From: Pratik Shinde <pratikshinde320@gmail.com>
To: linux-erofs@lists.ozlabs.org, bluce.liguifu@huawei.com,
miaoxie@huawei.com, fangwei1@huawei.com
Subject: [PATCH] code for calculating crc checksum of erofs blocks.
Date: Sun, 13 Oct 2019 16:19:11 +0530 [thread overview]
Message-ID: <20191013104911.30358-1-pratikshinde320@gmail.com> (raw)
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.
Signed-off-by: Pratik Shinde <pratikshinde320@gmail.com>
---
include/erofs/config.h | 3 +++
include/erofs/io.h | 8 ++++++
lib/config.c | 2 ++
lib/io.c | 27 +++++++++++++++++++
mkfs/main.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 113 insertions(+)
diff --git a/include/erofs/config.h b/include/erofs/config.h
index 9711638..e167cd4 100644
--- a/include/erofs/config.h
+++ b/include/erofs/config.h
@@ -16,6 +16,8 @@ enum {
FORCE_INODE_EXTENDED,
};
+#define EROFS_FEATURE_BLK_CKSUM 1
+
struct erofs_configure {
const char *c_version;
int c_dbg_lvl;
@@ -29,6 +31,7 @@ struct erofs_configure {
int c_compr_level_master;
int c_force_inodeversion;
u64 c_unix_timestamp;
+ int c_blk_cksum;
};
extern struct erofs_configure cfg;
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/config.c b/lib/config.c
index 46625d7..b5ddff8 100644
--- a/lib/config.c
+++ b/lib/config.c
@@ -9,6 +9,7 @@
#include <string.h>
#include "erofs/print.h"
#include "erofs/internal.h"
+#include "erofs/config.h"
struct erofs_configure cfg;
@@ -22,6 +23,7 @@ void erofs_init_configure(void)
cfg.c_compr_level_master = -1;
cfg.c_force_inodeversion = 0;
cfg.c_unix_timestamp = -1;
+ cfg.c_blk_cksum = EROFS_FEATURE_BLK_CKSUM;
}
void erofs_show_config(void)
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..239d6e7 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)) {
+ cfg.c_blk_cksum = ~EROFS_FEATURE_BLK_CKSUM;
+ }
}
return 0;
}
@@ -180,6 +187,7 @@ 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 +210,68 @@ 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_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_set_checksum() {
+ struct erofs_super_block *sb;
+ char buf[EROFS_BLKSIZ];
+ int ret = 0;
+ u32 crc;
+
+ ret = erofs_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");
+ 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;
@@ -301,6 +371,9 @@ int main(int argc, char **argv)
err = -EIO;
else
err = dev_resize(nblocks);
+ if (cfg.c_blk_cksum & EROFS_FEATURE_BLK_CKSUM) {
+ erofs_set_checksum();
+ }
exit:
z_erofs_compress_exit();
dev_close();
--
2.9.3
next reply other threads:[~2019-10-13 10:49 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-13 10:49 Pratik Shinde [this message]
2019-10-14 1:56 ` [PATCH] code for calculating crc checksum of erofs blocks Gao Xiang
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