xfs: streamline the directory iteration code for scrub

Currently, online scrub reuses the xfs_readdir code to walk every entry
in a directory.  This isn't awesome for performance, since we end up
cycling the directory ILOCK needlessly and coding around the particular
quirks of the VFS dir_context interface.

Create a streamlined version of readdir that keeps the ILOCK (since the
walk function isn't going to copy stuff to userspace), skips a whole lot
of directory walk cursor checks (since we start at 0 and walk to the
end) and has a sane way to return error codes.

Note: Porting the dotdot checking code is left for a subsequent patch.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 3bdbc838c4d1..ac9d03cd2623 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -158,6 +158,7 @@ xfs-y				+= $(addprefix scrub/, \
 				   ialloc.o \
 				   inode.o \
 				   parent.o \
+				   readdir.o \
 				   refcount.o \
 				   rmap.o \
 				   scrub.o \