xfs: refactor default quota grace period setting code

Refactor the code that sets the default quota grace period into a helper
function so that we can override the ondisk behavior later.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Collins <allison.henderson@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/libxfs/xfs_format.h

@@ -1209,6 +1209,11 @@ static inline void xfs_dinode_put_rdev(struct xfs_dinode *dip, xfs_dev_t rdev)
  * been reached, and therefore no expiration has been set.  Therefore, the
  * ondisk min and max defined here can be used directly to constrain the incore
  * quota expiration timestamps on a Unix system.
+ *
+ * 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
+ * units of seconds.  A value of zero means to use the default period.
  */
 
 /*
@@ -1223,6 +1228,14 @@ static inline void xfs_dinode_put_rdev(struct xfs_dinode *dip, xfs_dev_t rdev)
  */
 #define XFS_DQ_LEGACY_EXPIRY_MAX	((int64_t)U32_MAX)
 
+/*
+ * 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
+ * either limit.
+ */
+#define XFS_DQ_GRACE_MIN		((int64_t)0)
+#define XFS_DQ_GRACE_MAX		((int64_t)U32_MAX)
+
 /*
  * This is the main portion of the on-disk representation of quota information
  * for a user.  We pad this with some more expansion room to construct the on

fs/xfs/xfs_dquot.c

@@ -110,6 +110,14 @@ xfs_dquot_set_timeout(
 					  qi->qi_expiry_max);
 }
 
+/* Set the length of the default grace period. */
+time64_t
+xfs_dquot_set_grace_period(
+	time64_t		grace)
+{
+	return clamp_t(time64_t, grace, XFS_DQ_GRACE_MIN, XFS_DQ_GRACE_MAX);
+}
+
 /*
  * Determine if this quota counter is over either limit and set the quota
  * timers as appropriate.

fs/xfs/xfs_dquot.h

@@ -238,5 +238,6 @@ int xfs_qm_dqiterate(struct xfs_mount *mp, xfs_dqtype_t type,
 		xfs_qm_dqiterate_fn iter_fn, void *priv);
 
 time64_t xfs_dquot_set_timeout(struct xfs_mount *mp, time64_t timeout);
+time64_t xfs_dquot_set_grace_period(time64_t grace);
 
 #endif /* __XFS_DQUOT_H__ */

fs/xfs/xfs_qm_syscalls.c

@@ -486,8 +486,8 @@ xfs_setqlim_timer(
 {
 	if (qlim) {
 		/* Set the length of the default grace period. */
-		res->timer = timer;
-		qlim->time = timer;
+		res->timer = xfs_dquot_set_grace_period(timer);
+		qlim->time = res->timer;
 	} else {
 		/* Set the grace period expiration on a quota. */
 		res->timer = xfs_dquot_set_timeout(mp, timer);