fs/9p: Revert "fs/9p: fix dups even in uncached mode"

This reverts commit be57855f.

It caused a regression involving duplicate inode numbers in
some tester trees.  The bad behavior seems to be dependent on inode
reuse policy in underlying file system, so it did not trigger in my
test setup.
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>

fs/9p/vfs_super.c

@@ -244,6 +244,21 @@ static int v9fs_statfs(struct dentry *dentry, struct kstatfs *buf)
 	return res;
 }
 
+static int v9fs_drop_inode(struct inode *inode)
+{
+	struct v9fs_session_info *v9ses;
+
+	v9ses = v9fs_inode2v9ses(inode);
+	if (v9ses->cache & (CACHE_META|CACHE_LOOSE))
+		return generic_drop_inode(inode);
+	/*
+	 * in case of non cached mode always drop the
+	 * inode because we want the inode attribute
+	 * to always match that on the server.
+	 */
+	return 1;
+}
+
 static int v9fs_write_inode(struct inode *inode,
 			    struct writeback_control *wbc)
 {
@@ -278,6 +293,7 @@ static const struct super_operations v9fs_super_ops_dotl = {
 	.alloc_inode = v9fs_alloc_inode,
 	.free_inode = v9fs_free_inode,
 	.statfs = v9fs_statfs,
+	.drop_inode = v9fs_drop_inode,
 	.evict_inode = v9fs_evict_inode,
 	.show_options = v9fs_show_options,
 	.umount_begin = v9fs_umount_begin,