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-rw-r--r--bcache-super-show.c145
1 files changed, 145 insertions, 0 deletions
diff --git a/bcache-super-show.c b/bcache-super-show.c
new file mode 100644
index 0000000..6f9f6a7
--- /dev/null
+++ b/bcache-super-show.c
@@ -0,0 +1,145 @@
+#define _FILE_OFFSET_BITS 64
+#define __USE_FILE_OFFSET64
+#define _XOPEN_SOURCE 500
+
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <linux/fs.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <uuid/uuid.h>
+
+#include "bcache.h"
+
+
+static void usage()
+{
+ fprintf(stderr, "Usage: bcache-super-show [-f] <device>\n");
+}
+
+
+int main(int argc, char **argv)
+{
+ bool force_csum = false;
+ int o;
+ extern char *optarg;
+ struct cache_sb sb;
+ char uuid[40];
+ uint64_t expected_csum;
+
+ while ((o = getopt(argc, argv, "f")) != EOF)
+ switch (o) {
+ case 'f':
+ force_csum = 1;
+ break;
+
+ default:
+ usage();
+ exit(1);
+ }
+
+ argv += optind;
+ argc -= optind;
+
+ if (argc != 1) {
+ usage();
+ exit(1);
+ }
+
+ int fd = open(argv[0], O_RDONLY);
+ if (fd < 0) {
+ printf("Can't open dev %s: %s\n", argv[0], strerror(errno));
+ exit(2);
+ }
+
+ if (pread(fd, &sb, sizeof(sb), 4096) != sizeof(sb)) {
+ fprintf(stderr, "Couldn't read\n");
+ exit(2);
+ }
+
+ printf("sb.magic\t\t");
+ if (! memcmp(sb.magic, bcache_magic, 16)) {
+ printf("ok\n");
+ } else {
+ printf("bad magic\n");
+ fprintf(stderr, "Invalid superblock (bad magic)\n");
+ exit(2);
+ }
+
+ printf("sb.first_sector\t\t%" PRIu64, sb.offset);
+ if (sb.offset == SB_SECTOR) {
+ printf(" [match]\n");
+ } else {
+ printf(" [expected %ds]\n", SB_SECTOR);
+ fprintf(stderr, "Invalid superblock (bad sector)\n");
+ exit(2);
+ }
+
+ printf("sb.csum\t\t\t0x%" PRIx64, sb.csum);
+ expected_csum = csum_set(&sb);
+ if (sb.csum == expected_csum) {
+ printf(" [match]\n");
+ } else {
+ printf(" [expected %" PRIX64 "]\n", expected_csum);
+ if (! force_csum) {
+ fprintf(stderr, "Corrupt superblock (bad csum)\n");
+ exit(2);
+ }
+ }
+
+ printf("sb.version\t\t%" PRIu64, sb.version);
+ switch (sb.version) {
+ case 1:
+ printf(" [backing device]\n");
+ break;
+
+ case 2:
+ printf(" [cache device]\n");
+ break;
+
+ case 3:
+ printf(" [backing device with offset]\n");
+ // XXX Kernel side bcache.h says different, and implements neither
+ return 0; //break;
+
+ default:
+ printf(" [unknown]\n");
+ // exit code?
+ return 0;
+ }
+
+ putchar('\n');
+
+ uuid_unparse(sb.uuid, uuid);
+ printf("dev.uuid\t\t%s\n", uuid);
+
+ printf(
+ "dev.sectors_per_block\t%u\n"
+ "dev.sectors_per_bucket\t%u\n"
+ "dev.bucket_count\t%ju\n"
+ "dev.cache_count\t\t%u\n" // expect version == 2 ? 1 : 0
+ "dev.data.first_bucket\t%u\n",
+ sb.block_size,
+ sb.bucket_size,
+ sb.nbuckets,
+ sb.nr_this_dev,
+ sb.first_bucket);
+
+ printf("dev.data.first_sector\t%u\n", sb.bucket_size * sb.first_bucket);
+ putchar('\n');
+
+ uuid_unparse(sb.set_uuid, uuid);
+ printf("cset.uuid\t\t%s\n", uuid);
+
+ printf("cset.cache_count\t%u\n\n", sb.nr_in_set);
+
+ return 0;
+}