On Mon, Apr 03, 2017 at 11:19:51AM -0400, Jeff Layton wrote: > Yes, so just to be clear here if you bump a 32 bit counter every > microsecond you'll end up wrapping in a little over an hour. How fast > can DAX generate I/O errors? :) I admit to not having picked through the code, but how often do we try to do writebacks? And how often do we retry writebacks once an -EIO has happened? Once we mark a page as PG_error, do we keep trying to write it back and set the AS error each time? > I'm fine with a 32 bit counter (and even with using the low order bits > to store error flags) if we're ok with that limitation. The big > question there is whether it's ok to continue reporting -EIO when there > has actually been nothing but -ENOSPC errors since the last fsync. I > think it's a corner case that's not of terribly great concern so I'm > fine with that. Yeah, I was thinking about that, and I'm fine with it too. > We could try to mitigate it by zeroing out the value when i_writecount > goes to zero though. Then if you close all of the fds on the file, the > error is cleared. Or maybe we could add a new ioctl to explicitly zero > it out? I'm OK with zeroing the wb_err once i_writecount drops to 0. Everybody who cares has already been notified. The new ioctl feels like overkill.
