Re: [LTP] [PATCH 1/4] libswap: add known swap supported fs check

Li Wang
2024-01-22T09:13:13Z

On Mon, Jan 22, 2024 at 5:03 PM Petr Vorel <pvorel@suse.cz> wrote:

> Hi Li, Cyril,
>
> > This introduce an enhancement to the library's is_swap_supported
> > function to check for filesystem compatibility before attempting
> > to create and enable a swap file. A list of supported filesystems
> > is added (ext2, ext3, ext4, xfs, vfat, exfat, ntfs), and a check
> > against this list is performed to ensure that the swap operations
> > are only attempted on known compatible filesystems.
>
> > If the make_swapfile function fails, the error handling is now
> > more descriptive: it distinguishes between failures due to the
> > filesystem not supporting swap files and other types of failures.
> > Similarly, when attempting to enable the swap file with swapon,
> > the patch ensures that clearer error messages are provided in
> > cases where the operation is not supported by the filesystem.
>
> > Signed-off-by: Li Wang <liwang@redhat.com>
> > ---
> > libs/libltpswap/libswap.c | 33 ++++++++++++++++++++++++++-------
> > 1 file changed, 26 insertions(+), 7 deletions(-)
>
> > diff --git a/libs/libltpswap/libswap.c b/libs/libltpswap/libswap.c
> > index 13610709e..623f2fb3c 100644
> > --- a/libs/libltpswap/libswap.c
> > +++ b/libs/libltpswap/libswap.c
> > @@ -12,6 +12,17 @@
> > #include "libswap.h"
> > #include "lapi/syscalls.h"
>
> > +static const char *const swap_supported_fs[] = {
> > + "ext2",
> > + "ext3",
> > + "ext4",
> > + "xfs",
> > + "vfat",
> > + "exfat",
> > + "ntfs",
> > + NULL
> > +};
> > +
> > /*
> > * Make a swap file
> > */
> > @@ -40,23 +51,31 @@ int make_swapfile(const char *swapfile, int safe)
> > */
> > void is_swap_supported(const char *filename)
> > {
> > + int i, sw_support = 0;
> > int fibmap = tst_fibmap(filename);
> Just a note unrelated to this patchset. When testing on SLES kernel based
> on
> 5.3.18 we still get TCONF due missing FIBMAP ioctl support:
>
> tst_test.c:1669: TINFO: === Testing on btrfs ===
> tst_test.c:1118: TINFO: Formatting /dev/loop0 with btrfs opts='' extra
> opts=''
> tst_test.c:1132: TINFO: Mounting /dev/loop0 to /tmp/LTP_swazaqF1L/mntpoint
> fstyp=btrfs flags=0
> tst_ioctl.c:21: TINFO: FIBMAP ioctl is NOT supported: EINVAL (22)
> libswap.c:45: TINFO: FS_NOCOW_FL attribute set on mntpoint/swapfile01
>
> libswap.c:114: TCONF: Swapfile on btrfs not implemented
>

Interesting, can you try with the below command manually to see if swapfile
is supported correctly on the BTRFS?
"cut from man 5 btrfs"

# truncate -s 0 swapfile
# chattr +C swapfile
# fallocate -l 2G swapfile
# chmod 0600 swapfile
# mkswap swapfile
# swapon swapfile

>
> Am I wrong or could it be solved with FIEMAP (<linux/fiemap.h>)?
> If yes, I wonder if we should fallback on btrfs when FIBMAP is missing
>
> https://www.kernel.org/doc/Documentation/filesystems/fiemap.txt
>
> https://unix.stackexchange.com/questions/623859/how-do-you-find-the-physical-offset-for-a-file-in-btrfs
>
> Kind regards,
> Petr
>
>

--
Regards,
Li Wang