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, 231 insertions, 0 deletions

diff --git a/drivers/mfd/max77650.c b/drivers/mfd/max77650.c
new file mode 100644
index 000000000..75b5dc44e
--- /dev/null
+++ b/drivers/mfd/max77650.c
@@ -0,0 +1,231 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (C) 2018 BayLibre SAS
+// Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>
+//
+// Core MFD driver for MAXIM 77650/77651 charger/power-supply.
+// Programming manual: https://pdfserv.maximintegrated.com/en/an/AN6428.pdf
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max77650.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+
+#define MAX77650_INT_GPI_F_MSK		BIT(0)
+#define MAX77650_INT_GPI_R_MSK		BIT(1)
+#define MAX77650_INT_GPI_MSK \
+			(MAX77650_INT_GPI_F_MSK | MAX77650_INT_GPI_R_MSK)
+#define MAX77650_INT_nEN_F_MSK		BIT(2)
+#define MAX77650_INT_nEN_R_MSK		BIT(3)
+#define MAX77650_INT_TJAL1_R_MSK	BIT(4)
+#define MAX77650_INT_TJAL2_R_MSK	BIT(5)
+#define MAX77650_INT_DOD_R_MSK		BIT(6)
+
+#define MAX77650_INT_THM_MSK		BIT(0)
+#define MAX77650_INT_CHG_MSK		BIT(1)
+#define MAX77650_INT_CHGIN_MSK		BIT(2)
+#define MAX77650_INT_TJ_REG_MSK		BIT(3)
+#define MAX77650_INT_CHGIN_CTRL_MSK	BIT(4)
+#define MAX77650_INT_SYS_CTRL_MSK	BIT(5)
+#define MAX77650_INT_SYS_CNFG_MSK	BIT(6)
+
+#define MAX77650_INT_GLBL_OFFSET	0
+#define MAX77650_INT_CHG_OFFSET		1
+
+#define MAX77650_SBIA_LPM_MASK		BIT(5)
+#define MAX77650_SBIA_LPM_DISABLED	0x00
+
+enum {
+	MAX77650_INT_GPI,
+	MAX77650_INT_nEN_F,
+	MAX77650_INT_nEN_R,
+	MAX77650_INT_TJAL1_R,
+	MAX77650_INT_TJAL2_R,
+	MAX77650_INT_DOD_R,
+	MAX77650_INT_THM,
+	MAX77650_INT_CHG,
+	MAX77650_INT_CHGIN,
+	MAX77650_INT_TJ_REG,
+	MAX77650_INT_CHGIN_CTRL,
+	MAX77650_INT_SYS_CTRL,
+	MAX77650_INT_SYS_CNFG,
+};
+
+static const struct resource max77650_charger_resources[] = {
+	DEFINE_RES_IRQ_NAMED(MAX77650_INT_CHG, "CHG"),
+	DEFINE_RES_IRQ_NAMED(MAX77650_INT_CHGIN, "CHGIN"),
+};
+
+static const struct resource max77650_gpio_resources[] = {
+	DEFINE_RES_IRQ_NAMED(MAX77650_INT_GPI, "GPI"),
+};
+
+static const struct resource max77650_onkey_resources[] = {
+	DEFINE_RES_IRQ_NAMED(MAX77650_INT_nEN_F, "nEN_F"),
+	DEFINE_RES_IRQ_NAMED(MAX77650_INT_nEN_R, "nEN_R"),
+};
+
+static const struct mfd_cell max77650_cells[] = {
+	{
+		.name		= "max77650-regulator",
+		.of_compatible	= "maxim,max77650-regulator",
+	}, {
+		.name		= "max77650-charger",
+		.of_compatible	= "maxim,max77650-charger",
+		.resources	= max77650_charger_resources,
+		.num_resources	= ARRAY_SIZE(max77650_charger_resources),
+	}, {
+		.name		= "max77650-gpio",
+		.of_compatible	= "maxim,max77650-gpio",
+		.resources	= max77650_gpio_resources,
+		.num_resources	= ARRAY_SIZE(max77650_gpio_resources),
+	}, {
+		.name		= "max77650-led",
+		.of_compatible	= "maxim,max77650-led",
+	}, {
+		.name		= "max77650-onkey",
+		.of_compatible	= "maxim,max77650-onkey",
+		.resources	= max77650_onkey_resources,
+		.num_resources	= ARRAY_SIZE(max77650_onkey_resources),
+	},
+};
+
+static const struct regmap_irq max77650_irqs[] = {
+	[MAX77650_INT_GPI] = {
+		.reg_offset = MAX77650_INT_GLBL_OFFSET,
+		.mask = MAX77650_INT_GPI_MSK,
+		.type = {
+			.type_falling_val = MAX77650_INT_GPI_F_MSK,
+			.type_rising_val = MAX77650_INT_GPI_R_MSK,
+			.types_supported = IRQ_TYPE_EDGE_BOTH,
+		},
+	},
+	REGMAP_IRQ_REG(MAX77650_INT_nEN_F,
+		       MAX77650_INT_GLBL_OFFSET, MAX77650_INT_nEN_F_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_nEN_R,
+		       MAX77650_INT_GLBL_OFFSET, MAX77650_INT_nEN_R_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_TJAL1_R,
+		       MAX77650_INT_GLBL_OFFSET, MAX77650_INT_TJAL1_R_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_TJAL2_R,
