On Mon, Jan 09, 2023 at 08:48:49AM -0500, Jeff Layton wrote: > On Mon, 2023-01-09 at 05:18 +0000, Matthew Wilcox (Oracle) wrote: > > Convert both callers to use the "new" errseq infrastructure. > > I looked at making this sort of change across the board alongside the > original wb_err patches, but I backed off at the time. > > With the above patch, this function will no longer report a writeback > error that occurs before the sample. Given that writeback can happen at > any time, that seemed like it might be an undesirable change, and I > didn't follow through. > > It is true that the existing flag-based code may miss errors too, if > multiple tasks are test_and_clear'ing the bits, but I think the above is > even more likely to happen, esp. under memory pressure. > > To do this right, we probably need to look at these callers and have > them track a long-term errseq_t "since" value before they ever dirty the > pages, and then continually check-and-advance vs. that. > > For instance, the main caller of the above function is jbd2. Would it be > reasonable to add in a new errseq_t value to the jnode for tracking > errors? Doesn't b4678df184b3 address this problem? If nobody has seen the error, we return 0 instead of the current value of wb_err, ensuring that somebody always sees the error.
