Hi Gao,

okay. I will make those changes. Yes I would like to do kernel side changes
too. Which branch to use for this? kernel's master?

-Pratik

On Tue, 15 Oct, 2019, 5:15 AM Gao Xiang, <hsiangkao@aol.com> wrote:

> Hi Pratik,
>
> Some nitpick comments... Let me know if you have other thoughts
>
> On Mon, Oct 14, 2019 at 08:29:43PM +0530, Pratik Shinde wrote:
> > 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
> >
> > modified patch based on review comments.
> >
> > Signed-off-by: Pratik Shinde <pratikshinde320@gmail.com>
> > ---
> >  include/erofs/internal.h |  1 +
> >  include/erofs/io.h       |  8 +++++
> >  lib/io.c                 | 27 +++++++++++++++++
> >  mkfs/main.c              | 76
> ++++++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 112 insertions(+)
> >
> > 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/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..baaf02a 100644
> > --- a/mkfs/main.c
> > +++ b/mkfs/main.c
> > @@ -22,6 +22,10 @@
> >
> >  #define EROFS_SUPER_END (EROFS_SUPER_OFFSET + sizeof(struct
> erofs_super_block))
> >
> > +/* number of blocks for calculating checksum */
> > +#define EROFS_CKSUM_BLOCKS   1
> > +#define EROFS_FEATURE_SB_CHKSUM      0x0001
>
> How about Moving EROFS_FEATURE_SB_CHKSUM to erofs_fs.h since it's
> an on-disk definition,
>
> > +
> >  static void usage(void)
> >  {
> >       fprintf(stderr, "usage: [options] FILE DIRECTORY\n\n");
> > @@ -85,6 +89,10 @@ 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 +188,7 @@ 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
> >       };
> >       const unsigned int sb_blksize =
> >               round_up(EROFS_SUPER_END, EROFS_BLKSIZ);
> > @@ -202,6 +211,70 @@ 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) {
> > +             erofs_err("Failed to calculate erofs checksum - %s",
> > +                       erofs_strerror(err));
> > +             return err;
> > +     }
> > +     *crc = crc32c(0, (const unsigned char *)buf, nblks * EROFS_BLKSIZ);
> > +     free(buf);
> > +     return 0;
> > +}
> > +
> > +void erofs_write_checksum()
>
> How about naming write_sb_checksum?
> My idea is that this is a checksum in super block (rather than
> a checksum only for super block [0th block])
>
> Let me know if you have another thought...
>
> > +{
> > +     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) {
> > +             erofs_err("error reading super-block structure");
> > +             return;
> > +     }
> > +
> > +     sb = (struct erofs_super_block *)((u8 *)buf + EROFS_SUPER_OFFSET);
> > +     if (le32_to_cpu(sb->magic) != EROFS_SUPER_MAGIC_V1) {
> > +             erofs_err("not an erofs image");
>
> As the previous comments, I am little care about these print messages
> since users will only see this and "error reading super-block structure"
> "not an erofs image" makes confused for them... (They don't know what
> the internal process is doing)
>
> BTW, it looks good to me as a whole... Do you have some time on
> kernel side as well? :)
>
> Thanks,
> Gao Xiang
>
> > +             return;
> > +     }
> > +     sb->checksum = cpu_to_le32(crc);
> > +     ret = blk_write(buf, 0, 1);
> > +     if (ret) {
> > +             erofs_err("error writing 0th block to disk - %s",
> > +                       erofs_strerror(ret));
> > +             return;
> > +     }
> > +}
> > +
> >  int main(int argc, char **argv)
> >  {
> >       int err = 0;
> > @@ -217,6 +290,7 @@ 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 +375,8 @@ int main(int argc, char **argv)
> >               err = -EIO;
> >       else
> >               err = dev_resize(nblocks);
> > +     if (sbi.feature & EROFS_FEATURE_SB_CHKSUM)
> > +             erofs_write_checksum();
> >  exit:
> >       z_erofs_compress_exit();
> >       dev_close();
> > --
> > 2.9.3
> >
>