[PATCH v8] erofs-utils: support calculating checksum of erofs blocks
Gao Xiang
gaoxiang25 at huawei.com
Wed Oct 30 13:55:06 AEDT 2019
Hi Chao,
On Wed, Oct 30, 2019 at 10:39:18AM +0800, Chao Yu wrote:
> On 2019/10/28 22:23, Gao Xiang wrote:
> > From: Pratik Shinde <pratikshinde320 at gmail.com>
> >
> > Added code for calculating crc of erofs blocks (4K size).
> > For now it calculates checksum of first block. but it can
> > be modified to calculate crc for any no. of blocks.
> >
> > Note that the first 1024 bytes are not checksumed to allow
> > for the installation of x86 boot sectors and other oddities.
> >
> > Fill 'feature_compat' field of erofs_super_block so that it
> > can be used on kernel side. also fixing one typo.
> >
> > Signed-off-by: Pratik Shinde <pratikshinde320 at gmail.com>
> > Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
> > ---
> >
> > changes since v7:
> > - get rid of `chksum_blocks' pointed out by Chao.
> >
> >
> > include/erofs/internal.h | 1 +
> > include/erofs/io.h | 8 +++++
> > include/erofs_fs.h | 3 +-
> > lib/io.c | 27 ++++++++++++++++
> > mkfs/main.c | 68 ++++++++++++++++++++++++++++++++++++++++
> > 5 files changed, 106 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/erofs/internal.h b/include/erofs/internal.h
> > index 25ce7b54442d..9e2bb9ce33b6 100644
> > --- a/include/erofs/internal.h
> > +++ b/include/erofs/internal.h
> > @@ -52,6 +52,7 @@ struct erofs_sb_info {
> > erofs_blk_t meta_blkaddr;
> > erofs_blk_t xattr_blkaddr;
> >
> > + u32 feature_compat;
> > u32 feature_incompat;
> > u64 build_time;
> > u32 build_time_nsec;
> > diff --git a/include/erofs/io.h b/include/erofs/io.h
> > index 97750478b5ab..e0ca8d949130 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 f29aa2516a99..bcc4f0c630ad 100644
> > --- a/include/erofs_fs.h
> > +++ b/include/erofs_fs.h
> > @@ -13,6 +13,8 @@
> > #define EROFS_SUPER_MAGIC_V1 0xE0F5E1E2
> > #define EROFS_SUPER_OFFSET 1024
> >
> > +#define EROFS_FEATURE_COMPAT_SB_CHKSUM 0x00000001
> > +
> > /*
> > * Any bits that aren't in EROFS_ALL_FEATURE_INCOMPAT should
> > * be incompatible with this kernel version.
> > @@ -39,7 +41,6 @@ struct erofs_super_block {
> > __u8 uuid[16]; /* 128-bit uuid for volume */
> > __u8 volume_name[16]; /* volume name */
> > __le32 feature_incompat;
> > -
> > __u8 reserved2[44];
> > };
> >
> > diff --git a/lib/io.c b/lib/io.c
> > index 7f5f94dd6b1e..52f9424d201b 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;
>
> Minor thing, I notice caller wrap this errno to EIO, so we'd better print errno
> here or by caller? Other part looks good to me anyway.
Oops, I didn't notice that... that's a good point,
let me resend with fix later...
