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/rtc/rtc-cv1800.c b/drivers/rtc/rtc-cv1800.c
new file mode 100644
index 000000000..678c2c10b
--- /dev/null
+++ b/drivers/rtc/rtc-cv1800.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * rtc-cv1800.c: RTC driver for Sophgo cv1800 RTC
+ *
+ * Author: Jingbao Qiu <qiujingbao.dlmu@gmail.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/rtc.h>
+
+#define SEC_PULSE_GEN          0x1004
+#define ALARM_TIME             0x1008
+#define ALARM_ENABLE           0x100C
+#define SET_SEC_CNTR_VAL       0x1010
+#define SET_SEC_CNTR_TRIG      0x1014
+#define SEC_CNTR_VAL           0x1018
+
+/*
+ * When in VDDBKUP domain, this MACRO register
+ * does not power down
+ */
+#define MACRO_RO_T             0x14A8
+#define MACRO_RG_SET_T         0x1498
+
+#define ALARM_ENABLE_MASK      BIT(0)
+#define SEL_SEC_PULSE          BIT(31)
+
+struct cv1800_rtc_priv {
+	struct rtc_device *rtc_dev;
+	struct regmap *rtc_map;
+	struct clk *clk;
+	int irq;
+};
+
+static bool cv1800_rtc_enabled(struct device *dev)
+{
+	struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
+	u32 reg;
+
+	regmap_read(info->rtc_map, SEC_PULSE_GEN, &reg);
+
+	return (reg & SEL_SEC_PULSE) == 0;
+}
+
+static void cv1800_rtc_enable(struct device *dev)
+{
+	struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
+
+	/* Sec pulse generated internally */
+	regmap_update_bits(info->rtc_map, SEC_PULSE_GEN, SEL_SEC_PULSE, 0);
+}
+
+static int cv1800_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
+
+	regmap_write(info->rtc_map, ALARM_ENABLE, enabled);
+
+	return 0;
+}
+
+static int cv1800_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
+	unsigned long alarm_time;
+
+	alarm_time = rtc_tm_to_time64(&alrm->time);
+
+	cv1800_rtc_alarm_irq_enable(dev, 0);
+
+	regmap_write(info->rtc_map, ALARM_TIME, alarm_time);
+
+	cv1800_rtc_alarm_irq_enable(dev, alrm->enabled);
+
+	return 0;
+}
+
+static int cv1800_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
+	u32 enabled;
+	u32 time;
+
+	if (!cv1800_rtc_enabled(dev)) {
+		alarm->enabled = 0;
+		return 0;
+	}
+
+	regmap_read(info->rtc_map, ALARM_ENABLE, &enabled);
+
+	alarm->enabled = enabled & ALARM_ENABLE_MASK;
+
+	regmap_read(info->rtc_map, ALARM_TIME, &time);
+
+	rtc_time64_to_tm(time, &alarm->time);
+
+	return 0;
+}
+
+static int cv1800_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
+	u32 sec;
+
+	if (!cv1800_rtc_enabled(dev))
+		return -EINVAL;
+
+	regmap_read(info->rtc_map, SEC_CNTR_VAL, &sec);
+
+	rtc_time64_to_tm(sec, tm);
+
+	return 0;
+}
+
+static int cv1800_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
+	unsigned long sec;
+
+	sec = rtc_tm_to_time64(tm);
+
+	regmap_write(info->rtc_map, SET_SEC_CNTR_VAL, sec);
+	regmap_write(info->rtc_map, SET_SEC_CNTR_TRIG, 1);
+
+	regmap_write(info->rtc_map, MACRO_RG_SET_T, sec);
+
+	cv1800_rtc_enable(dev);
+
+	return 0;
+}
+
+static irqreturn_t cv1800_rtc_irq_handler(int irq, void *dev_id)
+{
+	struct cv1800_rtc_priv *info = dev_id;
+
+	rtc_update_irq(info->rtc_dev, 1, RTC_IRQF | RTC_AF);
+
+	regmap_write(info->rtc_map, ALARM_ENABLE, 0);
+
+	return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops cv1800_rtc_ops = {
+	.read_time = cv1800_rtc_read_time,
+	.set_time = cv1800_rtc_set_time,
+	.read_alarm = cv1800_rtc_read_alarm,
+	.set_alarm = cv1800_rtc_set_alarm,
+	.alarm_irq_enable = cv1800_rtc_alarm_irq_enable,
+};
+
+static int cv1800_rtc_probe(struct platform_device *pdev)
+{
+	struct cv1800_rtc_priv *rtc;
+	int ret;
+
+	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+	if (!rtc)
+		return -ENOMEM;
+
+	rtc->rtc_map = device_node_to_regmap(pdev->dev.parent->of_node);
+	if (IS_ERR(rtc->rtc_map))
+		return dev_err_probe(&pdev->dev, PTR_ERR(rtc->rtc_map),
+				     "cannot get parent regmap\n");
+
+	rtc->irq = platform_get_irq(pdev, 0);
+	if (rtc->irq < 0)
+		return rtc->irq;
+
+	rtc->clk = devm_clk_get_enabled(pdev->dev.parent, "rtc");
+	if (IS_ERR(rtc->clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(rtc->clk),
+				     "rtc clk not found\n");
+
+	platform_set_drvdata(pdev, rtc);
+
+	device_init_wakeup(&pdev->dev, 1);
+
+	rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(rtc->rtc_dev))
+		return PTR_ERR(rtc->rtc_dev);
+
+	rtc->rtc_dev->ops = &cv1800_rtc_ops;
+	rtc->rtc_dev->range_max = U32_MAX;
+
+	ret = devm_request_irq(&pdev->dev, rtc->irq, cv1800_rtc_irq_handler,
+			       IRQF_TRIGGER_HIGH, "rtc alarm", rtc);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret,
+				     "cannot register interrupt handler\n");
+
+	return devm_rtc_register_device(rtc->rtc_dev);
+}
+
+static const struct platform_device_id cv1800_rtc_id[] = {
+	{ .name = "cv1800b-rtc" },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(platform, cv1800_rtc_id);
+
+static struct platform_driver cv1800_rtc_driver = {
+	.driver = {
+		.name = "sophgo-cv1800-rtc",
+	},
+	.probe = cv1800_rtc_probe,
+	.id_table = cv1800_rtc_id,
+};
+
+module_platform_driver(cv1800_rtc_driver);
+MODULE_AUTHOR("Jingbao Qiu");
+MODULE_DESCRIPTION("Sophgo cv1800 RTC Driver");
+MODULE_LICENSE("GPL");