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David Howells ca9ca1a5d5 netfs: Fix missing zero-length check in unbuffered write
Fix netfs_unbuffered_write_iter() to return immediately if
generic_write_checks() returns 0, indicating there's nothing to write.
Note that netfs_file_write_iter() already does this.

Also, whilst we're at it, put in checks for the size being zero before we
even take the locks.  Note that generic_write_checks() can still reduce the
size to zero, so we still need that check.

Without this, a warning similar to the following is logged to dmesg:

	netfs: Zero-sized write [R=1b6da]

and the syscall fails with EIO, e.g.:

	/sbin/ldconfig.real: Writing of cache extension data failed: Input/output error

This can be reproduced on 9p by:

	xfs_io -f -c 'pwrite 0 0' /xfstest.test/foo

Fixes: 153a9961b5 ("netfs: Implement unbuffered/DIO write support")
Reported-by: Eric Van Hensbergen <ericvh@kernel.org>
Link: https://lore.kernel.org/r/ZbQUU6QKmIftKsmo@FV7GG9FTHL/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20240129094924.1221977-3-dhowells@redhat.com
Tested-by: Dominique Martinet <asmadeus@codewreck.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Dominique Martinet <asmadeus@codewreck.org>
cc: Jeff Layton <jlayton@kernel.org>
cc:  <v9fs@lists.linux.dev>
cc:  <linux_oss@crudebyte.com>
cc:  <netfs@lists.linux.dev>
cc:  <linux-fsdevel@vger.kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-01-29 14:53:21 +01:00
Documentation platform-drivers-x86 for v6.8-2 2024-01-27 09:48:55 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
arch - fix for boot issue on single core Lantiq Danube devices 2024-01-28 10:43:06 -08:00
block block: Fix WARNING in _copy_from_iter 2024-01-23 08:56:55 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto crypto: scomp - fix req->dst buffer overflow 2023-12-29 11:25:56 +08:00
drivers cxl fixes for 6.8-rc2 2024-01-28 13:55:56 -08:00
fs netfs: Fix missing zero-length check in unbuffered write 2024-01-29 14:53:21 +01:00
include - Make sure 32-bit syscall registers are properly sign-extended 2024-01-28 09:45:11 -08:00
init init: Kconfig: Disable -Wstringop-overflow for GCC-11 2024-01-21 17:45:31 -06:00
io_uring io_uring: enable audit and restrict cred override for IORING_OP_FIXED_FD_INSTALL 2024-01-23 15:25:14 -07:00
ipc shm: Slim down dependencies 2023-12-20 19:26:31 -05:00
kernel - Prevent an inconsistent futex operation leading to stale state 2024-01-28 10:38:16 -08:00
lib RISC-V Patches for the 6.8 Merge Window, Part 4 2024-01-20 11:06:04 -08:00
mm memblock: fix crash when reserved memory is not added to memory 2024-01-28 09:41:39 -08:00
net Including fixes from bpf, netfilter and WiFi. 2024-01-25 10:58:35 -08:00
rust Rust changes for v6.8 2024-01-11 13:05:41 -08:00
samples samples/cgroup: add .gitignore file for generated samples 2024-01-24 11:52:40 -08:00
scripts Makefile: Enable -Wstringop-overflow globally 2024-01-21 17:45:31 -06:00
security integrity-6.8-rc1 2024-01-24 16:51:59 -08:00
sound sound fixes for 6.8-rc1 2024-01-19 12:30:29 -08:00
tools cxl fixes for 6.8-rc2 2024-01-28 13:55:56 -08:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt Generic: 2024-01-17 13:03:37 -08:00
.clang-format clang-format: Update with v6.7-rc4's `for_each` macro list 2023-12-08 23:54:38 +01:00
.cocciconfig
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.mailmap Char/Misc and other Driver changes for 6.8-rc1 2024-01-17 16:47:17 -08:00
.rustfmt.toml rust: add `.rustfmt.toml` 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS Including fixes from bpf and netfilter. 2024-01-18 17:33:50 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS platform-drivers-x86 for v6.8-2 2024-01-27 09:48:55 -08:00
Makefile Linux 6.8-rc2 2024-01-28 17:01:12 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.