On Fri, Apr 19, 2024 at 10:35:27AM +0200, Dmitry Vyukov wrote: > On Fri, 5 Apr 2024 at 18:20, Aleksandr Nogikh <[email protected]> wrote: > > > > On Fri, Apr 5, 2024 at 1:16 AM Kent Overstreet > > <[email protected]> wrote: > > > > > > On Thu, Apr 04, 2024 at 10:33:07AM +0200, Dmitry Vyukov wrote: > > > > On Thu, 4 Apr 2024 at 01:59, Kent Overstreet > > > > <[email protected]> wrote: > > > > > > > > > > Hi - what would it take to get syzbot going for bcachefs? > > > > > > > > Hi Kent, > > > > > > > > There are 2 parts: > > > > > > > > The easy one: we need to enable it in syzbot configs. Should we > > > > configure it as follows? > > > > > > > > CONFIG_BCACHEFS_FS=y > > > > CONFIG_BCACHEFS_QUOTA=y > > > > CONFIG_BCACHEFS_ERASURE_CODING=y > > > > CONFIG_BCACHEFS_POSIX_ACL=y > > > > CONFIG_BCACHEFS_DEBUG=y > > > > # CONFIG_BCACHEFS_TESTS is not set > > > > # CONFIG_BCACHEFS_LOCK_TIME_STATS is not set > > > > # CONFIG_BCACHEFS_NO_LATENCY_ACCT is not set > > > > CONFIG_BCACHEFS_SIX_OPTIMISTIC_SPIN=y > > > > > > > > In particular, I am interested in CONFIG_BCACHEFS_DEBUG. Does it > > > > really add more debug checks rather than lots of console printing w/o > > > > checks? Some "DEBUG" kernel configs are misleading here. Checks will > > > > be useful on syzbot, lots of printing not so much. > > > > For the record: I've just sent > > https://github.com/google/syzkaller/pull/4647 with syzbot config > > updates. > > > > > > > > CONFIG_BCACHEFS_DEBUG adds piles of assertions and no extra console > > > printing :) > > > > > > > Second part: syzbot will need to exercise the fs in some useful way. > > > > Is it just a "normal" fs with files, or something special? > > > > > > It's a normal - but multi device - filesystem, similar featureset to > > > btrfs. > > > > > > > Is it mounted from an image, or an image-less fs? If it needs images, > > > > how can they be created? > > > > > > apt install bcachefs-tools > > > mkfs.bcachefs <dev> > > > mount <dev> /mnt > > We've enabled the configs, but we don't have good image seeds yet. > Aleksandr tried to generate them, he is currently OOO, but maybe you > can help meanwhile. > He said that running: > > $ mkfs.bcachefs test.img > > gives this error (on a quite big image, I don't know how large exactly it > was): > > insufficient space for superblocks: start 8 end 4104 > 4096 size 2048 > > Why could it give such an error and how to avoid it?
What was the precise size? I'll see if I'm able to reproduce > Also what would be a good sets of options to generate seed images? > We try to "sample" space of different images to create seeds. To give > you an idea here is what we do for other file systems: > https://github.com/google/syzkaller/blob/af24b0505c748561efb50f1d03c824d6642f6c0b/tools/syz-imagegen/imagegen.go#L60-L516 --encrypted --no_passphrase --compression=lz4 --no-checksum That shousd get us reasonable coverage to start with.
