Date: Mon, 19 Feb 2018 10:33:43 -0800 (PST) From: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net> To: rb@gid.co.uk Cc: Willem Jan Withagen <wjw@digiware.nl>, FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: Using fstatfs on a ZFS disk Message-ID: <201802191833.w1JIXhVL078022@pdx.rh.CN85.dnsmgr.net> In-Reply-To: <456B0CAA-367F-478A-BB61-153942C3EB7A@gid.co.uk>
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> Hi,
>
> > On 19 Feb 2018, at 15:50, Willem Jan Withagen <wjw@digiware.nl> wrote:
> >
> > On 19-2-2018 16:00, Bob Bishop wrote:
> >> Hi,
> >>> On 19 Feb 2018, at 14:48, Willem Jan Withagen <wjw@digiware.nl> wrote:
> >>>
> >>> Hi,
> >>>
> >>> I'm trying to find the values of the returned f_type for ZFS
> >>> in the fstatfs call when a file is on ZFS....
> >>>
> >>> But I have not yet found the definitions of the ENUMS that
> >>> would fill that value... Let alone the value for ZFS.
> >> I chased this particular wild goose myself recently. It?s FS_... in /usr/include/sys/disklabel,h that you want.
> >
> > Hi Bob,
> >
> > I grepped on MAGIC and FS, but the combo did not deliver anything useful. So this is already more that I found.
> > I did get:
> > /usr/include/ufs/ffs/fs.h:#define FS_UFS1_MAGIC 0x011954 /* UFS1 fast filesystem magic number */
> > /usr/include/ufs/ffs/fs.h:#define FS_UFS2_MAGIC 0x19540119 /* UFS2 fast filesystem magic number */
> > /usr/include/ufs/ffs/fs.h:#define FS_BAD_MAGIC 0x19960408 /* UFS incomplete newfs magic number */
>
> Those I believe are magic numbers for UFS superblocks...
>
> > So I was looking for something like: FS_ZFS_MAGIC
>
> ... so you won?t find that.
>
> > disklabel.h contains:
> > #ifdef FSTYPENAMES
> > static const char *fstypenames[] = {
> >
> > And further search:
> > /usr/include/sys/disk/bsd.h:#define FS_ZFS 27 /* Sun's ZFS */
> >
> > Running:
> > #include "stdio.h"
> >
> > #include <sys/param.h>
> > #include <sys/mount.h>
> >
> > int main() {
> > struct statfs fstr;
> > char * str;
> >
> > str = "/tmp";
> > statfs(str, &fstr);
> > printf("%s, ftype: 0x%x.\n", str, fstr.f_type);
> > }
> > results in:
> > /tmp, ftype: 0xde.
> >
> > Now 0xde != 27, so the question is, where is this 0xde specified.
> > And more important is this f_type constant over all FreeBSD ZFS filesystems?
>
> You got me. And a quick look at sys/kern/vfs_syscalls.c doesn?t help except to imply that the type is set when the filesystem is mounted. I have no idea where 0xde comes from.
Could that 0xde be the start of 0xdeadcode?
0xde is 222 decimal, that does not ring a bell for me either.
> > --WjW
> >
> >>> struct statfs {
> >>> uint32_t f_version; /* structure version number */
> >>> uint32_t f_type; /* type of filesystem */
> >>> uint64_t f_flags; /* copy of mount exported flags */
> >>> ......
> >>> }
> >>>
> >>> Any hints where to look would be welcomed.
> >>>
> >>> Thanx,
> >>> --WjW
> >> --
> >> Bob Bishop
> >> rb@gid.co.uk
> --
> Bob Bishop t: +44 (0)118 940 1243
> rb@gid.co.uk m: +44 (0)783 626 4518
--
Rod Grimes rgrimes@freebsd.org
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