From dd05add7b2b6004c5fa3a1f276f56d8668f86b65 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara 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 Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Christian Brauner Cc: Matthew Wilcox Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org --- samples/livepatch/livepatch-callbacks-mod.c | 42 +++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 samples/livepatch/livepatch-callbacks-mod.c (limited to 'samples/livepatch/livepatch-callbacks-mod.c') diff --git a/samples/livepatch/livepatch-callbacks-mod.c b/samples/livepatch/livepatch-callbacks-mod.c new file mode 100644 index 000000000..d1851b471 --- /dev/null +++ b/samples/livepatch/livepatch-callbacks-mod.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2017 Joe Lawrence + */ + +/* + * livepatch-callbacks-mod.c - (un)patching callbacks demo support module + * + * + * Purpose + * ------- + * + * Simple module to demonstrate livepatch (un)patching callbacks. + * + * + * Usage + * ----- + * + * This module is not intended to be standalone. See the "Usage" + * section of livepatch-callbacks-demo.c. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include + +static int livepatch_callbacks_mod_init(void) +{ + pr_info("%s\n", __func__); + return 0; +} + +static void livepatch_callbacks_mod_exit(void) +{ + pr_info("%s\n", __func__); +} + +module_init(livepatch_callbacks_mod_init); +module_exit(livepatch_callbacks_mod_exit); +MODULE_DESCRIPTION("Live patching demo for (un)patching callbacks, support module"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1