Btrfs: Add btree locking to the tree defragmentation code

The online btree defragger is simplified and rewritten to use
standard btree searches instead of a walk up / down mechanism.

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

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 89cc4f611869..a9b3a25a45b7 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2201,6 +2201,7 @@ int drop_snap_lookup_refcount(struct btrfs_root *root, u64 start, u64 len,
 {
         mutex_unlock(&root->fs_info->alloc_mutex);
         lookup_extent_ref(NULL, root, start, len, refs);
+        cond_resched();
         mutex_lock(&root->fs_info->alloc_mutex);
         return lookup_extent_ref(NULL, root, start, len, refs);
 }
@@ -2280,6 +2281,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
 
                         next = read_tree_block(root, bytenr, blocksize,
                                                ptr_gen);
+                        cond_resched();
                         mutex_lock(&root->fs_info->alloc_mutex);
 
                         /* we've dropped the lock, double check */
@@ -2329,6 +2331,7 @@ out:
         *level += 1;
         BUG_ON(ret);
         mutex_unlock(&root->fs_info->alloc_mutex);
+        cond_resched();
         return 0;
 }
 
@@ -2448,6 +2451,10 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
                         break;
                 if (wret < 0)
                         ret = wret;
+                if (trans->transaction->in_commit) {
+                        ret = -EAGAIN;
+                        break;
+                }
         }
         for (i = 0; i <= orig_level; i++) {
                 if (path->nodes[i]) {