From: Christoph Hellwig <hch@infradead.org>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Amir Goldstein <amir73il@gmail.com>,
linux-xfs@vger.kernel.org, sandeen@sandeen.net
Subject: Re: [PATCH 08/11] xfs: widen ondisk timestamps to deal with y2038 problem
Date: Sat, 22 Aug 2020 08:33:19 +0100 [thread overview]
Message-ID: <20200822073319.GH1629@infradead.org> (raw)
In-Reply-To: <159797594159.965217.2504039364311840477.stgit@magnolia>
> * in the AGI header so that we can skip the finobt walk at mount time when
> @@ -855,12 +862,18 @@ struct xfs_agfl {
> *
> * Inode timestamps consist of signed 32-bit counters for seconds and
> * nanoseconds; time zero is the Unix epoch, Jan 1 00:00:00 UTC 1970.
> + *
> + * When bigtime is enabled, timestamps become an unsigned 64-bit nanoseconds
> + * counter. Time zero is the start of the classic timestamp range.
> */
> union xfs_timestamp {
> struct {
> __be32 t_sec; /* timestamp seconds */
> __be32 t_nsec; /* timestamp nanoseconds */
> };
> +
> + /* Nanoseconds since the bigtime epoch. */
> + __be64 t_bigtime;
> };
So do we really need the union here? What about:
(1) keep the typedef instead of removing it
(2) switch the typedef to be just a __be64, and use trivial helpers
to extract the two separate legacy sec/nsec field
(3) PROFIT!!!
> +/* Convert an ondisk timestamp into the 64-bit safe incore format. */
> void
> xfs_inode_from_disk_timestamp(
> + struct xfs_dinode *dip,
> struct timespec64 *tv,
> const union xfs_timestamp *ts)
I think passing ts by value might lead to somewhat better code
generation on modern ABIs (and older ABIs just fall back to pass
by reference transparently).
> {
> + if (dip->di_version >= 3 &&
> + (dip->di_flags2 & cpu_to_be64(XFS_DIFLAG2_BIGTIME))) {
Do we want a helper for this condition?
> + uint64_t t = be64_to_cpu(ts->t_bigtime);
> + uint64_t s;
> + uint32_t n;
> +
> + s = div_u64_rem(t, NSEC_PER_SEC, &n);
> + tv->tv_sec = s - XFS_INO_BIGTIME_EPOCH;
> + tv->tv_nsec = n;
> + return;
> + }
> +
> tv->tv_sec = (int)be32_to_cpu(ts->t_sec);
> tv->tv_nsec = (int)be32_to_cpu(ts->t_nsec);
Nit: for these kinds of symmetric conditions and if/else feels a little
more natural.
> + xfs_log_dinode_to_disk_ts(from, &to->di_crtime, &from->di_crtime);
This adds a > 80 char line.
> + if (from->di_flags2 & XFS_DIFLAG2_BIGTIME) {
> + uint64_t t;
> +
> + t = (uint64_t)(ts->tv_sec + XFS_INO_BIGTIME_EPOCH);
> + t *= NSEC_PER_SEC;
> + its->t_bigtime = t + ts->tv_nsec;
This calculation is dupliated in two places, might be worth
adding a little helper (which will need to get the sec/nsec values
passed separately due to the different structures).
> + xfs_inode_to_log_dinode_ts(from, &to->di_crtime, &from->di_crtime);
Another line over 8 characters here.
> + if (xfs_sb_version_hasbigtime(&mp->m_sb)) {
> + sb->s_time_min = XFS_INO_BIGTIME_MIN;
> + sb->s_time_max = XFS_INO_BIGTIME_MAX;
> + } else {
> + sb->s_time_min = XFS_INO_TIME_MIN;
> + sb->s_time_max = XFS_INO_TIME_MAX;
> + }
This is really a comment on the earlier patch, but maybe we should
name the old constants with "OLD" or "LEGACY" or "SMALL" in the name?
