Re: [PATCH v3] common: Check for fiemap range argument support

Eric Sandeen
2017-11-14T15:09:24Z

On 11/2/17 3:13 AM, Nikolay Borisov wrote:
> From: Nikolay Borsiov <nborisov@suse.com>
>
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> ---
> v3:
> * Changed the way we detect ranged args. Now use a regexp which checks
> explicitly for the ranged args
> common/rc | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/common/rc b/common/rc
> index e2a8229..f7a5fe9 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -2053,8 +2053,15 @@ _require_xfs_io_command()
> -c "$command 4k 8k" $testfile 2>&1`
> ;;
> "fiemap")
> + if echo "$param" | egrep -q "[[:digit:]]+[bskmgtpe]? [[:digit:]]+[bskmgtpe]?$"
> + then
> + $XFS_IO_PROG -c "help fiemap" | head -n 1 | grep -q "[offset [len]]" || \
> + _notrun "xfs_io $command range param support is missing"
> + fi
> +

What if, rather than difficult to read regexps, we actually checked the functionality?
The check already writes a testfile; you could try fiemapping past EOF and see what
you get, i.e. for a file in a single 4k block:

$ io/xfs_io -c "fiemap" short
short:
0: [0..7]: 2788960..2788967

Mapping past EOF will give you no extents (if the range values are honored by the
command):

$ io/xfs_io -c "fiemap 4k 4k" short
short:

> testio=`$XFS_IO_PROG -F -f -c "pwrite 0 20k" -c "fsync" \
> -c "fiemap -v $param" $testfile 2>&1`

so I think you could switch based on [ -n $param ] about whether we were asked
to check a range and if so, map past EOF, and return success or fail based
on what you get back. The only slight weirdness is that you're asking to check
a specific range (_require_xfs_io_command "fiemap" "0 4k") but possibly testing
a different one ("20k 4k") but not sure if that matters.

It'd be a bit of a departure but with enough comments, maybe ok to do it as:

_require_xfs_io_command "fiemap" "ranged"

and use the "ranged" param to DTRT in the test.

-Eric

> +
> param_checked=1
> ;;
> "flink" )
>