vboxsf: Add vboxsf_[create|release]_sf_handle() helpers

Factor out the code to create / release a struct vboxsf_handle into
2 new helper functions.

This is a preparation patch for adding atomic_open support.

Fixes: 0fd1695766 ("fs: Add VirtualBox guest shared folder (vboxsf) support")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

fs/vboxsf/file.c

@@ -20,18 +20,40 @@ struct vboxsf_handle {
 	struct list_head head;
 };
 
-static int vboxsf_file_open(struct inode *inode, struct file *file)
+struct vboxsf_handle *vboxsf_create_sf_handle(struct inode *inode,
+					      u64 handle, u32 access_flags)
 {
 	struct vboxsf_inode *sf_i = VBOXSF_I(inode);
+	struct vboxsf_handle *sf_handle;
+
+	sf_handle = kmalloc(sizeof(*sf_handle), GFP_KERNEL);
+	if (!sf_handle)
+		return ERR_PTR(-ENOMEM);
+
+	/* the host may have given us different attr then requested */
+	sf_i->force_restat = 1;
+
+	/* init our handle struct and add it to the inode's handles list */
+	sf_handle->handle = handle;
+	sf_handle->root = VBOXSF_SBI(inode->i_sb)->root;
+	sf_handle->access_flags = access_flags;
+	kref_init(&sf_handle->refcount);
+
+	mutex_lock(&sf_i->handle_list_mutex);
+	list_add(&sf_handle->head, &sf_i->handle_list);
+	mutex_unlock(&sf_i->handle_list_mutex);
+
+	return sf_handle;
+}
+
+static int vboxsf_file_open(struct inode *inode, struct file *file)
+{
+	struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
 	struct shfl_createparms params = {};
 	struct vboxsf_handle *sf_handle;
 	u32 access_flags = 0;
 	int err;
 
-	sf_handle = kmalloc(sizeof(*sf_handle), GFP_KERNEL);
-	if (!sf_handle)
-		return -ENOMEM;
-
 	/*
 	 * We check the value of params.handle afterwards to find out if
 	 * the call succeeded or failed, as the API does not seem to cleanly
@@ -83,24 +105,15 @@ static int vboxsf_file_open(struct inode *inode, struct file *file)
 	err = vboxsf_create_at_dentry(file_dentry(file), &params);
 	if (err == 0 && params.handle == SHFL_HANDLE_NIL)
 		err = (params.result == SHFL_FILE_EXISTS) ? -EEXIST : -ENOENT;
-	if (err) {
-		kfree(sf_handle);
+	if (err)
 		return err;
+
+	sf_handle = vboxsf_create_sf_handle(inode, params.handle, access_flags);
+	if (IS_ERR(sf_handle)) {
+		vboxsf_close(sbi->root, params.handle);
+		return PTR_ERR(sf_handle);
 	}
 
-	/* the host may have given us different attr then requested */
-	sf_i->force_restat = 1;
-
-	/* init our handle struct and add it to the inode's handles list */
-	sf_handle->handle = params.handle;
-	sf_handle->root = VBOXSF_SBI(inode->i_sb)->root;
-	sf_handle->access_flags = access_flags;
-	kref_init(&sf_handle->refcount);
-
-	mutex_lock(&sf_i->handle_list_mutex);
-	list_add(&sf_handle->head, &sf_i->handle_list);
-	mutex_unlock(&sf_i->handle_list_mutex);
-
 	file->private_data = sf_handle;
 	return 0;
 }
@@ -114,22 +127,26 @@ static void vboxsf_handle_release(struct kref *refcount)
 	kfree(sf_handle);
 }
 
-static int vboxsf_file_release(struct inode *inode, struct file *file)
+void vboxsf_release_sf_handle(struct inode *inode, struct vboxsf_handle *sf_handle)
 {
 	struct vboxsf_inode *sf_i = VBOXSF_I(inode);
-	struct vboxsf_handle *sf_handle = file->private_data;
-
-	/*
-	 * When a file is closed on our (the guest) side, we want any subsequent
-	 * accesses done on the host side to see all changes done from our side.
-	 */
-	filemap_write_and_wait(inode->i_mapping);
 
 	mutex_lock(&sf_i->handle_list_mutex);
 	list_del(&sf_handle->head);
 	mutex_unlock(&sf_i->handle_list_mutex);
 
 	kref_put(&sf_handle->refcount, vboxsf_handle_release);
+}
+
+static int vboxsf_file_release(struct inode *inode, struct file *file)
+{
+	/*
+	 * When a file is closed on our (the guest) side, we want any subsequent
+	 * accesses done on the host side to see all changes done from our side.
+	 */
+	filemap_write_and_wait(inode->i_mapping);
+
+	vboxsf_release_sf_handle(inode, file->private_data);
 	return 0;
 }
 

fs/vboxsf/vfsmod.h

@@ -18,6 +18,8 @@
 #define VBOXSF_SBI(sb)	((struct vboxsf_sbi *)(sb)->s_fs_info)
 #define VBOXSF_I(i)	container_of(i, struct vboxsf_inode, vfs_inode)
 
+struct vboxsf_handle;
+
 struct vboxsf_options {
 	unsigned long ttl;
 	kuid_t uid;
@@ -80,6 +82,11 @@ extern const struct file_operations vboxsf_reg_fops;
 extern const struct address_space_operations vboxsf_reg_aops;
 extern const struct dentry_operations vboxsf_dentry_ops;
 
+/* from file.c */
+struct vboxsf_handle *vboxsf_create_sf_handle(struct inode *inode,
+					      u64 handle, u32 access_flags);
+void vboxsf_release_sf_handle(struct inode *inode, struct vboxsf_handle *sf_handle);
+
 /* from utils.c */
 struct inode *vboxsf_new_inode(struct super_block *sb);
 int vboxsf_init_inode(struct vboxsf_sbi *sbi, struct inode *inode,