From: Miklos Szeredi <mszeredi@suse.cz>
Date: Mon, 21 Nov 2011 11:11:30 +0000 (+0100)
Subject: vfs: keep list of mounts for each superblock
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=39f7c4db1d2d9e2e2a90abdf34811783089d217d;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

vfs: keep list of mounts for each superblock

Keep track of vfsmounts belonging to a superblock.  List is protected
by vfsmount_lock.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/fs/mount.h b/fs/mount.h
index 0921b51e27e2..4ef36d93e5a2 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -29,6 +29,7 @@ struct mount {
 #endif
 	struct list_head mnt_mounts;	/* list of children, anchored here */
 	struct list_head mnt_child;	/* and going through their mnt_child */
+	struct list_head mnt_instance;	/* mount instance on sb->s_mounts */
 	const char *mnt_devname;	/* Name of device e.g. /dev/dsk/hda1 */
 	struct list_head mnt_list;
 	struct list_head mnt_expire;	/* link in fs-specific expiry list */
diff --git a/fs/namespace.c b/fs/namespace.c
index db65e2e4921f..145217b088d1 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -671,6 +671,9 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
 	mnt->mnt.mnt_sb = root->d_sb;
 	mnt->mnt_mountpoint = mnt->mnt.mnt_root;
 	mnt->mnt_parent = mnt;
+	br_write_lock(vfsmount_lock);
+	list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts);
+	br_write_unlock(vfsmount_lock);
 	return &mnt->mnt;
 }
 EXPORT_SYMBOL_GPL(vfs_kern_mount);
@@ -699,6 +702,9 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
 		mnt->mnt.mnt_root = dget(root);
 		mnt->mnt_mountpoint = mnt->mnt.mnt_root;
 		mnt->mnt_parent = mnt;
+		br_write_lock(vfsmount_lock);
+		list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
+		br_write_unlock(vfsmount_lock);
 
 		if (flag & CL_SLAVE) {
 			list_add(&mnt->mnt_slave, &old->mnt_slave_list);
@@ -781,6 +787,7 @@ put_again:
 		acct_auto_close_mnt(&mnt->mnt);
 		goto put_again;
 	}
+	list_del(&mnt->mnt_instance);
 	br_write_unlock(vfsmount_lock);
 	mntfree(mnt);
 }
diff --git a/fs/super.c b/fs/super.c
index 0413f51a9f0f..993ca8f128d6 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -142,6 +142,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
 		INIT_LIST_HEAD(&s->s_dentry_lru);
 		INIT_LIST_HEAD(&s->s_inode_lru);
 		spin_lock_init(&s->s_inode_lru_lock);
+		INIT_LIST_HEAD(&s->s_mounts);
 		init_rwsem(&s->s_umount);
 		mutex_init(&s->s_lock);
 		lockdep_set_class(&s->s_umount, &type->s_umount_key);
@@ -200,6 +201,7 @@ static inline void destroy_super(struct super_block *s)
 	free_percpu(s->s_files);
 #endif
 	security_sb_free(s);
+	WARN_ON(!list_empty(&s->s_mounts));
 	kfree(s->s_subtype);
 	kfree(s->s_options);
 	kfree(s);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index cc1021fd19ef..03385acd71e8 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1428,6 +1428,7 @@ struct super_block {
 #else
 	struct list_head	s_files;
 #endif
+	struct list_head	s_mounts;	/* list of mounts; _not_ for fs use */
 	/* s_dentry_lru, s_nr_dentry_unused protected by dcache.c lru locks */
 	struct list_head	s_dentry_lru;	/* unused dentry lru */
 	int			s_nr_dentry_unused;	/* # of dentry on lru */