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, 244 insertions, 0 deletions

diff --git a/drivers/input/joystick/cobra.c b/drivers/input/joystick/cobra.c
new file mode 100644
index 000000000..ffa6d49c8
--- /dev/null
+++ b/drivers/input/joystick/cobra.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 1999-2001 Vojtech Pavlik
+ */
+
+/*
+ * Creative Labs Blaster GamePad Cobra driver for Linux
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/gameport.h>
+#include <linux/input.h>
+#include <linux/jiffies.h>
+
+#define DRIVER_DESC	"Creative Labs Blaster GamePad Cobra driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+#define COBRA_MAX_STROBE	45	/* 45 us max wait for first strobe */
+#define COBRA_LENGTH		36
+
+static int cobra_btn[] = { BTN_START, BTN_SELECT, BTN_TL, BTN_TR, BTN_X, BTN_Y, BTN_Z, BTN_A, BTN_B, BTN_C, BTN_TL2, BTN_TR2, 0 };
+
+struct cobra {
+	struct gameport *gameport;
+	struct input_dev *dev[2];
+	int reads;
+	int bads;
+	unsigned char exists;
+	char phys[2][32];
+};
+
+static unsigned char cobra_read_packet(struct gameport *gameport, unsigned int *data)
+{
+	unsigned long flags;
+	unsigned char u, v, w;
+	__u64 buf[2];
+	int r[2], t[2];
+	int i, j, ret;
+
+	int strobe = gameport_time(gameport, COBRA_MAX_STROBE);
+
+	for (i = 0; i < 2; i++) {
+		r[i] = buf[i] = 0;
+		t[i] = COBRA_MAX_STROBE;
+	}
+
+	local_irq_save(flags);
+
+	u = gameport_read(gameport);
+
+	do {
+		t[0]--; t[1]--;
+		v = gameport_read(gameport);
+		for (i = 0, w = u ^ v; i < 2 && w; i++, w >>= 2)
+			if (w & 0x30) {
+				if ((w & 0x30) < 0x30 && r[i] < COBRA_LENGTH && t[i] > 0) {
+					buf[i] |= (__u64)((w >> 5) & 1) << r[i]++;
+					t[i] = strobe;
+					u = v;
+				} else t[i] = 0;
+			}
+	} while (t[0] > 0 || t[1] > 0);
+
+	local_irq_restore(flags);
+
+	ret = 0;
+
+	for (i = 0; i < 2; i++) {
+
+		if (r[i] != COBRA_LENGTH) continue;
+
+		for (j = 0; j < COBRA_LENGTH && (buf[i] & 0x04104107f) ^ 0x041041040; j++)
+			buf[i] = (buf[i] >> 1) | ((__u64)(buf[i] & 1) << (COBRA_LENGTH - 1));
+
+		if (j < COBRA_LENGTH) ret |= (1 << i);
+
+		data[i] = ((buf[i] >>  7) & 0x000001f) | ((buf[i] >>  8) & 0x00003e0)
+			| ((buf[i] >>  9) & 0x0007c00) | ((buf[i] >> 10) & 0x00f8000)
+			| ((buf[i] >> 11) & 0x1f00000);
+
+	}
+
+	return ret;
+}
+
+static void cobra_poll(struct gameport *gameport)
+{
+	struct cobra *cobra = gameport_get_drvdata(gameport);
+	struct input_dev *dev;
+	unsigned int data[2];
+	int i, j, r;
+
+	cobra->reads++;
+
+	if ((r = cobra_read_packet(gameport, data)) != cobra->exists) {
+		cobra->bads++;
+		return;
+	}
+
+	for (i = 0; i < 2; i++)
+		if (cobra->exists & r & (1 << i)) {
+
+			dev = cobra->dev[i];
+
+			input_report_abs(dev, ABS_X, ((data[i] >> 4) & 1) - ((data[i] >> 3) & 1));
+			input_report_abs(dev, ABS_Y, ((data[i] >> 2) & 1) - ((data[i] >> 1) & 1));
+
+			for (j = 0; cobra_btn[j]; j++)
+				input_report_key(dev, cobra_btn[j], data[i] & (0x20 << j));
+
+			input_sync(dev);
+
+		}
+}
+
+static int cobra_open(struct input_dev *dev)
+{
