Re: [PATCH AUTOSEL 4.19 059/206] ext4: make dioread_nolock the default

[Theodore Y. Ts'o]

On Thu, Sep 17, 2020 at 07:58:59PM -0700, Eric Biggers wrote:
> On Thu, Sep 17, 2020 at 10:05:35PM -0400, Sasha Levin wrote:
> > From: Theodore Ts'o <tytso@xxxxxxx>
> > 
> > [ Upstream commit 244adf6426ee31a83f397b700d964cff12a247d3 ]
> > 
> > This fixes the direct I/O versus writeback race which can reveal stale
> > data, and it improves the tail latency of commits on slow devices.
> > 
> > Link: https://lore.kernel.org/r/20200125022254.1101588-1-tytso@xxxxxxx
> > Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>I
> 
> Any particular reason to be backporting this?  I thought I saw some fixes for
> dioread_nolock go by, after it was made the default.  Are you getting all of
> those fixes too?

Agreed, making dioread_nolock the default has enough issues that it's
not something that I'd suggest backporting at this point.  It's a
fundamental behavioral change that it's not something we should change
in a stable kernel.

						- Ted