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David Howells cfc3b2e0c2 afs: Fix accidental truncation when storing data
[ Upstream commit 03275585ca ]

When an AFS FS.StoreData RPC call is made, amongst other things it is
given the resultant file size to be.  On the server, this is processed
by truncating the file to new size and then writing the data.

Now, kafs has a lock (vnode->io_lock) that serves to serialise
operations against a specific vnode (ie.  inode), but the parameters for
the op are set before the lock is taken.  This allows two writebacks
(say sync and kswapd) to race - and if writes are ongoing the writeback
for a later write could occur before the writeback for an earlier one if
the latter gets interrupted.

Note that afs_writepages() cannot take i_mutex and only takes a shared
lock on vnode->validate_lock.

Also note that the server does the truncation and the write inside a
lock, so there's no problem at that end.

Fix this by moving the calculation for the proposed new i_size inside
the vnode->io_lock.  Also reset the iterator (which we might have read
from) and update the mtime setting there.

Fixes: bd80d8a80e ("afs: Use ITER_XARRAY for writing")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/3526895.1687960024@warthog.procyon.org.uk/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-07-19 16:36:48 +02:00
arch riscv: move memblock_allow_resize() after linear mapping is ready 2023-07-19 16:36:48 +02:00
block blk-throttle: Fix io statistics for cgroup v1 2023-07-19 16:36:40 +02:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:36:19 +02:00
Documentation xsk: Honor SO_BINDTODEVICE on bind 2023-07-19 16:36:47 +02:00
drivers octeontx-af: fix hardware timestamp configuration 2023-07-19 16:36:48 +02:00
fs afs: Fix accidental truncation when storing data 2023-07-19 16:36:48 +02:00
include net: dsa: sja1105: always enable the send_meta options 2023-07-19 16:36:48 +02:00
init kbuild: Fix CFI failures with GCOV 2023-07-19 16:36:23 +02:00
io_uring io_uring/net: use the correct msghdr union member in io_sendmsg_copy_hdr 2023-06-21 07:34:17 -06:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel bpf, btf: Warn but return no error for NULL btf from __register_btf_kfunc_id_set() 2023-07-19 16:36:47 +02:00
lib lib/bitmap: drop optimization of bitmap_{from,to}_arr64 2023-07-19 16:36:39 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm splice: Fix filemap_splice_read() to use the correct inode 2023-07-19 16:35:07 +02:00
net net: dsa: sja1105: always enable the send_meta options 2023-07-19 16:36:48 +02:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples samples/bpf: xdp1 and xdp2 reduce XDPBUFSIZE to 60 2023-07-19 16:35:25 +02:00
scripts kbuild: deb-pkg: remove the CONFIG_MODULES check in buildeb 2023-07-19 16:36:24 +02:00
security apparmor: fix: kzalloc perms tables for shared dfas 2023-07-19 16:36:21 +02:00
sound ALSA: pcm: Fix potential data race at PCM memory allocation helpers 2023-07-19 16:36:21 +02:00
tools tools/virtio: fix build break for aarch64 2023-07-19 16:36:41 +02:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Avoid illegal stage2 mapping on invalid memory slot 2023-06-22 15:14:57 -04:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Ben Dooks 2023-06-19 13:19:35 -07:00
.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 MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
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 Networking fixes for 6.4-rc8, including fixes from ipsec, bpf, 2023-06-22 17:59:51 -07:00
Makefile Linux 6.4.3 2023-07-11 06:31:05 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.