From: Paul Clements <paul.clements@steeleye.com>
Date: Thu, 7 Dec 2006 04:40:53 +0000 (-0800)
Subject: [PATCH] nbd: show nbd client pid in sysfs
X-Git-Tag: v2.6.20-rc1~145^2^2~33
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=6b39bb6548d60b9a18826134b5ccd5c3cef85fe2;p=linux-2.6-omap-h63xx.git

[PATCH] nbd: show nbd client pid in sysfs

Allow nbd to expose the nbd-client daemon's PID in /sys/block/nbd<x>/pid.

This is helpful for tracking connection status of a device and for
determining which nbd devices are currently in use.

Signed-off-by: Paul Clements <paul.clements@steeleye.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 9d1035e8d9d..7bf2cfbd628 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -355,14 +355,30 @@ harderror:
 	return NULL;
 }
 
+static ssize_t pid_show(struct gendisk *disk, char *page)
+{
+	return sprintf(page, "%ld\n",
+		(long) ((struct nbd_device *)disk->private_data)->pid);
+}
+
+static struct disk_attribute pid_attr = {
+	.attr = { .name = "pid", .mode = S_IRUGO },
+	.show = pid_show,
+};
+
 static void nbd_do_it(struct nbd_device *lo)
 {
 	struct request *req;
 
 	BUG_ON(lo->magic != LO_MAGIC);
 
+	lo->pid = current->pid;
+	sysfs_create_file(&lo->disk->kobj, &pid_attr.attr);
+
 	while ((req = nbd_read_stat(lo)) != NULL)
 		nbd_end_request(req);
+
+	sysfs_remove_file(&lo->disk->kobj, &pid_attr.attr);
 	return;
 }
 
diff --git a/include/linux/nbd.h b/include/linux/nbd.h
index d6b6dc09ad9..0f3e6930254 100644
--- a/include/linux/nbd.h
+++ b/include/linux/nbd.h
@@ -64,6 +64,7 @@ struct nbd_device {
 	struct gendisk *disk;
 	int blksize;
 	u64 bytesize;
+	pid_t pid; /* pid of nbd-client, if attached */
 };
 
 #endif