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, 338 insertions, 0 deletions

diff --git a/drivers/mfd/max8907.c b/drivers/mfd/max8907.c
new file mode 100644
index 000000000..7bac1d651
--- /dev/null
+++ b/drivers/mfd/max8907.c
@@ -0,0 +1,338 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * max8907.c - mfd driver for MAX8907
+ *
+ * Copyright (C) 2010 Gyungoh Yoo <jack.yoo@maxim-ic.com>
+ * Copyright (C) 2010-2012, NVIDIA CORPORATION. All rights reserved.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max8907.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+static const struct mfd_cell max8907_cells[] = {
+	{ .name = "max8907-regulator", },
+	{ .name = "max8907-rtc", },
+};
+
+static bool max8907_gen_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_ON_OFF_IRQ1:
+	case MAX8907_REG_ON_OFF_STAT:
+	case MAX8907_REG_ON_OFF_IRQ2:
+	case MAX8907_REG_CHG_IRQ1:
+	case MAX8907_REG_CHG_IRQ2:
+	case MAX8907_REG_CHG_STAT:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max8907_gen_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_ON_OFF_IRQ1:
+	case MAX8907_REG_ON_OFF_IRQ2:
+	case MAX8907_REG_CHG_IRQ1:
+	case MAX8907_REG_CHG_IRQ2:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max8907_gen_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	return !max8907_gen_is_volatile_reg(dev, reg);
+}
+
+static const struct regmap_config max8907_regmap_gen_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.volatile_reg = max8907_gen_is_volatile_reg,
+	.precious_reg = max8907_gen_is_precious_reg,
+	.writeable_reg = max8907_gen_is_writeable_reg,
+	.max_register = MAX8907_REG_LDO20VOUT,
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static bool max8907_rtc_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	if (reg <= MAX8907_REG_RTC_YEAR2)
+		return true;
+
+	switch (reg) {
+	case MAX8907_REG_RTC_STATUS:
+	case MAX8907_REG_RTC_IRQ:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max8907_rtc_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_RTC_IRQ:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max8907_rtc_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_RTC_STATUS:
+	case MAX8907_REG_RTC_IRQ:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static const struct regmap_config max8907_regmap_rtc_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.volatile_reg = max8907_rtc_is_volatile_reg,
+	.precious_reg = max8907_rtc_is_precious_reg,
+	.writeable_reg = max8907_rtc_is_writeable_reg,
+	.max_register = MAX8907_REG_MPL_CNTL,
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static const struct regmap_irq max8907_chg_irqs[] = {
+	{ .reg_offset = 0, .mask = 1 << 0, },
+	{ .reg_offset = 0, .mask = 1 << 1, },
+	{ .reg_offset = 0, .mask = 1 << 2, },
+	{ .reg_offset = 1, .mask = 1 << 0, },
+	{ .reg_offset = 1, .mask = 1 << 1, },
+	{ .reg_offset = 1, .mask = 1 << 2, },
+	{ .reg_offset = 1, .mask = 1 << 3, },
+	{ .reg_offset = 1, .mask = 1 << 4, },
+	{ .reg_offset = 1, .mask = 1 << 5, },
+	{ .reg_offset = 1, .mask = 1 << 6, },
+	{ .reg_offset = 1, .mask = 1 << 7, },
+};
+
