Btrfs: Do snapshot deletion in smaller chunks.

Before, snapshot deletion was a single atomic unit.  This caused considerable
lock contention and required an unbounded amount of space.  Now,
the drop_progress field in the root item is used to indicate how far along
snapshot deletion is, and to resume where it left off.

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

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 0287bd51d87c..73c2e75a136d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -333,10 +333,10 @@ struct btrfs_root {
         u64 objectid;
         u64 last_trans;
         u32 blocksize;
-        int ref_cows;
         u32 type;
         u64 highest_inode;
         u64 last_inode_alloc;
+        int ref_cows;
 };
 
 /* the lower bits in the key flags defines the item type */
@@ -1073,7 +1073,7 @@ int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, struct btrfs_root
 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path);
 int btrfs_leaf_free_space(struct btrfs_root *root, struct btrfs_leaf *leaf);
 int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
-                        *root, struct buffer_head *snap);
+                        *root);
 /* root-item.c */
 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                    struct btrfs_key *key);