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, 218 insertions, 0 deletions

diff --git a/drivers/extcon/extcon-qcom-spmi-misc.c b/drivers/extcon/extcon-qcom-spmi-misc.c
new file mode 100644
index 000000000..3c522c9c9
--- /dev/null
+++ b/drivers/extcon/extcon-qcom-spmi-misc.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * extcon-qcom-spmi-misc.c - Qualcomm USB extcon driver to support USB ID
+ *			and VBUS detection based on extcon-usb-gpio.c.
+ *
+ * Copyright (C) 2016 Linaro, Ltd.
+ * Stephen Boyd <stephen.boyd@linaro.org>
+ */
+
+#include <linux/devm-helpers.h>
+#include <linux/extcon-provider.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+#define USB_ID_DEBOUNCE_MS	5	/* ms */
+
+struct qcom_usb_extcon_info {
+	struct extcon_dev *edev;
+	int id_irq;
+	int vbus_irq;
+	struct delayed_work wq_detcable;
+	unsigned long debounce_jiffies;
+};
+
+static const unsigned int qcom_usb_extcon_cable[] = {
+	EXTCON_USB,
+	EXTCON_USB_HOST,
+	EXTCON_NONE,
+};
+
+static void qcom_usb_extcon_detect_cable(struct work_struct *work)
+{
+	bool state = false;
+	int ret;
+	union extcon_property_value val;
+	struct qcom_usb_extcon_info *info = container_of(to_delayed_work(work),
+						    struct qcom_usb_extcon_info,
+						    wq_detcable);
+
+	if (info->id_irq > 0) {
+		/* check ID and update cable state */
+		ret = irq_get_irqchip_state(info->id_irq,
+				IRQCHIP_STATE_LINE_LEVEL, &state);
+		if (ret)
+			return;
+
+		if (!state) {
+			val.intval = true;
+			extcon_set_property(info->edev, EXTCON_USB_HOST,
+						EXTCON_PROP_USB_SS, val);
+		}
+		extcon_set_state_sync(info->edev, EXTCON_USB_HOST, !state);
+	}
+
+	if (info->vbus_irq > 0) {
+		/* check VBUS and update cable state */
+		ret = irq_get_irqchip_state(info->vbus_irq,
+				IRQCHIP_STATE_LINE_LEVEL, &state);
+		if (ret)
+			return;
+
+		if (state) {
+			val.intval = true;
+			extcon_set_property(info->edev, EXTCON_USB,
+						EXTCON_PROP_USB_SS, val);
+		}
+		extcon_set_state_sync(info->edev, EXTCON_USB, state);
+	}
+}
+
+static irqreturn_t qcom_usb_irq_handler(int irq, void *dev_id)
+{
+	struct qcom_usb_extcon_info *info = dev_id;
+
+	queue_delayed_work(system_power_efficient_wq, &info->wq_detcable,
+			   info->debounce_jiffies);
+
+	return IRQ_HANDLED;
+}
+
+static int qcom_usb_extcon_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct qcom_usb_extcon_info *info;
+	int ret;
+
+	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->edev = devm_extcon_dev_allocate(dev, qcom_usb_extcon_cable);
+	if (IS_ERR(info->edev)) {
+		dev_err(dev, "failed to allocate extcon device\n");
+		return -ENOMEM;
+	}
+
+	ret = devm_extcon_dev_register(dev, info->edev);
+	if (ret < 0) {
+		dev_err(dev, "failed to register extcon device\n");
+		return ret;
+	}
+
+	ret = extcon_set_property_capability(info->edev,
+			EXTCON_USB, EXTCON_PROP_USB_SS);
+	ret |= extcon_set_property_capability(info->edev,
+			EXTCON_USB_HOST, EXTCON_PROP_USB_SS);
+	if (ret) {
+		dev_err(dev, "failed to register extcon props rc=%d\n",
+						ret);
+		return ret;
+	}
+
+	info->debounce_jiffies = msecs_to_jiffies(USB_ID_DEBOUNCE_MS);
+
+	ret = devm_delayed_work_autocancel(dev, &info->wq_detcable,
+					   qcom_usb_extcon_detect_cable);
+	if (ret)
+		return ret;
+
+	info->id_irq = platform_get_irq_byname_optional(pdev, "usb_id");
+	if (info->id_irq > 0) {
+		ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
+					qcom_usb_irq_handler,
+					IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					pdev->name, info);
+		if (ret < 0) {
+			dev_err(dev, "failed to request handler for ID IRQ\n");
+			return ret;
+		}
+	}
+
+	info->vbus_irq = platform_get_irq_byname_optional(pdev, "usb_vbus");
+	if (info->vbus_irq > 0) {
+		ret = devm_request_threaded_irq(dev, info->vbus_irq, NULL,
+					qcom_usb_irq_handler,
+					IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					pdev->name, info);
+		if (ret < 0) {
+			dev_err(dev, "failed to request handler for VBUS IRQ\n");
+			return ret;
+		}
+	}
+
+	if (info->id_irq < 0 && info->vbus_irq < 0) {
+		dev_err(dev, "ID and VBUS IRQ not found\n");
+		return -EINVAL;
+	}
+
+	platform_set_drvdata(pdev, info);
+	devm_device_init_wakeup(dev);
+
+	/* Perform initial detection */
+	qcom_usb_extcon_detect_cable(&info->wq_detcable.work);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int qcom_usb_extcon_suspend(struct device *dev)
+{
+	struct qcom_usb_extcon_info *info = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (device_may_wakeup(dev)) {
+		if (info->id_irq > 0)
+			ret = enable_irq_wake(info->id_irq);
+		if (info->vbus_irq > 0)
+			ret = enable_irq_wake(info->vbus_irq);
+	}
+
+	return ret;
+}
+
+static int qcom_usb_extcon_resume(struct device *dev)
+{
+	struct qcom_usb_extcon_info *info = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (device_may_wakeup(dev)) {
+		if (info->id_irq > 0)
+			ret = disable_irq_wake(info->id_irq);
+		if (info->vbus_irq > 0)
+			ret = disable_irq_wake(info->vbus_irq);
+	}
+
+	return ret;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(qcom_usb_extcon_pm_ops,
+			 qcom_usb_extcon_suspend, qcom_usb_extcon_resume);
+
+static const struct of_device_id qcom_usb_extcon_dt_match[] = {
+	{ .compatible = "qcom,pm8941-misc", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, qcom_usb_extcon_dt_match);
+
+static struct platform_driver qcom_usb_extcon_driver = {
+	.probe		= qcom_usb_extcon_probe,
+	.driver		= {
+		.name	= "extcon-pm8941-misc",
+		.pm	= &qcom_usb_extcon_pm_ops,
+		.of_match_table = qcom_usb_extcon_dt_match,
+	},
+};
+module_platform_driver(qcom_usb_extcon_driver);
+
+MODULE_DESCRIPTION("QCOM USB ID extcon driver");
+MODULE_AUTHOR("Stephen Boyd <stephen.boyd@linaro.org>");
+MODULE_LICENSE("GPL v2");