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, 129 insertions, 0 deletions

diff --git a/drivers/pinctrl/pinctrl-utils.c b/drivers/pinctrl/pinctrl-utils.c
new file mode 100644
index 000000000..b880e44b8
--- /dev/null
+++ b/drivers/pinctrl/pinctrl-utils.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Utils functions to implement the pincontrol driver.
+ *
+ * Copyright (c) 2013, NVIDIA Corporation.
+ *
+ * Author: Laxman Dewangan <ldewangan@nvidia.com>
+ */
+#include <linux/array_size.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+#include <linux/pinctrl/pinctrl.h>
+
+#include "core.h"
+#include "pinctrl-utils.h"
+
+int pinctrl_utils_reserve_map(struct pinctrl_dev *pctldev,
+		struct pinctrl_map **map, unsigned int *reserved_maps,
+		unsigned int *num_maps, unsigned int reserve)
+{
+	unsigned int old_num = *reserved_maps;
+	unsigned int new_num = *num_maps + reserve;
+	struct pinctrl_map *new_map;
+
+	if (old_num >= new_num)
+		return 0;
+
+	new_map = krealloc_array(*map, new_num, sizeof(*new_map), GFP_KERNEL);
+	if (!new_map) {
+		dev_err(pctldev->dev, "krealloc(map) failed\n");
+		return -ENOMEM;
+	}
+
+	memset(new_map + old_num, 0, (new_num - old_num) * sizeof(*new_map));
+
+	*map = new_map;
+	*reserved_maps = new_num;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pinctrl_utils_reserve_map);
+
+int pinctrl_utils_add_map_mux(struct pinctrl_dev *pctldev,
+		struct pinctrl_map **map, unsigned int *reserved_maps,
+		unsigned int *num_maps, const char *group,
+		const char *function)
+{
+	if (WARN_ON(*num_maps == *reserved_maps))
+		return -ENOSPC;
+
+	(*map)[*num_maps].type = PIN_MAP_TYPE_MUX_GROUP;
+	(*map)[*num_maps].data.mux.group = group;
+	(*map)[*num_maps].data.mux.function = function;
+	(*num_maps)++;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pinctrl_utils_add_map_mux);
+
+int pinctrl_utils_add_map_configs(struct pinctrl_dev *pctldev,
+		struct pinctrl_map **map, unsigned int *reserved_maps,
+		unsigned int *num_maps, const char *group,
+		unsigned long *configs, unsigned int num_configs,
+		enum pinctrl_map_type type)
+{
+	unsigned long *dup_configs;
+
+	if (WARN_ON(*num_maps == *reserved_maps))
+		return -ENOSPC;
+
+	dup_configs = kmemdup_array(configs, num_configs,
+				sizeof(*dup_configs), GFP_KERNEL);
+	if (!dup_configs)
+		return -ENOMEM;
+
+	(*map)[*num_maps].type = type;
+	(*map)[*num_maps].data.configs.group_or_pin = group;
+	(*map)[*num_maps].data.configs.configs = dup_configs;
+	(*map)[*num_maps].data.configs.num_configs = num_configs;
+	(*num_maps)++;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pinctrl_utils_add_map_configs);
+
+int pinctrl_utils_add_config(struct pinctrl_dev *pctldev,
+		unsigned long **configs, unsigned int *num_configs,
+		unsigned long config)
+{
+	unsigned int old_num = *num_configs;
+	unsigned int new_num = old_num + 1;
+	unsigned long *new_configs;
+
+	new_configs = krealloc(*configs, sizeof(*new_configs) * new_num,
+			       GFP_KERNEL);
+	if (!new_configs) {
+		dev_err(pctldev->dev, "krealloc(configs) failed\n");
+		return -ENOMEM;
+	}
+
+	new_configs[old_num] = config;
+
+	*configs = new_configs;
+	*num_configs = new_num;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pinctrl_utils_add_config);
+
+void pinctrl_utils_free_map(struct pinctrl_dev *pctldev,
+	      struct pinctrl_map *map, unsigned int num_maps)
+{
+	int i;
+
+	for (i = 0; i < num_maps; i++) {
+		switch (map[i].type) {
+		case PIN_MAP_TYPE_CONFIGS_GROUP:
+		case PIN_MAP_TYPE_CONFIGS_PIN:
+			kfree(map[i].data.configs.configs);
+			break;
+		default:
+			break;
+		}
+	}
+	kfree(map);
+}
+EXPORT_SYMBOL_GPL(pinctrl_utils_free_map);