Re: [PATCH V2] Btrfs: Full direct I/O and AIO read implementation.

[jim owens <owens6336@gmail.com>]

Chris Mason wrote:
> [ use i_mutex for reads? ]
> 
> But, we already need the code that btrfs_page_mkwrite uses.  It should
> be enough to wait for the ordered extents and have the extent range
> locked.

You don't mean have the lock_extent active while I issue the
btrfs_wait_ordered_range as I found that was a deadlock when
I tried it before.  AFAICS without i_mutex I have to do this
all unlocked and hope they are not being stupid.

> The cost of i_mutex on parallel readers + high speed devices can be
> surprising.

OK, I did not have i_mutex until the very last days of coding when
I could not find any way to fix my problems.  I'll see if I can
come up with something that makes Josef think my vector code is
pretty by comparison ;)

jim