blkid: recognize btrfs

Add btrfs detection to libblkid, now that the disk format should be
recognizable in the future.

# misc/blkid /tmp/fsfile
/tmp/fsfile: LABEL="mylabel" UUID="102b07f0-0e79-4b42-8a4e-1dde418bbe6d" TYPE="btrfs"

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/lib/blkid/probe.c b/lib/blkid/probe.c
index 1ed7d46..68cc966 100644 (file)
--- a/lib/blkid/probe.c
+++ b/lib/blkid/probe.c
@@ -1293,6 +1293,22 @@ static int probe_lvm2(struct blkid_probe *probe,
 
        return 0;
 }
+
+static int probe_btrfs(struct blkid_probe *probe,
+                       struct blkid_magic *id,
+                       unsigned char *buf)
+{
+       struct btrfs_super_block *bs;
+       const char *label = 0;
+
+       bs = (struct btrfs_super_block *)buf;
+
+       if (strlen(bs->label))
+               label = bs->label;
+       blkid_set_tag(probe->dev, "LABEL", label, sizeof(bs->label));
+       set_uuid(probe->dev, bs->fsid, 0);
+       return 0;
+}
 /*
  * Various filesystem magics that we can check for.  Note that kboff and
  * sboff are in kilobytes and bytes respectively.  All magics are in
@@ -1386,6 +1402,7 @@ static struct blkid_magic type_array[] = {
   { "lvm2pv",   0,  0x018,  8, "LVM2 001",             probe_lvm2 },
   { "lvm2pv",   1,  0x018,  8, "LVM2 001",             probe_lvm2 },
   { "lvm2pv",   1,  0x218,  8, "LVM2 001",             probe_lvm2 },
+  { "btrfs",    64,  0x40,  8, "_BHRfS_M",             probe_btrfs },
   {   NULL,     0,      0,  0, NULL,                   NULL }
 };
 

diff --git a/lib/blkid/probe.h b/lib/blkid/probe.h
index bee5a51..37fc9c0 100644 (file)
--- a/lib/blkid/probe.h
+++ b/lib/blkid/probe.h
@@ -621,6 +621,110 @@ struct lvm2_pv_label_header {
        __u8    pv_uuid[LVM2_ID_LEN];
 } __attribute__ ((packed));
 
+
+/*
+ * this is a very generous portion of the super block, giving us
+ * room to translate 14 chunks with 3 stripes each.
+ */
+#define BTRFS_SYSTEM_CHUNK_ARRAY_SIZE 2048
+#define BTRFS_LABEL_SIZE 256
+#define BTRFS_UUID_SIZE 16
+#define BTRFS_FSID_SIZE 16
+#define BTRFS_CSUM_SIZE 32
+
+struct btrfs_dev_item {
+       /* the internal btrfs device id */
+       __u64 devid;
+
+       /* size of the device */
+       __u64 total_bytes;
+
+       /* bytes used */
+       __u64 bytes_used;
+
+       /* optimal io alignment for this device */
+       __u32 io_align;
+
+       /* optimal io width for this device */
+       __u32 io_width;
+
+       /* minimal io size for this device */
+       __u32 sector_size;
+
+       /* type and info about this device */
+       __u64 type;
+
+       /* expected generation for this device */
+       __u64 generation;
+
+       /*
+        * starting byte of this partition on the device,
+        * to allowr for stripe alignment in the future
+        */
+       __u64 start_offset;
+
+       /* grouping information for allocation decisions */
+       __u32 dev_group;
+
+       /* seek speed 0-100 where 100 is fastest */
+       __u8 seek_speed;
+
+       /* bandwidth 0-100 where 100 is fastest */
+       __u8 bandwidth;
+
+       /* btrfs generated uuid for this device */
+       __u8 uuid[BTRFS_UUID_SIZE];
+
+       /* uuid of FS who owns this device */
+       __u8 fsid[BTRFS_UUID_SIZE];
+} __attribute__ ((__packed__));
+
+/*
+ * the super block basically lists the main trees of the FS
+ * it currently lacks any block count etc etc
+ */
+struct btrfs_super_block {
+       __u8 csum[BTRFS_CSUM_SIZE];
+       /* the first 3 fields must match struct btrfs_header */
+       __u8 fsid[BTRFS_FSID_SIZE];    /* FS specific uuid */
+       __u64 bytenr; /* this block number */
+       __u64 flags;
+
+       /* allowed to be different from the btrfs_header from here own down */
+       __u64 magic;
+       __u64 generation;
+       __u64 root;
+       __u64 chunk_root;
+       __u64 log_root;
+
+       /* this will help find the new super based on the log root */
+       __u64 log_root_transid;
+       __u64 total_bytes;
+       __u64 bytes_used;
+       __u64 root_dir_objectid;
+       __u64 num_devices;
+       __u32 sectorsize;
+       __u32 nodesize;
+       __u32 leafsize;
+       __u32 stripesize;
+       __u32 sys_chunk_array_size;
+       __u64 chunk_root_generation;
+       __u64 compat_flags;
+       __u64 compat_ro_flags;
+       __u64 incompat_flags;
+       __u16 csum_type;
+       __u8 root_level;
+       __u8 chunk_root_level;
+       __u8 log_root_level;
+       struct btrfs_dev_item dev_item;
+
+       char label[BTRFS_LABEL_SIZE];
+
+       /* future expansion */
+       __u64 reserved[32];
+       __u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
+} __attribute__ ((__packed__));
+
 /*
  * Byte swap functions
  */