+static const struct regmap_irq_chip max8907_chg_irq_chip = {
+	.name = "max8907 chg",
+	.status_base = MAX8907_REG_CHG_IRQ1,
+	.mask_base = MAX8907_REG_CHG_IRQ1_MASK,
+	.wake_base = MAX8907_REG_CHG_IRQ1_MASK,
+	.irq_reg_stride = MAX8907_REG_CHG_IRQ2 - MAX8907_REG_CHG_IRQ1,
+	.num_regs = 2,
+	.irqs = max8907_chg_irqs,
+	.num_irqs = ARRAY_SIZE(max8907_chg_irqs),
+};
+
+static const struct regmap_irq max8907_on_off_irqs[] = {
+	{ .reg_offset = 0, .mask = 1 << 0, },
+	{ .reg_offset = 0, .mask = 1 << 1, },
+	{ .reg_offset = 0, .mask = 1 << 2, },
+	{ .reg_offset = 0, .mask = 1 << 3, },
+	{ .reg_offset = 0, .mask = 1 << 4, },
+	{ .reg_offset = 0, .mask = 1 << 5, },
+	{ .reg_offset = 0, .mask = 1 << 6, },
+	{ .reg_offset = 0, .mask = 1 << 7, },
+	{ .reg_offset = 1, .mask = 1 << 0, },
+	{ .reg_offset = 1, .mask = 1 << 1, },
+};
+
+static const struct regmap_irq_chip max8907_on_off_irq_chip = {
+	.name = "max8907 on_off",
+	.status_base = MAX8907_REG_ON_OFF_IRQ1,
+	.mask_base = MAX8907_REG_ON_OFF_IRQ1_MASK,
+	.irq_reg_stride = MAX8907_REG_ON_OFF_IRQ2 - MAX8907_REG_ON_OFF_IRQ1,
+	.num_regs = 2,
+	.irqs = max8907_on_off_irqs,
+	.num_irqs = ARRAY_SIZE(max8907_on_off_irqs),
+};
+
+static const struct regmap_irq max8907_rtc_irqs[] = {
+	{ .reg_offset = 0, .mask = 1 << 2, },
+	{ .reg_offset = 0, .mask = 1 << 3, },
+};
+
+static const struct regmap_irq_chip max8907_rtc_irq_chip = {
+	.name = "max8907 rtc",
+	.status_base = MAX8907_REG_RTC_IRQ,
+	.mask_base = MAX8907_REG_RTC_IRQ_MASK,
+	.num_regs = 1,
+	.irqs = max8907_rtc_irqs,
+	.num_irqs = ARRAY_SIZE(max8907_rtc_irqs),
+};
+
+static struct max8907 *max8907_pm_off;
+static void max8907_power_off(void)
+{
+	regmap_update_bits(max8907_pm_off->regmap_gen, MAX8907_REG_RESET_CNFG,
+			MAX8907_MASK_POWER_OFF, MAX8907_MASK_POWER_OFF);
+}
+
+static int max8907_i2c_probe(struct i2c_client *i2c)
+{
+	struct max8907 *max8907;
+	int ret;
+	struct max8907_platform_data *pdata = dev_get_platdata(&i2c->dev);
+	bool pm_off = false;
+
+	if (pdata)
+		pm_off = pdata->pm_off;
+	else if (i2c->dev.of_node)
+		pm_off = of_property_read_bool(i2c->dev.of_node,
+					"maxim,system-power-controller");
+
+	max8907 = devm_kzalloc(&i2c->dev, sizeof(struct max8907), GFP_KERNEL);
+	if (!max8907) {
+		ret = -ENOMEM;
+		goto err_alloc_drvdata;
+	}
+
+	max8907->dev = &i2c->dev;
+	max8907->i2c_gen = i2c;
+	i2c_set_clientdata(i2c, max8907);
+	max8907->regmap_gen = devm_regmap_init_i2c(i2c,
+						&max8907_regmap_gen_config);
+	if (IS_ERR(max8907->regmap_gen)) {
+		ret = PTR_ERR(max8907->regmap_gen);
+		dev_err(&i2c->dev, "gen regmap init failed: %d\n", ret);
+		goto err_regmap_gen;
+	}
+
+	max8907->i2c_rtc = i2c_new_dummy_device(i2c->adapter, MAX8907_RTC_I2C_ADDR);
+	if (IS_ERR(max8907->i2c_rtc)) {
+		ret = PTR_ERR(max8907->i2c_rtc);
+		goto err_dummy_rtc;
+	}
+	i2c_set_clientdata(max8907->i2c_rtc, max8907);
+	max8907->regmap_rtc = devm_regmap_init_i2c(max8907->i2c_rtc,
+						&max8907_regmap_rtc_config);
+	if (IS_ERR(max8907->regmap_rtc)) {
+		ret = PTR_ERR(max8907->regmap_rtc);
+		dev_err(&i2c->dev, "rtc regmap init failed: %d\n", ret);
