Btrfs: early extent mapping support

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 53 insertions, 23 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8d51a07051d9..653f18aab330 100644
--- 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))