[src/trunk]: src/sys/kern No need to keep a not yet visible mount busy. Move...

[hannken <hannken%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/72f10463e0b3
branches:  trunk
changeset: 823257:72f10463e0b3
user:      hannken <hannken%NetBSD.org@localhost>
date:      Mon Apr 17 08:32:55 2017 +0000

description:
No need to keep a not yet visible mount busy.  Move vfs_busy()
from vfs_mountalloc() to vfs_rootmountalloc().

XXX: Do we really need to vfs_busy() for vfs_mountroot?

diffstat:

 sys/kern/vfs_mount.c |  13 +++++--------
 1 files changed, 5 insertions(+), 8 deletions(-)

diffs (76 lines):

diff -r 8d13ce8d21cc -r 72f10463e0b3 sys/kern/vfs_mount.c
--- a/sys/kern/vfs_mount.c      Mon Apr 17 08:32:00 2017 +0000
+++ b/sys/kern/vfs_mount.c      Mon Apr 17 08:32:55 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_mount.c,v 1.56 2017/04/17 08:32:01 hannken Exp $   */
+/*     $NetBSD: vfs_mount.c,v 1.57 2017/04/17 08:32:55 hannken Exp $   */
 
 /*-
  * Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.56 2017/04/17 08:32:01 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.57 2017/04/17 08:32:55 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -148,7 +148,6 @@
 vfs_mountalloc(struct vfsops *vfsops, vnode_t *vp)
 {
        struct mount *mp;
-       int error __diagused;
 
        mp = kmem_zalloc(sizeof(*mp), KM_SLEEP);
        if (mp == NULL)
@@ -160,8 +159,6 @@
        mutex_init(&mp->mnt_unmounting, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&mp->mnt_renamelock, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&mp->mnt_updating, MUTEX_DEFAULT, IPL_NONE);
-       error = vfs_busy(mp);
-       KASSERT(error == 0);
        mp->mnt_vnodecovered = vp;
        mount_initspecific(mp);
 
@@ -184,6 +181,7 @@
 {
        struct vfsops *vfsp = NULL;
        struct mount *mp;
+       int error __diagused;
 
        mutex_enter(&vfs_list_lock);
        LIST_FOREACH(vfsp, &vfs_list, vfs_list)
@@ -199,6 +197,8 @@
 
        if ((mp = vfs_mountalloc(vfsp, NULL)) == NULL)
                return ENOMEM;
+       error = vfs_busy(mp);
+       KASSERT(error == 0);
        mp->mnt_flag = MNT_RDONLY;
        (void)strlcpy(mp->mnt_stat.f_fstypename, vfsp->vfs_name,
            sizeof(mp->mnt_stat.f_fstypename));
@@ -721,7 +721,6 @@
        }
 
        if ((error = fstrans_mount(mp)) != 0) {
-               vfs_unbusy(mp);
                vfs_rele(mp);
                return error;
        }
@@ -789,7 +788,6 @@
 
        /* Hold an additional reference to the mount across VFS_START(). */
        vfs_ref(mp);
-       vfs_unbusy(mp);
        (void) VFS_STATVFS(mp, &mp->mnt_stat);
        error = VFS_START(mp, 0);
        if (error) {
@@ -810,7 +808,6 @@
        vp->v_mountedhere = NULL;
        mutex_exit(&mp->mnt_updating);
        fstrans_unmount(mp);
-       vfs_unbusy(mp);
        vfs_rele(mp);
 
        return error;