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

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

On Thu, Jul 30, 2026 at 04:33:37PM +0530, Ojaswin Mujoo wrote:
> On Wed, Jul 29, 2026 at 08:44:51AM -0700, Darrick J. Wong wrote:
> > On Wed, Jul 29, 2026 at 11:06:57AM +0530, Ojaswin Mujoo wrote:
> > > 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 <disgoel@linux.ibm.com>
> > > > > Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
> > > > > ---
> > > > >  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"
> > > 
> > 
> > Hmmm.  This is getting complicated, because generic tests can run on any
> > filesystem and we have no idea how much space an inode actually
> > consumes, or if the filesystem even has any real concept of inodes.
> > 
> > Can we instead check the vfstest output for the ENOSPC error message and
> > _notrun it if that is found?
> 
> Yes this sounds simple enough. The below diff works for me:
> 
>   diff --git a/tests/generic/645 b/tests/generic/645
>   index d6eb75e6..3d8ca905 100755
>   --- a/tests/generic/645
>   +++ b/tests/generic/645
>   @@ -22,7 +22,14 @@ _wants_kernel_commit dacfd001eaf2 \
>    echo "Silence is golden"
>   
>    $here/src/vfs/vfstest --test-nested-userns \
>   -       --device "$TEST_DEV" --mount "$TEST_DIR" --fstype "$FSTYP"
>   +       --device "$TEST_DEV" --mount "$TEST_DIR" --fstype "$FSTYP" \
>   +       > $tmp.vfstest 2>&1
>   
>   +if grep -q "No space left on device" $tmp.vfstest; then
>   +       _notrun "No space left on device"
>   +fi
>   +
>   +cat $tmp.vfstest
>    status=$?
> 
> If this looks good I cans send a formal patch.

Yes! :)

--D

> 
> Regards,
> ojaswin 
> 
> > 
> > --D
> > 
> > > 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
> > > > > 
> > > > > 
> > >