On Wed, 2007-06-20 at 11:21 +0530, Bharata B Rao wrote: > From: Bharata B Rao <[EMAIL PROTECTED]> > Subject: Union mount documentation. Hi,
first of all I'm happy to see that people are still working on unionfs; I'd love to have functionality like this show up in Linux. I'll not claim to have any VFS knowledge whatsoever, but I was just wondering what happens in the following scenario: FS A is mounted twice, in /mnt/A and /mnt/union FS B is mounted twice, in /mnt/B and as topmost union mount on /mnt/union lets for simplicity say both filesystems are entirely empty user does on FS A: mkdir /mnt/A/somedir touch /mnt/A/somedir/somefile and then 2 things happen in parallel 1) touch /mnt/B/somefile 2) mv /mnt/union/somedir /mnt/union/somefile since the underlying FS for 2) is FS A... how will this work out locking wise? Will the VS lock the union directory only? Or will this operate only on the underlying FS? How is dcache consistency guaranteed for scenarios like this? Greetings, Arjan van de Ven -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/