UUIDs

61-bcache.rules

@@ -0,0 +1,3 @@
+KERNEL=="sd*", ENV{DEVTYPE}=="disk", IMPORT{program}="/sbin/probe-bcache -o udev $tempnode"
+
+ENV{ID_FS_UUID_ENC}=="?*", SYMLINK+="disk/by-uuid/$env{ID_FS_UUID_ENC}"

Makefile

@@ -1,15 +1,20 @@
 
-PREFIX=/usr/local
+#PREFIX=/usr/local
 CFLAGS=-O2 -Wall -g
 
-all: make-bcache
+all: make-bcache probe-bcache
 
 clean:
 	rm -f make-bcache bcache-test *.o
 
-install: make-bcache
+install: make-bcache probe-bcache
 	install -m0755 make-bcache ${PREFIX}/sbin/
-	install -m0755 bcache-test ${PREFIX}/sbin/
+	install -m0755 probe-bcache ${PREFIX}/sbin/
+	install -m0644 61-bcache.rules /lib/udev/rules.d/
+	install -m0755 initramfs /usr/share/initramfs-tools/hooks/bcache
+#	install -m0755 bcache-test ${PREFIX}/sbin/
 
 
 bcache-test: LDFLAGS += -lm -lssl -lcrypto
+make-bcache: LDFLAGS += -luuid
+probe-bcache: LDFLAGS += -luuid

bcache.h

@@ -0,0 +1,29 @@
+#ifndef _BCACHE_H
+#define _BCACHE_H
+
+static const char bcache_magic[] = {
+	0xc6, 0x85, 0x73, 0xf6, 0x4e, 0x1a, 0x45, 0xca,
+	0x82, 0x65, 0xf5, 0x7f, 0x48, 0xba, 0x6d, 0x81 };
+
+struct cache_sb {
+	uint8_t		magic[16];
+#define CACHE_CLEAN	1
+#define CACHE_SYNC	2
+	uint32_t	version;
+	uint16_t	block_size;	/* sectors */
+	uint16_t	bucket_size;	/* sectors */
+	uint32_t	journal_start;	/* buckets */
+	uint32_t	first_bucket;	/* start of data */
+	uint64_t	nbuckets;	/* device size */
+	uint64_t	btree_root;
+	uint16_t	btree_level;
+	uint16_t	_pad[3];
+	uint8_t		uuid[16];
+};
+
+struct bucket_disk {
+	uint16_t	priority;
+	uint8_t		generation;
+} __attribute((packed));
+
+#endif

initramfs

@@ -0,0 +1,11 @@
+#!/bin/sh -e
+
+case "$1" in
+prereqs)
+    echo "udev"
+    exit 0
+    ;;
+esac
+
+cp -p /lib/udev/rules.d/61-bcache.rules $DESTDIR/lib/udev/rules.d/
+cp -p /sbin/probe-bcache $DESTDIR/sbin

make-bcache.c

@@ -12,27 +12,9 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <uuid/uuid.h>
 
-static const char bcache_magic[] = {
-	0xc6, 0x85, 0x73, 0xf6, 0x4e, 0x1a, 0x45, 0xca,
-	0x82, 0x65, 0xf5, 0x7f, 0x48, 0xba, 0x6d, 0x81 };
-
-struct cache_sb {
-	uint8_t  magic[16];
-	uint32_t version;
-	uint16_t block_size;		/* sectors */
-	uint16_t bucket_size;		/* sectors */
-	uint32_t journal_start;		/* buckets */
-	uint32_t first_bucket;		/* start of data */
-	uint64_t nbuckets;		/* device size */
-	uint64_t btree_root;
-	uint16_t btree_level;
-};
-
-struct bucket_disk {
-	uint16_t	priority;
-	uint8_t		generation;
-} __attribute((packed));
+#include "bcache.h"
 
 char zero[4096];
 
@@ -85,12 +67,21 @@ int main(int argc, char **argv)
 	int64_t nblocks, bucketsize = 32, blocksize = 8;
 	int fd, i, c;
 	struct cache_sb sb;
+	char uuid[40];
 
-	while ((c = getopt(argc, argv, "b:")) != -1)
+	uuid_generate(sb.uuid);
+
+	while ((c = getopt(argc, argv, "U:b:")) != -1)
 		switch (c) {
 		case 'b':
 			bucketsize = hatoi(optarg) / 512;
 			break;
+		case 'U':
+			if (uuid_parse(optarg, sb.uuid)) {
+				printf("Bad uuid\n");
+				exit(EXIT_FAILURE);
+			}
+			break;
 		}
 
 	if (argc <= optind) {
@@ -117,6 +108,7 @@ int main(int argc, char **argv)
 	sb.block_size = blocksize;
 	sb.bucket_size = bucketsize;
 	sb.nbuckets = nblocks / sb.bucket_size;
+	uuid_unparse(sb.uuid, uuid);
 
 	do
 		sb.first_bucket = ((--sb.nbuckets * sizeof(struct bucket_disk)) + (24 << 9)) / (sb.bucket_size << 9) + 1;
@@ -131,12 +123,14 @@ int main(int argc, char **argv)
 	       "bucket_size:		%u\n"
 	       "journal_start:		%u\n"
 	       "first_bucket:		%u\n"
-	       "nbuckets:		%ju\n",
+	       "nbuckets:		%ju\n"
+	       "UUID:			%s\n",
 	       sb.block_size,
 	       sb.bucket_size,
 	       sb.journal_start,
 	       sb.first_bucket,
-	       sb.nbuckets);
+	       sb.nbuckets,
+	       uuid);
 
 	/* Zero out priorities */
 	lseek(fd, 4096, SEEK_SET);

probe-bcache.c

@@ -0,0 +1,67 @@
+#define _FILE_OFFSET_BITS	64
+#define __USE_FILE_OFFSET64
+#define _XOPEN_SOURCE 500
+
+#include <fcntl.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"
+
+int main(int argc, char **argv)
+{
+	bool udev = false;
+	int i, o;
+	extern char *optarg;
+	struct cache_sb sb;
+	char uuid[40];
+
+	while ((o = getopt(argc, argv, "o:")) != EOF)
+		switch (o) {
+		case 'o':
+			if (strcmp("udev", optarg)) {
+				printf("Invalid output format %s\n", optarg);
+				exit(EXIT_FAILURE);
+			}
+			udev = true;
+			break;
+		}
+
+
+	argv += optind;
+	argc -= optind;
+
+	for (i = 0; i < argc; i++) {
+		int fd = open(argv[i], O_RDONLY);
+		if (fd == -1)
+			continue;
+
+
+		if (pread(fd, &sb, sizeof(sb), 4096) != sizeof(sb))
+			continue;
+
+		if (memcmp(sb.magic, bcache_magic, 16))
+			continue;
+
+		uuid_unparse(sb.uuid, uuid);
+
+		if (udev)
+			printf("ID_FS_UUID=%s\n"
+			       "ID_FS_UUID_ENC=%s\n"
+			       "ID_FS_TYPE=bcache\n",
+			       uuid, uuid);
+		else
+			printf("%s: UUID=\"\" TYPE=\"bcache\"\n", uuid);
+	}
+
+	return 0;
+}