On Mon, Aug 20, 2018 at 08:36:26AM -0700, Darrick J. Wong wrote: > On Mon, Aug 20, 2018 at 10:27:42AM -0500, Eric Sandeen wrote: > > > > > > On 8/20/18 10:06 AM, Brian Foster wrote: > > > On Tue, Jul 24, 2018 at 09:43:46AM -0700, Darrick J. Wong wrote: > > >> On Mon, Jul 23, 2018 at 11:39:53PM -0700, Eric Sandeen wrote: > > >>> On 6/4/18 11:24 PM, Dave Chinner wrote: > > >>>> From: Dave Chinner <dchinner@xxxxxxxxxx> > > >>>> > > >>>> There are rules for vald extent size hints. We enforce them when > > >>>> applications set them, but fuzzers violate those rules and that > > >>>> screws us over. > > >>>> > > >>>> This results in alignment assertion failures when setting up > > >>>> allocations such as this in direct IO: > > >>>> > > >>>> XFS: Assertion failed: ap->length, file: fs/xfs/libxfs/xfs_bmap.c, line: 3432 > > >>>> .... > > >>>> Call Trace: > > >>>> xfs_bmap_btalloc+0x415/0x910 > > >>>> xfs_bmapi_write+0x71c/0x12e0 > > >>>> xfs_iomap_write_direct+0x2a9/0x420 > > >>>> xfs_file_iomap_begin+0x4dc/0xa70 > > >>>> iomap_apply+0x43/0x100 > > >>>> iomap_file_buffered_write+0x62/0x90 > > >>>> xfs_file_buffered_aio_write+0xba/0x300 > > >>>> __vfs_write+0xd5/0x150 > > >>>> vfs_write+0xb6/0x180 > > >>>> ksys_write+0x45/0xa0 > > >>>> do_syscall_64+0x5a/0x180 > > >>>> entry_SYSCALL_64_after_hwframe+0x49/0xbe > > >>>> > > >>>> And from xfs_db: > > >>>> > > >>>> core.extsize = 10380288 > > >>>> > > >>>> Which is not an integer multiple of the block size, and so violates > > >>>> Rule #7 for setting extent size hints. Validate extent size hint > > >>>> rules in the inode verifier to catch this. > > >>> > > >>> So, I think that if I do: > > >>> > > >>> # mkfs.xfs -f -m crc=0 $TEST_DEV > > >>> # ./check xfs/229 > > >>> # ./check xfs/229 > > >>> > > >>> I trip the verifier, because I end up with freed inodes on disk with an > > >>> extent size hints but zeroed flags. > > >>> > > >>> xfs_ifree sets di_flags = 0 but doesn't clear di_extsize; xfs_inode_validate_extsize > > >>> says if extsize !=0 and the hint flag is set, it fails > > >>> > > >>> Anyone else see this? > > >> > > >> Yeah, I think I just hit this on the TEST_DEV in xfs/242. > > >> > > >> git blame says I lifted the code from the scrub code, and I probably > > >> wrote the code having read the ioctl code (which clears the extsize > > >> field if the iflag isn't set). > > >> > > >>> (crc=0 needed because that causes us to actually reread the inode chunks > > >>> in xfs_iread vs. /* shortcut IO on inode allocation if possible */ > > >> > > >> Hmmm, so a v5 fs mounted with ikeep will also read an inode chunk when > > >> creating an inode. It looks like we do that (instead of zeroing the > > >> incore inode and setting a random i_generation) to preserve the existing > > >> generation number? > > >> > > >> In any case, it's pretty clear that kernels have been writing out freed > > >> inode cores with di_mode == 0, di_flags == 0, and di_extsize == (some > > >> number) so we clearly can't have that in the verifier. It looks like we > > >> only examine di_extsize if either EXTSZ flag are set, so it's not > > >> causing incorrect behavior. Maybe it can be a preening fix in > > >> scrub/repair. > > >> > > > > > > I just stumbled on this problem with xfs/229 that Eric reported. I'm > > > confused by the comment above regarding this not causing incorrect > > > behavior. > > > > I think Darrick meant that having a nonzero extent size hint on disk > > won't cause incorrect behavior because "we only examine di_extsize if > > either EXTSZ flag are set" > > Yeah, he probably did. :) > Got it, thanks. > I think Brian's suggestion of > > if (i_mode != 0 && !hint && extsize != 0) > barf_error(); > > sounds reasonable (having not tested that at all). > I'll run it through xfstests and get it posted if nothing else fails. BTW, do we have a similar issue with the cowextsize hint (assuming v5+ikeep)? It looks like it's cleared similarly in xfs_ialloc(), but I'm not sure if it's cleared somewhere else on free... Brian > --D > > > -Eric
