On Sep 2, 2014, at 12:24 PM, Brassow Jonathan <jbrassow@xxxxxxxxxx> wrote: > > On Aug 29, 2014, at 2:29 PM, Eivind Sarto wrote: > >> I am seeing occasional data corruption during raid1 resync. >> Reviewing the raid1 code, I suspect that commit 79ef3a8aa1cb1523cc231c9a90a278333c21f761 introduced a bug. >> Prior to this commit raise_barrier() used to wait for conf->nr_pending to become zero. It no longer does this. >> It is not easy to reproduce the corruption, so I wanted to ask about the following potential fix while I am still testing it. >> Once I validate that the fix indeed works, I will post a proper patch. >> Do you have any feedback? >> >> — drivers/md/raid1.c 2014-08-22 15:19:15.000000000 -0700 >> +++ /tmp/raid1.c 2014-08-29 12:07:51.000000000 -0700 >> @@ -851,7 +851,7 @@ static void raise_barrier(struct r1conf >> * handling. >> */ >> wait_event_lock_irq(conf->wait_barrier, >> - !conf->array_frozen && >> + !conf->array_frozen && !conf->nr_pending && >> conf->barrier < RESYNC_DEPTH && >> (conf->start_next_window >= >> conf->next_resync + RESYNC_SECTORS), > > This patch does not work - at least, it doesn't fix the issues I'm seeing. My system hangs (in various places, like the resync thread) after commit 79ef3a8. When testing this patch, I also added some code to dm-raid.c to allow me to print-out some of the variables when I encounter a problem. After applying this patch and printing the variables, I see: > Sep 2 14:04:15 bp-01 kernel: device-mapper: raid: start_next_window = 12288 > Sep 2 14:04:15 bp-01 kernel: device-mapper: raid: current_window_requests = -46 > 5257 > Sep 2 14:04:15 bp-01 kernel: device-mapper: raid: next_window_requests = -11562 > Sep 2 14:04:15 bp-01 kernel: device-mapper: raid: nr_pending = 0 > Sep 2 14:04:15 bp-01 kernel: device-mapper: raid: nr_waiting = 0 > Sep 2 14:04:15 bp-01 kernel: device-mapper: raid: nr_queued = 0 > Sep 2 14:04:15 bp-01 kernel: device-mapper: raid: barrier = 1 > Sep 2 14:04:15 bp-01 kernel: device-mapper: raid: array_frozen = 0 > > Some of those values look pretty bizarre to me and suggest the accounting is pretty messed up. > > brassow > After reviewing commit 79ef3a8aa1cb1523cc231c9a90a278333c21f761 I notice that wait_barrier() will now only exclude writes. User reads are not excluded even if the fall within the resync window. The old implementation used to exclude both reads and writes while resync-IO is active. Could this be a cause of data corruption? -eivind-- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
