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, 157 insertions, 0 deletions

diff --git a/drivers/input/joystick/amijoy.c b/drivers/input/joystick/amijoy.c
new file mode 100644
index 000000000..3752dc2a2
--- /dev/null
+++ b/drivers/input/joystick/amijoy.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 1998-2001 Vojtech Pavlik
+ */
+
+/*
+ * Driver for Amiga joysticks for Linux/m68k
+ */
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/mutex.h>
+
+#include <asm/amigahw.h>
+#include <asm/amigaints.h>
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION("Driver for Amiga joysticks");
+MODULE_LICENSE("GPL");
+
+static int amijoy[2] = { 0, 1 };
+module_param_array_named(map, amijoy, uint, NULL, 0);
+MODULE_PARM_DESC(map, "Map of attached joysticks in form of <a>,<b> (default is 0,1)");
+
+static int amijoy_used;
+static DEFINE_MUTEX(amijoy_mutex);
+static struct input_dev *amijoy_dev[2];
+static char *amijoy_phys[2] = { "amijoy/input0", "amijoy/input1" };
+
+static irqreturn_t amijoy_interrupt(int irq, void *dummy)
+{
+	int i, data = 0, button = 0;
+
+	for (i = 0; i < 2; i++)
+		if (amijoy[i]) {
+
+			switch (i) {
+				case 0: data = ~amiga_custom.joy0dat; button = (~ciaa.pra >> 6) & 1; break;
+				case 1: data = ~amiga_custom.joy1dat; button = (~ciaa.pra >> 7) & 1; break;
+			}
+
+			input_report_key(amijoy_dev[i], BTN_TRIGGER, button);
+
+			input_report_abs(amijoy_dev[i], ABS_X, ((data >> 1) & 1) - ((data >> 9) & 1));
+			data = ~(data ^ (data << 1));
+			input_report_abs(amijoy_dev[i], ABS_Y, ((data >> 1) & 1) - ((data >> 9) & 1));
+
+			input_sync(amijoy_dev[i]);
+		}
+	return IRQ_HANDLED;
+}
+
+static int amijoy_open(struct input_dev *dev)
+{
+	int err;
+
+	err = mutex_lock_interruptible(&amijoy_mutex);
+	if (err)
+		return err;
+
+	if (!amijoy_used && request_irq(IRQ_AMIGA_VERTB, amijoy_interrupt, 0, "amijoy", amijoy_interrupt)) {
+		printk(KERN_ERR "amijoy.c: Can't allocate irq %d\n", IRQ_AMIGA_VERTB);
+		err = -EBUSY;
+		goto out;
+	}
+
+	amijoy_used++;
+out:
+	mutex_unlock(&amijoy_mutex);
+	return err;
+}
+
+static void amijoy_close(struct input_dev *dev)
+{
+	mutex_lock(&amijoy_mutex);
+	if (!--amijoy_used)
+		free_irq(IRQ_AMIGA_VERTB, amijoy_interrupt);
+	mutex_unlock(&amijoy_mutex);
+}
+
+static int __init amijoy_init(void)
+{
+	int i, j;
+	int err;
+
+	if (!MACH_IS_AMIGA)
+		return -ENODEV;
+
+	for (i = 0; i < 2; i++) {
+		if (!amijoy[i])
+			continue;
+
+		amijoy_dev[i] = input_allocate_device();
+		if (!amijoy_dev[i]) {
+			err = -ENOMEM;
+			goto fail;
+		}
+
+		if (!request_mem_region(CUSTOM_PHYSADDR + 10 + i * 2, 2, "amijoy [Denise]")) {
+			input_free_device(amijoy_dev[i]);
+			err = -EBUSY;
+			goto fail;
+		}
+
+		amijoy_dev[i]->name = "Amiga joystick";
+		amijoy_dev[i]->phys = amijoy_phys[i];
+		amijoy_dev[i]->id.bustype = BUS_AMIGA;
+		amijoy_dev[i]->id.vendor = 0x0001;
+		amijoy_dev[i]->id.product = 0x0003;
+		amijoy_dev[i]->id.version = 0x0100;
+
+		amijoy_dev[i]->open = amijoy_open;
+		amijoy_dev[i]->close = amijoy_close;
+
+		amijoy_dev[i]->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+		amijoy_dev[i]->absbit[0] = BIT_MASK(ABS_X) | BIT_MASK(ABS_Y);
+		amijoy_dev[i]->keybit[BIT_WORD(BTN_LEFT)] = BIT_MASK(BTN_LEFT) |
+			BIT_MASK(BTN_MIDDLE) | BIT_MASK(BTN_RIGHT);
+		for (j = 0; j < 2; j++) {
+			input_set_abs_params(amijoy_dev[i], ABS_X + j,
+					     -1, 1, 0, 0);
+		}
+
+		err = input_register_device(amijoy_dev[i]);
+		if (err) {
+			input_free_device(amijoy_dev[i]);
+			goto fail;
+		}
+	}
+	return 0;
+
+ fail:	while (--i >= 0)
+		if (amijoy[i]) {
+			input_unregister_device(amijoy_dev[i]);
+			release_mem_region(CUSTOM_PHYSADDR + 10 + i * 2, 2);
+		}
+	return err;
+}
+
+static void __exit amijoy_exit(void)
+{
+	int i;
+
+	for (i = 0; i < 2; i++)
+		if (amijoy[i]) {
+			input_unregister_device(amijoy_dev[i]);
+			release_mem_region(CUSTOM_PHYSADDR + 10 + i * 2, 2);
+		}
+}
+
+module_init(amijoy_init);
+module_exit(amijoy_exit);