btrfs: actively run the delayed refs while deleting large files

When we are deleting large files with large extents, we are building up
a huge set of delayed refs for processing.  Truncate isn't checking
often enough to see if we need to back off and process those, or let
a commit proceed.

The end result is long stalls after the rm, and very long commit times.
During the commits, other processes back up waiting to start new
transactions and we get into trouble.

Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 016c90fc85db..a089b5944efc 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -4251,8 +4251,12 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
                                           &BTRFS_I(inode)->runtime_flags);
                                 clear_bit(BTRFS_INODE_COPY_EVERYTHING,
                                           &BTRFS_I(inode)->runtime_flags);
-                                ret = btrfs_truncate_inode_items(trans, log,
-                                                                 inode, 0, 0);
+                                while(1) {
+                                        ret = btrfs_truncate_inode_items(trans,
+                                                         log, inode, 0, 0);
+                                        if (ret != -EAGAIN)
+                                                break;
+                                }
                         }
                 } else if (test_and_clear_bit(BTRFS_INODE_COPY_EVERYTHING,
                                               &BTRFS_I(inode)->runtime_flags) ||