Re: [ 16/46] NFSv4.1: Remove a bogus BUG_ON() innfs4_layoutreturn_done

[Ben Hutchings]

On Wed, 2012-09-12 at 16:39 -0700, Greg Kroah-Hartman wrote:
> From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
> 
> 3.0-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
> 
> commit 47fbf7976e0b7d9dcdd799e2a1baba19064d9631 upstream.
> 
> Ever since commit 0a57cdac3f (NFSv4.1 send layoutreturn to fence
> disconnected data server) we've been sending layoutreturn calls
> while there is potentially still outstanding I/O to the data
> servers. The reason we do this is to avoid races between replayed
> writes to the MDS and the original writes to the DS.
> 
> When this happens, the BUG_ON() in nfs4_layoutreturn_done can
> be triggered because it assumes that we would never call
> layoutreturn without knowing that all I/O to the DS is
> finished. The fix is to remove the BUG_ON() now that the
> assumptions behind the test are obsolete.
> 
> Reported-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
> Reported-by: Tigran Mkrtchyan <tigran.mkrtchyan@xxxxxxx>
> Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[...]

The upstream commit has:

    Cc: stable@xxxxxxxxxxxxxxx [>=3.5]

and so I ignored it for 3.2.  Is it actually needed for the earlier
stable series?

Ben.

-- 
Ben Hutchings
Experience is what causes a person to make new mistakes instead of old ones.

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