Valerie Aurora: > 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? I think the idea of fallthru entry is good, even if it is implemented as a special symlink. How do you think about the file paths in /proc/pid/maps and /proc/pid/fd? They refer the file paths, and some apps depend upon these path. I remember that the package manager in debian didn't work when the path is wrong. (But I don't know whether it is true still). Will FS have to support such case? J. R. Okajima -- 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
