Re: POSIX violation by writeback error

Matthew Wilcox
2018-09-04T21:02:47Z

On Tue, Sep 04, 2018 at 01:35:34PM -0700, Vito Caputo wrote:
> Implement a new class of swap space for backing dirty pages which fail
> to write back. Pages in this space survive reboots, essentially backing
> the implicit commitment POSIX establishes in the face of asynchronous
> writeback errors. Rather than evicting these pages as clean, they are
> swapped out to the persistent swap.

You not only need to track which index within a file this swapped page
belongs to but also which file. And that starts to get tricky. It may
or may not have a name; it may or may not have a persistent inode number;
it may or may not have a persistent fhandle. If it's on network storage,
it may have been modified by another machine. If it's on removable
storage, it may have been modified by another machine.