Merge v7.1.5linux-rolling-stable

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

5 files changed, 61 insertions, 47 deletions

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 4f9ade82b08a..97d9d227b66d 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -597,19 +597,19 @@ void kernfs_put(struct kernfs_node *kn)
 	 */
 	parent = kernfs_parent(kn);
 
-	WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS,
-		  "kernfs_put: %s/%s: released with incorrect active_ref %d\n",
-		  parent ? rcu_dereference(parent->name) : "",
-		  rcu_dereference(kn->name), atomic_read(&kn->active));
+	if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS) {
+		guard(rcu)();
+		WARN_ONCE(1,
+			  "kernfs_put: %s/%s: released with incorrect active_ref %d\n",
+			  parent ? rcu_dereference(parent->name) : "",
+			  rcu_dereference(kn->name), atomic_read(&kn->active));
+	}
 
 	if (kernfs_type(kn) == KERNFS_LINK)
 		kernfs_put(kn->symlink.target_kn);
 
-	if (kn->iattr && kn->iattr->xattrs) {
-		simple_xattrs_free(kn->iattr->xattrs, NULL);
-		kfree(kn->iattr->xattrs);
-		kn->iattr->xattrs = NULL;
-	}
+	if (kn->iattr)
+		simple_xattrs_free(&root->xa_cache, &kn->iattr->xattrs, NULL);
 
 	spin_lock(&root->kernfs_idr_lock);
 	idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
@@ -624,6 +624,7 @@ void kernfs_put(struct kernfs_node *kn)
 	} else {
 		/* just released the root kn, free @root too */
 		idr_destroy(&root->ino_idr);
+		simple_xattr_cache_cleanup(&root->xa_cache);
 		kfree_rcu(root, rcu);
 	}
 }
@@ -700,6 +701,9 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
 	}
 
 	if (parent) {
+		kernfs_get(parent);
+		rcu_assign_pointer(kn->__parent, parent);
+
 		ret = security_kernfs_init_security(parent, kn);
 		if (ret)
 			goto err_out4;
@@ -708,11 +712,10 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
 	return kn;
 
  err_out4:
+	RCU_INIT_POINTER(kn->__parent, NULL);
+	kernfs_put(parent);
 	if (kn->iattr) {
-		if (kn->iattr->xattrs) {
-			simple_xattrs_free(kn->iattr->xattrs, NULL);
-			kfree(kn->iattr->xattrs);
-		}
+		simple_xattrs_free(&root->xa_cache, &kn->iattr->xattrs, NULL);
 		kmem_cache_free(kernfs_iattrs_cache, kn->iattr);
 	}
  err_out3:
@@ -747,10 +750,6 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
 
 	kn = __kernfs_new_node(kernfs_root(parent), parent,
 			       name, mode, uid, gid, flags);
-	if (kn) {
-		kernfs_get(parent);
-		rcu_assign_pointer(kn->__parent, parent);
-	}
 	return kn;
 }
 
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 1163aa769738..8e0e90c93372 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -40,22 +40,15 @@ struct kernfs_open_node {
 static DEFINE_SPINLOCK(kernfs_notify_lock);
 static struct kernfs_node *kernfs_notify_list = KERNFS_NOTIFY_EOL;
 
+/* Compatibility wrappers - use the common hashed node lock */
 static inline struct mutex *kernfs_open_file_mutex_ptr(struct kernfs_node *kn)
 {
-	int idx = hash_ptr(kn, NR_KERNFS_LOCK_BITS);
-
-	return &kernfs_locks->open_file_mutex[idx];
+	return kernfs_node_lock_ptr(kn);
 }
 
 static inline struct mutex *kernfs_open_file_mutex_lock(struct kernfs_node *kn)
 {
-	struct mutex *lock;
-
-	lock = kernfs_open_file_mutex_ptr(kn);
-
-	mutex_lock(lock);
-
-	return lock;
+	return kernfs_node_lock(kn);
 }
 
 /**
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 38b28aa7cd02..2cb20294aaf5 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -37,6 +37,7 @@ static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, bool alloc)
 	if (!ret)
 		return NULL;
 
+	INIT_LIST_HEAD_RCU(&ret->xattrs);
 	/* assign default attributes */
 	ret->ia_uid = GLOBAL_ROOT_UID;
 	ret->ia_gid = GLOBAL_ROOT_GID;
@@ -144,8 +145,7 @@ ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
 	if (!attrs)
 		return -ENOMEM;
 
-	return simple_xattr_list(d_inode(dentry), READ_ONCE(attrs->xattrs),
-				 buf, size);
+	return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
 }
 
 static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
@@ -297,34 +297,35 @@ int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
 		     void *value, size_t size)
 {
 	struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
-	struct simple_xattrs *xattrs;
+	struct simple_xattr_cache *cache = &kernfs_root(kn)->xa_cache;
 
 	if (!attrs)
 		return -ENODATA;
 
