On Wed, Nov 25, 2020 at 5:36 PM Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > > On Wed, Nov 25, 2020 at 04:03:06PM +0200, Amir Goldstein wrote: > > On Wed, Nov 25, 2020 at 12:46 PM Sargun Dhillon <sargun@xxxxxxxxx> wrote: > > > > > > Volatile remounts validate the following at the moment: > > > * Has the module been reloaded / the system rebooted > > > * Has the workdir been remounted > > > > > > This adds a new check for errors detected via the superblock's > > > errseq_t. At mount time, the errseq_t is snapshotted to disk, > > > and upon remount it's re-verified. This allows for kernel-level > > > detection of errors without forcing userspace to perform a > > > sync and allows for the hidden detection of writeback errors. > > > > > > > Looks fine as long as you verify that the reuse is also volatile. > > > > Care to also add the alleged issues that Vivek pointed out with existing > > volatile mount to the documentation? (unless Vivek intends to do fix those) > > I thought current writeback error issue with volatile mounts needs to > be fixed with shutting down filesystem. (And mere documentation is not > enough). > Documentation is the bare minimum. If someone implements the shutdown approach that would be best. > Amir, are you planning to improve your ovl-shutdown patches to detect > writeback errors for volatile mounts. Or you want somebody else to > look at it. I did not intend to work on this. Whoever wants to pick this up doesn't need to actually implement the shutdown ioctl, may implement only an "internal shutdown" on error. > > W.r.t this patch set, I still think that first we should have patches > to shutdown filesystem on writeback errors (for volatile mount), and > then detecting writeback errors on remount makes more sense. > I agree that would be very nice, but I can also understand the argument that volatile mount has an issue, which does not get any better or any worse as a result of Sargun's patches. If anything, they improve the situation: Currently, the user does have a way to know if any data was lost on a volatile mount. After a successful mount cycle, the user knows that no data was lost during the last volatile mount period. Thanks, Amir.
