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, 112 insertions, 0 deletions

diff --git a/drivers/mfd/rohm-pwrbutton.c b/drivers/mfd/rohm-pwrbutton.c
new file mode 100644
index 000000000..96a6d1f01
--- /dev/null
+++ b/drivers/mfd/rohm-pwrbutton.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Shared helper for ROHM PMIC power button registration
+ *
+ * Copyright 2018, 2019 ROHM Semiconductors
+ * Copyright 2026 Google LLC
+ */
+
+#include <linux/device/devres.h>
+#include <linux/gfp_types.h>
+#include <linux/input.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+#include "rohm-pwrbutton.h"
+
+#define GPIO_KEYS  0	/* Node corresponding to gpio-keys device itself */
+#define PWRON_KEY  1	/* Node describing power button in gpio-keys */
+
+static int rohm_pwrbutton_register_swnodes(const struct software_node *nodes)
+{
+	const struct software_node * const node_group[] = {
+		&nodes[GPIO_KEYS], &nodes[PWRON_KEY], NULL
+	};
+
+	return software_node_register_node_group(node_group);
+}
+
+static void rohm_pwrbutton_unregister_swnodes(void *data)
+{
+	const struct software_node *nodes = data;
+	const struct software_node * const node_group[] = {
+		&nodes[GPIO_KEYS], &nodes[PWRON_KEY], NULL
+	};
+
+	software_node_unregister_node_group(node_group);
+}
+
+int rohm_register_pwrbutton(struct device *dev, int irq, const char *name,
+			    bool wakeup, struct irq_domain *irq_domain)
+{
+	const struct resource res[] = {
+		DEFINE_RES_IRQ_NAMED(irq, name),
+	};
+	struct mfd_cell gpio_keys_cell = {
+		.name = "gpio-keys",
+		.resources = res,
+		.num_resources = ARRAY_SIZE(res),
+	};
+	struct property_entry *parent_props;
+	struct property_entry *child_props;
+	struct software_node *nodes;
+	int n_props;
+	int ret;
+
+	if (irq <= 0)
+		return -EINVAL;
+
+	nodes = devm_kcalloc(dev, 2, sizeof(*nodes), GFP_KERNEL);
+	if (!nodes)
+		return -ENOMEM;
+
+	nodes[GPIO_KEYS].name = devm_kasprintf(dev, GFP_KERNEL, "%s-power-key", dev_name(dev));
+	if (!nodes[GPIO_KEYS].name)
+		return -ENOMEM;
+
+	parent_props = devm_kcalloc(dev, 2, sizeof(*parent_props), GFP_KERNEL);
+	if (!parent_props)
+		return -ENOMEM;
+
+	parent_props[0] = PROPERTY_ENTRY_STRING("label", name);
+	nodes[GPIO_KEYS].properties = parent_props;
+
+	n_props = 2; /* linux,code and terminator */
+	if (wakeup)
+		n_props++;
+
+	child_props = devm_kcalloc(dev, n_props, sizeof(*child_props), GFP_KERNEL);
+	if (!child_props)
+		return -ENOMEM;
+
+	child_props[0] = PROPERTY_ENTRY_U32("linux,code", KEY_POWER);
+	if (wakeup)
+		child_props[1] = PROPERTY_ENTRY_BOOL("wakeup-source");
+
+	nodes[PWRON_KEY].parent = &nodes[GPIO_KEYS];
+	nodes[PWRON_KEY].properties = child_props;
+
+	ret = rohm_pwrbutton_register_swnodes(nodes);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, rohm_pwrbutton_unregister_swnodes, nodes);
+	if (ret)
+		return ret;
+
+	gpio_keys_cell.swnode = &nodes[GPIO_KEYS];
+
+	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO, &gpio_keys_cell, 1,
+				   NULL, 0, irq_domain);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to register power-button");
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rohm_register_pwrbutton);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Dmitry Torokhov <dmitry.torokhov@gmail.com>");
+MODULE_DESCRIPTION("Shared helper for ROHM PMIC power button registration");