| Message ID | 1445462203-44072-1-git-send-email-jaegeuk@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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. > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Jaegeuk, > -----Original Message----- > From: Jaegeuk Kim [mailto:jaegeuk@kernel.org] > Sent: Thursday, October 22, 2015 6:30 AM > To: linux-kernel@vger.kernel.org; linux-fsdevel@vger.kernel.org; > linux-f2fs-devel@lists.sourceforge.net > 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@kernel.org> > > --- > > 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@lists.sourceforge.net > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Chao, On Thu, Oct 22, 2015 at 07:24:01PM +0800, Chao Yu wrote: > Hi Jaegeuk, > > > -----Original Message----- > > From: Jaegeuk Kim [mailto:jaegeuk@kernel.org] > > Sent: Thursday, October 22, 2015 6:30 AM > > To: linux-kernel@vger.kernel.org; linux-fsdevel@vger.kernel.org; > > linux-f2fs-devel@lists.sourceforge.net > > 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. When I disabled the existing function by: commit e19ef527aa32f057710ec842fe656bffc263b0bb Author: Jaegeuk Kim <jaegeuk@kernel.org> Date: Mon May 18 11:45:15 2015 -0700 f2fs: avoid buggy functions I found a mismatch of results between the existing __find_rev_next_bit and f2fs_test_bit work. I remember it happened on __find_rev_next_bit sometimes by xfstests which include trim_fs. (I didn't get an error from __find_rev_zero_bit though.) Since I have no time to investigate the bug in more detail at that time, I just disabled it. But, now I'm trying to refactor the flow to fix this. Thanks, > > Thanks, > > > > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > > > --- > > > 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@lists.sourceforge.net > > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
In bitmaps of f2fs, bytes are sorted in ascending order, but bits in a byte are sorted in descending order. It seems to be the reason why __reverse_ulong is needed. May I ask why f2fs bitmap apply such order? > -----Original Message----- > From: Jaegeuk Kim [mailto:jaegeuk@kernel.org] > Sent: Friday, October 23, 2015 12:36 AM > To: Chao Yu > Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net > Subject: Re: [f2fs-dev] [PATCH] f2fs: refactor __find_rev_next_{zero}_bit > > Hi Chao, > > On Thu, Oct 22, 2015 at 07:24:01PM +0800, Chao Yu wrote: > > Hi Jaegeuk, > > > > > -----Original Message----- > > > From: Jaegeuk Kim [mailto:jaegeuk@kernel.org] > > > Sent: Thursday, October 22, 2015 6:30 AM > > > To: linux-kernel@vger.kernel.org; linux-fsdevel@vger.kernel.org; > > > linux-f2fs-devel@lists.sourceforge.net > > > 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. > > When I disabled the existing function by: > > commit e19ef527aa32f057710ec842fe656bffc263b0bb > Author: Jaegeuk Kim <jaegeuk@kernel.org> > Date: Mon May 18 11:45:15 2015 -0700 > > f2fs: avoid buggy functions > > I found a mismatch of results between the existing __find_rev_next_bit and f2fs_test_bit work. I remember it happened on > __find_rev_next_bit sometimes by xfstests which include trim_fs. > (I didn't get an error from __find_rev_zero_bit though.) > > Since I have no time to investigate the bug in more detail at that time, I just disabled it. But, now I'm trying to refactor the flow to fix > this. > > Thanks, > > > > > Thanks, > > > > > > > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > > > > --- > > > > 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@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > > ------------------------------------------------------------------------------ > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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) 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)
This patch refactors __find_rev_next_{zero}_bit which was disabled previously due to bugs. Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> --- fs/f2fs/segment.c | 106 +++++++++++++++++++++++++----------------------------- 1 file changed, 49 insertions(+), 57 deletions(-)