>
> Reviewed-by: Chao Yu <yuchao0 at huawei.com>
Thanks for taking time on utils as well :-)
Thanks,
Gao Xiang
>
> Thanks,
>
> > + }
> > + return 0;
> > +}
> > diff --git a/mkfs/main.c b/mkfs/main.c
> > index ab57896e9ca8..eeb6ccc55b82 100644
> > --- a/mkfs/main.c
> > +++ b/mkfs/main.c
> > @@ -109,6 +109,12 @@ static int parse_extended_opts(const char *opts)
> > return -EINVAL;
> > cfg.c_force_inodeversion = FORCE_INODE_EXTENDED;
> > }
> > +
> > + if (MATCH_EXTENTED_OPT("nosbcrc", token, keylen)) {
> > + if (vallen)
> > + return -EINVAL;
> > + sbi.feature_compat &= ~EROFS_FEATURE_COMPAT_SB_CHKSUM;
> > + }
> > }
> > return 0;
> > }
> > @@ -218,6 +224,8 @@ int erofs_mkfs_update_super_block(struct erofs_buffer_head *bh,
> > .meta_blkaddr = sbi.meta_blkaddr,
> > .xattr_blkaddr = sbi.xattr_blkaddr,
> > .feature_incompat = cpu_to_le32(sbi.feature_incompat),
> > + .feature_compat = cpu_to_le32(sbi.feature_compat &
> > + ~EROFS_FEATURE_COMPAT_SB_CHKSUM),
> > };
> > const unsigned int sb_blksize =
> > round_up(EROFS_SUPER_END, EROFS_BLKSIZ);
> > @@ -240,6 +248,62 @@ int erofs_mkfs_update_super_block(struct erofs_buffer_head *bh,
> > return 0;
> > }
> >
> > +#define CRC32C_POLY_LE 0x82F63B78
> > +static inline u32 crc32c(u32 crc, const u8 *in, size_t len)
> > +{
> > + int i;
> > +
> > + while (len--) {
> > + crc ^= *in++;
> > + for (i = 0; i < 8; i++)
> > + crc = (crc >> 1) ^ ((crc & 1) ? CRC32C_POLY_LE : 0);
> > + }
> > + return crc;
> > +}
> > +
> > +static int erofs_superblock_csum_set(void)
> > +{
> > + int ret;
> > + u8 buf[EROFS_BLKSIZ];
> > + u32 crc;
> > + struct erofs_super_block *sb;
> > +
> > + ret = blk_read(buf, 0, 1);
> > + if (ret) {
> > + erofs_err("failed to read superblock to fill checksum");
> > + return -EIO;
> > + }
> > +
> > + /*
> > + * skip the first 1024 bytes, to allow for the installation
> > + * of x86 boot sectors and other oddities.
> > + */
> > + sb = (struct erofs_super_block *)(buf + EROFS_SUPER_OFFSET);
> > +
> > + if (le32_to_cpu(sb->magic) != EROFS_SUPER_MAGIC_V1) {
> > + erofs_err("internal error: not an erofs valid image");
> > + return -EFAULT;
> > + }
> > +
> > + /* turn on checksum feature */
> > + sb->feature_compat = cpu_to_le32(le32_to_cpu(sb->feature_compat) |
> > + EROFS_FEATURE_COMPAT_SB_CHKSUM);
> > + crc = crc32c(~0, (u8 *)sb, EROFS_BLKSIZ - EROFS_SUPER_OFFSET);
> > +
> > + /* set up checksum field to erofs_super_block */
> > + sb->checksum = cpu_to_le32(crc);
> > +
> > + ret = blk_write(buf, 0, 1);
> > + if (ret) {
> > + erofs_err("failed to write checksumed superblock: %s",
> > + erofs_strerror(ret));
> > + return ret;
> > + }
> > +
> > + erofs_info("superblock checksum 0x%08x written", crc);
> > + return 0;
> > +}
> > +
> > int main(int argc, char **argv)
> > {
> > int err = 0;
> > @@ -255,6 +319,7 @@ int main(int argc, char **argv)
> >
> > cfg.c_legacy_compress = false;
> > sbi.feature_incompat = EROFS_FEATURE_INCOMPAT_LZ4_0PADDING;
> > + sbi.feature_compat = EROFS_FEATURE_COMPAT_SB_CHKSUM;
> >
> > err = mkfs_parse_options_cfg(argc, argv);
> > if (err) {
> > @@ -337,6 +402,9 @@ int main(int argc, char **argv)
> > err = -EIO;
> > else
> > err = dev_resize(nblocks);
> > +
> > + if (!err && (sbi.feature_compat & EROFS_FEATURE_COMPAT_SB_CHKSUM))
> > + err = erofs_superblock_csum_set();
> > exit:
> > z_erofs_compress_exit();
> > dev_close();
> >
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