+	struct cobra *cobra = input_get_drvdata(dev);
+
+	gameport_start_polling(cobra->gameport);
+	return 0;
+}
+
+static void cobra_close(struct input_dev *dev)
+{
+	struct cobra *cobra = input_get_drvdata(dev);
+
+	gameport_stop_polling(cobra->gameport);
+}
+
+static int cobra_connect(struct gameport *gameport, struct gameport_driver *drv)
+{
+	struct cobra *cobra;
+	struct input_dev *input_dev;
+	unsigned int data[2];
+	int i, j;
+	int err;
+
+	cobra = kzalloc_obj(*cobra);
+	if (!cobra)
+		return -ENOMEM;
+
+	cobra->gameport = gameport;
+
+	gameport_set_drvdata(gameport, cobra);
+
+	err = gameport_open(gameport, drv, GAMEPORT_MODE_RAW);
+	if (err)
+		goto fail1;
+
+	cobra->exists = cobra_read_packet(gameport, data);
+
+	for (i = 0; i < 2; i++)
+		if ((cobra->exists >> i) & data[i] & 1) {
+			printk(KERN_WARNING "cobra.c: Device %d on %s has the Ext bit set. ID is: %d"
+				" Contact vojtech@ucw.cz\n", i, gameport->phys, (data[i] >> 2) & 7);
+			cobra->exists &= ~(1 << i);
+		}
+
+	if (!cobra->exists) {
+		err = -ENODEV;
+		goto fail2;
+	}
+
+	gameport_set_poll_handler(gameport, cobra_poll);
+	gameport_set_poll_interval(gameport, 20);
+
+	for (i = 0; i < 2; i++) {
+		if (~(cobra->exists >> i) & 1)
+			continue;
+
+		cobra->dev[i] = input_dev = input_allocate_device();
+		if (!input_dev) {
+			err = -ENOMEM;
+			goto fail3;
+		}
+
+		snprintf(cobra->phys[i], sizeof(cobra->phys[i]),
+			 "%s/input%d", gameport->phys, i);
+
+		input_dev->name = "Creative Labs Blaster GamePad Cobra";
+		input_dev->phys = cobra->phys[i];
+		input_dev->id.bustype = BUS_GAMEPORT;
+		input_dev->id.vendor = GAMEPORT_ID_VENDOR_CREATIVE;
+		input_dev->id.product = 0x0008;
+		input_dev->id.version = 0x0100;
+		input_dev->dev.parent = &gameport->dev;
+
+		input_set_drvdata(input_dev, cobra);
+
+		input_dev->open = cobra_open;
+		input_dev->close = cobra_close;
+
+		input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+		input_set_abs_params(input_dev, ABS_X, -1, 1, 0, 0);
+		input_set_abs_params(input_dev, ABS_Y, -1, 1, 0, 0);
+		for (j = 0; cobra_btn[j]; j++)
+			set_bit(cobra_btn[j], input_dev->keybit);
+
+		err = input_register_device(cobra->dev[i]);
+		if (err)
+			goto fail4;
+	}
+
+	return 0;
+
+ fail4:	input_free_device(cobra->dev[i]);
+ fail3:	while (--i >= 0)
+		if (cobra->dev[i])
+			input_unregister_device(cobra->dev[i]);
+ fail2:	gameport_close(gameport);
+ fail1:	gameport_set_drvdata(gameport, NULL);
+	kfree(cobra);
+	return err;
+}
+
+static void cobra_disconnect(struct gameport *gameport)
+{
+	struct cobra *cobra = gameport_get_drvdata(gameport);
+	int i;
+
+	for (i = 0; i < 2; i++)
+		if ((cobra->exists >> i) & 1)
+			input_unregister_device(cobra->dev[i]);
+	gameport_close(gameport);
+	gameport_set_drvdata(gameport, NULL);
+	kfree(cobra);
+}
+
+static struct gameport_driver cobra_drv = {
+	.driver		= {
+		.name	= "cobra",
+	},
+	.description	= DRIVER_DESC,
+	.connect	= cobra_connect,
+	.disconnect	= cobra_disconnect,
+};
+
+module_gameport_driver(cobra_drv);