+		goto err_regmap_rtc;
+	}
+
+	ret = regmap_add_irq_chip(max8907->regmap_gen, max8907->i2c_gen->irq,
+				  IRQF_ONESHOT | IRQF_SHARED,
+				  -1, &max8907_chg_irq_chip,
+				  &max8907->irqc_chg);
+	if (ret != 0) {
+		dev_err(&i2c->dev, "failed to add chg irq chip: %d\n", ret);
+		goto err_irqc_chg;
+	}
+	ret = regmap_add_irq_chip(max8907->regmap_gen, max8907->i2c_gen->irq,
+				  IRQF_ONESHOT | IRQF_SHARED, -1,
+				  &max8907_on_off_irq_chip,
+				  &max8907->irqc_on_off);
+	if (ret != 0) {
+		dev_err(&i2c->dev, "failed to add on off irq chip: %d\n", ret);
+		goto err_irqc_on_off;
+	}
+	ret = regmap_add_irq_chip(max8907->regmap_rtc, max8907->i2c_gen->irq,
+				  IRQF_ONESHOT | IRQF_SHARED, -1,
+				  &max8907_rtc_irq_chip,
+				  &max8907->irqc_rtc);
+	if (ret != 0) {
+		dev_err(&i2c->dev, "failed to add rtc irq chip: %d\n", ret);
+		goto err_irqc_rtc;
+	}
+
+	ret = mfd_add_devices(max8907->dev, -1, max8907_cells,
+			      ARRAY_SIZE(max8907_cells), NULL, 0, NULL);
+	if (ret != 0) {
+		dev_err(&i2c->dev, "failed to add MFD devices %d\n", ret);
+		goto err_add_devices;
+	}
+
+	if (pm_off && !pm_power_off) {
+		max8907_pm_off = max8907;
+		pm_power_off = max8907_power_off;
+	}
+
+	return 0;
+
+err_add_devices:
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_rtc);
+err_irqc_rtc:
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_on_off);
+err_irqc_on_off:
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_chg);
+err_irqc_chg:
+err_regmap_rtc:
+	i2c_unregister_device(max8907->i2c_rtc);
+err_dummy_rtc:
+err_regmap_gen:
+err_alloc_drvdata:
+	return ret;
+}
+
+static void max8907_i2c_remove(struct i2c_client *i2c)
+{
+	struct max8907 *max8907 = i2c_get_clientdata(i2c);
+
+	mfd_remove_devices(max8907->dev);
+
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_rtc);
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_on_off);
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_chg);
+
+	i2c_unregister_device(max8907->i2c_rtc);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id max8907_of_match[] = {
+	{ .compatible = "maxim,max8907" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, max8907_of_match);
+#endif
+
+static const struct i2c_device_id max8907_i2c_id[] = {
+	{ "max8907" },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, max8907_i2c_id);
+
+static struct i2c_driver max8907_i2c_driver = {
+	.driver = {
+		.name = "max8907",
+		.of_match_table = of_match_ptr(max8907_of_match),
+	},
+	.probe = max8907_i2c_probe,
+	.remove = max8907_i2c_remove,
+	.id_table = max8907_i2c_id,
+};
+
+static int __init max8907_i2c_init(void)
+{
+	int ret = -ENODEV;
+
+	ret = i2c_add_driver(&max8907_i2c_driver);
+	if (ret != 0)
+		pr_err("Failed to register I2C driver: %d\n", ret);
+
+	return ret;
+}
+subsys_initcall(max8907_i2c_init);
+
+static void __exit max8907_i2c_exit(void)
+{
+	i2c_del_driver(&max8907_i2c_driver);
+}
+module_exit(max8907_i2c_exit);
+
+MODULE_DESCRIPTION("MAX8907 multi-function core driver");
+MODULE_AUTHOR("Gyungoh Yoo <jack.yoo@maxim-ic.com>");
+MODULE_LICENSE("GPL v2");