From 8d51c2a2ca038bac418326ce11c941775a71f600 Mon Sep 17 00:00:00 2001
From: Alex Hornung <ahornung@gmail.com>
Date: Fri, 19 Nov 2010 14:31:26 +0000
Subject: [PATCH] subr_disk - Keep an open count

---
 sys/kern/subr_disk.c | 18 +++++++++++++++++-
 sys/sys/disk.h       |  2 ++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/sys/kern/subr_disk.c b/sys/kern/subr_disk.c
index 76c141a4a0..f30df6366a 100644
--- a/sys/kern/subr_disk.c
+++ b/sys/kern/subr_disk.c
@@ -140,7 +140,7 @@ static LIST_HEAD(, disk) disklist = LIST_HEAD_INITIALIZER(&disklist);
 static struct lwkt_token disklist_token;
 
 static struct dev_ops disk_ops = {
-	{ "disk", 0, D_DISK | D_MPSAFE },
+	{ "disk", 0, D_DISK | D_MPSAFE | D_TRACKCLOSE },
 	.d_open = diskopen,
 	.d_close = diskclose,
 	.d_read = physread,
@@ -681,6 +681,12 @@ disk_setdisktype(struct disk *disk, const char *type)
 	return udev_dict_set_cstr(disk->d_cdev, "disk-type", __DECONST(char *, type));
 }
 
+int
+disk_getopencount(struct disk *disk)
+{
+	return disk->d_opencount;
+}
+
 static void
 _setdiskinfo(struct disk *disk, struct disk_info *info)
 {
@@ -959,6 +965,11 @@ out:
 	}
 	rel_mplock();
 
+	KKASSERT(dp->d_opencount >= 0);
+	/* If the open was successful, bump open count */
+	if (error == 0)
+		atomic_add_int(&dp->d_opencount, 1);
+
 	return(error);
 }
 
@@ -976,6 +987,11 @@ diskclose(struct dev_close_args *ap)
 	error = 0;
 	dp = dev->si_disk;
 
+	KKASSERT(dp->d_opencount >= 1);
+	/* If this is not the last close, just ignore it */
+	if ((atomic_fetchadd_int(&dp->d_opencount, -1)) > 1)
+		return 0;
+
 	get_mplock();
 	dsclose(dev, ap->a_devtype, dp->d_slice);
 	if (!dsisopen(dp->d_slice)) {
diff --git a/sys/sys/disk.h b/sys/sys/disk.h
index 9477acddab..6a3a6da11d 100644
--- a/sys/sys/disk.h
+++ b/sys/sys/disk.h
@@ -127,6 +127,7 @@ struct disk {
 	struct dev_ops		*d_dev_ops;	/* our device switch */
 	struct dev_ops		*d_raw_ops;	/* the raw device switch */
 	u_int			d_flags;
+	int			d_opencount;	/* The current open count */
 	cdev_t			d_rawdev;	/* backing raw device */
 	cdev_t			d_cdev;		/* special whole-disk part */
 	struct diskslices	*d_slice;
@@ -153,6 +154,7 @@ cdev_t disk_locate (const char *devname);
 void disk_destroy (struct disk *disk);
 void disk_setdiskinfo (struct disk *disk, struct disk_info *info);
 int disk_setdisktype(struct disk *disk, const char *type);
+int disk_getopencount(struct disk *disk);
 void disk_setdiskinfo_sync(struct disk *disk, struct disk_info *info);
 int disk_dumpcheck (cdev_t dev, u_int64_t *count, u_int64_t *blkno, u_int *secsize);
 int disk_dumpconf(cdev_t dev, u_int onoff);
-- 
2.41.0