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, 154 insertions, 0 deletions

diff --git a/drivers/net/phy/cicada.c b/drivers/net/phy/cicada.c
new file mode 100644
index 000000000..d87cf8b94
--- /dev/null
+++ b/drivers/net/phy/cicada.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * drivers/net/phy/cicada.c
+ *
+ * Driver for Cicada PHYs
+ *
+ * Author: Andy Fleming
+ *
+ * Copyright (c) 2004 Freescale Semiconductor, Inc.
+ */
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/unistd.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/mii.h>
+#include <linux/ethtool.h>
+#include <linux/phy.h>
+
+#include <linux/io.h>
+#include <asm/irq.h>
+#include <linux/uaccess.h>
+
+/* Cicada Extended Control Register 1 */
+#define MII_CIS8201_EXT_CON1           0x17
+#define MII_CIS8201_EXTCON1_INIT       0x0000
+
+/* Cicada Interrupt Mask Register */
+#define MII_CIS8201_IMASK		0x19
+#define MII_CIS8201_IMASK_IEN		0x8000
+#define MII_CIS8201_IMASK_SPEED	0x4000
+#define MII_CIS8201_IMASK_LINK		0x2000
+#define MII_CIS8201_IMASK_DUPLEX	0x1000
+#define MII_CIS8201_IMASK_MASK		0xf000
+
+/* Cicada Interrupt Status Register */
+#define MII_CIS8201_ISTAT		0x1a
+#define MII_CIS8201_ISTAT_STATUS	0x8000
+#define MII_CIS8201_ISTAT_SPEED	0x4000
+#define MII_CIS8201_ISTAT_LINK		0x2000
+#define MII_CIS8201_ISTAT_DUPLEX	0x1000
+
+/* Cicada Auxiliary Control/Status Register */
+#define MII_CIS8201_AUX_CONSTAT        0x1c
+#define MII_CIS8201_AUXCONSTAT_INIT    0x0004
+#define MII_CIS8201_AUXCONSTAT_DUPLEX  0x0020
+#define MII_CIS8201_AUXCONSTAT_SPEED   0x0018
+#define MII_CIS8201_AUXCONSTAT_GBIT    0x0010
+#define MII_CIS8201_AUXCONSTAT_100     0x0008
+
+MODULE_DESCRIPTION("Cicadia PHY driver");
+MODULE_AUTHOR("Andy Fleming");
+MODULE_LICENSE("GPL");
+
+static int cis820x_config_init(struct phy_device *phydev)
+{
+	int err;
+
+	err = phy_write(phydev, MII_CIS8201_AUX_CONSTAT,
+			MII_CIS8201_AUXCONSTAT_INIT);
+
+	if (err < 0)
+		return err;
+
+	err = phy_write(phydev, MII_CIS8201_EXT_CON1,
+			MII_CIS8201_EXTCON1_INIT);
+
+	return err;
+}
+
+static int cis820x_ack_interrupt(struct phy_device *phydev)
+{
+	int err = phy_read(phydev, MII_CIS8201_ISTAT);
+
+	return (err < 0) ? err : 0;
+}
+
+static int cis820x_config_intr(struct phy_device *phydev)
+{
+	int err;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		err = cis820x_ack_interrupt(phydev);
+		if (err)
+			return err;
+
+		err = phy_write(phydev, MII_CIS8201_IMASK,
+				MII_CIS8201_IMASK_MASK);
+	} else {
+		err = phy_write(phydev, MII_CIS8201_IMASK, 0);
+		if (err)
+			return err;
+
+		err = cis820x_ack_interrupt(phydev);
+	}
+
+	return err;
+}
+
+static irqreturn_t cis820x_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	irq_status = phy_read(phydev, MII_CIS8201_ISTAT);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (!(irq_status & MII_CIS8201_IMASK_MASK))
+		return IRQ_NONE;
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
+/* Cicada 8201, a.k.a Vitesse VSC8201 */
+static struct phy_driver cis820x_driver[] = {
+{
+	.phy_id		= 0x000fc410,
+	.name		= "Cicada Cis8201",
+	.phy_id_mask	= 0x000ffff0,
+	/* PHY_GBIT_FEATURES */
+	.config_init	= &cis820x_config_init,
+	.config_intr	= &cis820x_config_intr,
+	.handle_interrupt = &cis820x_handle_interrupt,
+}, {
+	.phy_id		= 0x000fc440,
+	.name		= "Cicada Cis8204",
+	.phy_id_mask	= 0x000fffc0,
+	/* PHY_GBIT_FEATURES */
+	.config_init	= &cis820x_config_init,
+	.config_intr	= &cis820x_config_intr,
+	.handle_interrupt = &cis820x_handle_interrupt,
+} };
+
+module_phy_driver(cis820x_driver);
+
+static const struct mdio_device_id __maybe_unused cicada_tbl[] = {
+	{ 0x000fc410, 0x000ffff0 },
+	{ 0x000fc440, 0x000fffc0 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, cicada_tbl);