On Thu, Oct 29 2015, Song Liu wrote: > In kernel space, r5l checksum will use crc32c: > http://marc.info/?l=linux-raid&m=144598970529191 > mdadm need to change too. > > This patch ports a simplified crc32c algorithm from kernel code, > and used in super1.c:write_empty_r5l_meta_block(); > > Signed-off-by: Song Liu <songliubraving@xxxxxx> > Signed-off-by: Shaohua Li <shli@xxxxxx> applied, thanks. NeilBrown > --- > Makefile | 2 +- > crc32c.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > super1.c | 11 +++---- > 3 files changed, 109 insertions(+), 8 deletions(-) > create mode 100644 crc32c.c > > diff --git a/Makefile b/Makefile > index 544e6cb..fde2e63 100644 > --- a/Makefile > +++ b/Makefile > @@ -133,7 +133,7 @@ OBJS = mdadm.o config.o policy.o mdstat.o ReadMe.o util.o maps.o lib.o \ > mdopen.o super0.o super1.o super-ddf.o super-intel.o bitmap.o \ > super-mbr.o super-gpt.o \ > restripe.o sysfs.o sha1.o mapfile.o crc32.o sg_io.o msg.o xmalloc.o \ > - platform-intel.o probe_roms.o > + platform-intel.o probe_roms.o crc32c.o > > CHECK_OBJS = restripe.o sysfs.o maps.o lib.o xmalloc.o dlink.o > > diff --git a/crc32c.c b/crc32c.c > new file mode 100644 > index 0000000..156cba1 > --- /dev/null > +++ b/crc32c.c > @@ -0,0 +1,104 @@ > +/* > + * Oct 28, 2015 Song Liu simplified the code and port it to mdadm > + * > + * Aug 8, 2011 Bob Pearson with help from Joakim Tjernlund and George Spelvin > + * cleaned up code to current version of sparse and added the slicing-by-8 > + * algorithm to the closely similar existing slicing-by-4 algorithm. > + * > + * Oct 15, 2000 Matt Domsch <Matt_Domsch@xxxxxxxx> > + * Nicer crc32 functions/docs submitted by linux@xxxxxxxxxxx. Thanks! > + * Code was from the public domain, copyright abandoned. Code was > + * subsequently included in the kernel, thus was re-licensed under the > + * GNU GPL v2. > + * > + * Oct 12, 2000 Matt Domsch <Matt_Domsch@xxxxxxxx> > + * Same crc32 function was used in 5 other places in the kernel. > + * I made one version, and deleted the others. > + * There are various incantations of crc32(). Some use a seed of 0 or ~0. > + * Some xor at the end with ~0. The generic crc32() function takes > + * seed as an argument, and doesn't xor at the end. Then individual > + * users can do whatever they need. > + * drivers/net/smc9194.c uses seed ~0, doesn't xor with ~0. > + * fs/jffs2 uses seed 0, doesn't xor with ~0. > + * fs/partitions/efi.c uses seed ~0, xor's with ~0. > + * > + * This source code is licensed under the GNU General Public License, > + * Version 2. See the file COPYING for more details. > + */ > + > +#include <sys/types.h> > +#include <asm/types.h> > +#include <stdlib.h> > + > +/* > + * There are multiple 16-bit CRC polynomials in common use, but this is > + * *the* standard CRC-32 polynomial, first popularized by Ethernet. > + * x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x^1+x^0 > + */ > +#define CRCPOLY_LE 0xedb88320 > +#define CRCPOLY_BE 0x04c11db7 > + > +/* > + * This is the CRC32c polynomial, as outlined by Castagnoli. > + * x^32+x^28+x^27+x^26+x^25+x^23+x^22+x^20+x^19+x^18+x^14+x^13+x^11+x^10+x^9+ > + * x^8+x^6+x^0 > + */ > +#define CRC32C_POLY_LE 0x82F63B78 > + > +/** > + * crc32_le_generic() - Calculate bitwise little-endian Ethernet AUTODIN II > + * CRC32/CRC32C > + * @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for other > + * uses, or the previous crc32/crc32c value if computing incrementally. > + * @p: pointer to buffer over which CRC32/CRC32C is run > + * @len: length of buffer @p > + * @polynomial: CRC32/CRC32c LE polynomial > + */ > +static inline __u32 crc32_le_generic(__u32 crc, unsigned char const *p, > + size_t len, __u32 polynomial) > +{ > + int i; > + while (len--) { > + crc ^= *p++; > + for (i = 0; i < 8; i++) > + crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0); > + } > + return crc; > +} > + > +__u32 crc32_le(__u32 crc, unsigned char const *p, size_t len) > +{ > + return crc32_le_generic(crc, p, len, CRCPOLY_LE); > +} > + > +__u32 crc32c_le(__u32 crc, unsigned char const *p, size_t len) > +{ > + return crc32_le_generic(crc, p, len, CRC32C_POLY_LE); > +} > + > +/** > + * crc32_be_generic() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32 > + * @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for > + * other uses, or the previous crc32 value if computing incrementally. > + * @p: pointer to buffer over which CRC32 is run > + * @len: length of buffer @p > + * @polynomial: CRC32 BE polynomial > + */ > +static inline __u32 crc32_be_generic(__u32 crc, unsigned char const *p, > + size_t len, __u32 polynomial) > +{ > + int i; > + while (len--) { > + crc ^= *p++ << 24; > + for (i = 0; i < 8; i++) > + crc = > + (crc << 1) ^ ((crc & 0x80000000) ? polynomial : > + 0); > + } > + return crc; > +} > + > +__u32 crc32_be(__u32 crc, unsigned char const *p, size_t len) > +{ > + return crc32_be_generic(crc, p, len, CRCPOLY_BE); > +} > diff --git a/super1.c b/super1.c > index 58e6f9d..1735c2d 100644 > --- a/super1.c > +++ b/super1.c > @@ -1625,10 +1625,7 @@ static unsigned long choose_bm_space(unsigned long devsize) > static void free_super1(struct supertype *st); > > #define META_BLOCK_SIZE 4096 > -unsigned long crc32( > - unsigned long crc, > - const unsigned char *buf, > - unsigned len); > +__u32 crc32c_le(__u32 crc, unsigned char const *p, size_t len); > > static int write_empty_r5l_meta_block(struct supertype *st, int fd) > { > @@ -1652,9 +1649,9 @@ static int write_empty_r5l_meta_block(struct supertype *st, int fd) > mb->seq = __cpu_to_le64(random32()); > mb->position = __cpu_to_le64(0); > > - crc = crc32(0xffffffff, sb->set_uuid, sizeof(sb->set_uuid)); > - crc = crc32(crc, (void *)mb, META_BLOCK_SIZE); > - mb->checksum = __cpu_to_le32(crc); > + crc = crc32c_le(0xffffffff, sb->set_uuid, sizeof(sb->set_uuid)); > + crc = crc32c_le(crc, (void *)mb, META_BLOCK_SIZE); > + mb->checksum = crc; > > if (lseek64(fd, (sb->data_offset) * 512, 0) < 0LL) { > pr_err("cannot seek to offset of the meta block\n"); > -- > 2.4.6
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