git: sys/dev/disk/dm: Add dm-flakey target

[Tomohiro Kusumi]

commit b9790952d463c74d2706f84a3b2b5e035eb3059b
Author: Tomohiro Kusumi <kusumi.tomohiro at gmail.com>
Date:   Sun Nov 15 19:22:47 2015 +0900

    sys/dev/disk/dm: Add dm-flakey target
    
    This commit adds a new dm target dm-flakey.
    
    This target simulates failing devices for testing purposes.
    See dm_target_flakey(4) for details.
    
    Note that using this dm target may results in some unstable
    status including kernel panic. For example hammer is likely
    to cause kernel panic by write data corruption by dm-flakey.
    Don't use this target over any block device in production.
    
      ===== Example1 - Error write I/Os
      # kldload dm_target_flakey
      # dmsetup create flakey1 --table "0 234436482 flakey ${DEV} 0 1 1"
      # newfs_hammer -L TEST /dev/mapper/flakey1
      Volume 0 DEVICE /dev/mapper/flakey1 size 111.79GB
      initialize freemap volume 0
      initializing the undo map (504 MB)
      newfs_hammer: Write volume 0 (/dev/mapper/flakey1): Input/output error
      # dmsetup remove /dev/mapper/flakey1
    
      ===== Example2 - Silently drop write I/Os
      # newfs_hammer -L TEST ${DEV} > /dev/null
      # mount_hammer ${DEV} /HAMMER
      # cd /HAMMER
      # git clone /usr/local/src/dragonfly
      Cloning into 'dragonfly'...
      done.
      Checking out files: 100% (34434/34434), done.
      # cd
      # umount /HAMMER
      # dmsetup create flakey2 --table "0 234436482 flakey ${DEV} 0 1 1 1 drop_writes"
      # mount_hammer /dev/mapper/flakey2 /HAMMER
      # dmesg | tail -3
      HAMMER() Critical error inode=-1 error=5 while flushing meta-data
      HAMMER() Forcing read-only mode
      HAMMER(TEST) mounted clean, no recovery needed
      # hammer volume-list /HAMMER
      /dev/mapper/flakey2
      # mount | grep "/HAMMER"
      TEST on /HAMMER (hammer, local, read-only)
      # cd /HAMMER/dragonfly
      # git log -p > /dev/null; echo $?
      0
      # cd
      # umount /HAMMER
      # dmsetup remove /dev/mapper/flakey2
    
      ===== Example3 - Corrupt read I/Os
      # dd if=/dev/zero of=${DEV} bs=1024 count=10000 >/dev/null 2>&1
      # dmsetup create flakey3 --table "0 234436482 flakey ${DEV} 0 1 1 5 corrupt_bio_byte 1 r 65 0"
      # od -tx1 /dev/mapper/flakey3 | head -10
      0000000    41  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
      0000020    00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
      *
      0010000    41  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
      0010020    00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
      *
      0020000    41  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
      0020020    00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
      *
      0030000    41  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
      # dmsetup remove /dev/mapper/flakey3
      # kldunload dm_target_flakey

Summary of changes:
 share/man/man4/Makefile                            |   1 +
 .../man4/{dm_target_delay.4 => dm_target_flakey.4} |  74 +++-
 sys/conf/files                                     |   1 +
 sys/config/LINT64                                  |   1 +
 sys/dev/disk/dm/dm.h                               |   1 +
 sys/dev/disk/dm/targets/Makefile                   |   2 +-
 sys/dev/disk/dm/targets/flakey/Makefile            |   5 +
 sys/dev/disk/dm/targets/flakey/dm_target_flakey.c  | 411 +++++++++++++++++++++
 8 files changed, 481 insertions(+), 15 deletions(-)
 copy share/man/man4/{dm_target_delay.4 => dm_target_flakey.4} (50%)
 create mode 100644 sys/dev/disk/dm/targets/flakey/Makefile
 create mode 100644 sys/dev/disk/dm/targets/flakey/dm_target_flakey.c

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/b9790952d463c74d2706f84a3b2b5e035eb3059b


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