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, 43 insertions, 0 deletions

diff --git a/drivers/usb/phy/of.c b/drivers/usb/phy/of.c
new file mode 100644
index 000000000..1ab134f45
--- /dev/null
+++ b/drivers/usb/phy/of.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * USB of helper code
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/usb/of.h>
+#include <linux/usb/otg.h>
+
+static const char *const usbphy_modes[] = {
+	[USBPHY_INTERFACE_MODE_UNKNOWN]	= "",
+	[USBPHY_INTERFACE_MODE_UTMI]	= "utmi",
+	[USBPHY_INTERFACE_MODE_UTMIW]	= "utmi_wide",
+	[USBPHY_INTERFACE_MODE_ULPI]	= "ulpi",
+	[USBPHY_INTERFACE_MODE_SERIAL]	= "serial",
+	[USBPHY_INTERFACE_MODE_HSIC]	= "hsic",
+};
+
+/**
+ * of_usb_get_phy_mode - Get phy mode for given device_node
+ * @np:	Pointer to the given device_node
+ *
+ * The function gets phy interface string from property 'phy_type',
+ * and returns the corresponding enum usb_phy_interface
+ */
+enum usb_phy_interface of_usb_get_phy_mode(struct device_node *np)
+{
+	const char *phy_type;
+	int err, i;
+
+	err = of_property_read_string(np, "phy_type", &phy_type);
+	if (err < 0)
+		return USBPHY_INTERFACE_MODE_UNKNOWN;
+
+	for (i = 0; i < ARRAY_SIZE(usbphy_modes); i++)
+		if (!strcmp(phy_type, usbphy_modes[i]))
+			return i;
+
+	return USBPHY_INTERFACE_MODE_UNKNOWN;
+}
+EXPORT_SYMBOL_GPL(of_usb_get_phy_mode);