gnu-arch-users
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Gnu-arch-users] remove `dev' from inode sigs


From: Miles Bader
Subject: [Gnu-arch-users] remove `dev' from inode sigs
Date: 29 Jan 2004 10:31:58 +0900

Perhaps this has already been discussed, but I think the `dev' field
should be removed from inode signatures (in both {arch} and in revlibs):
they screw up use with NFS (even if the same client mounts the same
filesystem from the same host, the device-number can change!), and
they're not really necessary anyway.

The reason they're not necessary is that it's pretty much guaranteed
that all files in a given tree are on the same device, and that it's the
same device as the inode-signature file that refers to them.

The one case that might be worrying is when you've moved a tree to a new
filesystem, and so the inode numbers might not be valid.  I don't think
this is really problem because:

 (1) The overwhelming failure mode in such an instance is going to be
     false negatives, which are safe

 (2) Checking the device-number doesn't guard against this case anyway
     (because a new device/filesystem, with different inode numbers, can
     have the same device number)

 (3) There are other quick heuristics for validating the inode-sig file
     that probably have more or less the same success rate as the
     device-number, such as simply storing the inode-signature's own
     inode-info and making sure it's current

I think device-numbers are really only useful for ensuring two files are
on the same device at a _particular moment in time_.

Thoughts?  This little wrinkle is very annoying if you use NFS, and
removing it should be easy... :-)

-Miles
-- 
"Whatever you do will be insignificant, but it is very important that
 you do it."  Mahatma Gandhi




reply via email to

[Prev in Thread] Current Thread [Next in Thread]