Re: [PATCH] nfs: Don't try mounting device as nfs root unless typefully matches
From: Sasha Levin
Date: Mon Jan 09 2012 - 07:14:30 EST
On Sat, 2012-01-07 at 13:12 -0500, Jim Rees wrote:
> Chuck Lever wrote:
>
> On Jan 7, 2012, at 4:12 AM, Sasha Levin wrote:
>
> > Currently, we'll try mounting any device who's major device number is
> > UNNAMED_MAJOR as NFS root. This would happen for non-NFS devices as well (such
> > as 9p devices) but it wouldn't cause any issues since mounting the device
> > as NFS would fail quickly and the code proceeded to doing the proper mount:
> >
> > [ 101.522716] VFS: Unable to mount root fs via NFS, trying floppy.
> > [ 101.534499] VFS: Mounted root (9p filesystem) on device 0:18.
> >
> > Commit 6829a048 ("NFS: Retry mounting NFSROOT") has introduced retries when
> > mounting NFS root, which means that now we don't immediately fail and instead
> > it takes an additional 90+ seconds until we stop retrying.
> >
> > This meant that it would take an additional 90 seconds to boot when we're not
> > using a device type which gets detected in order before NFS.
>
> The long timeouts are kind of irrelevant, in my view. The real problem is
> that NFS was tried at all in this case. That behavior was not introduced
> by 6829a058.
>
> The comment does imply that 6829a048 introduced a bug, but that's not true.
> It uncovered a bug that was there before.
>
> I would change the part about "now we don't immediately fail." It didn't
> immediately fail before, but the timeout was short enough that you wouldn't
> notice it.
I tried to point out that 6829a048 changed the behavior which was
described in the first paragraph, I didn't try to imply that 6829a048 is
buggy on its own.
I'm fine with changing the changelog to whatever will make it clearer.
--
Sasha.
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