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. :) I think Brian's suggestion of if (i_mode != 0 && !hint && extsize != 0) barf_error(); sounds reasonable (having not tested that at all). --D > -Eric
