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A mirror of the official Linux kernel repository just in case
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NeilBrown 442ce0499c NFS: invalidate file size when taking a lock. 
Prior to commit ca0daa277a ("NFS: Cache aggressively when file is open
for writing"), NFS would revalidate, or invalidate, the file size when
taking a lock.  Since that commit it only invalidates the file content.

If the file size is changed on the server while wait for the lock, the
client will have an incorrect understanding of the file size and could
corrupt data.  This particularly happens when writing beyond the
(supposed) end of file and can be easily be demonstrated with
posix_fallocate().

If an application opens an empty file, waits for a write lock, and then
calls posix_fallocate(), glibc will determine that the underlying
filesystem doesn't support fallocate (assuming version 4.1 or earlier)
and will write out a '0' byte at the end of each 4K page in the region
being fallocated that is after the end of the file.
NFS will (usually) detect that these writes are beyond EOF and will
expand them to cover the whole page, and then will merge the pages.
Consequently, NFS will write out large blocks of zeroes beyond where it
thought EOF was.  If EOF had moved, the pre-existing part of the file
will be over-written.  Locking should have protected against this,
but it doesn't.

This patch restores the use of nfs_zap_caches() which invalidated the
cached attributes.  When posix_fallocate() asks for the file size, the
request will go to the server and get a correct answer.

cc: stable@vger.kernel.org (v4.8+)
Fixes: ca0daa277a ("NFS: Cache aggressively when file is open for writing")
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2017-07-27 11:22:42 -04:00
arch Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2017-06-11 16:17:29 -07:00
block block, bfq: access and cache blkg data only when safe 2017-06-08 09:51:10 -06:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto crypto : asymmetric_keys : verify_pefile:zero memory content before freeing 2017-06-09 13:29:50 +10:00
Documentation USB fixes for 4.12-rc5 2017-06-11 11:23:10 -07:00
drivers Improve performance by using a lockless update mechanism suggested by 2017-06-11 12:02:01 -07:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs NFS: invalidate file size when taking a lock. 2017-07-27 11:22:42 -04:00
include NFS: Store the raw NFS access mask in the inode's access cache 2017-07-21 11:51:19 -04:00
init Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-10 10:30:46 -07:00
ipc mm: introduce kv[mz]alloc helpers 2017-05-08 17:15:12 -07:00
kernel Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-06-10 10:49:42 -07:00
lib test_bpf: Add a couple of tests for BPF_JSGE. 2017-05-25 14:37:56 -04:00
mm mm: consider memblock reservations for deferred memory initialization sizing 2017-06-02 15:07:38 -07:00
net net/sunrpc/xprt_sock: fix regression in connection error reporting. 2017-07-21 08:49:58 -04:00
samples samples/bpf: run cleanup routines when receiving SIGTERM 2017-05-11 21:43:30 -04:00
scripts scripts/gdb: make lx-dmesg command work (reliably) 2017-06-02 15:07:38 -07:00
security KEYS: fix refcount_inc() on zero 2017-06-09 13:29:50 +10:00
sound ALSA: timer: Fix missing queue indices reset at SNDRV_TIMER_IOCTL_SELECT 2017-06-07 10:25:23 +02:00
tools perf symbols: Kill dso__build_id_is_kmod() 2017-06-08 15:39:34 -03:00
usr initramfs: fix disabling of initramfs (and its compression) 2017-06-02 15:07:37 -07:00
virt KVM: arm/arm64: Handle possible NULL stage2 pud when ageing pages 2017-06-06 15:28:40 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS A few overdue GPIO patches for the v4.12 kernel: 2017-06-11 11:34:27 -07:00
Makefile Linux 4.12-rc5 2017-06-11 16:48:20 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.