Move a locking function that was spread throughout disk device drivers into

the disk structure.

The locking was mostly used in disk device drivers to prevent multiple
disklabel operations from going on simultaneously against the device.

Added disk_construct(), a constructor for the disk structure, that
initializes the lock structure in disk. It is called by default in
disk_attach() if it hasn't been called yet.

Added disk_lock and disk_unlock

2 files changed, 48 insertions, 2 deletions

diff --git a/sys/kern/subr_disk.c b/sys/kern/subr_disk.c
index 5d8f8fda806..a166a72c4a1 100644
--- a/sys/kern/subr_disk.c
+++ b/sys/kern/subr_disk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_disk.c,v 1.17 1999/11/17 04:31:22 d Exp $	*/
+/*	$OpenBSD: subr_disk.c,v 1.18 2000/04/09 19:26:35 csapuntz Exp $	*/
 /*	$NetBSD: subr_disk.c,v 1.17 1996/03/16 23:17:08 christos Exp $	*/
 
 /*
@@ -53,9 +53,11 @@
 #include <sys/time.h>
 #include <sys/disklabel.h>
 #include <sys/conf.h>
+#include <sys/lock.h>
 #include <sys/disk.h>
 #include <sys/dkio.h>
 #include <sys/dkstat.h>		/* XXX */
+#include <sys/proc.h>
 
 #include <dev/rndvar.h>
 
@@ -266,6 +268,19 @@ disk_find(name)
 	return (NULL);
 }
 
+int
+disk_construct(diskp, lockname)
+	struct disk *diskp;
+	char *lockname;
+{
+	lockinit(&diskp->dk_lock, PRIBIO | PCATCH, lockname,
+		 0, LK_CANRECURSE);
+	
+	diskp->dk_flags |= DKF_CONSTRUCTED;
+	    
+	return (0);
+}
+
 /*
  * Attach a disk.
  */
@@ -275,6 +290,9 @@ disk_attach(diskp)
 {
 	int s;
 
+	if (!diskp->dk_flags & DKF_CONSTRUCTED)
+		disk_construct(diskp, diskp->dk_name);
+
 	/*
 	 * Allocate and initialize the disklabel structures.  Note that
 	 * it's not safe to sleep here, since we're probably going to be
@@ -378,6 +396,26 @@ disk_unbusy(diskp, bcount)
 	add_disk_randomness(bcount ^ diff_time.tv_usec);
 }
 
+
+int
+disk_lock(dk)
+	struct disk *dk;
+{
+	int error;
+
+	error = lockmgr(&dk->dk_lock, LK_EXCLUSIVE, 0, curproc);
+
+	return (error);
+}
+
+void
+disk_unlock(dk)
+	struct disk *dk;
+{
+	lockmgr(&dk->dk_lock, LK_RELEASE, 0, curproc);
+}
+
+
 /*
  * Reset the metrics counters on the given disk.  Note that we cannot
  * reset the busy counter, as it may case a panic in disk_unbusy().
diff --git a/sys/sys/disk.h b/sys/sys/disk.h
index 1fc3da62527..3802fc6243d 100644
--- a/sys/sys/disk.h
+++ b/sys/sys/disk.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: disk.h,v 1.4 1996/05/02 13:13:21 deraadt Exp $	*/
+/*	$OpenBSD: disk.h,v 1.5 2000/04/09 19:26:35 csapuntz Exp $	*/
 /*	$NetBSD: disk.h,v 1.11 1996/04/28 20:22:50 thorpej Exp $	*/
 
 /*
@@ -54,6 +54,7 @@
 
 #include <sys/time.h>
 #include <sys/queue.h>
+#include <sys/lock.h>
 
 struct buf;
 struct disklabel;
@@ -61,7 +62,10 @@ struct cpu_disklabel;
 
 struct disk {
 	TAILQ_ENTRY(disk) dk_link;	/* link in global disklist */
+	struct lock     dk_lock;        /* disk lock */
 	char		*dk_name;	/* disk name */
+	int             dk_flags;       /* disk flags */
+#define DKF_CONSTRUCTED  0x0001
 	int		dk_bopenmask;	/* block devices open */
 	int		dk_copenmask;	/* character devices open */
 	int		dk_openmask;	/* composite (bopen|copen) */
@@ -138,6 +142,7 @@ TAILQ_HEAD(disklist_head, disk);	/* the disklist is a TAILQ */
 extern	int disk_count;			/* number of disks in global disklist */
 
 void	disk_init __P((void));
+int     disk_construct __P((struct disk *, char *));
 void	disk_attach __P((struct disk *));
 void	disk_detach __P((struct disk *));
 void	disk_busy __P((struct disk *));
@@ -145,6 +150,9 @@ void	disk_unbusy __P((struct disk *, long));
 void	disk_resetstat __P((struct disk *));
 struct	disk *disk_find __P((char *));
 
+int     disk_lock __P((struct disk *));
+void    disk_unlock __P((struct disk *));
+
 struct device;
 void	dk_establish __P((struct disk *, struct device *));
 #endif