-	xattrs = READ_ONCE(attrs->xattrs);
-	if (!xattrs)
-		return -ENODATA;
-
-	return simple_xattr_get(xattrs, name, value, size);
+	return simple_xattr_get(cache, &attrs->xattrs, name, value, size);
 }
 
 int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
 		     const void *value, size_t size, int flags)
 {
 	struct simple_xattr *old_xattr;
-	struct simple_xattrs *xattrs;
 	struct kernfs_iattrs *attrs;
+	struct simple_xattr_cache *cache = &kernfs_root(kn)->xa_cache;
 
 	attrs = kernfs_iattrs(kn);
 	if (!attrs)
 		return -ENOMEM;
 
-	xattrs = simple_xattrs_lazy_alloc(&attrs->xattrs, value, flags);
-	if (IS_ERR_OR_NULL(xattrs))
-		return PTR_ERR(xattrs);
+	/*
+	 * Protect xattr modifications with the hashed per-node mutex.
+	 * Multiple superblocks (with different namespaces) can share the same
+	 * kernfs_node, so inode locking alone is insufficient. The hashed mutex
+	 * ensures serialization of concurrent xattr operations on the same node,
+	 * including the lazy allocation of the xattrs structure itself.
+	 */
+	CLASS(kernfs_node_lock, lock)(kn);
 
-	old_xattr = simple_xattr_set(xattrs, name, value, size, flags);
+	old_xattr = simple_xattr_set(cache, &attrs->xattrs, name, value, size, flags);
 	if (IS_ERR(old_xattr))
 		return PTR_ERR(old_xattr);
 
@@ -362,7 +363,6 @@ static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
 {
 	const char *full_name = xattr_full_name(handler, suffix);
 	struct kernfs_node *kn = inode->i_private;
-	struct simple_xattrs *xattrs;
 	struct kernfs_iattrs *attrs;
 
 	if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR))
@@ -372,11 +372,11 @@ static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
 	if (!attrs)
 		return -ENOMEM;
 
-	xattrs = simple_xattrs_lazy_alloc(&attrs->xattrs, value, flags);
-	if (IS_ERR_OR_NULL(xattrs))
-		return PTR_ERR(xattrs);
+	/* See comment in kernfs_xattr_set() about locking. */
+	CLASS(kernfs_node_lock, lock)(kn);
 
-	return simple_xattr_set_limited(xattrs, &attrs->xattr_limits,
+	return simple_xattr_set_limited(&kernfs_root(kn)->xa_cache,
+					&attrs->xattrs, &attrs->xattr_limits,
 					full_name, value, size, flags);
 }
 
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 8d8912f50b05..aa784b540b36 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -26,7 +26,7 @@ struct kernfs_iattrs {
 	struct timespec64	ia_mtime;
 	struct timespec64	ia_ctime;
 
-	struct simple_xattrs	*xattrs;
+	struct list_head	xattrs;
 	struct simple_xattr_limits xattr_limits;
 };
 
@@ -54,6 +54,8 @@ struct kernfs_root {
 	rwlock_t		kernfs_rename_lock;
 
 	struct rcu_head		rcu;
+
+	struct simple_xattr_cache xa_cache;
 };
 
 /* +1 to avoid triggering overflow warning when negating it */
@@ -211,4 +213,24 @@ extern const struct inode_operations kernfs_symlink_iops;
  * kernfs locks
  */
 extern struct kernfs_global_locks *kernfs_locks;
+
+/* Hashed mutex helpers - protect per-node data structures */
+static inline struct mutex *kernfs_node_lock_ptr(struct kernfs_node *kn)
+{
+	int idx = hash_ptr(kn, NR_KERNFS_LOCK_BITS);
+
+	return &kernfs_locks->node_mutex[idx];
+}
+
+static inline struct mutex *kernfs_node_lock(struct kernfs_node *kn)
+{
+	struct mutex *lock = kernfs_node_lock_ptr(kn);
+
+	mutex_lock(lock);
+	return lock;
+}
+
+DEFINE_CLASS(kernfs_node_lock, struct mutex *,
+	     mutex_unlock(_T), kernfs_node_lock(kn), struct kernfs_node *kn)
+
 #endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 6e3217b6e481..f183a96778b9 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -446,7 +446,7 @@ static void __init kernfs_mutex_init(void)
 	int count;
 
 	for (count = 0; count < NR_KERNFS_LOCKS; count++)
-		mutex_init(&kernfs_locks->open_file_mutex[count]);
+		mutex_init(&kernfs_locks->node_mutex[count]);
 }
 
 static void __init kernfs_lock_init(void)