[klibc] [PATCH] btrfs support

[Benjamin Cama]

Hi,

As I use btrfs as root FS, I wanted fstype to be able to recognize it.
The following patch add support for this FS.

Regards,
benjamin

Signed-off-by: Benjamin Cama <benoar at free.fr>

---
diff --git a/usr/kinit/fstype/btrfs_fs.h b/usr/kinit/fstype/btrfs_fs.h
new file mode 100644
index 0000000..e1f933e
--- /dev/null
+++ b/usr/kinit/fstype/btrfs_fs.h
@@ -0,0 +1,51 @@
+#ifndef __BTRFS_FS_H
+#define __BTRFS_FS_H
+
+/* Extracted from fs/btrfs/ctree.h and shortened a bit */
+
+#define BTRFS_MAGIC "_BHRfS_M"
+
+#define BTRFS_CSUM_SIZE 32
+#define BTRFS_FSID_SIZE 16
+
+/*
+ * 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 4 fields must match struct btrfs_header */
+        __u8 fsid[BTRFS_FSID_SIZE];    /* FS specific uuid */
+        __le64 bytenr; /* this block number */
+        __le64 flags;
+
+        /* allowed to be different from the btrfs_header from here own down */
+        __le64 magic;
+        __le64 generation;
+        __le64 root;
+        __le64 chunk_root;
+        __le64 log_root;
+
+        /* this will help find the new super based on the log root */
+        __le64 log_root_transid;
+        __le64 total_bytes;
+        __le64 bytes_used;
+        __le64 root_dir_objectid;
+        __le64 num_devices;
+        __le32 sectorsize;
+        __le32 nodesize;
+        __le32 leafsize;
+        __le32 stripesize;
+        __le32 sys_chunk_array_size;
+        __le64 chunk_root_generation;
+        __le64 compat_flags;
+        __le64 compat_ro_flags;
+        __le64 incompat_flags;
+        __le16 csum_type;
+        __u8 root_level;
+        __u8 chunk_root_level;
+        __u8 log_root_level;
+	/* truncated here for klibc */
+} __attribute__ ((__packed__));
+
+#endif /* __BTRFS_FS_H */
diff --git a/usr/kinit/fstype/fstype.c b/usr/kinit/fstype/fstype.c
index 69e0e30..c50bf01 100644
--- a/usr/kinit/fstype/fstype.c
+++ b/usr/kinit/fstype/fstype.c
@@ -36,6 +36,7 @@
 #include "gfs2_fs.h"
 #include "ocfs2_fs.h"
 #include "nilfs_fs.h"
+#include "btrfs_fs.h"
 
 /*
  * Slightly cleaned up version of jfs_superblock to
@@ -461,6 +462,18 @@ static int nilfs2_image(const void *buf, unsigned long long *bytes)
 	return 0;
 }
 
+static int btrfs_image(const void *buf, unsigned long long *bytes)
+{
+	const struct btrfs_super_block *sb =
+	    (const struct btrfs_super_block *)buf;
+
+	if (!memcmp(&sb->magic, BTRFS_MAGIC, sizeof(BTRFS_MAGIC)-1)) {
+		*bytes = (unsigned long long)__le64_to_cpu(sb->total_bytes);
+		return 1;
+	}
+	return 0;
+}
+
 struct imagetype {
 	off_t block;
 	const char name[12];
@@ -496,6 +509,7 @@ static struct imagetype images[] = {
 	{64, "reiserfs", reiserfs_image},
 	{64, "reiser4", reiser4_image},
 	{64, "gfs2", gfs2_image},
+	{64, "btrfs", btrfs_image},
 	{32, "jfs", jfs_image},
 	{32, "iso9660", iso_image},
 	{0, "luks", luks_image},