[PATCH V2 3/3] Adding device_dma_parameters->offset_preserve_mask to NVMe driver.

[Jianxiong Gao]

> Why is this setting being done and undone on each IO? Wouldn't it be
> more efficient to set it once during device initialization?
>
> And more importantly, this isn't thread safe: one CPU may be setting the
> device's dma alignment mask to 0 while another CPU is expecting it to be
> NVME_CTRL_PAGE_SIZE - 1.

 I was having trouble getting the OS booted when setting it once during
 initialization. However when I rebased to the latest rc6 this morning it
 seems to be working with setting the mask on probe. I am still testing out
 and will appreciate any idea what may cause the nvme driver to fail
 with a single mask.
-- 
Jianxiong Gao