[patch] Re: SU+J on 9.1-RC2 ISO

[Mateusz Guzik]

On Fri, Nov 02, 2012 at 07:30:04PM +0100, Bas Smeelen wrote:
> On 11/02/2012 07:17 PM, Bas Smeelen wrote:
> > On 11/02/2012 07:08 PM, Bas Smeelen wrote:
> >> On 11/02/2012 06:27 PM, Adam Strohl wrote:
> >>> On 11/3/2012 0:13, Mike Jakubik wrote:
> >>>> You can disable SU+J after installing, though it would be nice if the
> >>>> installer gave you a choice.
> >>> This assumes that you know about this flaw, which most people do not.
> >>>
> >>> I didn't until I discovered it by panic-ing a perfectly fine running
> >>> server.  Getting burned by a known bug like this shouldn't be "SOP"
> >>> for users of FreeBSD.
> >>>
> >>> If anything it should be turned off by default, and people can turn it
> >>> on if they want given the landmine it plants.  If they know how to
> >>> turn it on they're much more likely to be aware of the issue.
> >>>
> >>>
> >>>
> To sum it up
> SU+J should be turned off by default because of
> 1. It does not work with dumping a live system e.g. snapshot
> 2. it is not recommended for SSD installs
> 3. "Smart" admins can turn it on if they want
> 
> root at sys:/usr/src/usr.sbin/bsdinstall/partedit # diff -u gpart_ops.c 
> gpart_ops.cnew
> --- gpart_ops.c    2012-08-06 01:54:33.000000000 +0200
> +++ gpart_ops.cnew    2012-11-02 19:07:45.000000000 +0100
> @@ -90,8 +90,8 @@
>               {"SU", "Softupdates",
>                   "Enable softupdates (default)", 1 },
>               {"SUJ", "Softupdates journaling",
> -                "Enable file system journaling (default - "
> -                "turn off for SSDs)", 1 },
> +                "Disable file system journaling (default - "
> +                "turn on for adventurish admins)", 0 },
>               {"TRIM", "Enable SSD TRIM support",
>                   "Enable TRIM support, useful on solid-state drives",
>                   0 },
> 
> Please comment, then I can file a PR or not

As was noted in my another mail, the kernel will no longer crash when an
attempt to take a snapshot is made. Also AFAIR SUJ can be disabled
later.

Given that I prefer the following:

diff --git a/usr.sbin/bsdinstall/partedit/gpart_ops.c b/usr.sbin/bsdinstall/partedit/gpart_ops.c
index 479365a..80296c2 100644
--- a/usr.sbin/bsdinstall/partedit/gpart_ops.c
+++ b/usr.sbin/bsdinstall/partedit/gpart_ops.c
@@ -91,7 +91,7 @@ newfs_command(const char *fstype, char *command, int use_default)
 			    "Enable softupdates (default)", 1 },
 			{"SUJ", "Softupdates journaling",
 			    "Enable file system journaling (default - "
-			    "turn off for SSDs)", 1 },
+			    "turn off for SSDs or if you use snapshots)", 1 },
 			{"TRIM", "Enable SSD TRIM support",
 			    "Enable TRIM support, useful on solid-state drives",
 			    0 },

http://people.freebsd.org/~mjg/patches/suj-snapshot-comment.diff

-- 
Mateusz Guzik <mjguzik gmail.com>