On 11/8/2021 11:27 PM, Christoph Hellwig wrote:
> On Fri, Nov 05, 2021 at 07:16:38PM -0600, Jane Chu wrote:
>> static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
>> void *addr, size_t bytes, struct iov_iter *i, int mode)
>> {
>> + phys_addr_t pmem_off;
>> + size_t len, lead_off;
>> + struct pmem_device *pmem = dax_get_private(dax_dev);
>> + struct device *dev = pmem->bb.dev;
>> +
>> + if (unlikely(mode == DAX_OP_RECOVERY)) {
>> + lead_off = (unsigned long)addr & ~PAGE_MASK;
>> + len = PFN_PHYS(PFN_UP(lead_off + bytes));
>> + if (is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) / 512, len)) {
>> + if (lead_off || !(PAGE_ALIGNED(bytes))) {
>> + dev_warn(dev, "Found poison, but addr(%p) and/or bytes(%#lx) not page aligned\n",
>> + addr, bytes);
>> + return (size_t) -EIO;
>> + }
>> + pmem_off = PFN_PHYS(pgoff) + pmem->data_offset;
>> + if (pmem_clear_poison(pmem, pmem_off, bytes) !=
>> + BLK_STS_OK)
>> + return (size_t) -EIO;
>> + }
>> + }
>
> This is in the wrong spot. As seen in my WIP series individual drivers
> really should not hook into copying to and from the iter, because it
> really is just one way to write to a nvdimm. How would dm-writecache
> clear the errors with this scheme?
How does dm-writecache detect and clear errors today?
>
> So IMHO going back to the separate recovery method as in your previous
> patch really is the way to go. If/when the 64-bit store happens we
> need to figure out a good way to clear the bad block list for that.
>
Yeah, the separate .dax_clear_poison API may not be arbitrarily called
though. It must be followed by a 'write' operation, and so, unless we
bind the two operations together, how do we enforce that to avoid
silent data corruption?
thanks!
-jane
