chflags on zfs (sappnd)

Markus Gebert markus.gebert at
Wed Nov 17 17:03:47 UTC 2010

On 17.11.2010, at 11:49, George Mamalakis wrote:

> Hi everbody,
> from I understand that chflags are supported by zfs. But if I have a file with sappnd on a zfs filesystem, I am unable to execute a command like this:
> # touch lili
> # chflags sappnd lili
> # ls -lrto lili
> -rw-r--r--  1 root  wheel  sappnd 5 Nov 17 12:38 lili
> # echo "lala" >> lili
> # echo "lala" >> lili
> -su: echo: write error: Operation not permitted
> So, the first time it worked, but it stops working on any consequent time (when the file is no more empty).
> I found a bug report on:


> where a patch is suggested. Nevertheless, even though my sources are newer than the suggested patch, my source tree does not contain it.
> Do we know anything more about it?

The fix was committed to CURRENT on Oct 8th (r213634). The commit message talks about MFC after a week, however to me it looks like the fix hasn't made it to 8-STABLE yet.

Also, there seems to be a related commit r213673 which essentially reverts r213634 and has a more general approach to handling ioflags with zfs. This commit was on Oct 10th, again 1 week MFC grace period, again not in 8-STABLE yet, at least to my knowlegde.

Maybe MFC was simply forgotten, maybe there's a good reason to delay it, I don't know. We're using my patch (the one mentioned in the PRs) for now and append-only works as intended. Applying the changes in r213673 to 8-STABLE might be an option too, if you're considering patching to get the append flag working.

Anyway, hopefully one of these fixes gets MFCd to 8-STABLE soon.


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