UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity
768,043 Commits 6 Branches 27 Tags 3.2 GiB
C 97%
Assembly 1.4%
C++ 0.6%
Makefile 0.3%
Shell 0.3%
Other 0.3%
Go to file
Ilya Dryomov 5b1fe7bec8 dm cache metadata: set dirty on all cache blocks after a crash 
Quoting Documentation/device-mapper/cache.txt:

  The 'dirty' state for a cache block changes far too frequently for us
  to keep updating it on the fly.  So we treat it as a hint.  In normal
  operation it will be written when the dm device is suspended.  If the
  system crashes all cache blocks will be assumed dirty when restarted.

This got broken in commit f177940a80 ("dm cache metadata: switch to
using the new cursor api for loading metadata") in 4.9, which removed
the code that consulted cmd->clean_when_opened (CLEAN_SHUTDOWN on-disk
flag) when loading cache blocks.  This results in data corruption on an
unclean shutdown with dirty cache blocks on the fast device.  After the
crash those blocks are considered clean and may get evicted from the
cache at any time.  This can be demonstrated by doing a lot of reads
to trigger individual evictions, but uncache is more predictable:

  ### Disable auto-activation in lvm.conf to be able to do uncache in
  ### time (i.e. see uncache doing flushing) when the fix is applied.

  # xfs_io -d -c 'pwrite -b 4M -S 0xaa 0 1G' /dev/vdb
  # vgcreate vg_cache /dev/vdb /dev/vdc
  # lvcreate -L 1G -n lv_slowdev vg_cache /dev/vdb
  # lvcreate -L 512M -n lv_cachedev vg_cache /dev/vdc
  # lvcreate -L 256M -n lv_metadev vg_cache /dev/vdc
  # lvconvert --type cache-pool --cachemode writeback vg_cache/lv_cachedev --poolmetadata vg_cache/lv_metadev
  # lvconvert --type cache vg_cache/lv_slowdev --cachepool vg_cache/lv_cachedev
  # xfs_io -d -c 'pwrite -b 4M -S 0xbb 0 512M' /dev/mapper/vg_cache-lv_slowdev
  # xfs_io -d -c 'pread -v 254M 512' /dev/mapper/vg_cache-lv_slowdev | head -n 2
  0fe00000:  bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb  ................
  0fe00010:  bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb  ................
  # dmsetup status vg_cache-lv_slowdev
  0 2097152 cache 8 27/65536 128 8192/8192 1 100 0 0 0 8192 7065 2 metadata2 writeback 2 migration_threshold 2048 smq 0 rw -
                                                            ^^^^
                                7065 * 64k = 441M yet to be written to the slow device
  # echo b >/proc/sysrq-trigger

  # vgchange -ay vg_cache
  # xfs_io -d -c 'pread -v 254M 512' /dev/mapper/vg_cache-lv_slowdev | head -n 2
  0fe00000:  bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb  ................
  0fe00010:  bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb  ................
  # lvconvert --uncache vg_cache/lv_slowdev
  Flushing 0 blocks for cache vg_cache/lv_slowdev.
  Logical volume "lv_cachedev" successfully removed
  Logical volume vg_cache/lv_slowdev is not cached.
  # xfs_io -d -c 'pread -v 254M 512' /dev/mapper/vg_cache-lv_slowdev | head -n 2
  0fe00000:  aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa  ................
  0fe00010:  aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa  ................

This is the case with both v1 and v2 cache pool metatata formats.

After applying this patch:

  # vgchange -ay vg_cache
  # xfs_io -d -c 'pread -v 254M 512' /dev/mapper/vg_cache-lv_slowdev | head -n 2
  0fe00000:  bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb  ................
  0fe00010:  bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb  ................
  # lvconvert --uncache vg_cache/lv_slowdev
  Flushing 3724 blocks for cache vg_cache/lv_slowdev.
  ...
  Flushing 71 blocks for cache vg_cache/lv_slowdev.
  Logical volume "lv_cachedev" successfully removed
  Logical volume vg_cache/lv_slowdev is not cached.
  # xfs_io -d -c 'pread -v 254M 512' /dev/mapper/vg_cache-lv_slowdev | head -n 2
  0fe00000:  bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb  ................
  0fe00010:  bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb  ................

Cc: stable@vger.kernel.org
Fixes: f177940a80 ("dm cache metadata: switch to using the new cursor api for loading metadata")
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
 		2018-08-09 12:14:32 -04:00
Documentation dm thin: include metadata_low_watermark threshold in pool status 2018-07-30 11:49:08 -04:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
arch alpha: fix osf_wait4() breakage 2018-07-22 11:51:30 -07:00
block for-linus-20180713 2018-07-14 12:28:00 -07:00
certs certs/blacklist: fix const confusion 2018-06-26 09:43:03 -07:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-07-19 07:32:44 -07:00
drivers dm cache metadata: set dirty on all cache blocks after a crash 2018-08-09 12:14:32 -04:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-07-22 12:04:51 -07:00
include dm kcopyd: return void from dm_kcopyd_copy() 2018-07-31 17:33:21 -04:00
init Kbuild fixes for v4.18 2018-06-30 13:05:30 -07:00
ipc ipc: use new return type vm_fault_t 2018-06-15 07:55:25 +09:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-07-21 17:21:34 -07:00
lib Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-07-21 16:52:08 -07:00
mm mm: make vm_area_alloc() initialize core fields 2018-07-21 15:24:03 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-07-18 19:32:54 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-07-18 19:32:54 -07:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-07-18 19:32:54 -07:00
security selinux/stable-4.18 PR 20180629 2018-06-30 11:15:12 -07:00
sound ALSA: hda/realtek - Yet another Clevo P950 quirk entry 2018-07-18 12:17:46 +02:00
tools Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-07-21 16:52:08 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt Miscellaneous bugfixes, plus a small patchlet related to Spectre v2. 2018-07-18 11:08:44 -07:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.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 updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'asoc-4.17' into asoc-4.18 for compress dependencies 2018-04-26 12:24:28 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: add basic helper macros to scripts/Kconfig.include 2018-05-29 03:31:19 +09:00
MAINTAINERS MAINTAINERS: Peter has moved 2018-07-21 12:50:46 -07:00
Makefile Linux 4.18-rc6 2018-07-22 14:12:20 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
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.