Re: [PATCH v2 3/6] ext4: Use ext4_get_block_write() for DAX

From: Theodore Ts'o
Date: Fri Jul 03 2015 - 15:07:20 EST


On Fri, Jul 03, 2015 at 02:48:24PM -0400, Matthew Wilcox wrote:
>
> At boot, I "modprobe pmem".

Is there a reason why it's important to build and load pmem as a
module? If I use CONFIG_BLK_DEV_PMEM=y (which is more convenient
given how I launch my KVM test appliance), should I expect any
problems?

I assume that this won't detect any bugs caused by missing CLFLUSH
instructions, but I assume that when using NVM as a block device, this
isn't much of an issue, as long as we don't care about torn writes?
(How using NVM with metdata checksums, or any checksums for that
matter, seems to be an interesting question --- how do we recover from
a checksum failure after a power failure?)

- Ted
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