vn_start_write(9) recursion ?

[Kostik Belousov]

On Fri, Apr 28, 2006 at 04:02:05PM +0200, Pawel Jakub Dawidek wrote:
> On Fri, Apr 28, 2006 at 03:08:55PM +0300, Kostik Belousov wrote:
> +> vn_start_write(9) shall not be called recursively (at least, not without
> +> V_NOWAIT flag). Otherwise, system may deadlock if vn_write_suspend(9)
> +> is called between.
> 
> Yes, you are right. Nice catch, actually.
> 
> I hacked this patch to detect it:
> 
> 	http://people.freebsd.org/~pjd/patches/vn_start_write_recursion.patch
> 
> And it panics on boot.

Incredible ! Please, commit it !

This would save me at least a day starring at struct mount with
mnt_writeopcount and (still) no writers.

For instance, such situation occurs in quotactl/quotaoff case.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 187 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-fs/attachments/20060428/bc0fffa6/attachment.pgp