The offending system is indeed ARMv7 (specifically a Marvell ARMADA® 388), but I believe the Broadcom BCM2835 in my Raspberry Pi is actually ARMv6 (with hardware float support).
On Mon, Jan 18, 2021 at 4:01 AM Qu Wenruo <quwenruo.bt...@gmx.com> wrote: > > > > On 2021/1/18 下午7:55, Erik Jensen wrote: > > On Mon, Jan 18, 2021 at 3:07 AM Qu Wenruo <quwenruo.bt...@gmx.com> wrote: > >> On 2021/1/18 下午6:33, Erik Jensen wrote: > >>> I ended up having other priorities occupying my time since 2019, and the > >>> "solution" of exporting the individual drives on my NAS using NBD and > >>> mounting them on my desktop worked, even if it wasn't pretty. > >>> > >>> However, I am currently looking into Syncthing, which I would like to > >>> run on the NAS directly. That would, of course, require accessing the > >>> filesystem directly on the NAS rather than just exporting the raw > >>> devices, which means circling back to this issue. > >>> > >>> After updating my NAS, I have determined that the issue still occurs > >>> with Linux 5.8. > >>> > >>> What's the next best step for debugging the issue? Ideally, I'd like to > >>> help track down the issue to find a proper fix, rather than just trying > >>> to bypass the issue. I wasn't sure if the suggestion to comment out > >>> btrfs_verify_dev_extents() was more geared toward the former or the > >>> latter. > >> > >> After rewinding my memory on this case, the problem is really that the > >> ARM btrfs kernel is reading garbage, while X86 or ARM user space tool > >> works as expected. > >> > >> Can you recompile your kernel on the ARM board to add extra debugging > >> messages? > >> If possible, we can try to add some extra debug points to bombarding > >> your dmesg. > >> > >> Or do you have other ARM boards to test the same fs? > >> > >> > >> Thanks, > >> Qu > > > > It's pretty easy to build a kernel with custom patches applied, though > > the actual building takes a while, so I'd be happy to add whatever > > debug messages would be useful. I also have an old Raspberry Pi > > (original model B) I can dig out and try to get going, tomorrow. I > > can't hook it up to the drives directly, but I should be able to > > access them via NBD like I was doing from my desktop. > > RPI 1B would be a little slow but should be enough to expose the > problem, if the problem is for all arm builds (as long as you're also > using armv7 for the offending system). > > Thanks, > Qu > > > If I can't get > > that going for whatever reason, I could also try running an emulated > > ARM system with QEMU. > > > >>> > >>> On Fri, Jun 28, 2019 at 1:15 AM Qu Wenruo <quwenruo.bt...@gmx.com > >>> <mailto:quwenruo.bt...@gmx.com>> wrote: > >>> > >>> > >>> > >>> On 2019/6/28 下午4:00, Erik Jensen wrote: > >>> >> So it's either the block layer reading some wrong from the disk > >>> or btrfs > >>> >> layer doesn't do correct endian convert. > >>> > > >>> > My ARM board is running in little endian mode, so it doesn't seem > >>> like > >>> > endianness should be an issue. (It is 32-bits versus my desktop's > >>> 64, > >>> > though.) I've also tried exporting the drives via NBD to my x86_64 > >>> > system, and that worked fine, so if the problem is under btrfs, it > >>> > would have to be in the encryption layer, but fsck succeeding on > >>> the > >>> > ARM board would seem to rule that out, as well. > >>> > > >>> >> Would you dump the following data (X86 and ARM should output the > >>> same > >>> >> content, thus one output is enough). > >>> >> # btrfs ins dump-tree -b 17628726968320 /dev/dm-3 > >>> >> # btrfs ins dump-tree -b 17628727001088 /dev/dm-3 > >>> > > >>> > Attached, and also 17628705964032, since that's the block > >>> mentioned in > >>> > my most recent mount attempt (see below). > >>> > >>> The trees are completely fine. > >>> > >>> So it should be something else causing the problem. > >>> > >>> > > >>> >> And then, for the ARM system, please apply the following diff, > >>> and try > >>> >> mount again. > >>> >> The diff adds extra debug info, to exam the vital members of a > >>> tree block. > >>> >> > >>> >> Correct fs should output something like: > >>> >> BTRFS error (device dm-4): bad tree block start, want 30408704 > >>> have 0 > >>> >> tree block gen=4 owner=5 nritems=2 level=0 > >>> >> csum: > >>> >> > >>> > >>> a304e483-0000-0000-0000-00000000000000000000-0000-0000-0000-000000000000 > >>> >> > >>> >> The csum one is the most important one, if there aren't so many > >>> zeros, > >>> >> it means at that timing, btrfs just got a bunch of garbage, thus > >>> we > >>> >> could do further debug. > >>> > > >>> > [ 131.725573] BTRFS info (device dm-1): disk space caching is > >>> enabled > >>> > [ 131.731884] BTRFS info (device dm-1): has skinny extents > >>> > [ 133.046145] BTRFS error (device dm-1): bad tree block start, > >>> want > >>> > 17628705964032 have 2807793151171243621 > >>> > [ 133.055775] tree block gen=7888986126946982446 > >>> > owner=11331573954727661546 nritems=4191910623 level=112 > >>> > [ 133.065661] csum: > >>> > > >>> > >>> 416a456c-1e68-dbc3-185d-aaad410beaef5493ab3f-3cb9-4ba1-2214-b41cba9656fc > >>> > >>> Completely garbage here, so I'd say the data we got isn't what we > >>> want. > >>> > >>> > [ 133.108383] BTRFS error (device dm-1): bad tree block start, > >>> want > >>> > 17628705964032 have 2807793151171243621 > >>> > [ 133.117999] tree block gen=7888986126946982446 > >>> > owner=11331573954727661546 nritems=4191910623 level=112 > >>> > [ 133.127756] csum: > >>> > > >>> > >>> 416a456c-1e68-dbc3-185d-aaad410beaef5493ab3f-3cb9-4ba1-2214-b41cba9656fc > >>> > >>> But strangely, the 2nd try still gives us the same result, if it's > >>> really some garbage, we should get some different result. > >>> > >>> > [ 133.136241] BTRFS error (device dm-1): failed to verify dev > >>> extents > >>> > against chunks: -5 > >>> > >>> You can try to skip the dev extents verification by commenting out > >>> the > >>> btrfs_verify_dev_extents() call in disk-io.c::open_ctree(). > >>> > >>> It may fail at another location though. > >>> > >>> The more strange part is, we have the device tree root node read out > >>> without problem. > >>> > >>> Thanks, > >>> Qu > >>> > >>> > [ 133.166165] BTRFS error (device dm-1): open_ctree failed > >>> > > >>> > I copied some files over last time I had it mounted on my desktop, > >>> > which may be why it's now failing at a different block. > >>> > > >>> > Thanks! > >>> > > >>>
