volume_id: add support for btrfs

function                                             old     new   delta
volume_id_probe_btrfs                                  -      96     +96
fs2                                                   48      52      +4
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/0 up/down: 100/0)             Total: 100 bytes

Signed-off-by: Vladimir Dronnikov <dronnikov@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 100 insertions, 0 deletions

diff --git a/util-linux/volume_id/btrfs.c b/util-linux/volume_id/btrfs.c
new file mode 100644
index 000000000..98f150793
--- /dev/null
+++ b/util-linux/volume_id/btrfs.c
@@ -0,0 +1,100 @@
+/*
+ * volume_id - reads filesystem label and uuid
+ *
+ * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
+ * Copyright (C) 2009 Vladimir Dronnikov <dronnikov@gmail.com>
+ *
+ *	This library is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU Lesser General Public
+ *	License as published by the Free Software Foundation; either
+ *	version 2.1 of the License, or (at your option) any later version.
+ *
+ *	This library is distributed in the hope that it will be useful,
+ *	but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ *	Lesser General Public License for more details.
+ *
+ *	You should have received a copy of the GNU Lesser General Public
+ *	License along with this library; if not, write to the Free Software
+ *	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "volume_id_internal.h"
+
+#define BTRFS_UUID_SIZE 16
+#define BTRFS_LABEL_SIZE 256
+#define BTRFS_CSUM_SIZE 32
+#define BTRFS_FSID_SIZE 16
+
+#define BTRFS_MAGIC "_BHRfS_M"
+
+struct btrfs_dev_item {
+	uint64_t devid;
+	uint64_t total_bytes;
+	uint64_t bytes_used;
+	uint32_t io_align;
+	uint32_t io_width;
+	uint32_t sector_size;
+	uint64_t type;
+	uint64_t generation;
+	uint64_t start_offset;
+	uint32_t dev_group;
+	uint8_t seek_speed;
+	uint8_t bandwidth;
+	uint8_t uuid[BTRFS_UUID_SIZE];
+	uint8_t fsid[BTRFS_UUID_SIZE];
+} PACKED;
+
+struct btrfs_super_block {
+	uint8_t csum[BTRFS_CSUM_SIZE];
+	uint8_t fsid[BTRFS_FSID_SIZE];	// UUID
+	uint64_t bytenr;
+	uint64_t flags;
+	uint8_t magic[8];
+	uint64_t generation;
+	uint64_t root;
+	uint64_t chunk_root;
+	uint64_t log_root;
+	uint64_t log_root_transid;
+	uint64_t total_bytes;
+	uint64_t bytes_used;
+	uint64_t root_dir_objectid;
+	uint64_t num_devices;
+	uint32_t sectorsize;
+	uint32_t nodesize;
+	uint32_t leafsize;
+	uint32_t stripesize;
+	uint32_t sys_chunk_array_size;
+	uint64_t chunk_root_generation;
+	uint64_t compat_flags;
+	uint64_t compat_ro_flags;
+	uint64_t incompat_flags;
+	uint16_t csum_type;
+	uint8_t root_level;
+	uint8_t chunk_root_level;
+	uint8_t log_root_level;
+	struct btrfs_dev_item dev_item;
+	uint8_t label[BTRFS_LABEL_SIZE];	// LABEL
+	// ...
+} PACKED;
+
+int volume_id_probe_btrfs(struct volume_id *id /*,uint64_t off*/)
+{
+#define off ((uint64_t) (64 * 1024))
+	struct btrfs_super_block *sb;
+
+	dbg("btrfs: probing at offset 0x%llx", (unsigned long long) off);
+
+	sb = volume_id_get_buffer(id, off, sizeof(*sb));
+	if (sb == NULL)
+		return -1;
+
+	if (memcmp(sb->magic, BTRFS_MAGIC, 8) != 0)
+		return -1;
+
+	// N.B.: btrfs supports 256-byte labels
+	volume_id_set_label_string(id, sb->label, VOLUME_ID_LABEL_SIZE);
+	volume_id_set_uuid(id, sb->fsid, UUID_DCE);
+
+	return 0;
+}