1 files changed, 38 insertions, 8 deletions

diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index af141fc8cfe6..683a5b9ce22a 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -321,10 +321,19 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
 	if (ino->flags & AUTOFS_INF_PENDING)
 		goto out;
 	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
-		ino->flags |= AUTOFS_INF_EXPIRING;
-		init_completion(&ino->expire_complete);
+		ino->flags |= AUTOFS_INF_NO_RCU;
 		spin_unlock(&sbi->fs_lock);
-		return root;
+		synchronize_rcu();
+		spin_lock(&sbi->fs_lock);
+		if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
+			ino->flags |= AUTOFS_INF_EXPIRING;
+			smp_mb();
+			ino->flags &= ~AUTOFS_INF_NO_RCU;
+			init_completion(&ino->expire_complete);
+			spin_unlock(&sbi->fs_lock);
+			return root;
+		}
+		ino->flags &= ~AUTOFS_INF_NO_RCU;
 	}
 out:
 	spin_unlock(&sbi->fs_lock);
@@ -442,12 +451,29 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
 	dentry = NULL;
 	while ((dentry = get_next_positive_subdir(dentry, root))) {
 		spin_lock(&sbi->fs_lock);
-		expired = should_expire(dentry, mnt, timeout, how);
-		if (expired) {
+		ino = autofs4_dentry_ino(dentry);
+		if (ino->flags & AUTOFS_INF_NO_RCU)
+			expired = NULL;
+		else
+			expired = should_expire(dentry, mnt, timeout, how);
+		if (!expired) {
+			spin_unlock(&sbi->fs_lock);
+			continue;
+		}
+		ino = autofs4_dentry_ino(expired);
+		ino->flags |= AUTOFS_INF_NO_RCU;
+		spin_unlock(&sbi->fs_lock);
+		synchronize_rcu();
+		spin_lock(&sbi->fs_lock);
+		if (should_expire(expired, mnt, timeout, how)) {
 			if (expired != dentry)
 				dput(dentry);
 			goto found;
 		}
+
+		ino->flags &= ~AUTOFS_INF_NO_RCU;
+		if (expired != dentry)
+			dput(expired);
 		spin_unlock(&sbi->fs_lock);
 	}
 	return NULL;
@@ -455,8 +481,9 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
 found:
 	DPRINTK("returning %p %.*s",
 		expired, (int)expired->d_name.len, expired->d_name.name);
-	ino = autofs4_dentry_ino(expired);
 	ino->flags |= AUTOFS_INF_EXPIRING;
+	smp_mb();
+	ino->flags &= ~AUTOFS_INF_NO_RCU;
 	init_completion(&ino->expire_complete);
 	spin_unlock(&sbi->fs_lock);
 	spin_lock(&sbi->lookup_lock);
@@ -476,11 +503,14 @@ int autofs4_expire_wait(struct dentry *dentry, int rcu_walk)
 	int status;
 
 	/* Block on any pending expire */
+	if (!(ino->flags & (AUTOFS_INF_EXPIRING | AUTOFS_INF_NO_RCU)))
+		return 0;
+	if (rcu_walk)
+		return -ECHILD;
+
 	spin_lock(&sbi->fs_lock);
 	if (ino->flags & AUTOFS_INF_EXPIRING) {
 		spin_unlock(&sbi->fs_lock);
-		if (rcu_walk)
-			return -ECHILD;
 
 		DPRINTK("waiting for expire %p name=%.*s",
 			 dentry, dentry->d_name.len, dentry->d_name.name);