xfs: create function to scan and clear EOFBLOCKS inodes

xfs_inodes_free_eofblocks() implements scanning functionality for
EOFBLOCKS inodes. It uses the AG iterator to walk the tagged inodes
and free post-EOF blocks via the xfs_inode_free_eofblocks() execute
function. The scan can be invoked in best-effort mode or wait
(force) mode.

A best-effort scan (default) handles all inodes that do not have a
dirty cache and we successfully acquire the io lock via trylock. In
wait mode, we continue to cycle through an AG until all inodes are
handled.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 6f46e03..cb52346 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -589,6 +589,7 @@
 
 DEFINE_INODE_EVENT(xfs_inode_set_eofblocks_tag);
 DEFINE_INODE_EVENT(xfs_inode_clear_eofblocks_tag);
+DEFINE_INODE_EVENT(xfs_inode_free_eofblocks_invalid);
 
 DECLARE_EVENT_CLASS(xfs_iref_class,
 	TP_PROTO(struct xfs_inode *ip, unsigned long caller_ip),