On Thu, Aug 13, 2015 at 9:51 AM, Ross Zwisler
<ross.zwisler@xxxxxxxxxxxxxxx> wrote:
> Update the DAX I/O path so that all operations that store data (I/O
> writes, zeroing blocks, punching holes, etc.) properly synchronize the
> stores to media using the PMEM API. This ensures that the data DAX is
> writing is durable on media before the operation completes.
>
> Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
[..]
> @@ -145,18 +147,27 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
> retval = dax_get_addr(bh, &addr, blkbits);
> if (retval < 0)
> break;
> - if (buffer_unwritten(bh) || buffer_new(bh))
> + if (buffer_unwritten(bh) || buffer_new(bh)) {
> dax_new_buf(addr, retval, first, pos,
> end);
> + need_wmb = true;
> + }
> addr += first;
> size = retval - first;
> }
> max = min(pos + size, end);
> }
>
> - if (iov_iter_rw(iter) == WRITE)
> + if (iov_iter_rw(iter) == WRITE) {
> len = copy_from_iter_nocache(addr, max - pos, iter);
> - else if (!hole)
> + /*
> + * copy_from_iter_nocache() uses non-temporal stores
> + * for iovec iterators so we can skip the write back.
> + */
> + if (!iter_is_iovec(iter))
> + wb_cache_pmem((void __pmem *)addr, max - pos);
> + need_wmb = true;
I think this should become copy_from_iter_pmem() and hide the
wb_cache_pmem() as an internal arch detail. I.e. wb_cache_pmem()
should not be a global api when its usage is architecture specific.
Otherwise are you asserting that all architecture implementations of
copy_from_iter_nocache() are pmem safe?
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