On Wed, Feb 19, 2020 at 10:02:10AM -0600, Scott Cheloha wrote:
> On Wed, Feb 19, 2020 at 04:00:34PM +0100, Otto Moerbeek wrote:
> >
> > [...]
> >
> > FFS1, the default filesystem, uses 32-bit signed timestamps on disk.
> > That means that in 2038, there's going to be a problem, timestamps
> > will the be interperet as coming from the start of the 1900's.
> >
> > FFS2 does not have this limitation, but at the moment, we cannot boot
> > from it. I'm working on that as well, but for now I like to propose a
> > diff that interprets all timestamps in FFS1 as unsigned.
> >
> > * On disk format dos not change
> > * Current timestamp values do not change
>
> Doesn't this change the interpretation of timestamps before 1970?
>
> Humor me:
>
> # date 196901010000
> Wed Jan 1 00:00:00 CST 1969
> # touch test && ls -l test
> -rw-r--r-- 1 ssc ssc 0 Jan 1 00:00 test
> # stat test
> 1038 8878266 -rw-r--r-- 1 ssc ssc 0 0 "Jan 1 00:00:58 1969" "Jan 1 00:00:58
> 1969" "Jan 1 00:00:58 1969" 32768 0 0 test
>
> ... so what happens to such files? The timestamps wrap around?
>
> I'm not sure if that should prevent us from implementing this stopgap,
> but it's worth considering.
>
> > I have checked various tools like dump(8) and restore(8), they work
> > properly. Code normally works with the fields from struct stat, which
> > is already 64-bit. I can imagine code setting timestamps to -1
> > explicitly, that could cause surprises.
> >
> > So I'm asking for wider testing of the diff below.
>
> One small bug below.
>
> > Index: ufs/ffs/ffs_alloc.c
> > ===================================================================
> > RCS file: /cvs/src/sys/ufs/ffs/ffs_alloc.c,v
> > retrieving revision 1.109
> > diff -u -p -r1.109 ffs_alloc.c
> > --- ufs/ffs/ffs_alloc.c 19 Jul 2019 00:24:31 -0000 1.109
> > +++ ufs/ffs/ffs_alloc.c 16 Feb 2020 19:33:07 -0000
> > @@ -888,7 +888,8 @@ ffs_fragextend(struct inode *ip, int cg,
> > return (0);
> >
> > cgp = (struct cg *)bp->b_data;
> > - cgp->cg_ffs2_time = cgp->cg_time = time_second;
> > + cgp->cg_ffs2_time = time_second;
> > + cgp->cg_time = time_second;
>
> You shouldn't re-read time_second here unless you want to introduce a
> possible difference between cg_ffs2_time and cg_time.
>
> You should also, in general, avoid time_second. There is a split-read
> bug on 32-bit platforms at the 2038 cross-over.
>
> That one I'm less certain about, though. time_second assignment is
> brief compared to the alternative:
>
> struct timespec now;
>
> nanotime(&now);
> cgp->cg_ffs2_time = now.tv_sec;
> cgp->cg_time = now.tv_sec;
>
> ... and the window for the split-read bug is very small...
>
> At minimum, don't re-read time_second.
OK, I'll change that. Ne aware the filesystems is full of time_second.
-Otto
>
> > bno = dtogd(fs, bprev);
> > for (i = numfrags(fs, osize); i < frags; i++)
> > Index: ufs/ffs/fs.h
> > ===================================================================
> > RCS file: /cvs/src/sys/ufs/ffs/fs.h,v
> > retrieving revision 1.42
> > diff -u -p -r1.42 fs.h
> > --- ufs/ffs/fs.h 27 Nov 2016 13:27:55 -0000 1.42
> > +++ ufs/ffs/fs.h 16 Feb 2020 19:33:07 -0000
> > @@ -199,7 +199,7 @@ struct fs {
> > int32_t fs_dblkno; /* offset of first data / frags */
> > int32_t fs_cgoffset; /* cylinder group offset in cylinder */
> > int32_t fs_cgmask; /* used to calc mod fs_ntrak */
> > - int32_t fs_ffs1_time; /* last time written */
> > + u_int32_t fs_ffs1_time; /* last time written */
> > int32_t fs_ffs1_size; /* # of blocks in fs / frags */
> > int32_t fs_ffs1_dsize; /* # of data blocks in fs */
> > int32_t fs_ncg; /* # of cylinder groups */
> > @@ -285,7 +285,7 @@ struct fs {
> > int32_t fs_avgfpdir; /* expected # of files per directory */
> > int32_t fs_sparecon[26]; /* reserved for future constants */
> > u_int32_t fs_flags; /* see FS_ flags below */
> > - int32_t fs_fscktime; /* last time fsck(8)ed */
> > + u_int32_t fs_fscktime; /* last time fsck(8)ed */
> > int32_t fs_contigsumsize; /* size of cluster summary array */
> > int32_t fs_maxsymlinklen; /* max length of an internal symlink */
> > int32_t fs_inodefmt; /* format of on-disk inodes */
> > @@ -376,7 +376,7 @@ struct fs {
> > struct cg {
> > int32_t cg_firstfield; /* historic cyl groups linked list */
> > int32_t cg_magic; /* magic number */
> > - int32_t cg_time; /* time last written */
> > + u_int32_t cg_time; /* time last written */
> > int32_t cg_cgx; /* we are the cgx'th cylinder group */
> > int16_t cg_ncyl; /* number of cyl's this cg */
> > int16_t cg_niblk; /* number of inode blocks this cg */
> > Index: ufs/ufs/dinode.h
> > ===================================================================
> > RCS file: /cvs/src/sys/ufs/ufs/dinode.h,v
> > retrieving revision 1.18
> > diff -u -p -r1.18 dinode.h
> > --- ufs/ufs/dinode.h 30 May 2013 19:19:09 -0000 1.18
> > +++ ufs/ufs/dinode.h 16 Feb 2020 19:33:07 -0000
> > @@ -72,11 +72,11 @@ struct ufs1_dinode {
> > u_int32_t inumber; /* 4: Lfs: inode number. */
> > } di_u;
> > u_int64_t di_size; /* 8: File byte count. */
> > - int32_t di_atime; /* 16: Last access time. */
> > + u_int32_t di_atime; /* 16: Last access time. */
> > int32_t di_atimensec; /* 20: Last access time. */
> > - int32_t di_mtime; /* 24: Last modified time. */
> > + u_int32_t di_mtime; /* 24: Last modified time. */
> > int32_t di_mtimensec; /* 28: Last modified time. */
> > - int32_t di_ctime; /* 32: Last inode change time. */
> > + u_int32_t di_ctime; /* 32: Last inode change time. */
> > int32_t di_ctimensec; /* 36: Last inode change time. */
> > int32_t di_db[NDADDR]; /* 40: Direct disk blocks. */
> > int32_t di_ib[NIADDR]; /* 88: Indirect disk blocks. */
> >
>
