From: David Teigland <teigland@redhat.com>
Subject: [RHEL5.1 PATCH] GFS2: posix lock fixes
Date: Mon, 11 Jun 2007 14:54:07 -0500
Bugzilla: 243195
Message-Id: <20070611195407.GB19371@redhat.com>
Changelog: [gfs2] posix lock fixes


bz 243195

Some fixes for posix locks in GFS2:
- doing F_SETLK/FUNLK or F_GETLK should return 0 if there are no locks on
  the file (instead of ENOENT)
- F_GETLK should return 0 if there's a conflicting lock
- in F_GETLK, set the owner field in the info struct passed to userspace,
  so a process will detect conflicts with its own locks

upstream: gfs2-2.6-nmw.git or beyond

Index: linux-rhel51-quilt/fs/gfs2/locking/dlm/plock.c
===================================================================
--- linux-rhel51-quilt.orig/fs/gfs2/locking/dlm/plock.c	2007-06-08 09:01:02.000000000 -0500
+++ linux-rhel51-quilt/fs/gfs2/locking/dlm/plock.c	2007-06-11 14:34:10.000000000 -0500
@@ -137,6 +137,9 @@
 
 	rv = op->info.rv;
 
+	if (rv == -ENOENT)
+		rv = 0;
+
 	kfree(op);
 	return rv;
 }
@@ -159,6 +162,7 @@
 	op->info.number		= name->ln_number;
 	op->info.start		= fl->fl_start;
 	op->info.end		= fl->fl_end;
+	op->info.owner          = (__u64)(long) fl->fl_owner;
 
 	send_op(op);
 	wait_event(recv_wq, (op->done != 0));
@@ -170,15 +174,20 @@
 	}
 	spin_unlock(&ops_lock);
 
+	/* info.rv from userspace is 1 for conflict, 0 for no-conflict,
+	   -ENOENT if there are no locks on the file */
+
 	rv = op->info.rv;
 
-	if (rv == 0)
-		fl->fl_type = F_UNLCK;
+	fl->fl_type = F_UNLCK;
+	if (rv == -ENOENT)
+		rv = 0;
 	else if (rv > 0) {
 		fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
 		fl->fl_pid = op->info.pid;
 		fl->fl_start = op->info.start;
 		fl->fl_end = op->info.end;
+		rv = 0;
 	}
 
 	kfree(op);