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, 428 insertions, 0 deletions

diff --git a/drivers/clocksource/timer-armada-370-xp.c b/drivers/clocksource/timer-armada-370-xp.c
new file mode 100644
index 000000000..b5a984aa1
--- /dev/null
+++ b/drivers/clocksource/timer-armada-370-xp.c
@@ -0,0 +1,428 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Marvell Armada 370/XP SoC timer handling.
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * Lior Amsalem <alior@marvell.com>
+ * Gregory CLEMENT <gregory.clement@free-electrons.com>
+ * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+ *
+ * Timer 0 is used as free-running clocksource, while timer 1 is
+ * used as clock_event_device.
+ *
+ * ---
+ * Clocksource driver for Armada 370 and Armada XP SoC.
+ * This driver implements one compatible string for each SoC, given
+ * each has its own characteristics:
+ *
+ *   * Armada 370 has no 25 MHz fixed timer.
+ *
+ *   * Armada XP cannot work properly without such 25 MHz fixed timer as
+ *     doing otherwise leads to using a clocksource whose frequency varies
+ *     when doing cpufreq frequency changes.
+ *
+ * See Documentation/devicetree/bindings/timer/marvell,armada-370-timer.yaml
+ */
+
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/timer.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/sched_clock.h>
+#include <linux/percpu.h>
+#include <linux/syscore_ops.h>
+
+#include <asm/delay.h>
+
+/*
+ * Timer block registers.
+ */
+#define TIMER_CTRL_OFF		0x0000
+#define  TIMER0_EN		 BIT(0)
+#define  TIMER0_RELOAD_EN	 BIT(1)
+#define  TIMER0_25MHZ            BIT(11)
+#define  TIMER0_DIV(div)         ((div) << 19)
+#define  TIMER1_EN		 BIT(2)
+#define  TIMER1_RELOAD_EN	 BIT(3)
+#define  TIMER1_25MHZ            BIT(12)
+#define  TIMER1_DIV(div)         ((div) << 22)
+#define TIMER_EVENTS_STATUS	0x0004
+#define  TIMER0_CLR_MASK         (~0x1)
+#define  TIMER1_CLR_MASK         (~0x100)
+#define TIMER0_RELOAD_OFF	0x0010
+#define TIMER0_VAL_OFF		0x0014
+#define TIMER1_RELOAD_OFF	0x0018
+#define TIMER1_VAL_OFF		0x001c
+
+#define LCL_TIMER_EVENTS_STATUS	0x0028
+/* Global timers are connected to the coherency fabric clock, and the
+   below divider reduces their incrementing frequency. */
+#define TIMER_DIVIDER_SHIFT     5
+#define TIMER_DIVIDER           (1 << TIMER_DIVIDER_SHIFT)
+
+/*
+ * SoC-specific data.
+ */
+static void __iomem *timer_base, *local_base;
+static unsigned int timer_clk;
+static bool timer25Mhz = true;
+static u32 enable_mask;
+
+/*
+ * Number of timer ticks per jiffy.
+ */
+static u32 ticks_per_jiffy;
+
+static struct clock_event_device __percpu *armada_370_xp_evt;
+
+static void local_timer_ctrl_clrset(u32 clr, u32 set)
+{
+	writel((readl(local_base + TIMER_CTRL_OFF) & ~clr) | set,
+		local_base + TIMER_CTRL_OFF);
+}
+
+static u64 notrace armada_370_xp_read_sched_clock(void)
+{
+	return ~readl(timer_base + TIMER0_VAL_OFF);
+}
+
+/*
+ * Clockevent handling.
+ */
+static int
+armada_370_xp_clkevt_next_event(unsigned long delta,
+				struct clock_event_device *dev)
+{
+	/*
+	 * Clear clockevent timer interrupt.
+	 */
+	writel(TIMER0_CLR_MASK, local_base + LCL_TIMER_EVENTS_STATUS);
+
+	/*
+	 * Setup new clockevent timer value.
+	 */
+	writel(delta, local_base + TIMER0_VAL_OFF);
+
+	/*
+	 * Enable the timer.
+	 */
+	local_timer_ctrl_clrset(TIMER0_RELOAD_EN, enable_mask);
+	return 0;
+}
+
+static int armada_370_xp_clkevt_shutdown(struct clock_event_device *evt)
+{
+	/*
+	 * Disable timer.
+	 */
+	local_timer_ctrl_clrset(TIMER0_EN, 0);
+
+	/*
+	 * ACK pending timer interrupt.
+	 */
+	writel(TIMER0_CLR_MASK, local_base + LCL_TIMER_EVENTS_STATUS);
+	return 0;
+}
+
+static int armada_370_xp_clkevt_set_periodic(struct clock_event_device *evt)
+{
+	/*
+	 * Setup timer to fire at 1/HZ intervals.
