Expand this man page to provide some details on the structure

of the quota data files and how they are maintained.

1 files changed, 83 insertions, 1 deletions

diff --git a/share/man/man5/quota.user.5 b/share/man/man5/quota.user.5
index 6d713bb..6523d51 100644
--- a/share/man/man5/quota.user.5
+++ b/share/man/man5/quota.user.5
@@ -23,7 +23,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 22, 2001
+.Dd February 3, 2007
 .Dt QUOTA.USER 5
 .Os
 .Sh NAME
@@ -39,8 +39,90 @@ These files are created by
 .Xr quotacheck 8 ,
 and should be edited with
 .Xr edquota 8 .
+It is possible to specify a different location and file name with the
+.Dq Li userquota
+and
+.Dq Li groupquota
+options in the
+.Xr fstab 5 
+file.
+.Pp
+.Pp
+The data files contain the following information:
+.Pp
+.Bl -bullet -indent offset -compact
+.It
+Current block usage
+.It
+Current number of files
+.It
+Soft block limit
+.It
+Soft file limit
+.It
+Hard block limit
+.It
+Hard file limit
+.It
+Block grace time remaining if over the soft limit
+.It
+File grace time remaining if over the soft limit
+.El
+.Pp
+.Pp
+See
+.Xr edquota 8
+for an explanation on the various limits and grace periods.
+.Pp
+During normal quota operations the 
+.Xr quotactl 2
+interface is used to query or set quota information and the kernel 
+will maintain the data files as needed.
+If quotas are disabled on
+a file system, but marked as having quotas enabled in
+.Xr fstab 5 ,
+then the quota data files will be used directly.
+.Pp
+The data files are stored as an array of
+.Dq Li struct dqblk
+structures, as defined in
+.In ufs/ufs/quota.h ,
+and indexed by UID or GID.
+The data files will be written as a sparse file if possible.
+Data is only maintained for ids that have either non-zero usage or
+non-zero quota limits.
+If an attempt is made to access data for an id that would exist past the
+end of the current data file, a quota structure with all values set
+to zero will be created, and the data file extended as needed.
+The
+.Xr quotacheck 8
+utility will truncate the data files to the minimum size needed
+to store the highest id with either non-zero file usage or
+non-zero quota limits.
+.Pp
+The data record for id 0 has special meaning.  If the
+.Dq Dv dqb_btime
+or
+.Dq Dv dbq_itime
+fields are non-zero, they are used to indicate the grace period on
+that file system for users who have exceeded their soft limit.
+These times can be set by 
+.Xr edquota 8 
+with the
+.Fl t
+flag.
+If no explicit grace period has been set with
+.Xr edquota 8 ,
+then the default value of 7 days will be used.
+The default values are defined by
+.Dv MAX_DQ_TIME
+and
+.Dv MAX_IQ_TIME
+in
+.In ufs/ufs/quota.h .
 .Sh SEE ALSO
 .Xr quota 1 ,
+.Xr quotactl 2 ,
 .Xr fstab 5 ,
 .Xr edquota 8 ,
 .Xr quotacheck 8 ,