tree eb5a38d99ac247345642582ec726253ab5dee3ae
parent fa0d3fce7ceff0aae62f3e19678713bc5a7f3377
author Ross Zwisler <ross.zwisler@linux.intel.com> 1478565093 +1100
committer Dave Chinner <david@fromorbit.com> 1478565093 +1100

ext2: remove support for DAX PMD faults

DAX PMD support was added via the following commit:

commit e7b1ea2ad658 ("ext2: huge page fault support")

I believe this path to be untested as ext2 doesn't reliably provide block
allocations that are aligned to 2MiB.  In my testing I've been unable to
get ext2 to actually fault in a PMD.  It always fails with a "pfn
unaligned" message because the sector returned by ext2_get_block() isn't
aligned.

I've tried various settings for the "stride" and "stripe_width" extended
options to mkfs.ext2, without any luck.

Since we can't reliably get PMDs, remove support so that we don't have an
untested code path that we may someday traverse when we happen to get an
aligned block allocation.  This should also make 4k DAX faults in ext2 a
bit faster since they will no longer have to call the PMD fault handler
only to get a response of VM_FAULT_FALLBACK.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <david@fromorbit.com>