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.
