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, 102 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/tsc2007.h b/drivers/input/touchscreen/tsc2007.h
new file mode 100644
index 000000000..e346fb4f7
--- /dev/null
+++ b/drivers/input/touchscreen/tsc2007.h
@@ -0,0 +1,102 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/*
+ * Copyright (c) 2008 MtekVision Co., Ltd.
+ *	Kwangwoo Lee <kwlee@mtekvision.com>
+ *
+ * Using code from:
+ *  - ads7846.c
+ *	Copyright (c) 2005 David Brownell
+ *	Copyright (c) 2006 Nokia Corporation
+ *  - corgi_ts.c
+ *	Copyright (C) 2004-2005 Richard Purdie
+ *  - omap_ts.[hc], ads7846.h, ts_osk.c
+ *	Copyright (C) 2002 MontaVista Software
+ *	Copyright (C) 2004 Texas Instruments
+ *	Copyright (C) 2005 Dirk Behme
+ */
+
+#ifndef _TSC2007_H
+#define _TSC2007_H
+
+#include <linux/input/touchscreen.h>
+struct gpio_desc;
+
+#define TSC2007_MEASURE_TEMP0		(0x0 << 4)
+#define TSC2007_MEASURE_AUX		(0x2 << 4)
+#define TSC2007_MEASURE_TEMP1		(0x4 << 4)
+#define TSC2007_ACTIVATE_XN		(0x8 << 4)
+#define TSC2007_ACTIVATE_YN		(0x9 << 4)
+#define TSC2007_ACTIVATE_YP_XN		(0xa << 4)
+#define TSC2007_SETUP			(0xb << 4)
+#define TSC2007_MEASURE_X		(0xc << 4)
+#define TSC2007_MEASURE_Y		(0xd << 4)
+#define TSC2007_MEASURE_Z1		(0xe << 4)
+#define TSC2007_MEASURE_Z2		(0xf << 4)
+
+#define TSC2007_POWER_OFF_IRQ_EN	(0x0 << 2)
+#define TSC2007_ADC_ON_IRQ_DIS0		(0x1 << 2)
+#define TSC2007_ADC_OFF_IRQ_EN		(0x2 << 2)
+#define TSC2007_ADC_ON_IRQ_DIS1		(0x3 << 2)
+
+#define TSC2007_12BIT			(0x0 << 1)
+#define TSC2007_8BIT			(0x1 << 1)
+
+#define MAX_12BIT			((1 << 12) - 1)
+
+#define ADC_ON_12BIT	(TSC2007_12BIT | TSC2007_ADC_ON_IRQ_DIS0)
+
+#define READ_Y		(ADC_ON_12BIT | TSC2007_MEASURE_Y)
+#define READ_Z1		(ADC_ON_12BIT | TSC2007_MEASURE_Z1)
+#define READ_Z2		(ADC_ON_12BIT | TSC2007_MEASURE_Z2)
+#define READ_X		(ADC_ON_12BIT | TSC2007_MEASURE_X)
+#define PWRDOWN		(TSC2007_12BIT | TSC2007_POWER_OFF_IRQ_EN)
+
+struct ts_event {
+	u16	x;
+	u16	y;
+	u16	z1, z2;
+};
+
+struct tsc2007 {
+	struct input_dev	*input;
+	char			phys[32];
+
+	struct i2c_client	*client;
+
+	struct touchscreen_properties prop;
+	u16			model;
+	u16			x_plate_ohms;
+	u16			max_rt;
+	unsigned long		poll_period; /* in jiffies */
+	int			fuzzx;
+	int			fuzzy;
+	int			fuzzz;
+
+	struct gpio_desc	*gpiod;
+	int			irq;
+
+	wait_queue_head_t	wait;
+	bool			stopped;
+
+	int			(*get_pendown_state)(struct device *);
+	void			(*clear_penirq)(void);
+
+	struct mutex		mlock;
+};
+
+int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd);
+u32 tsc2007_calculate_resistance(struct tsc2007 *tsc, struct ts_event *tc);
+bool tsc2007_is_pen_down(struct tsc2007 *ts);
+
+#if IS_ENABLED(CONFIG_TOUCHSCREEN_TSC2007_IIO)
+/* defined in tsc2007_iio.c */
+int tsc2007_iio_configure(struct tsc2007 *ts);
+#else
+static inline int tsc2007_iio_configure(struct tsc2007 *ts)
+{
+	return 0;
+}
+#endif /* CONFIG_TOUCHSCREEN_TSC2007_IIO */
+
+#endif /* _TSC2007_H */