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Filename Latest commit message Latest commit date
Coly Li d59b237959 bcache: only permit to recovery read error when cache device is clean
When bcache does read I/Os, for example in writeback or writethrough mode,
if a read request on cache device is failed, bcache will try to recovery
the request by reading from cached device. If the data on cached device is
not synced with cache device, then requester will get a stale data.

For critical storage system like database, providing stale data from
recovery may result an application level data corruption, which is
unacceptible.

With this patch, for a failed read request in writeback or writethrough
mode, recovery a recoverable read request only happens when cache device
is clean. That is to say, all data on cached device is up to update.

For other cache modes in bcache, read request will never hit
cached_dev_read_error(), they don't need this patch.

Please note, because cache mode can be switched arbitrarily in run time, a
writethrough mode might be switched from a writeback mode. Therefore
checking dc->has_data in writethrough mode still makes sense.

Changelog:
V4: Fix parens error pointed by Michael Lyle.
v3: By response from Kent Oversteet, he thinks recovering stale data is a
    bug to fix, and option to permit it is unnecessary. So this version
    the sysfs file is removed.
v2: rename sysfs entry from allow_stale_data_on_failure  to
    allow_stale_data_on_failure, and fix the confusing commit log.
v1: initial patch posted.

[small change to patch comment spelling by mlyle]

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Reported-by: Arne Wolf <awolf@lenovo.com>
Reviewed-by: Michael Lyle <mlyle@lyle.org>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Nix <nix@esperi.org.uk>
Cc: Kai Krakow <hurikhan77@gmail.com>
Cc: Eric Wheeler <bcache@lists.ewheeler.net>
Cc: Junhui Tang <tang.junhui@zte.com.cn>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-30 15:57:54 -06:00
arch Microblaze patches for 4.14-rc3 2017-09-25 15:37:19 -07:00
block block: Fix a race between blk_cleanup_queue() and timeout handling 2017-10-30 13:28:10 -06:00
certs
crypto crypto: af_alg - update correct dst SGL entry 2017-09-20 17:42:42 +08:00
Documentation null_blk: add usage hints for no_sched 2017-10-13 10:52:39 -06:00
drivers bcache: only permit to recovery read error when cache device is clean 2017-10-30 15:57:54 -06:00
firmware firmware: Restore support for built-in firmware 2017-09-16 10:58:48 -07:00
fs fs/block_dev: remove vfs_msg() interface 2017-10-12 12:30:24 -06:00
include elevator: allow name aliases 2017-10-25 12:36:50 -06:00
init Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-09-14 18:54:01 -07:00
ipc fix a typo in put_compat_shm_info() 2017-09-25 20:41:46 -04:00
kernel sysctl: remove /proc/sys/vm/nr_pdflush_threads 2017-10-04 11:24:16 -06:00
lib Merge branch 'parisc-4.14-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 2017-09-23 06:14:06 -10:00
mm mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately 2017-10-14 09:14:35 -06:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-09-23 05:41:27 -10:00
samples media updates for v4.14-rc1 2017-09-07 12:53:14 -07:00
scripts DeviceTree fixes for 4.14: 2017-09-24 16:04:12 -07:00
security Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2017-09-24 11:40:41 -07:00
sound vfs: constify path argument to kernel_read_file_from_path 2017-09-14 20:18:45 -07:00
tools Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-24 12:33:58 -07:00
usr
virt Revert "KVM: Don't accept obviously wrong gsi values via KVM_IRQFD" 2017-09-19 08:37:17 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS selinux/stable-4.14 PR 20170831 2017-09-12 13:21:00 -07:00
Kbuild
Kconfig
MAINTAINERS bcache: MAINTAINERS: set bcache to MAINTAINED 2017-10-16 09:07:26 -06:00
Makefile Linux 4.14-rc2 2017-09-24 16:38:56 -07:00
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.