Merge v7.1.5linux-rolling-stable

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

1 files changed, 18 insertions, 18 deletions

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);
 }