+	 */
+	writel(ticks_per_jiffy - 1, local_base + TIMER0_RELOAD_OFF);
+	writel(ticks_per_jiffy - 1, local_base + TIMER0_VAL_OFF);
+
+	/*
+	 * Enable timer.
+	 */
+	local_timer_ctrl_clrset(0, TIMER0_RELOAD_EN | enable_mask);
+	return 0;
+}
+
+static int armada_370_xp_clkevt_irq;
+
+static irqreturn_t armada_370_xp_timer_interrupt(int irq, void *dev_id)
+{
+	/*
+	 * ACK timer interrupt and call event handler.
+	 */
+	struct clock_event_device *evt = dev_id;
+
+	writel(TIMER0_CLR_MASK, local_base + LCL_TIMER_EVENTS_STATUS);
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Setup the local clock events for a CPU.
+ */
+static int armada_370_xp_timer_starting_cpu(unsigned int cpu)
+{
+	struct clock_event_device *evt = per_cpu_ptr(armada_370_xp_evt, cpu);
+	u32 clr = 0, set = 0;
+
+	if (timer25Mhz)
+		set = TIMER0_25MHZ;
+	else
+		clr = TIMER0_25MHZ;
+	local_timer_ctrl_clrset(clr, set);
+
+	evt->name		= "armada_370_xp_per_cpu_tick";
+	evt->features		= CLOCK_EVT_FEAT_ONESHOT |
+				  CLOCK_EVT_FEAT_PERIODIC;
+	evt->shift		= 32;
+	evt->rating		= 300;
+	evt->set_next_event	= armada_370_xp_clkevt_next_event;
+	evt->set_state_shutdown	= armada_370_xp_clkevt_shutdown;
+	evt->set_state_periodic	= armada_370_xp_clkevt_set_periodic;
+	evt->set_state_oneshot	= armada_370_xp_clkevt_shutdown;
+	evt->tick_resume	= armada_370_xp_clkevt_shutdown;
+	evt->irq		= armada_370_xp_clkevt_irq;
+	evt->cpumask		= cpumask_of(cpu);
+
+	clockevents_config_and_register(evt, timer_clk, 1, 0xfffffffe);
+	enable_percpu_irq(evt->irq, 0);
+
+	return 0;
+}
+
+static int armada_370_xp_timer_dying_cpu(unsigned int cpu)
+{
+	struct clock_event_device *evt = per_cpu_ptr(armada_370_xp_evt, cpu);
+
+	disable_percpu_irq(evt->irq);
+	return 0;
+}
+
+static u32 timer0_ctrl_reg, timer0_local_ctrl_reg;
+
+static int armada_370_xp_timer_suspend(void *data)
+{
+	timer0_ctrl_reg = readl(timer_base + TIMER_CTRL_OFF);
+	timer0_local_ctrl_reg = readl(local_base + TIMER_CTRL_OFF);
+	return 0;
+}
+
+static void armada_370_xp_timer_resume(void *data)
+{
+	writel(0xffffffff, timer_base + TIMER0_VAL_OFF);
+	writel(0xffffffff, timer_base + TIMER0_RELOAD_OFF);
+	writel(timer0_ctrl_reg, timer_base + TIMER_CTRL_OFF);
+	writel(timer0_local_ctrl_reg, local_base + TIMER_CTRL_OFF);
+}
+
+static const struct syscore_ops armada_370_xp_timer_syscore_ops = {
+	.suspend	= armada_370_xp_timer_suspend,
+	.resume		= armada_370_xp_timer_resume,
+};
+
+static struct syscore armada_370_xp_timer_syscore = {
+	.ops = &armada_370_xp_timer_syscore_ops,
+};
+
+static unsigned long armada_370_delay_timer_read(void)
+{
+	return ~readl(timer_base + TIMER0_VAL_OFF);
+}
+
+static struct delay_timer armada_370_delay_timer = {
+	.read_current_timer = armada_370_delay_timer_read,
+};
+
+static int __init armada_370_xp_timer_common_init(struct device_node *np)
+{
+	u32 clr = 0, set = 0;
+	int res;
+
+	timer_base = of_iomap(np, 0);
+	if (!timer_base) {
+		pr_err("Failed to iomap\n");
+		return -ENXIO;
+	}
+
+	local_base = of_iomap(np, 1);
+	if (!local_base) {
+		pr_err("Failed to iomap\n");
+		return -ENXIO;
+	}
+
+	if (timer25Mhz) {
+		set = TIMER0_25MHZ;		
+		enable_mask = TIMER0_EN;
+	} else {
+		clr = TIMER0_25MHZ;
+		enable_mask = TIMER0_EN | TIMER0_DIV(TIMER_DIVIDER_SHIFT);
+	}
+	atomic_io_modify(timer_base + TIMER_CTRL_OFF, clr | set, set);
+	local_timer_ctrl_clrset(clr, set);
+
+	/*
+	 * We use timer 0 as clocksource, and private(local) timer 0
+	 * for clockevents
+	 */
+	armada_370_xp_clkevt_irq = irq_of_parse_and_map(np, 4);
+
+	ticks_per_jiffy = (timer_clk + HZ / 2) / HZ;
+
+	/*
+	 * Setup free-running clocksource timer (interrupts
+	 * disabled).
