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, 213 insertions, 0 deletions

diff --git a/drivers/extcon/extcon-adc-jack.c b/drivers/extcon/extcon-adc-jack.c
new file mode 100644
index 000000000..e735f43dc
--- /dev/null
+++ b/drivers/extcon/extcon-adc-jack.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * drivers/extcon/extcon-adc-jack.c
+ *
+ * Analog Jack extcon driver with ADC-based detection capability.
+ *
+ * Copyright (C) 2016 Samsung Electronics
+ * Chanwoo Choi <cw00.choi@samsung.com>
+ *
+ * Copyright (C) 2012 Samsung Electronics
+ * MyungJoo Ham <myungjoo.ham@samsung.com>
+ *
+ * Modified for calling to IIO to get adc by <anish.singh@samsung.com>
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/iio/consumer.h>
+#include <linux/extcon/extcon-adc-jack.h>
+#include <linux/extcon-provider.h>
+
+/**
+ * struct adc_jack_data - internal data for adc_jack device driver
+ * @dev:		The device structure associated with the adc_jack.
+ * @edev:		extcon device.
+ * @cable_names:	list of supported cables.
+ * @adc_conditions:	list of adc value conditions.
+ * @num_conditions:	size of adc_conditions.
+ * @irq:		irq number of attach/detach event (0 if not exist).
+ * @handling_delay:	interrupt handler will schedule extcon event
+ *			handling at handling_delay jiffies.
+ * @handler:		extcon event handler called by interrupt handler.
+ * @chan:		iio channel being queried.
+ * @wakeup_source:	Indicates if the device can wake up the system.
+ */
+struct adc_jack_data {
+	struct device *dev;
+	struct extcon_dev *edev;
+
+	const unsigned int **cable_names;
+	struct adc_jack_cond *adc_conditions;
+	int num_conditions;
+
+	int irq;
+	unsigned long handling_delay; /* in jiffies */
+	struct delayed_work handler;
+
+	struct iio_channel *chan;
+	bool wakeup_source;
+};
+
+static void adc_jack_handler(struct work_struct *work)
+{
+	struct adc_jack_data *data = container_of(to_delayed_work(work),
+			struct adc_jack_data,
+			handler);
+	struct adc_jack_cond *def;
+	int ret, adc_val;
+	int i;
+
+	ret = iio_read_channel_raw(data->chan, &adc_val);
+	if (ret < 0) {
+		dev_err(data->dev, "read channel() error: %d\n", ret);
+		return;
+	}
+
+	/* Get state from adc value with adc_conditions */
+	for (i = 0; i < data->num_conditions; i++) {
+		def = &data->adc_conditions[i];
+		if (def->min_adc <= adc_val && def->max_adc >= adc_val) {
+			extcon_set_state_sync(data->edev, def->id, true);
+			return;
+		}
+	}
+
+	/* Set the detached state if adc value is not included in the range */
+	for (i = 0; i < data->num_conditions; i++) {
+		def = &data->adc_conditions[i];
+		extcon_set_state_sync(data->edev, def->id, false);
+	}
+}
+
+static irqreturn_t adc_jack_irq_thread(int irq, void *_data)
+{
+	struct adc_jack_data *data = _data;
+
+	queue_delayed_work(system_power_efficient_wq,
+			   &data->handler, data->handling_delay);
+	return IRQ_HANDLED;
+}
+
+static int adc_jack_probe(struct platform_device *pdev)
+{
+	struct adc_jack_data *data;
+	struct adc_jack_pdata *pdata = dev_get_platdata(&pdev->dev);
+	int i, err = 0;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	if (!pdata->cable_names) {
+		dev_err(&pdev->dev, "error: cable_names not defined.\n");
+		return -EINVAL;
+	}
+
+	data->dev = &pdev->dev;
+	data->edev = devm_extcon_dev_allocate(&pdev->dev, pdata->cable_names);
+	if (IS_ERR(data->edev)) {
+		dev_err(&pdev->dev, "failed to allocate extcon device\n");
+		return -ENOMEM;
+	}
+
+	if (!pdata->adc_conditions) {
+		dev_err(&pdev->dev, "error: adc_conditions not defined.\n");
+		return -EINVAL;
+	}
+	data->adc_conditions = pdata->adc_conditions;
+
+	/* Check the length of array and set num_conditions */
+	for (i = 0; data->adc_conditions[i].id != EXTCON_NONE; i++);
+	data->num_conditions = i;
+
+	data->chan = devm_iio_channel_get(&pdev->dev, pdata->consumer_channel);
+	if (IS_ERR(data->chan))
+		return PTR_ERR(data->chan);
+
+	data->handling_delay = msecs_to_jiffies(pdata->handling_delay_ms);
+	data->wakeup_source = pdata->wakeup_source;
+
+	INIT_DEFERRABLE_WORK(&data->handler, adc_jack_handler);
+
+	platform_set_drvdata(pdev, data);
+
+	err = devm_extcon_dev_register(&pdev->dev, data->edev);
+	if (err)
+		return err;
+
+	data->irq = platform_get_irq(pdev, 0);
+	if (data->irq < 0)
+		return -ENODEV;
+
+	err = request_any_context_irq(data->irq, adc_jack_irq_thread,
+			pdata->irq_flags, pdata->name, data);
+
+	if (err < 0) {
+		dev_err(&pdev->dev, "error: irq %d\n", data->irq);
+		return err;
+	}
+
+	if (data->wakeup_source)
+		device_init_wakeup(&pdev->dev, 1);
+
+	adc_jack_handler(&data->handler.work);
+	return 0;
+}
+
+static void adc_jack_remove(struct platform_device *pdev)
+{
+	struct adc_jack_data *data = platform_get_drvdata(pdev);
+
+	if (data->wakeup_source)
+		device_init_wakeup(&pdev->dev, false);
+	free_irq(data->irq, data);
+	cancel_work_sync(&data->handler.work);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int adc_jack_suspend(struct device *dev)
+{
+	struct adc_jack_data *data = dev_get_drvdata(dev);
+
+	cancel_delayed_work_sync(&data->handler);
+	if (device_may_wakeup(data->dev))
+		enable_irq_wake(data->irq);
+
+	return 0;
+}
+
+static int adc_jack_resume(struct device *dev)
+{
+	struct adc_jack_data *data = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(data->dev))
+		disable_irq_wake(data->irq);
+
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static SIMPLE_DEV_PM_OPS(adc_jack_pm_ops,
+		adc_jack_suspend, adc_jack_resume);
+
+static struct platform_driver adc_jack_driver = {
+	.probe          = adc_jack_probe,
+	.remove         = adc_jack_remove,
+	.driver         = {
+		.name   = "adc-jack",
+		.pm = &adc_jack_pm_ops,
+	},
+};
+
+module_platform_driver(adc_jack_driver);
+
+MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
+MODULE_DESCRIPTION("ADC Jack extcon driver");
+MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS("IIO_CONSUMER");