Clarify details in description of file leases.

Minor wording edits.

man2/fcntl.2

@@ -592,9 +592,9 @@ in Linux as part of the GNU C Library (Glibc).
 .B F_SETLEASE
 and
 .B F_GETLEASE
-(Linux 2.4 onwards) are used (respectively) to establish and
-retrieve the current setting of the calling process's lease on
-the file referred to by
+(Linux 2.4 onwards) are used (respectively) to establish a new lease,
+and retrieve the current lease, on the open file description
+referred to by the file descriptor
 .IR fd .
 A file lease provides a mechanism whereby the process holding
 the lease (the "lease holder") is notified (via delivery of a signal)
@@ -602,13 +602,12 @@ when a process (the "lease breaker") tries to
 .BR open (2)
 or
 .BR truncate (2)
-that file.
+the file referred to by that file descriptor.
 .TP
 .B F_SETLEASE
 Set or remove a file lease according to which of the following
 values is specified in the integer
 .IR arg :
-
 .RS
 .TP
 .B F_RDLCK
@@ -624,30 +623,39 @@ is opened read-only.
 Take out a write lease.
 This will cause the caller to be notified when
 the file is opened for reading or writing or is truncated.
-A write lease may be placed on a file only if no other process
-currently has the file open.
+A write lease may be placed on a file only if there are no
+other open file descriptors for the file.
 .TP
 .B F_UNLCK
 Remove our lease from the file.
 .RE
 .P
-A process may hold only one type of lease on a file.
+Leases are associated with an open file description (see
+.BR open (2)).
+This means that duplicate file descriptors (created by, for example,
+.BR fork (2)
+or
+.BR dup (2))
+refer to the same lease, and this lease may be modified
+or released using any of these descriptors.
+Furthermore, the lease is released by either an explicit
+.B F_UNLCK
+operation on any of these duplicate descriptors, or when all
+such descriptors have been closed.
 .P
 Leases may only be taken out on regular files.
 An unprivileged process may only take out a lease on a file whose
-UID matches the file system UID of the process.
+UID (owner) matches the file system UID of the process.
 A process with the
 .B CAP_LEASE
 capability may take out leases on arbitrary files.
 .TP
 .B F_GETLEASE
-Indicates what type of lease we hold on the file
-referred to by
+Indicates what type of lease is associated with the file descriptor
 .I fd
 by returning either
 .BR F_RDLCK ", " F_WRLCK ", or " F_UNLCK ,
-indicating, respectively, that the calling process holds a
-read, a write, or no lease on the file.
+indicating, respectively, a read lease , a write lease, or no lease.
 (The third argument to
 .BR fcntl ()
 is omitted.)
@@ -672,9 +680,10 @@ command specifying
 .I arg
 as
 .BR F_UNLCK .
-If we currently hold a write lease on the file,
+If the lease holder currently holds a write lease on the file,
 and the lease breaker is opening the file for reading,
-then it is sufficient to downgrade the lease to a read lease.
+then it is sufficient for the lease holder to downgrade
+the lease to a read lease.
 This is done by performing an
 .B F_SETLEASE
 command specifying