Hi Pratik, On Sat, Aug 24, 2019 at 02:52:31PM +0530, Pratik Shinde wrote: > Hi Gao, > Yes I will make the suboption naming similar to that of mk2fs.
Great! :) > > The reason I changed the position of 'checksum' field : > > Since we are calculating the checksum of erofs_super_block structure and > storing it in the same structure; we cannot include > this field for actual crc calculations. Keeping it at the end makes it easy > for me to calculate length of the data of which > checksum needs to be calculated. I saw similar logic in other filesystems > like ext4. No, that is just they didn't add checksum field at the beginning of its design. I think you can leave chksum to 0, and calculate chksum and fill it, to be specfic: In the erofs-utils, 1) fill .checksum to 0; 2) calculate crc32c of the entire erofs_super_block; 3) fill the real checksum to .checksum; In the kernel, 1) read .checksum to a variable; 2) fill .checksum to 0; 3) calculate crc32c of the entire erofs_super_block; 4) compare the given one and the calculated one; That is all :) > > We can write our own crc32() function. :) There is no problem. I thought > zlib already provides one & we can use it. I think we can use crc32c() since I already wrote comments for erofs in 4.19. Looking forward to your next version :) Thanks, Gao Xiang > anyways , I will write. > > --Pratik. > > On Sat, Aug 24, 2019 at 2:16 PM Gao Xiang <[email protected]> wrote: > > > Hi Pratik, > > > > On Sat, Aug 24, 2019 at 01:11:58PM +0530, Pratik Shinde wrote: > > > Adding code for superblock checksum calculation. > > > > > > This patch adds following things: > > > 1)Handle suboptions('-o') to mkfs utility. > > > > Thanks for your patch. :) > > > > Can we use "-O feature" instead in order to keep in line with mke2fs? > > > > > 2)Add superblock checksum calculation(-o sb_cksum) as suboption. > > > > ditto. and I think we can enable sbcrc by default since it is a compat > > feature, > > and add "-O nosbcrc" to disable it. > > > > > 3)Calculate superblock checksum if feature is enabled. > > > > > > Signed-off-by: Pratik Shinde <[email protected]> > > > > And could you please also read my following comments and fix them. > > and I'd like to accept your erofs-utils modification in advance. :) > > > > > > But now you can see we are moving EROFS out of staging now as > > the "real" part of Linux, this is the fundamental stuff of other > > new features if we want to develop more actively... So we can wait > > for the final result and add this new feature to kernel then... > > > > > --- > > > include/erofs/config.h | 1 + > > > include/erofs_fs.h | 40 +++++++++++++++++++++---------------- > > > mkfs/main.c | 53 > > +++++++++++++++++++++++++++++++++++++++++++++++++- > > > 3 files changed, 76 insertions(+), 18 deletions(-) > > > > > > diff --git a/include/erofs/config.h b/include/erofs/config.h > > > index 05fe6b2..40cd466 100644 > > > --- a/include/erofs/config.h > > > +++ b/include/erofs/config.h > > > @@ -22,6 +22,7 @@ struct erofs_configure { > > > char *c_src_path; > > > char *c_compr_alg_master; > > > int c_compr_level_master; > > > + int c_feature_flags; > > > > we can add this to sbi like requirements... > > > > > }; > > > > > > extern struct erofs_configure cfg; > > > diff --git a/include/erofs_fs.h b/include/erofs_fs.h > > > index 601b477..c9ef057 100644 > > > --- a/include/erofs_fs.h > > > +++ b/include/erofs_fs.h > > > @@ -20,25 +20,31 @@ > > > #define EROFS_REQUIREMENT_LZ4_0PADDING 0x00000001 > > > #define EROFS_ALL_REQUIREMENTS > > EROFS_REQUIREMENT_LZ4_0PADDING > > > > > > +/* > > > + * feature definations. > > > + */ > > > +#define EROFS_FEATURE_SB_CHKSUM 0x0001 > > > + > > > +#define EROFS_HAS_COMPAT_FEATURE(super,mask) \ > > > + ( le32_to_cpu((super)->features) & (mask) ) > > > + > > > struct erofs_super_block { > > > /* 0 */__le32 magic; /* in the little endian */ > > > -/* 4 */__le32 checksum; /* crc32c(super_block) */ > > > -/* 8 */__le32 features; /* (aka. feature_compat) */ > > > -/* 12 */__u8 blkszbits; /* support block_size == PAGE_SIZE only > > */ > > > -/* 13 */__u8 reserved; > > > - > > > -/* 14 */__le16 root_nid; > > > -/* 16 */__le64 inos; /* total valid ino # (== f_files - > > f_favail) */ > > > - > > > -/* 24 */__le64 build_time; /* inode v1 time derivation */ > > > -/* 32 */__le32 build_time_nsec; > > > -/* 36 */__le32 blocks; /* used for statfs */ > > > -/* 40 */__le32 meta_blkaddr; > > > -/* 44 */__le32 xattr_blkaddr; > > > -/* 48 */__u8 uuid[16]; /* 128-bit uuid for volume */ > > > -/* 64 */__u8 volume_name[16]; /* volume name */ > > > -/* 80 */__le32 requirements; /* (aka. feature_incompat) */ > > > - > > > +/* 4 */__le32 features; /* (aka. feature_compat) */ > > > +/* 8 */__u8 blkszbits; /* support block_size == PAGE_SIZE only > > */ > > > +/* 9 */__u8 reserved; > > > + > > > +/* 10 */__le16 root_nid; > > > +/* 12 */__le64 inos; /* total valid ino # (== f_files - > > f_favail) */ > > > +/* 20 */__le64 build_time; /* inode v1 time derivation */ > > > +/* 28 */__le32 build_time_nsec; > > > +/* 32 */__le32 blocks; /* used for statfs */ > > > +/* 36 */__le32 meta_blkaddr; > > > +/* 40 */__le32 xattr_blkaddr; > > > +/* 44 */__u8 uuid[16]; /* 128-bit uuid for volume */ > > > +/* 60 */__u8 volume_name[16]; /* volume name */ > > > +/* 76 */__le32 requirements; /* (aka. feature_incompat) */ > > > +/* 80 */__le32 checksum; /* crc32c(super_block) */ > > > /* 84 */__u8 reserved2[44]; > > > > Why modifying the above? > > > > > } __packed; /* 128 bytes */ > > > > > > diff --git a/mkfs/main.c b/mkfs/main.c > > > index f127fe1..26e14a3 100644 > > > --- a/mkfs/main.c > > > +++ b/mkfs/main.c > > > @@ -13,12 +13,14 @@ > > > #include <limits.h> > > > #include <libgen.h> > > > #include <sys/stat.h> > > > +#include <zlib.h> > > > > I have no idea that we should introduce "zlib" just for crc32c currently... > > Maybe we can add some independent crc32 function.. > > > > Thanks, > > Gao Xiang > > > > > #include "erofs/config.h" > > > #include "erofs/print.h" > > > #include "erofs/cache.h" > > > #include "erofs/inode.h" > > > #include "erofs/io.h" > > > #include "erofs/compress.h" > > > +#include "erofs/defs.h" > > > > > > #define EROFS_SUPER_END (EROFS_SUPER_OFFSET + sizeof(struct > > erofs_super_block)) > > > > > > @@ -31,6 +33,28 @@ static void usage(void) > > > fprintf(stderr, " -EX[,...] X=extended options\n"); > > > } > > > > > > +char *feature_opts[] = { > > > + "sb_cksum", NULL > > > +}; > > > +#define O_SB_CKSUM 0 > > > + > > > +static int parse_feature_subopts(char *opts) > > > +{ > > > + char *arg; > > > + > > > + while (*opts != '\0') { > > > + switch(getsubopt(&opts, feature_opts, &arg)) { > > > + case O_SB_CKSUM: > > > + cfg.c_feature_flags |= EROFS_FEATURE_SB_CHKSUM; > > > + break; > > > + default: > > > + erofs_err("incorrect suboption"); > > > + return -EINVAL; > > > + } > > > + } > > > + return 0; > > > +} > > > + > > > static int parse_extended_opts(const char *opts) > > > { > > > #define MATCH_EXTENTED_OPT(opt, token, keylen) \ > > > @@ -79,7 +103,7 @@ static int mkfs_parse_options_cfg(int argc, char > > *argv[]) > > > { > > > int opt, i; > > > > > > - while ((opt = getopt(argc, argv, "d:z:E:")) != -1) { > > > + while ((opt = getopt(argc, argv, "d:z:E:o:")) != -1) { > > > switch (opt) { > > > case 'z': > > > if (!optarg) { > > > @@ -113,6 +137,12 @@ static int mkfs_parse_options_cfg(int argc, char > > *argv[]) > > > return opt; > > > break; > > > > > > + case 'o': > > > + opt = parse_feature_subopts(optarg); > > > + if (opt) > > > + return opt; > > > + break; > > > + > > > default: /* '?' */ > > > return -EINVAL; > > > } > > > @@ -144,6 +174,21 @@ static int mkfs_parse_options_cfg(int argc, char > > *argv[]) > > > return 0; > > > } > > > > > > +u32 erofs_superblock_checksum(struct erofs_super_block *sb) > > > +{ > > > + int offset; > > > + u32 crc; > > > + > > > + offset = offsetof(struct erofs_super_block, checksum); > > > + if (offset < 0 || offset > sizeof(struct erofs_super_block)) { > > > + erofs_err("Invalid offset of checksum field: %d", offset); > > > + return -1; > > > + } > > > + crc = crc32(~0, (const unsigned char *)sb,(size_t)offset); > > > + erofs_dump("superblock checksum: 0x%x\n", crc); > > > + return 0; > > > +} > > > + > > > int erofs_mkfs_update_super_block(struct erofs_buffer_head *bh, > > > erofs_nid_t root_nid) > > > { > > > @@ -155,6 +200,7 @@ int erofs_mkfs_update_super_block(struct > > erofs_buffer_head *bh, > > > .meta_blkaddr = sbi.meta_blkaddr, > > > .xattr_blkaddr = 0, > > > .requirements = cpu_to_le32(sbi.requirements), > > > + .features = cpu_to_le32(cfg.c_feature_flags), > > > }; > > > const unsigned int sb_blksize = > > > round_up(EROFS_SUPER_END, EROFS_BLKSIZ); > > > @@ -169,6 +215,11 @@ int erofs_mkfs_update_super_block(struct > > erofs_buffer_head *bh, > > > sb.blocks = cpu_to_le32(erofs_mapbh(NULL, true)); > > > sb.root_nid = cpu_to_le16(root_nid); > > > > > > + if (EROFS_HAS_COMPAT_FEATURE(&sb, EROFS_FEATURE_SB_CHKSUM)) { > > > + u32 crc = erofs_superblock_checksum(&sb); > > > + sb.checksum = cpu_to_le32(crc); > > > + } > > > + > > > buf = calloc(sb_blksize, 1); > > > if (!buf) { > > > erofs_err("Failed to allocate memory for sb: %s", > > > -- > > > 2.9.3 > > > > >
