GFS2: No need to invalidate pages for a dio read

We recently fixed the writeback of pages prior to performing
direct i/o, however the initial fix was perhaps a bit heavy
handed. There is no need to invalidate pages if the direct i/o
is only a read, since they will be identical to what has been
flushed to disk anyway.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index cf858dad75d9..49436fa7cd4f 100644
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -1032,8 +1032,9 @@ static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
                         unmap_shared_mapping_range(ip->i_inode.i_mapping, offset, len);
                 rv = filemap_write_and_wait_range(mapping, lstart, end);
                 if (rv)
-                        return rv;
-                truncate_inode_pages_range(mapping, lstart, end);
+                        goto out;
+                if (rw == WRITE)
+                        truncate_inode_pages_range(mapping, lstart, end);
         }
 
         rv = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,