UL << (BITS_PER_LONG - size)); + if (tmp == ~0UL) /* Are any bits zero? */ return result + size; /* Nope. */ found_middle: return result + __reverse_ffz(tmp); -#endif } void register_inmem_page(struct inode *inode, struct page *page) |