+		       MAX77650_INT_GLBL_OFFSET, MAX77650_INT_TJAL2_R_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_DOD_R,
+		       MAX77650_INT_GLBL_OFFSET, MAX77650_INT_DOD_R_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_THM,
+		       MAX77650_INT_CHG_OFFSET, MAX77650_INT_THM_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_CHG,
+		       MAX77650_INT_CHG_OFFSET, MAX77650_INT_CHG_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_CHGIN,
+		       MAX77650_INT_CHG_OFFSET, MAX77650_INT_CHGIN_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_TJ_REG,
+		       MAX77650_INT_CHG_OFFSET, MAX77650_INT_TJ_REG_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_CHGIN_CTRL,
+		       MAX77650_INT_CHG_OFFSET, MAX77650_INT_CHGIN_CTRL_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_SYS_CTRL,
+		       MAX77650_INT_CHG_OFFSET, MAX77650_INT_SYS_CTRL_MSK),
+	REGMAP_IRQ_REG(MAX77650_INT_SYS_CNFG,
+		       MAX77650_INT_CHG_OFFSET, MAX77650_INT_SYS_CNFG_MSK),
+};
+
+static const struct regmap_irq_chip max77650_irq_chip = {
+	.name			= "max77650-irq",
+	.irqs			= max77650_irqs,
+	.num_irqs		= ARRAY_SIZE(max77650_irqs),
+	.num_regs		= 2,
+	.status_base		= MAX77650_REG_INT_GLBL,
+	.mask_base		= MAX77650_REG_INTM_GLBL,
+	.type_in_mask		= true,
+	.init_ack_masked	= true,
+	.clear_on_unmask	= true,
+};
+
+static const struct regmap_config max77650_regmap_config = {
+	.name		= "max77650",
+	.reg_bits	= 8,
+	.val_bits	= 8,
+};
+
+static int max77650_i2c_probe(struct i2c_client *i2c)
+{
+	struct regmap_irq_chip_data *irq_data;
+	struct device *dev = &i2c->dev;
+	struct irq_domain *domain;
+	struct regmap *map;
+	unsigned int val;
+	int rv, id;
+
+	map = devm_regmap_init_i2c(i2c, &max77650_regmap_config);
+	if (IS_ERR(map)) {
+		dev_err(dev, "Unable to initialise I2C Regmap\n");
+		return PTR_ERR(map);
+	}
+
+	rv = regmap_read(map, MAX77650_REG_CID, &val);
+	if (rv) {
+		dev_err(dev, "Unable to read Chip ID\n");
+		return rv;
+	}
+
+	id = MAX77650_CID_BITS(val);
+	switch (id) {
+	case MAX77650_CID_77650A:
+	case MAX77650_CID_77650C:
+	case MAX77650_CID_77651A:
+	case MAX77650_CID_77651B:
+		break;
+	default:
+		dev_err(dev, "Chip not supported - ID: 0x%02x\n", id);
+		return -ENODEV;
+	}
+
+	/*
+	 * This IC has a low-power mode which reduces the quiescent current
+	 * consumption to ~5.6uA but is only suitable for systems consuming
+	 * less than ~2mA. Since this is not likely the case even on
+	 * linux-based wearables - keep the chip in normal power mode.
+	 */
+	rv = regmap_update_bits(map,
+				MAX77650_REG_CNFG_GLBL,
+				MAX77650_SBIA_LPM_MASK,
+				MAX77650_SBIA_LPM_DISABLED);
+	if (rv) {
+		dev_err(dev, "Unable to change the power mode\n");
+		return rv;
+	}
+
+	rv = devm_regmap_add_irq_chip(dev, map, i2c->irq,
+				      IRQF_ONESHOT | IRQF_SHARED, 0,
+				      &max77650_irq_chip, &irq_data);
+	if (rv) {
+		dev_err(dev, "Unable to add Regmap IRQ chip\n");
+		return rv;
+	}
+
+	domain = regmap_irq_get_domain(irq_data);
+
+	return devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
+				    max77650_cells, ARRAY_SIZE(max77650_cells),
+				    NULL, 0, domain);
+}
+
+static const struct of_device_id max77650_of_match[] = {
+	{ .compatible = "maxim,max77650" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max77650_of_match);
+
+static struct i2c_driver max77650_i2c_driver = {
+	.driver = {
+		.name = "max77650",
+		.of_match_table = max77650_of_match,
+	},
+	.probe = max77650_i2c_probe,
+};
+module_i2c_driver(max77650_i2c_driver);
+
+MODULE_DESCRIPTION("MAXIM 77650/77651 multi-function core driver");
+MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
+MODULE_LICENSE("GPL v2");