On Wed, Sep 21, 2022 at 10:48:57AM +0800, Zorro Lang wrote:
> On Tue, Sep 20, 2022 at 09:35:13AM +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@xxxxxxxxxx>
> > ---
> > common/rc | 13 +++++++++++++
> > tests/generic/694 | 2 +-
> > 2 files changed, 14 insertions(+), 1 deletion(-)
> >
> > diff --git a/common/rc b/common/rc
> > index a25cbcd0..77866582 100644
> > --- a/common/rc
> > +++ b/common/rc
> > @@ -4925,6 +4925,19 @@ hexdump()
> > _fail "Use _hexdump(), please!"
> > }
> >
> > +# Helper to write a file containing specified number of bytes using
> > +# falloc if supported, otherwise use pwrite
> > +_create_sizedfile()
> > +{
> > + length=$1
> > + file=$2
> > +
> > + $XFS_IO_PROG -F -fc "falloc 0 $length" $file 2>&1 | grep -q "Operation not supported"
> > + if [ $? -eq 0 ]; then
> > + $XFS_IO_PROG -F -fc "pwrite -W 0 $length" $file >/dev/null
> > + fi
> > +}
>
> I think about it more, above code might ignore a failed falloc, if it's not failed
> by "Operation not supported" but really fails, this function won't print or return
> any valid things.
>
> So how about we write it like below (for reference only):
>
> # Try to create a file which inode->i_blocks = $length (maybe a little bigger
> # than expect)
> _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 $ret
> }
>
> Even though, I think this function might still not good, feel free to tell me if
> anyone has better idea/suggestion about how to get a file with specified
> inode->i_blocks.
Looks reasonable enough to /me...
--D
> Thanks,
> Zorro
>
> > +
> > init_rc
> >
> > ################################################################################
> > diff --git a/tests/generic/694 b/tests/generic/694
> > index dfd988df..64c3dd9a 100755
> > --- a/tests/generic/694
> > +++ b/tests/generic/694
> > @@ -30,7 +30,7 @@ junk_dir=$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_sizedfile 4G $junk_file
> >
> > iblocks=`stat -c '%b' $junk_file`
> >
> > --
> > 2.37.3
> >
>
