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>
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index e558dd9..d565b45 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -3514,6 +3514,7 @@
struct btrfs_fs_info *fs_info = extent_root->fs_info;
struct reloc_control *rc;
int ret;
+ int rw = 0;
int err = 0;
rc = kzalloc(sizeof(*rc), GFP_NOFS);
@@ -3524,15 +3525,22 @@
extent_io_tree_init(&rc->processed_blocks, NULL, GFP_NOFS);
INIT_LIST_HEAD(&rc->reloc_roots);
+ rc->extent_root = extent_root;
rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
BUG_ON(!rc->block_group);
+ if (!rc->block_group->ro) {
+ ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
+ if (ret) {
+ err = ret;
+ goto out;
+ }
+ rw = 1;
+ }
+
btrfs_init_workers(&rc->workers, "relocate",
fs_info->thread_pool_size, NULL);
- rc->extent_root = extent_root;
- btrfs_prepare_block_group_relocation(extent_root, rc->block_group);
-
rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
if (IS_ERR(rc->data_inode)) {
err = PTR_ERR(rc->data_inode);
@@ -3597,6 +3605,8 @@
WARN_ON(rc->block_group->reserved > 0);
WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
out:
+ if (err && rw)
+ btrfs_set_block_group_rw(extent_root, rc->block_group);
iput(rc->data_inode);
btrfs_stop_workers(&rc->workers);
btrfs_put_block_group(rc->block_group);