Btrfs: early extent mapping support

[linux-block.git] / fs / btrfs / disk-io.c

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8d51a07051d94dd5fbe5b30953c38bdbb7f14c35..653f18aab330adc8ae5f138f019d9db0ac884d79 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -12,25 +12,27 @@
 
 static int allocated_blocks = 0;
 
-struct ctree_header {
-       u64 root_block;
-} __attribute__ ((__packed__));
-
 static int get_free_block(struct ctree_root *root, u64 *block)
 {
        struct stat st;
        int ret;
 
+       if (root->alloc_extent->num_used >= root->alloc_extent->num_blocks)
+               return -1;
+
+       *block = root->alloc_extent->blocknr + root->alloc_extent->num_used;
+       root->alloc_extent->num_used += 1;
+       if (root->alloc_extent->num_used >= root->alloc_extent->num_blocks) {
+               struct alloc_extent *ae = root->alloc_extent;
+               root->alloc_extent = root->reserve_extent;
+               root->reserve_extent = ae;
+               ae->num_blocks = 0;
+       }
        st.st_size = 0;
        ret = fstat(root->fp, &st);
-       if (st.st_size > sizeof(struct ctree_header)) {
-               *block = (st.st_size -
-                       sizeof(struct ctree_header)) / CTREE_BLOCKSIZE;
-       } else {
-               *block = 0;
-       }
-       ret = ftruncate(root->fp, sizeof(struct ctree_header) + (*block + 1) *
-                       CTREE_BLOCKSIZE);
+       if (st.st_size < (*block + 1) * CTREE_BLOCKSIZE)
+               ret = ftruncate(root->fp,
+                               (*block + 1) * CTREE_BLOCKSIZE);
        return ret;
 }
 
@@ -72,7 +74,7 @@ struct tree_buffer *alloc_free_block(struct ctree_root *root)
 
 struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
 {
-       loff_t offset = blocknr * CTREE_BLOCKSIZE + sizeof(struct ctree_header);
+       loff_t offset = blocknr * CTREE_BLOCKSIZE;
        struct tree_buffer *buf;
        int ret;
 
@@ -101,7 +103,7 @@ struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
 int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)
 {
        u64 blocknr = buf->blocknr;
-       loff_t offset = blocknr * CTREE_BLOCKSIZE + sizeof(struct ctree_header);
+       loff_t offset = blocknr * CTREE_BLOCKSIZE;
        int ret;
 
        if (buf->blocknr != buf->node.header.blocknr)
@@ -114,11 +116,32 @@ int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)
        return 0;
 }
 
+struct ctree_super_block {
+       struct ctree_root_info root_info;
+       struct ctree_root_info extent_info;
+} __attribute__ ((__packed__));
+
+static int __setup_root(struct ctree_root *root, struct ctree_root *extent_root,
+                       struct ctree_root_info *info, int fp)
+{
+       root->fp = fp;
+       root->node = read_tree_block(root, info->tree_root);
+       root->extent_root = extent_root;
+       memcpy(&root->ai1, &info->alloc_extent, sizeof(info->alloc_extent));
+       memcpy(&root->ai2, &info->reserve_extent, sizeof(info->reserve_extent));
+       root->alloc_extent = &root->ai1;
+       root->reserve_extent = &root->ai2;
+       INIT_RADIX_TREE(&root->cache_radix, GFP_KERNEL);
+       printf("setup done reading root %p, used %lu\n", root, root->alloc_extent->num_used);
+       return 0;
+}
+
 struct ctree_root *open_ctree(char *filename)
 {
        struct ctree_root *root = malloc(sizeof(struct ctree_root));
+       struct ctree_root *extent_root = malloc(sizeof(struct ctree_root));
+       struct ctree_super_block super;
        int fp;
-       u64 root_block;
        int ret;
 
        fp = open(filename, O_CREAT | O_RDWR);
@@ -126,14 +149,20 @@ struct ctree_root *open_ctree(char *filename)
                free(root);
                return NULL;
        }
-       root->fp = fp;
-       INIT_RADIX_TREE(&root->cache_radix, GFP_KERNEL);
-       ret = pread(fp, &root_block, sizeof(u64), 0);
-       if (ret == sizeof(u64)) {
-               printf("reading root node at block %lu\n", root_block);
-               root->node = read_tree_block(root, root_block);
-       } else
-               root->node = NULL;
+       ret = pread(fp, &super, sizeof(struct ctree_super_block),
+                    CTREE_SUPER_INFO_OFFSET(CTREE_BLOCKSIZE));
+       if (ret == 0) {
+               ret = mkfs(fp);
+               if (ret)
+                       return NULL;
+               ret = pread(fp, &super, sizeof(struct ctree_super_block),
+                            CTREE_SUPER_INFO_OFFSET(CTREE_BLOCKSIZE));
+               if (ret != sizeof(struct ctree_super_block))
+                       return NULL;
+       }
+       BUG_ON(ret < 0);
+       __setup_root(root, extent_root, &super.root_info, fp);
+       __setup_root(extent_root, extent_root, &super.extent_info, fp);
        return root;
 }
 
@@ -160,6 +189,7 @@ int update_root_block(struct ctree_root *root)
 
 void tree_block_release(struct ctree_root *root, struct tree_buffer *buf)
 {
+       return;
        buf->count--;
        if (buf->count == 0) {
                if (!radix_tree_lookup(&root->cache_radix, buf->blocknr))