On Mon, Nov 17, 2014 at 11:59:48AM +0100, Konstantin wrote: > Josef Bacik wrote on 14.11.2014 at 23:00: > > On 11/14/2014 04:51 PM, Hugo Mills wrote: [snip] > >> Problem 2: Unexplained zeroes > >> > >> Failure to mount. Transid failure, "expected xyz, have 0". Chris > >> looked at an early one of these (for Ke, on IRC) back in September > >> (the 27th -- sadly, the public IRC logs aren't there for it, but I can > >> supply a copy of the private log). He rapidly came to the conclusion > >> that it was something bad going on with TRIM, replacing some blocks > >> with zeroes. Since then, I've seen a bunch of these coming past on > >> IRC. It seems to be a 3.17 thing. I can successfully predict the > >> presence of an SSD and -odiscard from the "have 0". I've successfully > >> persuaded several people to put this into bugzilla and capture > >> btrfs-images. btrfs recover doesn't generally seem to be helpful in > >> recovering data. [snip] > > So for #2 I've been looking at that the last two weeks. I'm always > > paranoid we're screwing up one of our data integrity sort of things, > > either not waiting on IO to complete properly or something like that. > > I've built a dm target to be as evil as possible and have been running > > it trying to make bad things happen. I got slightly side tracked > > since my stress test exposed a bug in the tree log stuff an csums > > which I just fixed. Now that I've fixed that I'm going back to try > > and make the "expected blah, have 0" type errors happen. [snip] > For #2, I had a strangely damaged BTRFS I reported a week or so ago > which may have similar background. Dmesg gives: > > parent transid verify failed on 586239082496 wanted 13329746340512024838 > found 588 > BTRFS: open_ctree failed > > The thing is that btrfsck crashes when trying to check this. As nobody > seemed to be interested I reformatted this disk today.
Whilst that's a genuine problem, it's not specifically the one I was referring to here, which shows up with "want=X, have=0" from btrfs check, and seems to be related to TRIM on SSDs. Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- Turning, pages turning in the widening bath, / The spine --- cannot bear the humidity. / Books fall apart; the binding cannot hold. / Page 129 is loosed upon the world.
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