Add disk format requirements for subvol backward and forward refs

diff --git a/ctree.h b/ctree.h
index 94a102d..f08429a 100644 (file)
--- a/ctree.h
+++ b/ctree.h
@@ -443,6 +443,15 @@ struct btrfs_root_item {
        u8 level;
 } __attribute__ ((__packed__));
 
+/*
+ * this is used for both forward and backward root refs
+ */
+struct btrfs_root_ref {
+       __le64 dirid;
+       __le64 sequence;
+       __le16 name_len;
+} __attribute__ ((__packed__));
+
 #define BTRFS_FILE_EXTENT_INLINE 0
 #define BTRFS_FILE_EXTENT_REG 1
 #define BTRFS_FILE_EXTENT_PREALLOC 2
@@ -635,50 +644,64 @@ struct btrfs_root {
  * the FS
  */
 #define BTRFS_INODE_ITEM_KEY           1
-#define BTRFS_INODE_REF_KEY            2
-#define BTRFS_XATTR_ITEM_KEY           8
-#define BTRFS_ORPHAN_ITEM_KEY          9
-
-/* reserve 3-15 close to the inode for later flexibility */
+#define BTRFS_INODE_REF_KEY            12
+#define BTRFS_XATTR_ITEM_KEY           24
+#define BTRFS_ORPHAN_ITEM_KEY          48
 
+#define BTRFS_DIR_LOG_ITEM_KEY  60
+#define BTRFS_DIR_LOG_INDEX_KEY 72
 /*
  * dir items are the name -> inode pointers in a directory.  There is one
  * for every name in a directory.
  */
-#define BTRFS_DIR_ITEM_KEY     16
-#define BTRFS_DIR_INDEX_KEY    17
+#define BTRFS_DIR_ITEM_KEY     84
+#define BTRFS_DIR_INDEX_KEY    96
+
 /*
  * extent data is for file data
  */
-#define BTRFS_EXTENT_DATA_KEY  18
+#define BTRFS_EXTENT_DATA_KEY  108
+
 /*
  * csum items have the checksums for data in the extents
  */
-#define BTRFS_CSUM_ITEM_KEY    19
-
-/* reserve 20-31 for other file stuff */
+#define BTRFS_CSUM_ITEM_KEY    120
 
 /*
  * root items point to tree roots.  There are typically in the root
  * tree used by the super block to find all the other trees
  */
-#define BTRFS_ROOT_ITEM_KEY    32
+#define BTRFS_ROOT_ITEM_KEY    132
+
+/*
+ * root backrefs tie subvols and snapshots to the directory entries that
+ * reference them
+ */
+#define BTRFS_ROOT_BACKREF_KEY 144
+
+/*
+ * root refs make a fast index for listing all of the snapshots and
+ * subvolumes referenced by a given root.  They point directly to the
+ * directory item in the root that references the subvol
+ */
+#define BTRFS_ROOT_REF_KEY     156
+
 /*
  * extent items are in the extent map tree.  These record which blocks
  * are used, and how many references there are to each block
  */
-#define BTRFS_EXTENT_ITEM_KEY  33
-#define BTRFS_EXTENT_REF_KEY   34
+#define BTRFS_EXTENT_ITEM_KEY  168
+#define BTRFS_EXTENT_REF_KEY   180
 
 /*
  * block groups give us hints into the extent allocation trees.  Which
  * blocks are free etc etc
  */
-#define BTRFS_BLOCK_GROUP_ITEM_KEY 50
+#define BTRFS_BLOCK_GROUP_ITEM_KEY 192
 
-#define BTRFS_DEV_EXTENT_KEY   75
-#define BTRFS_DEV_ITEM_KEY     76
-#define BTRFS_CHUNK_ITEM_KEY   77
+#define BTRFS_DEV_EXTENT_KEY   204
+#define BTRFS_DEV_ITEM_KEY     216
+#define BTRFS_CHUNK_ITEM_KEY   228
 
 /*
  * string items are for debugging.  They just store a short string of
@@ -1104,6 +1127,13 @@ static inline void btrfs_set_item_key(struct extent_buffer *eb,
        write_eb_member(eb, item, struct btrfs_item, key, disk_key);
 }
 
+/*
+ * struct btrfs_root_ref
+ */
+BTRFS_SETGET_FUNCS(root_ref_dirid, struct btrfs_root_ref, dirid, 64);
+BTRFS_SETGET_FUNCS(root_ref_sequence, struct btrfs_root_ref, sequence, 64);
+BTRFS_SETGET_FUNCS(root_ref_name_len, struct btrfs_root_ref, name_len, 16);
+
 /* struct btrfs_dir_item */
 BTRFS_SETGET_FUNCS(dir_data_len, struct btrfs_dir_item, data_len, 16);
 BTRFS_SETGET_FUNCS(dir_type, struct btrfs_dir_item, type, 8);

diff --git a/print-tree.c b/print-tree.c
index 96e1b34..eac4d52 100644 (file)
--- a/print-tree.c
+++ b/print-tree.c
@@ -159,6 +159,21 @@ static void print_file_extent_item(struct extent_buffer *eb,
 }
 
 
+static void print_root_ref(struct extent_buffer *leaf, int slot, char *tag)
+{
+       struct btrfs_root_ref *ref;
+       char namebuf[BTRFS_NAME_LEN];
+       int namelen;
+
+       ref = btrfs_item_ptr(leaf, slot, struct btrfs_root_ref);
+       namelen = btrfs_root_ref_name_len(leaf, ref);
+       read_extent_buffer(leaf, namebuf, (unsigned long)(ref + 1), namelen);
+       printf("\t\troot %s key dirid %llu sequence %llu name %.*s\n", tag,
+              (unsigned long long)btrfs_root_ref_dirid(leaf, ref),
+              (unsigned long long)btrfs_root_ref_sequence(leaf, ref),
+              namelen, namebuf);
+}
+
 void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
 {
        int i;
@@ -240,6 +255,12 @@ void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
                                       root_item.drop_level);
                        }
                        break;
+               case BTRFS_ROOT_REF_KEY:
+                       print_root_ref(l, i, "ref");
+                       break;
+               case BTRFS_ROOT_BACKREF_KEY:
+                       print_root_ref(l, i, "backref");
+                       break;
                case BTRFS_EXTENT_ITEM_KEY:
                        ei = btrfs_item_ptr(l, i, struct btrfs_extent_item);
                        printf("\t\textent data refs %u\n",

diff --git a/root-tree.c b/root-tree.c
index 019216c..189f82d 100644 (file)
--- a/root-tree.c
+++ b/root-tree.c
@@ -32,7 +32,7 @@ int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
        int slot;
 
        search_key.objectid = objectid;
-       search_key.type = (u8)-1;
+       search_key.type = BTRFS_ROOT_ITEM_KEY;
        search_key.offset = (u64)-1;
 
        path = btrfs_alloc_path();