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Commit f7a99c5b authored by Al Viro's avatar Al Viro
Browse files

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: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent d187663e

fs/dcache.c

+1 −1
Original line number Diff line number Diff line
@@ -2622,7 +2622,7 @@ static int prepend_path(const struct path *path, 
	if (!slash)

		error = prepend(buffer, buflen, "/", 1);

	if (!error)

		error = real_mount(vfsmnt)->mnt_ns ? 1 : 2;

		error = is_mounted(vfsmnt) ? 1 : 2;

	goto out;

}

fs/fs_struct.c

+10 −22
Original line number Diff line number Diff line
@@ -6,18 +6,6 @@ 
#include <linux/fs_struct.h>

#include "internal.h"



static inline void path_get_longterm(struct path *path)

{

	path_get(path);

	mnt_make_longterm(path->mnt);

}



static inline void path_put_longterm(struct path *path)

{

	mnt_make_shortterm(path->mnt);

	path_put(path);

}



/*

 * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.

 * It can block.
@@ -26,7 +14,7 @@ void set_fs_root(struct fs_struct *fs, struct path *path) 
{

	struct path old_root;



	path_get_longterm(path);

	path_get(path);

	spin_lock(&fs->lock);

	write_seqcount_begin(&fs->seq);

	old_root = fs->root;
@@ -34,7 +22,7 @@ void set_fs_root(struct fs_struct *fs, struct path *path) 
	write_seqcount_end(&fs->seq);

	spin_unlock(&fs->lock);

	if (old_root.dentry)

		path_put_longterm(&old_root);

		path_put(&old_root);

}



/*
@@ -45,7 +33,7 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path) 
{

	struct path old_pwd;



	path_get_longterm(path);

	path_get(path);

	spin_lock(&fs->lock);

	write_seqcount_begin(&fs->seq);

	old_pwd = fs->pwd;
@@ -54,7 +42,7 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path) 
	spin_unlock(&fs->lock);



	if (old_pwd.dentry)

		path_put_longterm(&old_pwd);

		path_put(&old_pwd);

}



static inline int replace_path(struct path *p, const struct path *old, const struct path *new)
@@ -84,7 +72,7 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root) 
			write_seqcount_end(&fs->seq);

			while (hits--) {

				count++;

				path_get_longterm(new_root);

				path_get(new_root);

			}

			spin_unlock(&fs->lock);

		}
@@ -92,13 +80,13 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root) 
	} while_each_thread(g, p);

	read_unlock(&tasklist_lock);

	while (count--)

		path_put_longterm(old_root);

		path_put(old_root);

}



void free_fs_struct(struct fs_struct *fs)

{

	path_put_longterm(&fs->root);

	path_put_longterm(&fs->pwd);

	path_put(&fs->root);

	path_put(&fs->pwd);

	kmem_cache_free(fs_cachep, fs);

}
@@ -132,9 +120,9 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old) 


		spin_lock(&old->lock);

		fs->root = old->root;

		path_get_longterm(&fs->root);

		path_get(&fs->root);

		fs->pwd = old->pwd;

		path_get_longterm(&fs->pwd);

		path_get(&fs->pwd);

		spin_unlock(&old->lock);

	}

	return fs;

fs/internal.h

+0 −2
Original line number Diff line number Diff line
@@ -50,8 +50,6 @@ extern int copy_mount_string(const void __user *, char **); 
extern struct vfsmount *lookup_mnt(struct path *);

extern int finish_automount(struct vfsmount *, struct path *);



extern void mnt_make_longterm(struct vfsmount *);

extern void mnt_make_shortterm(struct vfsmount *);

extern int sb_prepare_remount_readonly(struct super_block *);



extern void __init mnt_init(void);

fs/mount.h

+8 −1
Original line number Diff line number Diff line
@@ -22,7 +22,6 @@ struct mount { 
	struct vfsmount mnt;

#ifdef CONFIG_SMP

	struct mnt_pcp __percpu *mnt_pcp;

	atomic_t mnt_longterm;		/* how many of the refs are longterm */

#else

	int mnt_count;

	int mnt_writers;
@@ -49,6 +48,8 @@ struct mount { 
	int mnt_ghosts;

};



#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */



static inline struct mount *real_mount(struct vfsmount *mnt)

{

	return container_of(mnt, struct mount, mnt);
@@ -59,6 +60,12 @@ static inline int mnt_has_parent(struct mount *mnt) 
	return mnt != mnt->mnt_parent;

}



static inline int is_mounted(struct vfsmount *mnt)

{

	/* neither detached nor internal? */

	return !IS_ERR_OR_NULL(real_mount(mnt));

}



extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *, int);



static inline void get_mnt_ns(struct mnt_namespace *ns)

fs/namespace.c

+7 −46
Original line number Diff line number Diff line
@@ -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);

	}

}