> @@ -1494,6 +1499,10 @@ xfs_fc_fill_super(
> if (XFS_SB_VERSION_NUM(&mp->m_sb) == XFS_SB_VERSION_5)
> sb->s_flags |= SB_I_VERSION;
>
> + if (xfs_sb_version_hasbigtime(&mp->m_sb))
> + xfs_warn(mp,
> + "EXPERIMENTAL big timestamp feature in use. Use at your own risk!");
> +
Is there any good reason to mark this experimental?
next prev parent reply other threads:[~2020-08-22 7:33 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 2:11 [PATCH v3 00/11] xfs: widen timestamps to deal with y2038 Darrick J. Wong
2020-08-21 2:11 ` [PATCH 01/11] xfs: explicitly define inode timestamp range Darrick J. Wong
2020-08-22 7:12 ` Christoph Hellwig
2020-08-24 16:29 ` Darrick J. Wong
2020-08-23 23:54 ` Dave Chinner
2020-08-24 2:34 ` Darrick J. Wong
2020-08-21 2:11 ` [PATCH 02/11] xfs: refactor quota expiration timer modification Darrick J. Wong
2020-08-22 7:14 ` Christoph Hellwig
2020-08-23 23:57 ` Dave Chinner
2020-08-24 2:34 ` Darrick J. Wong
2020-08-21 2:11 ` [PATCH 03/11] xfs: refactor default quota grace period setting code Darrick J. Wong
2020-08-22 7:15 ` Christoph Hellwig
2020-08-24 0:01 ` Dave Chinner
2020-08-21 2:11 ` [PATCH 04/11] xfs: remove xfs_timestamp_t Darrick J. Wong
2020-08-22 7:15 ` Christoph Hellwig
2020-08-24 0:04 ` Dave Chinner
2020-08-21 2:12 ` [PATCH 05/11] xfs: move xfs_log_dinode_to_disk to the log code Darrick J. Wong
2020-08-22 7:16 ` Christoph Hellwig
2020-08-24 2:31 ` Darrick J. Wong
2020-08-24 0:06 ` Dave Chinner
2020-08-21 2:12 ` [PATCH 06/11] xfs: refactor inode timestamp coding Darrick J. Wong
2020-08-22 7:17 ` Christoph Hellwig
2020-08-24 0:10 ` Dave Chinner
2020-08-21 2:12 ` [PATCH 07/11] xfs: convert struct xfs_timestamp to union Darrick J. Wong
2020-08-22 7:18 ` Christoph Hellwig
2020-08-24 2:35 ` Darrick J. Wong
2020-08-21 2:12 ` [PATCH 08/11] xfs: widen ondisk timestamps to deal with y2038 problem Darrick J. Wong
2020-08-22 7:33 ` Christoph Hellwig [this message]
2020-08-24 2:43 ` Darrick J. Wong
2020-08-25 0:39 ` Darrick J. Wong
2020-08-24 1:25 ` Dave Chinner
2020-08-24 3:13 ` Darrick J. Wong
2020-08-24 6:15 ` Dave Chinner
2020-08-24 16:24 ` Darrick J. Wong
2020-08-24 21:13 ` Darrick J. Wong
2020-08-21 2:12 ` [PATCH 09/11] xfs: refactor quota timestamp coding Darrick J. Wong
2020-08-22 7:33 ` Christoph Hellwig
2020-08-24 2:38 ` Darrick J. Wong
2020-08-21 2:12 ` [PATCH 10/11] xfs: enable bigtime for quota timers Darrick J. Wong
2020-08-22 7:36 ` Christoph Hellwig
2020-08-24 2:39 ` Darrick J. Wong
2020-08-21 2:12 ` [PATCH 11/11] xfs: enable big timestamps Darrick J. Wong
-- strict thread matches above, loose matches on Subject: below --
2020-08-17 22:56 [PATCH v2 00/11] xfs: widen timestamps to deal with y2038 Darrick J. Wong
2020-08-17 22:57 ` [PATCH 08/11] xfs: widen ondisk timestamps to deal with y2038 problem Darrick J. Wong
2020-08-18 12:00 ` Amir Goldstein
2020-08-18 12:53 ` Amir Goldstein
2020-08-18 15:53 ` Darrick J. Wong
2020-08-18 20:52 ` Darrick J. Wong
2020-08-18 15:44 ` Darrick J. Wong
2020-08-18 23:35 ` Dave Chinner
2020-08-19 21:43 ` Darrick J. Wong
2020-08-19 23:58 ` Dave Chinner
2020-08-20 0:01 ` Darrick J. Wong
2020-08-20 4:42 ` griffin tucker
2020-08-20 16:23 ` Darrick J. Wong
2020-08-21 5:02 ` griffin tucker
2020-08-21 15:31 ` Mike Fleetwood
2020-08-20 5:11 ` Amir Goldstein
2020-08-20 22:47 ` Dave Chinner
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