Keep track of the mount point associated with a special device

to enable the collection of counts of synchronous and asynchronous
reads and writes for its associated filesystem. The counts are
displayed using `mount -v'.

Ensure that buffers used for paging indicate the vnode from
which they are operating so that counts of paging I/O operations
from the filesystem are collected.

This checkin only adds the setting of the mount point for the
UFS/FFS filesystem, but it would be trivial to add the setting
and clearing of the mount point at filesystem mount/unmount
time for other filesystems too.

Reviewed by: kib

1 files changed, 6 insertions, 0 deletions

diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
index 8871cdf..f38fbcb 100644
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -407,6 +407,8 @@ ffs_mount(struct mount *mp)
 				vn_finished_write(mp);
 				return (error);
 			}
+			if (devvp->v_type == VCHR && devvp->v_rdev != NULL)
+				devvp->v_rdev->si_mountpt = mp;
 			if (fs->fs_snapinum[0] != 0)
 				ffs_snapshot_mount(mp);
 			vn_finished_write(mp);
@@ -1050,6 +1052,8 @@ ffs_mountfs(devvp, mp, td)
 			ffs_flushfiles(mp, FORCECLOSE, td);
 			goto out;
 		}
+		if (devvp->v_type == VCHR && devvp->v_rdev != NULL)
+			devvp->v_rdev->si_mountpt = mp;
 		if (fs->fs_snapinum[0] != 0)
 			ffs_snapshot_mount(mp);
 		fs->fs_fmod = 1;
@@ -1295,6 +1299,8 @@ ffs_unmount(mp, mntflags)
 	g_vfs_close(ump->um_cp);
 	g_topology_unlock();
 	PICKUP_GIANT();
+	if (ump->um_devvp->v_type == VCHR && ump->um_devvp->v_rdev != NULL)
+		ump->um_devvp->v_rdev->si_mountpt = NULL;
 	vrele(ump->um_devvp);
 	dev_rel(ump->um_dev);
 	mtx_destroy(UFS_MTX(ump));