Btrfs: Introduce contexts for metadata reservation

Introducing metadata reseravtion contexts has two major advantages.
First, it makes metadata reseravtion more traceable. Second, it can
reclaim freed space and re-add them to the itself after transaction
committed.

Besides add btrfs_block_rsv structure and related helper functions,
This patch contains following changes:

Move code that decides if freed tree block should be pinned into
btrfs_free_tree_block().

Make space accounting more accurate, mainly for handling read only
block groups.

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

1 files changed, 9 insertions, 0 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 05f26acfd070..574594cf6b51 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -903,6 +903,7 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
         root->name = NULL;
         root->in_sysfs = 0;
         root->inode_tree = RB_ROOT;
+        root->block_rsv = NULL;
 
         INIT_LIST_HEAD(&root->dirty_list);
         INIT_LIST_HEAD(&root->orphan_list);
@@ -910,6 +911,7 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
         spin_lock_init(&root->node_lock);
         spin_lock_init(&root->list_lock);
         spin_lock_init(&root->inode_lock);
+        spin_lock_init(&root->accounting_lock);
         mutex_init(&root->objectid_mutex);
         mutex_init(&root->log_mutex);
         init_waitqueue_head(&root->log_writer_wait);
@@ -1620,6 +1622,13 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
         INIT_LIST_HEAD(&fs_info->space_info);
         btrfs_mapping_init(&fs_info->mapping_tree);
+        btrfs_init_block_rsv(&fs_info->global_block_rsv);
+        btrfs_init_block_rsv(&fs_info->delalloc_block_rsv);
+        btrfs_init_block_rsv(&fs_info->trans_block_rsv);
+        btrfs_init_block_rsv(&fs_info->chunk_block_rsv);
+        btrfs_init_block_rsv(&fs_info->empty_block_rsv);
+        INIT_LIST_HEAD(&fs_info->durable_block_rsv_list);
+        mutex_init(&fs_info->durable_block_rsv_mutex);
         atomic_set(&fs_info->nr_async_submits, 0);
         atomic_set(&fs_info->async_delalloc_pages, 0);
         atomic_set(&fs_info->async_submit_draining, 0);