Re: [PATCH v8 1/3] xfstests: btrfs: add functions to create dm-error device

[Eryu Guan <eguan@redhat.com>]

On Tue, Aug 25, 2015 at 12:39:26PM +0800, Anand Jain wrote:
> From: Anand Jain <Anand.Jain@oracle.com>
> 
> Controlled EIO from the device is achieved using the dm device.
> Helper functions are at common/dmerror.
> 
> Broadly steps will include calling _dmerror_init().
> _dmerror_init() will use SCRATCH_DEV to create dm linear device and assign
> DMERROR_DEV to /dev/mapper/error-test.
> 
> When test script is ready to get EIO, the test cases can call
> _dmerror_load_table() which then it will load the dm error.
> so that reading DMERROR_DEV will cause EIO. After the test case is
> complete, cleanup must be done by calling _dmerror_cleanup().
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> Reviewed-by: Filipe Manana <fdmanana@suse.com>
> ---
> v7->v8:
>  . Mainly avoid duplicate lines of code, create reusable functions
>   _common_dev_mount_options(), dmerror_mount_options(),
>   _dmerror_mount()
>  . Update _scratch_mount_option() to use _common_dev_mount_options()
> 
> v6->v7:
>  rename _init_dmerror() to _dmerror_init()
>  remove _scratch_mkfs_dmerror()
>  rename _mount_dmerror() to _dmerror_mount()
>  rename _cleaup_dmerror() to _dmerror_cleanup()
>  rename _load_dmerror_table() to _dmerror_load_table()
>  rename BLK_DEV_SIZE to blk_dev_size
>  remove _unmount_dmerror there were no consumer of it
>  use _fail instead of _fatal in rc/dmerror
>  update error log to make crisp sense
>  move _require_dmerror() from common/rc to common/dmerror and rename
>    it to dmerror_required() so that its consistent with other function
>    names with in the file
> 
> v5->v6: accepts Eryu's comments, thanks
>  . added missing $MKFS_OPTIONS at _scratch_mkfs_dmerror()
>  . used $MOUNT_PROG instead of mount at _mount_dmerror()
>  . correct typo $UMOUNT_PROG, no S at the end in _unmount_dmerror()
> 
> v4->v5: No Change. keep up with the patch set
> 
> v3->v4: rebase on latest xfstests code
> 
> v2.1->v3: accepts Filipe Manana's review comments, thanks
>  . correct if else statement in _require_dm_error()
>  . fix indent 
>    (a missed Dave comment in v1. looks like I goofed with git cli)
> 
> v2->v2.1: fixed missed typo error fixup in the commit.
> 
> v1->v2: accepts Dave Chinner's review comments, thanks
>  . use SCRATCH_DEV for dmerror backing device
>  . remove duplicate check of DM_BLK_DEV in _init_dm_error_dev()
>  . remove a wrong check when reading block size in _init_dm_error_dev()
>  . remove a wrong check with blockdev --setra in _init_dm_error_dev()
>  . remove unnecessary check in _load_dm_error_table()
>  . remove unnecessary dmerror device test by using dd
> 
>  common/dmerror | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  common/rc      | 13 +++++++++--
>  2 files changed, 85 insertions(+), 2 deletions(-)
>  create mode 100644 common/dmerror
> 
> diff --git a/common/dmerror b/common/dmerror
> new file mode 100644
> index 0000000..8ba2262
> --- /dev/null
> +++ b/common/dmerror
> @@ -0,0 +1,74 @@
> +##/bin/bash
> +#
> +# Copyright (c) 2015 Oracle.  All Rights Reserved.
> +#
> +# This program is free software; you can redistribute it and/or
> +# modify it under the terms of the GNU General Public License as
> +# published by the Free Software Foundation.
> +#
> +# This program is distributed in the hope that it would be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program; if not, write the Free Software Foundation,
> +# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
> +#
> +#
> +# common functions for setting up and tearing down a dmerror device
> +
> +# this test requires the device mapper error target
> +#
> +_dmerror_required()

I think this should be renamed to _require_dmerror or _require_dm_error,
following the naming convention through xfstests, and be moved to
common/rc, see _require_dm_flakey in common/rc

> +{
> +	_require_command "$DMSETUP_PROG" dmsetup

Need these two "requires" too

	_require_block_device $SCRATCH_DEV
	_require_sane_bdev_flush $SCRATCH_DEV

> +	$DMSETUP_PROG targets | grep error >/dev/null 2>&1

modprobe dm-error first? in case dm-error built as a module, as what
_require_dm_flakey does.

> +	[ $? -ne 0 ] && _notrun "This test requires dm error support"
> +}
> +
> +_dmerror_init()

I notice that all dm-error functions are named as _dmerror_xxx and
dm-flakey functions are named as _xxx_flakey, do we need to stick to the
same naming scheme as in flakey test? If that doesn't matter I prefer
the _dmerror_xxx format, personally :)

Thanks,
Eryu