Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull misc vfs updates from Al Viro:
 "Assorted patches from previous cycle(s)..."

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fix hostfs_open() use of ->f_path.dentry
  Make sure that make_create_in_sticky() never sees uninitialized value of dir_mode
  fs: Kill DCACHE_DONTCACHE dentry even if DCACHE_REFERENCED is set
  fs: Handle I_DONTCACHE in iput_final() instead of generic_drop_inode()
  fs/namespace.c: WARN if mnt_count has become negative

fs/dcache.c

@@ -793,10 +793,17 @@ static inline bool fast_dput(struct dentry *dentry)
 	 * a reference to the dentry and change that, but
 	 * our work is done - we can leave the dentry
 	 * around with a zero refcount.
+	 *
+	 * Nevertheless, there are two cases that we should kill
+	 * the dentry anyway.
+	 * 1. free disconnected dentries as soon as their refcount
+	 *    reached zero.
+	 * 2. free dentries if they should not be cached.
 	 */
 	smp_rmb();
 	d_flags = READ_ONCE(dentry->d_flags);
-	d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | DCACHE_DISCONNECTED;
+	d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST |
+			DCACHE_DISCONNECTED | DCACHE_DONTCACHE;
 
 	/* Nothing to do? Dropping the reference was all we needed? */
 	if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry))

fs/hostfs/hostfs_kern.c

@@ -315,7 +315,7 @@ static int hostfs_open(struct inode *ino, struct file *file)
 	if (mode & FMODE_WRITE)
 		r = w = 1;
 
-	name = dentry_name(file->f_path.dentry);
+	name = dentry_name(d_real(file->f_path.dentry, file->f_inode));
 	if (name == NULL)
 		return -ENOMEM;
 

fs/inode.c

@@ -1624,7 +1624,9 @@ static void iput_final(struct inode *inode)
 	else
 		drop = generic_drop_inode(inode);
 
-	if (!drop && (sb->s_flags & SB_ACTIVE)) {
+	if (!drop &&
+	    !(inode->i_state & I_DONTCACHE) &&
+	    (sb->s_flags & SB_ACTIVE)) {
 		inode_add_lru(inode);
 		spin_unlock(&inode->i_lock);
 		return;

fs/namei.c

@@ -2114,8 +2114,10 @@ static int link_path_walk(const char *name, struct nameidata *nd)
 		return PTR_ERR(name);
 	while (*name=='/')
 		name++;
-	if (!*name)
+	if (!*name) {
+		nd->dir_mode = 0; // short-circuit the 'hardening' idiocy
 		return 0;
+	}
 
 	/* At this point we know we have a real path component. */
 	for(;;) {

fs/namespace.c

@@ -156,10 +156,10 @@ static inline void mnt_add_count(struct mount *mnt, int n)
 /*
  * vfsmount lock must be held for write
  */
-unsigned int mnt_get_count(struct mount *mnt)
+int mnt_get_count(struct mount *mnt)
 {
 #ifdef CONFIG_SMP
-	unsigned int count = 0;
+	int count = 0;
 	int cpu;
 
 	for_each_possible_cpu(cpu) {
@@ -1139,6 +1139,7 @@ static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput);
 static void mntput_no_expire(struct mount *mnt)
 {
 	LIST_HEAD(list);
+	int count;
 
 	rcu_read_lock();
 	if (likely(READ_ONCE(mnt->mnt_ns))) {
@@ -1162,7 +1163,9 @@ static void mntput_no_expire(struct mount *mnt)
 	 */
 	smp_mb();
 	mnt_add_count(mnt, -1);
-	if (mnt_get_count(mnt)) {
+	count = mnt_get_count(mnt);
+	if (count != 0) {
+		WARN_ON(count < 0);
 		rcu_read_unlock();
 		unlock_mount_hash();
 		return;

fs/pnode.h

@@ -44,7 +44,7 @@ int propagate_mount_busy(struct mount *, int);
 void propagate_mount_unlock(struct mount *);
 void mnt_release_group_id(struct mount *);
 int get_dominating_id(struct mount *mnt, const struct path *root);
-unsigned int mnt_get_count(struct mount *mnt);
+int mnt_get_count(struct mount *mnt);
 void mnt_set_mountpoint(struct mount *, struct mountpoint *,
 			struct mount *);
 void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp,

include/linux/fs.h

@@ -2876,8 +2876,7 @@ extern int inode_needs_sync(struct inode *inode);
 extern int generic_delete_inode(struct inode *inode);
 static inline int generic_drop_inode(struct inode *inode)
 {
-	return !inode->i_nlink || inode_unhashed(inode) ||
-		(inode->i_state & I_DONTCACHE);
+	return !inode->i_nlink || inode_unhashed(inode);
 }
 extern void d_mark_dontcache(struct inode *inode);