RE: [PATCH] hfsplus: limit sb_maxbytes to partition size

[Viacheslav Dubeyko]

On Wed, 2026-03-04 at 05:08 -0800, Christoph Hellwig wrote:
> On Tue, Mar 03, 2026 at 05:28:07PM +0900, Hyunchul Lee wrote:
> > s_maxbytes currently is set to MAX_LFS_FILESIZE,
> > which allows writes beyond the partition size.
> 
> The "partition size" does not matter here.  s_maxbytes is the maximum
> size supported by the format and has nothing to do with the actual space
> allocated to the file system (which in Linux terminology would be the
> block device and not the partition anyway).
> 
> > 
> > As a result,
> > large-offset writes on small partitions can fail late
> > with ENOSPC.
> 
> That sounds like some other check is missing in hfsplus, but it
> should be about the available free space, not the device size.
> 

I agree with Christoph.

But, frankly speaking, I don't quite follow which particular issue is under fix
here. I can see that generic/268 failure has been mentioned. However, I can see
this:

sudo ./check generic/268 
FSTYP         -- hfsplus
PLATFORM      -- Linux/x86_64 hfsplus-testing-0001 6.19.0-rc1+ #95 SMP
PREEMPT_DYNAMIC Thu Feb 19 15:29:55 PST 2026
MKFS_OPTIONS  -- /dev/loop51
MOUNT_OPTIONS -- /dev/loop51 /mnt/scratch

generic/268       [not run] Reflink not supported by scratch filesystem type:
hfsplus
Ran: generic/268
Not run: generic/268
Passed all 1 tests

Which particular issue is under fix?

Thanks,
Slava.