netfs: zero the tail of a short DIO/unbuffered readgrafted

The buffered read collector zero-fills the tail of a short read that
stops below the inode's i_size (netfs_clear_unread()), so a read that
races an extending write still returns the expected number of bytes.
The non-buffered collector path does no such thing: it just records
how much was transferred.

Add the same zero-fill for the non-buffered case, gated on
NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short
result from it is known to be safe to treat as a hole, as opposed to
NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of
the file and should be reported short as-is. Only CLEAR_TAIL should
zero-fill here; a real EOF must stay a real short read.

No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest,
so this is inert on its own -- a following change teaches cifs to set
it in the one case that needs it.

Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org

1 files changed, 215 insertions, 0 deletions

diff --git a/drivers/hid/hid-roccat-lua.c b/drivers/hid/hid-roccat-lua.c
new file mode 100644
index 000000000..8e35e1a06
--- /dev/null
+++ b/drivers/hid/hid-roccat-lua.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Roccat Lua driver for Linux
+ *
+ * Copyright (c) 2012 Stefan Achatz <erazor_de@users.sourceforge.net>
+ */
+
+/*
+ */
+
+/*
+ * Roccat Lua is a gamer mouse which cpi, button and light settings can be
+ * configured.
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/hid-roccat.h>
+#include "hid-ids.h"
+#include "hid-roccat-common.h"
+#include "hid-roccat-lua.h"
+
+static ssize_t lua_sysfs_read(struct file *fp, struct kobject *kobj,
+		char *buf, loff_t off, size_t count,
+		size_t real_size, uint command)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct lua_device *lua = hid_get_drvdata(dev_get_drvdata(dev));
+	struct usb_device *usb_dev = interface_to_usbdev(to_usb_interface(dev));
+	int retval;
+
+	if (off >= real_size)
+		return 0;
+
+	if (off != 0 || count != real_size)
+		return -EINVAL;
+
+	mutex_lock(&lua->lua_lock);
+	retval = roccat_common2_receive(usb_dev, command, buf, real_size);
+	mutex_unlock(&lua->lua_lock);
+
+	return retval ? retval : real_size;
+}
+
+static ssize_t lua_sysfs_write(struct file *fp, struct kobject *kobj,
+		void const *buf, loff_t off, size_t count,
+		size_t real_size, uint command)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct lua_device *lua = hid_get_drvdata(dev_get_drvdata(dev));
+	struct usb_device *usb_dev = interface_to_usbdev(to_usb_interface(dev));
+	int retval;
+
+	if (off != 0 || count != real_size)
+		return -EINVAL;
+
+	mutex_lock(&lua->lua_lock);
+	retval = roccat_common2_send(usb_dev, command, buf, real_size);
+	mutex_unlock(&lua->lua_lock);
+
+	return retval ? retval : real_size;
+}
+
+#define LUA_SYSFS_W(thingy, THINGY) \
+static ssize_t lua_sysfs_write_ ## thingy(struct file *fp, \
+		struct kobject *kobj, const struct bin_attribute *attr, \
+		char *buf, loff_t off, size_t count) \
+{ \
+	return lua_sysfs_write(fp, kobj, buf, off, count, \
+			LUA_SIZE_ ## THINGY, LUA_COMMAND_ ## THINGY); \
+}
+
+#define LUA_SYSFS_R(thingy, THINGY) \
+static ssize_t lua_sysfs_read_ ## thingy(struct file *fp, \
+		struct kobject *kobj, const struct bin_attribute *attr, \
+		char *buf, loff_t off, size_t count) \
+{ \
+	return lua_sysfs_read(fp, kobj, buf, off, count, \
+			LUA_SIZE_ ## THINGY, LUA_COMMAND_ ## THINGY); \
+}
+
+#define LUA_BIN_ATTRIBUTE_RW(thingy, THINGY) \
+LUA_SYSFS_W(thingy, THINGY) \
+LUA_SYSFS_R(thingy, THINGY) \
+static const struct bin_attribute lua_ ## thingy ## _attr = { \
+	.attr = { .name = #thingy, .mode = 0660 }, \
+	.size = LUA_SIZE_ ## THINGY, \
+	.read = lua_sysfs_read_ ## thingy, \
+	.write = lua_sysfs_write_ ## thingy \
+};
+
+LUA_BIN_ATTRIBUTE_RW(control, CONTROL)
+
+static int lua_create_sysfs_attributes(struct usb_interface *intf)
+{
+	return sysfs_create_bin_file(&intf->dev.kobj, &lua_control_attr);
+}
+
+static void lua_remove_sysfs_attributes(struct usb_interface *intf)
+{
+	sysfs_remove_bin_file(&intf->dev.kobj, &lua_control_attr);
+}
+
+static int lua_init_lua_device_struct(struct usb_device *usb_dev,
+		struct lua_device *lua)
+{
+	mutex_init(&lua->lua_lock);
+
+	return 0;
+}
+
+static int lua_init_specials(struct hid_device *hdev)
+{
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+	struct usb_device *usb_dev = interface_to_usbdev(intf);
+	struct lua_device *lua;
+	int retval;
+
+	lua = kzalloc_obj(*lua);
+	if (!lua) {
+		hid_err(hdev, "can't alloc device descriptor\n");
+		return -ENOMEM;
+	}
+	hid_set_drvdata(hdev, lua);
+
+	retval = lua_init_lua_device_struct(usb_dev, lua);
+	if (retval) {
+		hid_err(hdev, "couldn't init struct lua_device\n");
+		goto exit;
+	}
+
+	retval = lua_create_sysfs_attributes(intf);
+	if (retval) {
+		hid_err(hdev, "cannot create sysfs files\n");
+		goto exit;
+	}
+
+	return 0;
+exit:
+	kfree(lua);
+	return retval;
+}
+
+static void lua_remove_specials(struct hid_device *hdev)
+{
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+	struct lua_device *lua;
+
+	lua_remove_sysfs_attributes(intf);
+
+	lua = hid_get_drvdata(hdev);
+	kfree(lua);
+}
+
+static int lua_probe(struct hid_device *hdev,
+		const struct hid_device_id *id)
+{
+	int retval;
+
+	if (!hid_is_usb(hdev))
+		return -EINVAL;
+
+	retval = hid_parse(hdev);
+	if (retval) {
+		hid_err(hdev, "parse failed\n");
+		goto exit;
+	}
+
+	retval = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (retval) {
+		hid_err(hdev, "hw start failed\n");
+		goto exit;
+	}
+
+	retval = lua_init_specials(hdev);
+	if (retval) {
+		hid_err(hdev, "couldn't install mouse\n");
+		goto exit_stop;
+	}
+
+	return 0;
+
+exit_stop:
+	hid_hw_stop(hdev);
+exit:
+	return retval;
+}
+
+static void lua_remove(struct hid_device *hdev)
+{
+	lua_remove_specials(hdev);
+	hid_hw_stop(hdev);
+}
+
+static const struct hid_device_id lua_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ROCCAT, USB_DEVICE_ID_ROCCAT_LUA) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(hid, lua_devices);
+
+static struct hid_driver lua_driver = {
+		.name = "lua",
+		.id_table = lua_devices,
+		.probe = lua_probe,
+		.remove = lua_remove
+};
+module_hid_driver(lua_driver);
+
+MODULE_AUTHOR("Stefan Achatz");
+MODULE_DESCRIPTION("USB Roccat Lua driver");
+MODULE_LICENSE("GPL v2");