[PATCH] erofs-utils: code for superblock checksum calculation.
Pratik Shinde
pratikshinde320 at gmail.com
Sat Aug 24 22:38:03 AEST 2019
Adding code for superblock checksum calculation.
incorporated the changes suggested in previous patch.
Signed-off-by: Pratik Shinde <pratikshinde320 at gmail.com>
---
include/erofs/config.h | 1 +
include/erofs_fs.h | 10 ++++++++
mkfs/main.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 74 insertions(+), 1 deletion(-)
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;
};
extern struct erofs_configure cfg;
diff --git a/include/erofs_fs.h b/include/erofs_fs.h
index 601b477..9ac2635 100644
--- a/include/erofs_fs.h
+++ b/include/erofs_fs.h
@@ -20,6 +20,16 @@
#define EROFS_REQUIREMENT_LZ4_0PADDING 0x00000001
#define EROFS_ALL_REQUIREMENTS EROFS_REQUIREMENT_LZ4_0PADDING
+/*
+ * feature definations.
+ */
+#define EROFS_DEFAULT_FEATURES EROFS_FEATURE_SB_CHKSUM
+#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) */
diff --git a/mkfs/main.c b/mkfs/main.c
index f127fe1..355fd2c 100644
--- a/mkfs/main.c
+++ b/mkfs/main.c
@@ -31,6 +31,45 @@ static void usage(void)
fprintf(stderr, " -EX[,...] X=extended options\n");
}
+#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);
+ }
+ }
+ erofs_dump("calculated crc: 0x%x\n", crc);
+ return crc;
+}
+
+char *feature_opts[] = {
+ "nosbcrc", NULL
+};
+#define O_SB_CKSUM 0
+
+static int parse_feature_subopts(char *opts)
+{
+ char *arg;
+
+ cfg.c_feature_flags = EROFS_DEFAULT_FEATURES;
+ 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 +118,8 @@ static int mkfs_parse_options_cfg(int argc, char *argv[])
{
int opt, i;
- while ((opt = getopt(argc, argv, "d:z:E:")) != -1) {
+ cfg.c_feature_flags = EROFS_DEFAULT_FEATURES;
+ while ((opt = getopt(argc, argv, "d:z:E:o:")) != -1) {
switch (opt) {
case 'z':
if (!optarg) {
@@ -113,6 +153,12 @@ 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 +190,15 @@ static int mkfs_parse_options_cfg(int argc, char *argv[])
return 0;
}
+u32 erofs_superblock_checksum(struct erofs_super_block *sb)
+{
+ u32 crc;
+ crc = crc32c(~0, (const unsigned char *)sb,
+ sizeof(struct erofs_super_block));
+ erofs_dump("superblock checksum: 0x%x\n", crc);
+ return crc;
+}
+
int erofs_mkfs_update_super_block(struct erofs_buffer_head *bh,
erofs_nid_t root_nid)
{
@@ -155,6 +210,7 @@ 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 +225,12 @@ 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)) {
+ sb.checksum = 0;
+ 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
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