Re: udev and devfs - The final word

viro
2004-01-05T01:58:30Z

On Sun, Jan 04, 2004 at 08:43:27PM -0500, Jeremy Maitin-Shepard wrote:

> Unfortunately, programs such as tar depend on inode numbers of distinct
> files being distinct even when the file is not open over a period of
> several minutes/seconds. This is needed to avoid dumping hard links
> more than once. Furthermore, there is no efficient way to write
> programs such as tar without depending on this capability. Thus, if
> st_ino cannot be used reliably for this purpose, it would be useful for
> there to be a system call for retrieving a true
> unique-within-the-filesystem identifier for the file.

No such thing. It's not the matter of having a syscall to extract such
identifier - it's that on a lot of filesystems (including many common Unix
ones) there's nothing that would qualify.

Note that tar et.al. do not behave well if used on actively modified directory
tree and ->st_ino reuse is the least of the problems in that area.