Re: [PATCH v4 1/2] common: new helper to alloacate fixed size files

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Sep 21, 2022 at 04:10:24PM +0200, Pavel Reichl wrote:
> Helper that creates files of specified size using falloc if supported,
> otherwise pwrite is used.
> 
> Signed-off-by: Pavel Reichl <preichl@redhat.com>
> ---
>  common/rc         | 22 ++++++++++++++++++++++
>  tests/generic/694 |  8 +++++++-
>  2 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/common/rc b/common/rc
> index a25cbcd0..3d4587b7 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -4925,6 +4925,28 @@ hexdump()
>  	_fail "Use _hexdump(), please!"
>  }
>  
> +# Try to create a file with inode->i_blocks = $length. There may be some small

Nit: It's really trying to create a file with i_blocks >= (length/blocksize).

> +# overhead, e.g. ext2 filesystem allocates a substantial number of blocks
> +# to store block mappings. Those are accounted to i_blocks.
> +_create_file_sized()
> +{
> +	local length=$1
> +	local file=$2
> +	local tmp=`mktemp -u`
> +	local ret=0
> +
> +	$XFS_IO_PROG -ft -c "falloc 0 $length" $file >$tmp.out 2>&1
> +	ret=$?
> +	if (grep -Eq "Operation not supported|command .* not found" $tmp.out);then
> +		# fallocate isn't supported, fallback to general buffer write
> +		$XFS_IO_PROG -ft -c "pwrite 0 $length" $file >$tmp.out 2>&1
> +		ret=$?
> +	fi
> +	[ $ret -ne 0 ] && cat $tmp.out
> +	rm -f $tmp.out
> +	return $ret
> +}
> +
>  init_rc
>  
>  ################################################################################
> diff --git a/tests/generic/694 b/tests/generic/694
> index dfd988df..09fb9e71 100755
> --- a/tests/generic/694
> +++ b/tests/generic/694
> @@ -21,6 +21,9 @@ _cleanup()
>  }
>  
>  _supported_fs generic
> +_fixed_by_kernel_commit 0c336d6e33f4 \
> +	"exfat: fix incorrect loading of i_blocks for large file"
> +
>  _require_test
>  _require_fs_space $TEST_DIR $((4 * 1024 * 1024)) #kB
>  
> @@ -30,7 +33,10 @@ junk_dir=$TEST_DIR/$seq
>  junk_file=$junk_dir/junk
>  mkdir -p $junk_dir
>  
> -$XFS_IO_PROG -f -c "pwrite -W 0 4G" $junk_file > /dev/null
> +_create_file_sized 4G $junk_file
> +if [ $? -ne 0 ]; then
> +	echo "_create_file_sized failed"

echo "could not create 4G test file" ?

--D

> +fi
>  
>  iblocks=`stat -c '%b' $junk_file`
>  
> -- 
> 2.37.3
>