diff options
author | Al Viro <viro@zeniv.linux.org.uk> | 2012-06-09 00:59:08 -0400 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2012-07-14 16:32:47 +0400 |
commit | f7a99c5b7c8bd3d3f533c8b38274e33f3da9096e (patch) | |
tree | 5c326c0ddd1f40eacbe2fd7c888f26b089389f99 /fs/namespace.c | |
parent | d187663ef24cd3d033f0cbf2867e70b36a3a90b8 (diff) | |
download | lwn-f7a99c5b7c8bd3d3f533c8b38274e33f3da9096e.tar.gz lwn-f7a99c5b7c8bd3d3f533c8b38274e33f3da9096e.zip |
get rid of ->mnt_longterm
it's enough to set ->mnt_ns of internal vfsmounts to something
distinct from all struct mnt_namespace out there; then we can
just use the check for ->mnt_ns != NULL in the fast path of
mntput_no_expire()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namespace.c')
-rw-r--r-- | fs/namespace.c | 53 |
1 files changed, 7 insertions, 46 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 1e4a5fe3d7b7..a524ea4dbd80 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -621,21 +621,6 @@ static void attach_mnt(struct mount *mnt, struct path *path) list_add_tail(&mnt->mnt_child, &real_mount(path->mnt)->mnt_mounts); } -static inline void __mnt_make_longterm(struct mount *mnt) -{ -#ifdef CONFIG_SMP - atomic_inc(&mnt->mnt_longterm); -#endif -} - -/* needs vfsmount lock for write */ -static inline void __mnt_make_shortterm(struct mount *mnt) -{ -#ifdef CONFIG_SMP - atomic_dec(&mnt->mnt_longterm); -#endif -} - /* * vfsmount lock must be held for write */ @@ -649,10 +634,8 @@ static void commit_tree(struct mount *mnt) BUG_ON(parent == mnt); list_add_tail(&head, &mnt->mnt_list); - list_for_each_entry(m, &head, mnt_list) { + list_for_each_entry(m, &head, mnt_list) m->mnt_ns = n; - __mnt_make_longterm(m); - } list_splice(&head, n->list.prev); @@ -804,7 +787,8 @@ static void mntput_no_expire(struct mount *mnt) put_again: #ifdef CONFIG_SMP br_read_lock(&vfsmount_lock); - if (likely(atomic_read(&mnt->mnt_longterm))) { + if (likely(mnt->mnt_ns)) { + /* shouldn't be the last one */ mnt_add_count(mnt, -1); br_read_unlock(&vfsmount_lock); return; @@ -1074,8 +1058,6 @@ void umount_tree(struct mount *mnt, int propagate, struct list_head *kill) list_del_init(&p->mnt_expire); list_del_init(&p->mnt_list); __touch_mnt_namespace(p->mnt_ns); - if (p->mnt_ns) - __mnt_make_shortterm(p); p->mnt_ns = NULL; list_del_init(&p->mnt_child); if (mnt_has_parent(p)) { @@ -2209,23 +2191,6 @@ static struct mnt_namespace *alloc_mnt_ns(void) return new_ns; } -void mnt_make_longterm(struct vfsmount *mnt) -{ - __mnt_make_longterm(real_mount(mnt)); -} - -void mnt_make_shortterm(struct vfsmount *m) -{ -#ifdef CONFIG_SMP - struct mount *mnt = real_mount(m); - if (atomic_add_unless(&mnt->mnt_longterm, -1, 1)) - return; - br_write_lock(&vfsmount_lock); - atomic_dec(&mnt->mnt_longterm); - br_write_unlock(&vfsmount_lock); -#endif -} - /* * Allocate a new namespace structure and populate it with contents * copied from the namespace of the passed in task structure. @@ -2265,18 +2230,13 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, q = new; while (p) { q->mnt_ns = new_ns; - __mnt_make_longterm(q); if (fs) { if (&p->mnt == fs->root.mnt) { fs->root.mnt = mntget(&q->mnt); - __mnt_make_longterm(q); - mnt_make_shortterm(&p->mnt); rootmnt = &p->mnt; } if (&p->mnt == fs->pwd.mnt) { fs->pwd.mnt = mntget(&q->mnt); - __mnt_make_longterm(q); - mnt_make_shortterm(&p->mnt); pwdmnt = &p->mnt; } } @@ -2320,7 +2280,6 @@ static struct mnt_namespace *create_mnt_ns(struct vfsmount *m) if (!IS_ERR(new_ns)) { struct mount *mnt = real_mount(m); mnt->mnt_ns = new_ns; - __mnt_make_longterm(mnt); new_ns->root = mnt; list_add(&new_ns->list, &mnt->mnt_list); } else { @@ -2615,7 +2574,7 @@ struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) * it is a longterm mount, don't release mnt until * we unmount before file sys is unregistered */ - mnt_make_longterm(mnt); + real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL; } return mnt; } @@ -2625,7 +2584,9 @@ void kern_unmount(struct vfsmount *mnt) { /* release long term mount so mount point can be released */ if (!IS_ERR_OR_NULL(mnt)) { - mnt_make_shortterm(mnt); + br_write_lock(&vfsmount_lock); + real_mount(mnt)->mnt_ns = NULL; + br_write_unlock(&vfsmount_lock); mntput(mnt); } } |