[PATCH 17/26] xfs: widen ondisk quota expiration timestamps to handle y2038+

Darrick J. Wong
2020-10-26T23:36:06Z

From: Darrick J. Wong <darrick.wong@oracle.com>

Source kernel commit: 4ea1ff3b49681af45a4a8c14baf7f0b3d11aa74a

Enable the bigtime feature for quota timers. We decrease the accuracy
of the timers to ~4s in exchange for being able to set timers up to the
bigtime maximum.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Collins <allison.henderson@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
include/xfs_mount.h | 5 +++++
libxfs/xfs_dquot_buf.c | 21 ++++++++++++++++++--
libxfs/xfs_format.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++-
libxfs/xfs_quota_defs.h | 3 ++-
4 files changed, 75 insertions(+), 4 deletions(-)

diff --git a/include/xfs_mount.h b/include/xfs_mount.h
index 20c8bfaf4fa8..be74a922b7a1 100644
--- a/include/xfs_mount.h
+++ b/include/xfs_mount.h
@@ -184,4 +184,9 @@ extern xfs_mount_t *libxfs_mount (xfs_mount_t *, xfs_sb_t *,
int libxfs_umount(struct xfs_mount *mp);
extern void libxfs_rtmount_destroy (xfs_mount_t *);

+/* Dummy xfs_dquot so that libxfs compiles. */
+struct xfs_dquot {
+ int q_type;
+};
+
#endif /* __XFS_MOUNT_H__ */
diff --git a/libxfs/xfs_dquot_buf.c b/libxfs/xfs_dquot_buf.c
index 04f62e31019d..0a5a237d2236 100644
--- a/libxfs/xfs_dquot_buf.c
+++ b/libxfs/xfs_dquot_buf.c
@@ -67,6 +67,13 @@ xfs_dquot_verify(
ddq_type != XFS_DQTYPE_GROUP)
return __this_address;

+ if ((ddq->d_type & XFS_DQTYPE_BIGTIME) &&
+ !xfs_sb_version_hasbigtime(&mp->m_sb))
+ return __this_address;
+
+ if ((ddq->d_type & XFS_DQTYPE_BIGTIME) && !ddq->d_id)
+ return __this_address;
+
if (id != -1 && id != be32_to_cpu(ddq->d_id))
return __this_address;

@@ -293,7 +300,12 @@ xfs_dquot_from_disk_ts(
struct xfs_disk_dquot *ddq,
__be32 dtimer)
{
- return be32_to_cpu(dtimer);
+ uint32_t t = be32_to_cpu(dtimer);
+
+ if (t != 0 && (ddq->d_type & XFS_DQTYPE_BIGTIME))
+ return xfs_dq_bigtime_to_unix(t);
+
+ return t;
}

/* Convert an incore timer value into an on-disk timer value. */
@@ -302,5 +314,10 @@ xfs_dquot_to_disk_ts(
struct xfs_dquot *dqp,
time64_t timer)
{
- return cpu_to_be32(timer);
+ uint32_t t = timer;
+
+ if (timer != 0 && (dqp->q_type & XFS_DQTYPE_BIGTIME))
+ t = xfs_dq_unix_to_bigtime(timer);
+
+ return cpu_to_be32(t);
}
diff --git a/libxfs/xfs_format.h b/libxfs/xfs_format.h
index dbc7008e4498..0ab424cc25ca 100644
--- a/libxfs/xfs_format.h
+++ b/libxfs/xfs_format.h
@@ -1263,13 +1263,15 @@ static inline bool xfs_dinode_has_bigtime(const struct xfs_dinode *dip)
#define XFS_DQTYPE_USER 0x01 /* user dquot record */
#define XFS_DQTYPE_PROJ 0x02 /* project dquot record */
#define XFS_DQTYPE_GROUP 0x04 /* group dquot record */
+#define XFS_DQTYPE_BIGTIME 0x80 /* large expiry timestamps */

/* bitmask to determine if this is a user/group/project dquot */
#define XFS_DQTYPE_REC_MASK (XFS_DQTYPE_USER | \
XFS_DQTYPE_PROJ | \
XFS_DQTYPE_GROUP)

