btrfs-progs: Add delayed refs infrastructure

This commit pulls those portions of the kernel implementation of
delayed refs which are necessary to have them working in user-space.
I've done the following modifications:

1. Replaced all kmem_cache_alloc calls to kmalloc.

2. Removed all locking-related code, since we are single threaded in
   userspace.

3. Removed code which deals with data refs - delayed refs in user space
   are going to be used only for cowonly trees.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/ctree.h b/ctree.h
index 4719962d..5242595f 100644
--- a/ctree.h
+++ b/ctree.h
@@ -2790,4 +2790,7 @@ int btrfs_punch_hole(struct btrfs_trans_handle *trans,
 int btrfs_read_file(struct btrfs_root *root, u64 ino, u64 start, int len,
 		    char *dest);
 
+/* extent-tree.c */
+int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, unsigned long nr);
+
 #endif