From: Dave Chinner <firstname.lastname@example.org> To: "Darrick J. Wong" <email@example.com> Cc: firstname.lastname@example.org, Christoph Hellwig <email@example.com>, Gao Xiang <firstname.lastname@example.org>, Amir Goldstein <email@example.com>, Allison Collins <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org Subject: Re: [PATCH v6 00/11] xfs: widen timestamps to deal with y2038 Date: Mon, 7 Sep 2020 07:43:22 +1000 [thread overview] Message-ID: <20200906214322.GJ12131@dread.disaster.area> (raw) In-Reply-To: <159901538766.548109.8040337941204954344.stgit@magnolia> On Tue, Sep 01, 2020 at 07:56:27PM -0700, Darrick J. Wong wrote: > Hi all, > > This series performs some refactoring of our timestamp and inode > encoding functions, then retrofits the timestamp union to handle > timestamps as a 64-bit nanosecond counter. Next, it adds bit shifting > to the non-root dquot timer fields to boost their effective size to 34 > bits. These two changes enable correct time handling on XFS through the > year 2486. > > On a current V5 filesystem, inodes timestamps are a signed 32-bit > seconds counter, with 0 being the Unix epoch. Quota timers are an > unsigned 32-bit seconds counter, with 0 also being the Unix epoch. > > This means that inode timestamps can range from: > -(2^31-1) (13 Dec 1901) through (2^31-1) (19 Jan 2038). > > And quota timers can range from: > 0 (1 Jan 1970) through (2^32-1) (7 Feb 2106). > > With the bigtime encoding turned on, inode timestamps are an unsigned > 64-bit nanoseconds counter, with 0 being the 1901 epoch. Quota timers > are a 34-bit unsigned second counter right shifted two bits, with 0 > being the Unix epoch, and capped at the maximum inode timestamp value. > > This means that inode timestamps can range from: > 0 (13 Dec 1901) through (2^64-1 / 1e9) (2 Jul 2486) > > Quota timers could theoretically range from: > 0 (1 Jan 1970) through (((2^34-1) + (2^31-1)) & ~3) (16 Jun 2582). > > But with the capping in place, the quota timers maximum is: > max((2^64-1 / 1e9) - (2^31-1), (((2^34-1) + (2^31-1)) & ~3) (2 Jul 2486). > > v2: rebase to 5.9, having landed the quota refactoring > v3: various suggestions by Amir and Dave > v4: drop the timestamp unions, add "is bigtime?" predicates everywhere > v5: reintroduce timestamp unions as *legacy* timestamp unions > v6: minor stylistic changes > > If you're going to start using this mess, you probably ought to just > pull from my git trees, which are linked below. > > This is an extraordinary way to destroy everything. Enjoy! > Comments and questions are, as always, welcome. The whole series looks good to me now. Reviewed-by: Dave Chinner <email@example.com> -- Dave Chinner firstname.lastname@example.org
prev parent reply other threads:[~2020-09-06 21:43 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-09-02 2:56 Darrick J. Wong 2020-09-02 2:56 ` [PATCH 01/11] xfs: explicitly define inode timestamp range Darrick J. Wong 2020-09-02 2:56 ` [PATCH 02/11] xfs: refactor quota expiration timer modification Darrick J. Wong 2020-09-02 2:56 ` [PATCH 03/11] xfs: refactor default quota grace period setting code Darrick J. Wong 2020-09-02 2:56 ` [PATCH 04/11] xfs: refactor quota timestamp coding Darrick J. Wong 2020-09-02 2:57 ` [PATCH 05/11] xfs: move xfs_log_dinode_to_disk to the log recovery code Darrick J. Wong 2020-09-02 2:57 ` [PATCH 06/11] xfs: redefine xfs_timestamp_t Darrick J. Wong 2020-09-02 2:57 ` [PATCH 07/11] xfs: redefine xfs_ictimestamp_t Darrick J. Wong 2020-09-02 2:57 ` [PATCH 08/11] xfs: widen ondisk inode timestamps to deal with y2038+ Darrick J. Wong 2020-09-02 2:57 ` [PATCH 09/11] xfs: widen ondisk quota expiration timestamps to handle y2038+ Darrick J. Wong 2020-09-02 2:57 ` [PATCH 10/11] xfs: trace timestamp limits Darrick J. Wong 2020-09-02 2:57 ` [PATCH 11/11] xfs: enable big timestamps Darrick J. Wong 2020-09-06 21:43 ` Dave Chinner [this message]
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