Re: [PATCH] generic/645: Confirm availability of free inodes

On Thu, Jun 25, 2026 at 11:42:59AM -0700, Darrick J. Wong wrote:
> On Wed, Jun 17, 2026 at 11:12:16AM +0530, Ojaswin Mujoo wrote:
> > When running generic/645 with ext4 using 64k block size + bigalloc, the
> > test fails with ENOSPC because the filesystem runs out of inodes before
> > the test completes.
> > 
> > The test creates approximately 10,001 files, however, in this particular
> > configuration a standard 5G FS only has around ~5100 inodes resulting in
> > the ENOSPC failure.
> > 
> > Add a check using _get_free_inode() to verify sufficient inodes are
> > available before running the test, else skip it.
> > 
> > Reported-by: Disha Goel <[email protected]>
> > Signed-off-by: Ojaswin Mujoo <[email protected]>
> > ---
> >  tests/generic/645 | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/tests/generic/645 b/tests/generic/645
> > index d6eb75e6..944b33db 100755
> > --- a/tests/generic/645
> > +++ b/tests/generic/645
> > @@ -19,6 +19,12 @@ _require_chown
> >  _wants_kernel_commit dacfd001eaf2 \
> >  	"fs/mnt_idmapping.c: Return -EINVAL when no map is written"
> >  
> > +_free_inodes=$(_get_free_inode $TEST_DIR)
> > +if [ $_free_inodes -ne 0 ] && [ $_free_inodes -lt 10001 ]; then
> 
> I'm assuming the > 0 check here is to cover weird filesystems like fat
> that don't advertise any inodes?  /me wonders if that ought to be a

Hey Darrick, sorry I missed this email earlier. Yes that's the idea. I
see there is a helper already

_require_inode_limits()
{
	if [ $(_get_free_inode $TEST_DIR) -eq 0 ]; then
		_notrun "$FSTYP does not have a fixed number of inodes available"
	fi
}

But this will end up skipping the FSes that don't have a concept of
free inodes.

> common helper where we can record that justification:
> 
> _require_free_inodes() {
> 	local path="$1"
> 	local nr="$2"
> 
> 	local _free_inodes=$(_get_free_inode "$path")
> 
> 	# Weird filesystems like vfat don't report any inodes, so we
> 	# can't check for sufficient free inodes; IOWs, FAFO.
> 	test "$_free_inodes" -eq 0 && return

If we do this, won't we pass the check for the case where say xfs has 0
free inodes. It's a rare chance IMObut still wondering if we want to
keep that edge case open.

What do you think in these options:
- use the above check
- use _require_free_inodes which will cause notruns on some FSes
- Maybe have a new helper to check if FS advertises free inodes and then
  use somthing like

  if ! __fs_advertises_free_inodes
    return
  else
    test "$_free_inodes" -lt "$nr" && \
    _notrun "Insufficient free inodes ($_free_inodes), need at least $nr"


Regards,
ojaswin

> 
> 	test "$_free_inodes" -lt "$nr" && \
> 		_notrun "Insufficient free inodes ($_free_inodes), need at least $nr"
> }
> 
> 
> _require_free_inodes $TEST_DIR 10001
> 
> (maybe clean up the comment a bit)

> 
> --D
> 
> > +	_notrun "Insufficient free inodes ($_free_inodes), need at least 10001"
> > +fi
> > +
> >  echo "Silence is golden"
> >  
> >  $here/src/vfs/vfstest --test-nested-userns \
> > -- 
> > 2.53.0
> > 
> >