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, 118 insertions, 0 deletions

diff --git a/drivers/usb/phy/phy-keystone.c b/drivers/usb/phy/phy-keystone.c
new file mode 100644
index 000000000..51155c551
--- /dev/null
+++ b/drivers/usb/phy/phy-keystone.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * phy-keystone - USB PHY, talking to dwc3 controller in Keystone.
+ *
+ * Copyright (C) 2013 Texas Instruments Incorporated - https://www.ti.com
+ *
+ * Author: WingMan Kwok <w-kwok2@ti.com>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/usb/usb_phy_generic.h>
+#include <linux/io.h>
+#include <linux/of.h>
+
+#include "phy-generic.h"
+
+/* USB PHY control register offsets */
+#define USB_PHY_CTL_UTMI		0x0000
+#define USB_PHY_CTL_PIPE		0x0004
+#define USB_PHY_CTL_PARAM_1		0x0008
+#define USB_PHY_CTL_PARAM_2		0x000c
+#define USB_PHY_CTL_CLOCK		0x0010
+#define USB_PHY_CTL_PLL			0x0014
+
+#define PHY_REF_SSP_EN			BIT(29)
+
+struct keystone_usbphy {
+	struct usb_phy_generic	usb_phy_gen;
+	void __iomem			*phy_ctrl;
+};
+
+static inline u32 keystone_usbphy_readl(void __iomem *base, u32 offset)
+{
+	return readl(base + offset);
+}
+
+static inline void keystone_usbphy_writel(void __iomem *base,
+					  u32 offset, u32 value)
+{
+	writel(value, base + offset);
+}
+
+static int keystone_usbphy_init(struct usb_phy *phy)
+{
+	struct keystone_usbphy *k_phy = dev_get_drvdata(phy->dev);
+	u32 val;
+
+	val  = keystone_usbphy_readl(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK);
+	keystone_usbphy_writel(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK,
+				val | PHY_REF_SSP_EN);
+	return 0;
+}
+
+static void keystone_usbphy_shutdown(struct usb_phy *phy)
+{
+	struct keystone_usbphy *k_phy = dev_get_drvdata(phy->dev);
+	u32 val;
+
+	val  = keystone_usbphy_readl(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK);
+	keystone_usbphy_writel(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK,
+				val & ~PHY_REF_SSP_EN);
+}
+
+static int keystone_usbphy_probe(struct platform_device *pdev)
+{
+	struct device		*dev = &pdev->dev;
+	struct keystone_usbphy	*k_phy;
+	int ret;
+
+	k_phy = devm_kzalloc(dev, sizeof(*k_phy), GFP_KERNEL);
+	if (!k_phy)
+		return -ENOMEM;
+
+	k_phy->phy_ctrl = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(k_phy->phy_ctrl))
+		return PTR_ERR(k_phy->phy_ctrl);
+
+	ret = usb_phy_gen_create_phy(dev, &k_phy->usb_phy_gen);
+	if (ret)
+		return ret;
+
+	k_phy->usb_phy_gen.phy.init = keystone_usbphy_init;
+	k_phy->usb_phy_gen.phy.shutdown = keystone_usbphy_shutdown;
+
+	platform_set_drvdata(pdev, k_phy);
+
+	return usb_add_phy_dev(&k_phy->usb_phy_gen.phy);
+}
+
+static void keystone_usbphy_remove(struct platform_device *pdev)
+{
+	struct keystone_usbphy *k_phy = platform_get_drvdata(pdev);
+
+	usb_remove_phy(&k_phy->usb_phy_gen.phy);
+}
+
+static const struct of_device_id keystone_usbphy_ids[] = {
+	{ .compatible = "ti,keystone-usbphy" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, keystone_usbphy_ids);
+
+static struct platform_driver keystone_usbphy_driver = {
+	.probe          = keystone_usbphy_probe,
+	.remove         = keystone_usbphy_remove,
+	.driver         = {
+		.name   = "keystone-usbphy",
+		.of_match_table = keystone_usbphy_ids,
+	},
+};
+
+module_platform_driver(keystone_usbphy_driver);
+
+MODULE_ALIAS("platform:keystone-usbphy");
+MODULE_AUTHOR("Texas Instruments Inc.");
+MODULE_DESCRIPTION("Keystone USB phy driver");
+MODULE_LICENSE("GPL v2");