From dd05add7b2b6004c5fa3a1f276f56d8668f86b65 Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <pc@manguebit.org>
Date: Sat, 26 Sep 2026 19:20:30 -0300
Subject: netfs: zero the tail of a short DIO/unbuffered read

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
---
 scripts/module-common.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 scripts/module-common.c

(limited to 'scripts/module-common.c')

diff --git a/scripts/module-common.c b/scripts/module-common.c
new file mode 100644
index 000000000..12fbc6d3a
--- /dev/null
+++ b/scripts/module-common.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/module.h>
+/*
+ * Include build-salt.h after module.h in order to
+ * inherit the definitions.
+ */
+#define INCLUDE_VERMAGIC
+#include <linux/build-salt.h>
+#include <linux/elfnote-lto.h>
+#include <linux/vermagic.h>
+
+#ifdef CONFIG_UNWINDER_ORC
+#include <asm/orc_header.h>
+ORC_HEADER;
+#endif
+
+BUILD_SALT;
+BUILD_LTO_INFO;
+
+MODULE_INFO(vermagic, VERMAGIC_STRING);
+
+#ifdef CONFIG_MITIGATION_RETPOLINE
+MODULE_INFO(retpoline, "Y");
+#endif
-- 
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