Fallthrus were invented as a placeholders for readdir() on a union-mounted directory - basically, to use the top-level file system's readdir() cookie mechanism. Fallthrus are persistent directory entries and are implemented by the underlying file system - such as ext2 or tmpfs - in whatever way it sees fit. We've implemented them for ext2 in two ways: as a regular directory entry with a magic inode number, and as a regular directory entry with a special file type. Recently, David Woodhouse suggested implementing fallthrus as full-length symlinks with a special flag. The interesting thing about this idea is that it could theoretically let us rename a file from the low level file system to another place in the low-level file system without copying the contents of the file up. Basically, we can arbitrarily swizzle the namespace of the low-level by maintaining a set of symlinks above. Is this useful? Is it implementable? Background reading: http://valerieaurora.org/union/ -VAL -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
