Making Suspend Safer for File Systems

Posted by Amit Shah on January 12, 2009

I saw these File System Freezing patches that got merged into Linus' tree yesterday and instantly thought that these patches could be used to freeze file systems before going into a suspended state. At the recent foss.in/2008, I met with Christoph Hellwig and one of the things we discussed was how he would never trust any file system to be in a consistent state after attempting suspend-to-disk.

The freezing patches are aimed at snapshotting as of now. Extending the suspend routines to make use of them is something I still have to look at. While working with file systems isn't entirely new to me -- I've worked on something called the Mosix File System earlier, it's been a really long time. It'll be quite interesting to work on this.

I had a brief chat with hch about this idea and while he says this still will not convince him to suspend to disk, it could be a good thing for suspend to ram where the laptop runs out of power but the fs could be in a good state. I agree. Though I'd like to use s-t-d with this!

I've had many ideas slip by without blogging about them for ages and later seen them implement by others. In this case, even if I don't end up implementing something, I'd at least have the satisfaction of having penned it down first.