Re: [REGRESSION] exfat: swapon(2) fails with EINVAL after iomap conversion

[Namjae Jeon]

On Wed, Jun 3, 2026 at 8:02 PM Jan Polensky <japo@xxxxxxxxxxxxx> wrote:
>
> Hi,
>
> we are seeing a regression on linux-next after commit
>
>   614f71ca1bdfaa2f25a6f147fe22f3ad031f8e2b
>   ("exfat: add iomap buffered I/O support")
>
> With this change, swapon(2) on an exfat swapfile fails with EINVAL.
>
> Observed fallout in LTP:
>   swapoff01
>   swapoff02
>   swapon01
>   swapon02
>   swapon03
>
> Example failure:
>
>   tst_test.c:1980: TINFO: === Testing on exfat ===
>   tst_test.c:1291: TINFO: Formatting /dev/loop0 with exfat opts='' extra opts=''
>   tst_test.c:1303: TINFO: Mounting /dev/loop0 to /tmp/LTP_swaKmkGVo/mntpoint fstyp=exfat flags=0
>   tse_swap.c:196: TINFO: create a swapfile size of 1 megabytes (MB)
>   tst_ioctl.c:26: TINFO: FIBMAP ioctl is supported
>   tse_swap.c:228: TFAIL: swapon() on exfat failed: EINVAL (22)
>
> and from swapon02:
>
>   swapon02.c:56: TWARN: swapon(alreadyused) failed: EINVAL (22)
>   swapon02.c:73: TFAIL: swapon(2) fail with File already used expected EBUSY: EINVAL (22)
>
> The iomap conversion changes exfat_aops to iomap based callbacks, but does not add a
> .swap_activate handler. The VFS documentation says that ->swap_activate() should call
> add_swap_extent(), or the helper iomap_swapfile_activate().
>
> So this looks like an exfat swap activation regression triggered by the iomap buffered I/O conversion.
You have already suggested a solution. Could you please provide a
patch for this ?
Thanks for the report.