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, 127 insertions, 0 deletions

diff --git a/drivers/accessibility/speakup/makemapdata.c b/drivers/accessibility/speakup/makemapdata.c
new file mode 100644
index 000000000..55e4ef8a9
--- /dev/null
+++ b/drivers/accessibility/speakup/makemapdata.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* makemapdata.c
+ * originally written by: Kirk Reiser.
+ *
+ ** Copyright (C) 2002  Kirk Reiser.
+ *  Copyright (C) 2003  David Borowski.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <libgen.h>
+#include <string.h>
+#include <ctype.h>
+#include "utils.h"
+
+static char buffer[256];
+
+static int get_define(void)
+{
+	char *c;
+
+	while (fgets(buffer, sizeof(buffer)-1, infile)) {
+		lc++;
+		if (strncmp(buffer, "#define", 7))
+			continue;
+		c = buffer + 7;
+		while (*c == ' ' || *c == '\t')
+			c++;
+		def_name = c;
+		while (*c && *c != ' ' && *c != '\t' && *c != '\n')
+			c++;
+		if (!*c || *c == '\n')
+			continue;
+		*c++ = '\0';
+		while (*c == ' ' || *c == '\t' || *c == '(')
+			c++;
+		def_val = c;
+		while (*c && *c != '\n' && *c != ')')
+			c++;
+		*c++ = '\0';
+		return 1;
+	}
+	fclose(infile);
+	infile = 0;
+	return 0;
+}
+
+int
+main(int argc, char *argv[])
+{
+	int value, i;
+	struct st_key *this;
+	const char *dir_name, *spk_dir_name;
+	char *cp;
+
+	dir_name = getenv("TOPDIR");
+	if (!dir_name)
+		dir_name = ".";
+	spk_dir_name = getenv("SPKDIR");
+	if (!spk_dir_name)
+		spk_dir_name = "drivers/accessibility/speakup";
+	bzero(key_table, sizeof(key_table));
+	add_key("shift",	1, is_shift);
+	add_key("altgr",	2, is_shift);
+	add_key("ctrl",	4, is_shift);
+	add_key("alt",	8, is_shift);
+	add_key("spk", 16, is_shift);
+	add_key("double", 32, is_shift);
+
+	open_input(dir_name, "include/linux/input.h");
+	while (get_define()) {
+		if (strncmp(def_name, "KEY_", 4))
+			continue;
+		value = atoi(def_val);
+		if (value > 0 && value < MAXKEYVAL)
+			add_key(def_name, value, is_input);
+	}
+
+	open_input(dir_name, "include/uapi/linux/input-event-codes.h");
+	while (get_define()) {
+		if (strncmp(def_name, "KEY_", 4))
+			continue;
+		value = atoi(def_val);
+		if (value > 0 && value < MAXKEYVAL)
+			add_key(def_name, value, is_input);
+	}
+
+	open_input(spk_dir_name, "spk_priv_keyinfo.h");
+	while (get_define()) {
+		if (strlen(def_val) > 5) {
+			//if (def_val[0] == '(')
+			//	def_val++;
+			cp = strchr(def_val, '+');
+			if (!cp)
+				continue;
+			if (cp[-1] == ' ')
+				cp[-1] = '\0';
+			*cp++ = '\0';
+			this = find_key(def_val);
+			while (*cp == ' ')
+				cp++;
+			if (!this || *cp < '0' || *cp > '9')
+				continue;
+			value = this->value+atoi(cp);
+		} else if (!strncmp(def_val, "0x", 2))
+			sscanf(def_val+2, "%x", &value);
+		else if (*def_val >= '0' && *def_val <= '9')
+			value = atoi(def_val);
+		else
+			continue;
+		add_key(def_name, value, is_spk);
+	}
+
+	printf("struct st_key_init init_key_data[] = {\n");
+	for (i = 0; i < HASHSIZE; i++) {
+		this = &key_table[i];
+		if (!this->name)
+			continue;
+		do {
+			printf("\t{ \"%s\", %d, %d, },\n", this->name, this->value, this->shift);
+			this = this->next;
+		} while (this);
+	}
+	printf("\t{ \".\", 0, 0 }\n};\n");
+
+	exit(0);
+}