+	 */
+	writel(0xffffffff, timer_base + TIMER0_VAL_OFF);
+	writel(0xffffffff, timer_base + TIMER0_RELOAD_OFF);
+
+	atomic_io_modify(timer_base + TIMER_CTRL_OFF,
+		TIMER0_RELOAD_EN | enable_mask,
+		TIMER0_RELOAD_EN | enable_mask);
+
+	armada_370_delay_timer.freq = timer_clk;
+	register_current_timer_delay(&armada_370_delay_timer);
+
+	/*
+	 * Set scale and timer for sched_clock.
+	 */
+	sched_clock_register(armada_370_xp_read_sched_clock, 32, timer_clk);
+
+	res = clocksource_mmio_init(timer_base + TIMER0_VAL_OFF,
+				    "armada_370_xp_clocksource",
+				    timer_clk, 300, 32, clocksource_mmio_readl_down);
+	if (res) {
+		pr_err("Failed to initialize clocksource mmio\n");
+		return res;
+	}
+
+	armada_370_xp_evt = alloc_percpu(struct clock_event_device);
+	if (!armada_370_xp_evt)
+		return -ENOMEM;
+
+	/*
+	 * Setup clockevent timer (interrupt-driven).
+	 */
+	res = request_percpu_irq(armada_370_xp_clkevt_irq,
+				armada_370_xp_timer_interrupt,
+				"armada_370_xp_per_cpu_tick",
+				armada_370_xp_evt);
+	/* Immediately configure the timer on the boot CPU */
+	if (res) {
+		pr_err("Failed to request percpu irq\n");
+		return res;
+	}
+
+	res = cpuhp_setup_state(CPUHP_AP_ARMADA_TIMER_STARTING,
+				"clockevents/armada:starting",
+				armada_370_xp_timer_starting_cpu,
+				armada_370_xp_timer_dying_cpu);
+	if (res) {
+		pr_err("Failed to setup hotplug state and timer\n");
+		return res;
+	}
+
+	register_syscore(&armada_370_xp_timer_syscore);
+	
+	return 0;
+}
+
+static int __init armada_xp_timer_init(struct device_node *np)
+{
+	struct clk *clk = of_clk_get_by_name(np, "fixed");
+	int ret;
+
+	if (IS_ERR(clk)) {
+		pr_err("Failed to get clock\n");
+		return PTR_ERR(clk);
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (ret)
+		return ret;
+
+	timer_clk = clk_get_rate(clk);
+
+	ret = armada_370_xp_timer_common_init(np);
+	if (ret)
+		clk_disable_unprepare(clk);
+
+	return ret;
+}
+TIMER_OF_DECLARE(armada_xp, "marvell,armada-xp-timer",
+		       armada_xp_timer_init);
+
+static int __init armada_375_timer_init(struct device_node *np)
+{
+	struct clk *clk;
+	int ret;
+
+	clk = of_clk_get_by_name(np, "fixed");
+	if (!IS_ERR(clk)) {
+		ret = clk_prepare_enable(clk);
+		if (ret)
+			return ret;
+		timer_clk = clk_get_rate(clk);
+	} else {
+
+		/*
+		 * This fallback is required in order to retain proper
+		 * devicetree backwards compatibility.
+		 */
+		clk = of_clk_get(np, 0);
+
+		/* Must have at least a clock */
+		if (IS_ERR(clk)) {
+			pr_err("Failed to get clock\n");
+			return PTR_ERR(clk);
+		}
+
+		ret = clk_prepare_enable(clk);
+		if (ret)
+			return ret;
+
+		timer_clk = clk_get_rate(clk) / TIMER_DIVIDER;
+		timer25Mhz = false;
+	}
+
+	ret = armada_370_xp_timer_common_init(np);
+	if (ret)
+		clk_disable_unprepare(clk);
+
+	return ret;
+}
+TIMER_OF_DECLARE(armada_375, "marvell,armada-375-timer",
+		       armada_375_timer_init);
+
+static int __init armada_370_timer_init(struct device_node *np)
+{
+	struct clk *clk;
+	int ret;
+
+	clk = of_clk_get(np, 0);
+	if (IS_ERR(clk)) {
+		pr_err("Failed to get clock\n");
+		return PTR_ERR(clk);
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (ret)
+		return ret;
+
+	timer_clk = clk_get_rate(clk) / TIMER_DIVIDER;
+	timer25Mhz = false;
+
+	ret = armada_370_xp_timer_common_init(np);
+	if (ret)
+		clk_disable_unprepare(clk);
+
+	return ret;
+}
+TIMER_OF_DECLARE(armada_370, "marvell,armada-370-timer",
+		       armada_370_timer_init);