[PATCH-v3] erofs-utils:code for calculating crc checksum of erofs blocks.
Gao Xiang
hsiangkao at aol.com
Wed Oct 16 02:18:47 AEDT 2019
Hi Guifu,
On Tue, Oct 15, 2019 at 11:11:43PM +0800, Li Guifu wrote:
> Hi Pratik, Gao Xiang
>
> Can sbi.fearture merge into sbi.feature_incompat ?
> If not, it will has two feature parameter
Nope, please refer to
https://lore.kernel.org/r/20190822142142.GB2730@mit.edu/
>
> It has the blocks field in the super block, chksum_blocks duplicates it.
> and chksum may be used to check whole erofs image file.
Nope, chksum_blocks is used for checksuming given blocks, blocks field is
designed to be used for statfs.
Thanks,
Gao Xiang
>
> > Added code for calculating crc of erofs blocks (4K size).for now it calculates
> > checksum of first block. but can modified to calculate crc for any no. of blocks
> >
> > 1) Added 'chksum_blocks' field to erofs_super_block
> > 2) removed unnecessary prints
> > 3) moved EROFS_FEATURE_SB_CHKSUM include/erofs_fs.h
> >
> > Signed-off-by: Pratik Shinde <pratikshinde320 at gmail.com>
> > ---
> > include/erofs/internal.h | 1 +
> > include/erofs/io.h | 8 ++++++
> > include/erofs_fs.h | 3 ++-
> > lib/io.c | 27 +++++++++++++++++++
> > mkfs/main.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++
> > 5 files changed, 108 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/erofs/internal.h b/include/erofs/internal.h
> > index 5384946..53335bc 100644
> > --- a/include/erofs/internal.h
> > +++ b/include/erofs/internal.h
> > @@ -55,6 +55,7 @@ struct erofs_sb_info {
> > u32 feature_incompat;
> > u64 build_time;
> > u32 build_time_nsec;
> > + u32 feature;
> > };
> > /* global sbi */
> > diff --git a/include/erofs/io.h b/include/erofs/io.h
> > index 9775047..e0ca8d9 100644
> > --- a/include/erofs/io.h
> > +++ b/include/erofs/io.h
> > @@ -19,6 +19,7 @@
> > int dev_open(const char *devname);
> > void dev_close(void);
> > int dev_write(const void *buf, u64 offset, size_t len);
> > +int dev_read(void *buf, u64 offset, size_t len);
> > int dev_fillzero(u64 offset, size_t len, bool padding);
> > int dev_fsync(void);
> > int dev_resize(erofs_blk_t nblocks);
> > @@ -31,5 +32,12 @@ static inline int blk_write(const void *buf, erofs_blk_t blkaddr,
> > blknr_to_addr(nblocks));
> > }
> > +static inline int blk_read(void *buf, erofs_blk_t start,
> > + u32 nblocks)
> > +{
> > + return dev_read(buf, blknr_to_addr(start),
> > + blknr_to_addr(nblocks));
> > +}
> > +
> > #endif
> > diff --git a/include/erofs_fs.h b/include/erofs_fs.h
> > index f29aa25..8bd29d6 100644
> > --- a/include/erofs_fs.h
> > +++ b/include/erofs_fs.h
> > @@ -19,6 +19,7 @@
> > */
> > #define EROFS_FEATURE_INCOMPAT_LZ4_0PADDING 0x00000001
> > #define EROFS_ALL_FEATURE_INCOMPAT EROFS_FEATURE_INCOMPAT_LZ4_0PADDING
> > +#define EROFS_FEATURE_SB_CHKSUM 0x0001
> > /* 128-byte erofs on-disk super block */
> > struct erofs_super_block {
> > @@ -39,7 +40,7 @@ struct erofs_super_block {
> > __u8 uuid[16]; /* 128-bit uuid for volume */
> > __u8 volume_name[16]; /* volume name */
> > __le32 feature_incompat;
> > -
> > + __le32 chksum_blocks; /* number of blocks used for checksum */
> > __u8 reserved2[44];
> > };
> > diff --git a/lib/io.c b/lib/io.c
> > index 7f5f94d..52f9424 100644
> > --- a/lib/io.c
> > +++ b/lib/io.c
> > @@ -207,3 +207,30 @@ int dev_resize(unsigned int blocks)
> > return dev_fillzero(st.st_size, length, true);
> > }
> > +int dev_read(void *buf, u64 offset, size_t len)
> > +{
> > + int ret;
> > +
> > + if (cfg.c_dry_run)
> > + return 0;
> > +
> > + if (!buf) {
> > + erofs_err("buf is NULL");
> > + return -EINVAL;
> > + }
> > + if (offset >= erofs_devsz || len > erofs_devsz ||
