Re: [PATCH] nfs: Don't try mounting device as nfs root unless type fully matches

Chuck Lever
2012-03-31T15:27:48Z

Oops. Trond? This got dropped somewhere.

On Mar 31, 2012, at 11:21 AM, Sasha Levin wrote:

> ping? I saw that this one didn't get pulled into the tree.
>
> On Mon, Jan 9, 2012 at 1:14 PM, Sasha Levin <levinsasha928@gmail.com> wrote:
>> 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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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com