Hi Jaegeuk, > -----Original Message----- > From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx] > Sent: Thursday, October 22, 2015 6:30 AM > To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx; > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > Subject: Re: [f2fs-dev] [PATCH] f2fs: refactor __find_rev_next_{zero}_bit > > On Wed, Oct 21, 2015 at 02:16:43PM -0700, Jaegeuk Kim wrote: > > This patch refactors __find_rev_next_{zero}_bit which was disabled previously > > due to bugs. Actually I didn't know the history here, could you please explain details about the bugs? then I can do the review. Thanks, > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> > > --- > > fs/f2fs/segment.c | 106 +++++++++++++++++++++++++----------------------------- > > 1 file changed, 49 insertions(+), 57 deletions(-) > > > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > index f37c212..50afc93 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 & 0xffffffff00000000) == 0) > > I fixed the sparse warning by modifying: > if ((word & 0xffffffff00000000UL) == 0) > > Thanks, > > > 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) > > -- > > 2.1.1 > > ------------------------------------------------------------------------------ > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
