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, 37 insertions, 0 deletions

diff --git a/tools/docs/check-variable-fonts.py b/tools/docs/check-variable-fonts.py
new file mode 100755
index 000000000..958d5a745
--- /dev/null
+++ b/tools/docs/check-variable-fonts.py
@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-only
+# Copyright (C) Akira Yokosawa, 2024
+#
+# Ported to Python by (c) Mauro Carvalho Chehab, 2025
+#
+# pylint: disable=C0103
+
+"""
+Detect problematic Noto CJK variable fonts.
+
+or more details, see .../tools/lib/python/kdoc/latex_fonts.py.
+"""
+
+import argparse
+import sys
+import os.path
+
+src_dir = os.path.dirname(os.path.realpath(__file__))
+sys.path.insert(0, os.path.join(src_dir, '../lib/python'))
+
+from kdoc.latex_fonts import LatexFontChecker
+
+checker = LatexFontChecker()
+
+parser=argparse.ArgumentParser(description=checker.description(),
+                               formatter_class=argparse.RawTextHelpFormatter)
+parser.add_argument("--deny-vf",
+                    help="XDG_CONFIG_HOME dir containing fontconfig/fonts.conf file")
+
+args=parser.parse_args()
+
+msg = LatexFontChecker(args.deny_vf).check()
+if msg:
+    print(msg)
+
+sys.exit(1)