Btrfs: create special free space cache inode
[linux-3.10.git] / fs / btrfs / inode.c
index c038644..1af1ea8 100644 (file)
@@ -1700,6 +1700,7 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
                                                ordered_extent->len);
                BUG_ON(ret);
        } else {
+               BUG_ON(root == root->fs_info->tree_root);
                ret = insert_reserved_file_extent(trans, inode,
                                                ordered_extent->file_offset,
                                                ordered_extent->start,
@@ -3196,7 +3197,7 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
 
        BUG_ON(new_size > 0 && min_type != BTRFS_EXTENT_DATA_KEY);
 
-       if (root->ref_cows)
+       if (root->ref_cows || root == root->fs_info->tree_root)
                btrfs_drop_extent_cache(inode, new_size & (~mask), (u64)-1, 0);
 
        path = btrfs_alloc_path();
@@ -3344,7 +3345,8 @@ delete:
                } else {
                        break;
                }
-               if (found_extent && root->ref_cows) {
+               if (found_extent && (root->ref_cows ||
+                                    root == root->fs_info->tree_root)) {
                        btrfs_set_path_blocking(path);
                        ret = btrfs_free_extent(trans, root, extent_start,
                                                extent_num_bytes, 0,
@@ -3675,7 +3677,8 @@ void btrfs_evict_inode(struct inode *inode)
        int ret;
 
        truncate_inode_pages(&inode->i_data, 0);
-       if (inode->i_nlink && btrfs_root_refs(&root->root_item) != 0)
+       if (inode->i_nlink && (btrfs_root_refs(&root->root_item) != 0 ||
+                              root == root->fs_info->tree_root))
                goto no_delete;
 
        if (is_bad_inode(inode)) {
@@ -3888,7 +3891,14 @@ static void inode_tree_del(struct inode *inode)
        }
        spin_unlock(&root->inode_lock);
 
-       if (empty && btrfs_root_refs(&root->root_item) == 0) {
+       /*
+        * Free space cache has inodes in the tree root, but the tree root has a
+        * root_refs of 0, so this could end up dropping the tree root as a
+        * snapshot, so we need the extra !root->fs_info->tree_root check to
+        * make sure we don't drop it.
+        */
+       if (empty && btrfs_root_refs(&root->root_item) == 0 &&
+           root != root->fs_info->tree_root) {
                synchronize_srcu(&root->fs_info->subvol_srcu);
                spin_lock(&root->inode_lock);
                empty = RB_EMPTY_ROOT(&root->inode_tree);
@@ -4282,14 +4292,24 @@ int btrfs_write_inode(struct inode *inode, struct writeback_control *wbc)
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_trans_handle *trans;
        int ret = 0;
+       bool nolock = false;
 
        if (BTRFS_I(inode)->dummy_inode)
                return 0;
 
+       smp_mb();
+       nolock = (root->fs_info->closing && root == root->fs_info->tree_root);
+
        if (wbc->sync_mode == WB_SYNC_ALL) {
-               trans = btrfs_join_transaction(root, 1);
+               if (nolock)
+                       trans = btrfs_join_transaction_nolock(root, 1);
+               else
+                       trans = btrfs_join_transaction(root, 1);
                btrfs_set_trans_block_group(trans, inode);
-               ret = btrfs_commit_transaction(trans, root);
+               if (nolock)
+                       ret = btrfs_end_transaction_nolock(trans, root);
+               else
+                       ret = btrfs_commit_transaction(trans, root);
        }
        return ret;
 }
@@ -6308,6 +6328,21 @@ void btrfs_destroy_inode(struct inode *inode)
                spin_unlock(&root->fs_info->ordered_extent_lock);
        }
 
+       if (root == root->fs_info->tree_root) {
+               struct btrfs_block_group_cache *block_group;
+
+               block_group = btrfs_lookup_block_group(root->fs_info,
+                                               BTRFS_I(inode)->block_group);
+               if (block_group && block_group->inode == inode) {
+                       spin_lock(&block_group->lock);
+                       block_group->inode = NULL;
+                       spin_unlock(&block_group->lock);
+                       btrfs_put_block_group(block_group);
+               } else if (block_group) {
+                       btrfs_put_block_group(block_group);
+               }
+       }
+
        spin_lock(&root->orphan_lock);
        if (!list_empty(&BTRFS_I(inode)->i_orphan)) {
                printk(KERN_INFO "BTRFS: inode %lu still on the orphan list\n",
@@ -6340,7 +6375,8 @@ int btrfs_drop_inode(struct inode *inode)
 {
        struct btrfs_root *root = BTRFS_I(inode)->root;
 
-       if (btrfs_root_refs(&root->root_item) == 0)
+       if (btrfs_root_refs(&root->root_item) == 0 &&
+           root != root->fs_info->tree_root)
                return 1;
        else
                return generic_drop_inode(inode);
@@ -6757,27 +6793,33 @@ out_unlock:
        return err;
 }
 
-int btrfs_prealloc_file_range(struct inode *inode, int mode,
-                             u64 start, u64 num_bytes, u64 min_size,
-                             loff_t actual_len, u64 *alloc_hint)
+static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
+                                      u64 start, u64 num_bytes, u64 min_size,
+                                      loff_t actual_len, u64 *alloc_hint,
+                                      struct btrfs_trans_handle *trans)
 {
-       struct btrfs_trans_handle *trans;
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_key ins;
        u64 cur_offset = start;
        int ret = 0;
+       bool own_trans = true;
 
+       if (trans)
+               own_trans = false;
        while (num_bytes > 0) {
-               trans = btrfs_start_transaction(root, 3);
-               if (IS_ERR(trans)) {
-                       ret = PTR_ERR(trans);
-                       break;
+               if (own_trans) {
+                       trans = btrfs_start_transaction(root, 3);
+                       if (IS_ERR(trans)) {
+                               ret = PTR_ERR(trans);
+                               break;
+                       }
                }
 
                ret = btrfs_reserve_extent(trans, root, num_bytes, min_size,
                                           0, *alloc_hint, (u64)-1, &ins, 1);
                if (ret) {
-                       btrfs_end_transaction(trans, root);
+                       if (own_trans)
+                               btrfs_end_transaction(trans, root);
                        break;
                }
 
@@ -6810,11 +6852,30 @@ int btrfs_prealloc_file_range(struct inode *inode, int mode,
                ret = btrfs_update_inode(trans, root, inode);
                BUG_ON(ret);
 
-               btrfs_end_transaction(trans, root);
+               if (own_trans)
+                       btrfs_end_transaction(trans, root);
        }
        return ret;
 }
 
+int btrfs_prealloc_file_range(struct inode *inode, int mode,
+                             u64 start, u64 num_bytes, u64 min_size,
+                             loff_t actual_len, u64 *alloc_hint)
+{
+       return __btrfs_prealloc_file_range(inode, mode, start, num_bytes,
+                                          min_size, actual_len, alloc_hint,
+                                          NULL);
+}
+
+int btrfs_prealloc_file_range_trans(struct inode *inode,
+                                   struct btrfs_trans_handle *trans, int mode,
+                                   u64 start, u64 num_bytes, u64 min_size,
+                                   loff_t actual_len, u64 *alloc_hint)
+{
+       return __btrfs_prealloc_file_range(inode, mode, start, num_bytes,
+                                          min_size, actual_len, alloc_hint, trans);
+}
+
 static long btrfs_fallocate(struct inode *inode, int mode,
                            loff_t offset, loff_t len)
 {