> > + offset > erofs_devsz - len) {
> > + erofs_err("read posion[%" PRIu64 ", %zd] is too large beyond"
> > + "the end of device(%" PRIu64 ").",
> > + offset, len, erofs_devsz);
> > + return -EINVAL;
> > + }
> > +
> > + ret = pread64(erofs_devfd, buf, len, (off64_t)offset);
> > + if (ret != (int)len) {
> > + erofs_err("Failed to read data from device - %s:[%" PRIu64 ", %zd].",
> > + erofs_devname, offset, len);
> > + return -errno;
> > + }
> > + return 0;
> > +}
> > diff --git a/mkfs/main.c b/mkfs/main.c
> > index 91a018f..0633e83 100644
> > --- a/mkfs/main.c
> > +++ b/mkfs/main.c
> > @@ -22,6 +22,9 @@
> > #define EROFS_SUPER_END (EROFS_SUPER_OFFSET + sizeof(struct erofs_super_block))
> > +/* number of blocks for calculating checksum */
> > +#define EROFS_CKSUM_BLOCKS 1
> > +
> > static void usage(void)
> > {
> > fprintf(stderr, "usage: [options] FILE DIRECTORY\n\n");
> > @@ -85,6 +88,10 @@ static int parse_extended_opts(const char *opts)
> > return -EINVAL;
> > cfg.c_force_inodeversion = FORCE_INODE_EXTENDED;
> > }
> > +
> > + if (MATCH_EXTENTED_OPT("nocrc", token, keylen)) {
> > + sbi.feature &= ~EROFS_FEATURE_SB_CHKSUM;
> > + }
> > }
> > return 0;
> > }
> > @@ -180,6 +187,8 @@ int erofs_mkfs_update_super_block(struct erofs_buffer_head *bh,
> > .meta_blkaddr = sbi.meta_blkaddr,
> > .xattr_blkaddr = 0,
> > .feature_incompat = cpu_to_le32(sbi.feature_incompat),
> > + .checksum = 0,
> > + .chksum_blocks = cpu_to_le32(EROFS_CKSUM_BLOCKS)
> > };
> > const unsigned int sb_blksize =
> > round_up(EROFS_SUPER_END, EROFS_BLKSIZ);
> > @@ -202,6 +211,64 @@ int erofs_mkfs_update_super_block(struct erofs_buffer_head *bh,
> > return 0;
> > }
> > +#define CRCPOLY 0x82F63B78
> > +static inline u32 crc32c(u32 seed, unsigned char const *in, size_t len)
> > +{
> > + int i;
> > + u32 crc = seed;
> > +
> > + while (len--) {
> > + crc ^= *in++;
> > + for (i = 0; i < 8; i++) {
> > + crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY : 0);
> > + }
> > + }
> > + return crc;
> > +}
> > +
> > +/* calculate checksum for first n blocks */
> > +u32 erofs_calc_blk_checksum(erofs_blk_t nblks, u32 *crc)
> > +{
> > + char *buf;
> > + int err = 0;
> > +
> > + buf = malloc(nblks * EROFS_BLKSIZ);
> > + err = blk_read(buf, 0, nblks);
> > + if (err) {
> > + return err;
> > + }
> > + *crc = crc32c(0, (const unsigned char *)buf, nblks * EROFS_BLKSIZ);
> > + free(buf);
> > + return 0;
> > +}
> > +
> > +void erofs_write_sb_checksum()
> > +{
> > + struct erofs_super_block *sb;
> > + char buf[EROFS_BLKSIZ];
> > + int ret = 0;
> > + u32 crc;
> > +
> > + ret = erofs_calc_blk_checksum(EROFS_CKSUM_BLOCKS, &crc);
> > + if (ret) {
> > + return;
> > + }
> > + ret = blk_read(buf, 0, 1);
> > + if (ret) {
> > + return;
> > + }
> > +
> > + sb = (struct erofs_super_block *)((u8 *)buf + EROFS_SUPER_OFFSET);
> > + if (le32_to_cpu(sb->magic) != EROFS_SUPER_MAGIC_V1) {
> > + return;
> > + }
> > + sb->checksum = cpu_to_le32(crc);
> > + ret = blk_write(buf, 0, 1);
> > + if (ret) {
> > + return;
> > + }
> > +}
> > +
> > int main(int argc, char **argv)
> > {
> > int err = 0;
> > @@ -217,6 +284,7 @@ int main(int argc, char **argv)
> > cfg.c_legacy_compress = false;
> > sbi.feature_incompat = EROFS_FEATURE_INCOMPAT_LZ4_0PADDING;
> > + sbi.feature = EROFS_FEATURE_SB_CHKSUM;
> > err = mkfs_parse_options_cfg(argc, argv);
> > if (err) {
> > @@ -301,6 +369,8 @@ int main(int argc, char **argv)
> > err = -EIO;
> > else
> > err = dev_resize(nblocks);
> > + if (sbi.feature & EROFS_FEATURE_SB_CHKSUM)
> > + erofs_write_sb_checksum();
> > exit:
> > z_erofs_compress_exit();
> > dev_close();
> >
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