fuse: respect FOPEN_KEEP_CACHE on opendir

The re-factoring of fuse_dir_open() missed the need to invalidate
directory inode page cache with open flag FOPEN_KEEP_CACHE.

Fixes: 7de64d521bf92 ("fuse: break up fuse_open_common()")
Reported-by: Prince Kumar <[e-mail]>
Closes: https://lore.kernel.org/linux-fsdevel/CAEW=[e-mail]/
Signed-off-by: Amir Goldstein <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Bernd Schubert <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

fs/fuse/dir.c

···
 		 */
 		if (ff->open_flags & (FOPEN_STREAM | FOPEN_NONSEEKABLE))
 			nonseekable_open(inode, file);
+		if (!(ff->open_flags & FOPEN_KEEP_CACHE))
+			invalidate_inode_pages2(inode->i_mapping);
 	}
 
 	return err;