-#define XFS_DQTYPE_ANY (XFS_DQTYPE_REC_MASK)
+#define XFS_DQTYPE_ANY (XFS_DQTYPE_REC_MASK | \
+ XFS_DQTYPE_BIGTIME)

/*
* XFS Quota Timers
@@ -1282,6 +1284,10 @@ static inline bool xfs_dinode_has_bigtime(const struct xfs_dinode *dip)
* ondisk min and max defined here can be used directly to constrain the incore
* quota expiration timestamps on a Unix system.
*
+ * When bigtime is enabled, we trade two bits of precision to expand the
+ * expiration timeout range to match that of big inode timestamps. The min and
+ * max recorded here are the on-disk limits, not a Unix timestamp.
+ *
* The grace period for each quota type is stored in the root dquot (id = 0)
* and is applied to a non-root dquot when it exceeds the soft or hard limits.
* The length of quota grace periods are unsigned 32-bit quantities measured in
@@ -1300,6 +1306,48 @@ static inline bool xfs_dinode_has_bigtime(const struct xfs_dinode *dip)
*/
#define XFS_DQ_LEGACY_EXPIRY_MAX ((int64_t)U32_MAX)

+/*
+ * Smallest possible ondisk quota expiration value with bigtime timestamps.
+ * This corresponds (after conversion to a Unix timestamp) with the incore
+ * expiration of Jan 1 00:00:04 UTC 1970.
+ */
+#define XFS_DQ_BIGTIME_EXPIRY_MIN (XFS_DQ_LEGACY_EXPIRY_MIN)
+
+/*
+ * Largest supported ondisk quota expiration value with bigtime timestamps.
+ * This corresponds (after conversion to a Unix timestamp) with an incore
+ * expiration of Jul 2 20:20:24 UTC 2486.
+ *
+ * The ondisk field supports values up to -1U, which corresponds to an incore
+ * expiration in 2514. This is beyond the maximum the bigtime inode timestamp,
+ * so we cap the maximum bigtime quota expiration to the max inode timestamp.
+ */
+#define XFS_DQ_BIGTIME_EXPIRY_MAX ((int64_t)4074815106U)
+
+/*
+ * The following conversion factors assist in converting a quota expiration
+ * timestamp between the incore and ondisk formats.
+ */
+#define XFS_DQ_BIGTIME_SHIFT (2)
+#define XFS_DQ_BIGTIME_SLACK ((int64_t)(1ULL << XFS_DQ_BIGTIME_SHIFT) - 1)
+
+/* Convert an incore quota expiration timestamp to an ondisk bigtime value. */
+static inline uint32_t xfs_dq_unix_to_bigtime(time64_t unix_seconds)
+{
+ /*
+ * Round the expiration timestamp up to the nearest bigtime timestamp
+ * that we can store, to give users the most time to fix problems.
+ */
+ return ((uint64_t)unix_seconds + XFS_DQ_BIGTIME_SLACK) >>
+ XFS_DQ_BIGTIME_SHIFT;
+}
+
+/* Convert an ondisk bigtime quota expiration value to an incore timestamp. */
+static inline time64_t xfs_dq_bigtime_to_unix(uint32_t ondisk_seconds)
+{
+ return (time64_t)ondisk_seconds << XFS_DQ_BIGTIME_SHIFT;
+}
+
/*
* Default quota grace periods, ranging from zero (use the compiled defaults)
* to ~136 years. These are applied to a non-root dquot that has exceeded
diff --git a/libxfs/xfs_quota_defs.h b/libxfs/xfs_quota_defs.h
index 9a99910d857e..0f0af4e35032 100644
--- a/libxfs/xfs_quota_defs.h
+++ b/libxfs/xfs_quota_defs.h
@@ -23,7 +23,8 @@ typedef uint8_t xfs_dqtype_t;
#define XFS_DQTYPE_STRINGS \
{ XFS_DQTYPE_USER, "USER" }, \
{ XFS_DQTYPE_PROJ, "PROJ" }, \
- { XFS_DQTYPE_GROUP, "GROUP" }
+ { XFS_DQTYPE_GROUP, "GROUP" }, \
+ { XFS_DQTYPE_BIGTIME, "BIGTIME" }

/*
* flags for q_flags field in the dquot.