On Tue, Sep 18, 2018 at 1:08 PM Vishal Verma <[email protected]> wrote:
>
> If there are badblocks present in the 'struct page' area for pfn
> namespaces, until now, the only way to clear them has been to force the
> namespace into raw mode, clear the errors, and re-enable the fsdax mode.
> This is clunky, given that it should be easy enough for the pfn driver
> to do the same.
>
> Add a new helper that uses the most recently available badblocks list to
> check whether there are any badblocks that lie in the volatile struct
> page area. If so, before initializing the struct pages, send down
> targeted writes via nvdimm_write_bytes to write zeroes to the affected
> blocks, and thus clear errors.
>
> Cc: Dan Williams <[email protected]>
> Signed-off-by: Vishal Verma <[email protected]>
> ---
> drivers/nvdimm/pfn_devs.c | 57
> +++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 57 insertions(+)
>
> diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
> index 3f7ad5bc443e..04b341758cd6 100644
> --- a/drivers/nvdimm/pfn_devs.c
> +++ b/drivers/nvdimm/pfn_devs.c
> @@ -361,8 +361,59 @@ struct device *nd_pfn_create(struct nd_region *nd_region)
> return dev;
> }
>
Perhaps a comment here about the fact that we are clearing the
volatile memmap metadata space associated with a pfn instance.
> +static int nd_pfn_clear_meta_errors(struct nd_pfn *nd_pfn)
Let's just say "memmap" rather than "meta" to be more explicit.
> +{
> + struct nd_region *nd_region = to_nd_region(nd_pfn->dev.parent);
> + struct nd_namespace_common *ndns = nd_pfn->ndns;
> + void *zero_page = page_address(ZERO_PAGE(0));
> + struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
> + sector_t first_bad, meta_start;
> + struct nd_namespace_io *nsio;
> + int num_bad, meta_num, rc;
> + bool bb_present;
> +
> + nsio = to_nd_namespace_io(&ndns->dev);
> + meta_start = (SZ_4K + sizeof(*pfn_sb)) >> 9;
> + meta_num = (le64_to_cpu(pfn_sb->dataoff) >> 9) - meta_start;
> +
> + do {
> + unsigned long zero_len;
> + u64 nsoff;
> +
> + bb_present = !!badblocks_check(&nd_region->bb, meta_start,
> + meta_num, &first_bad, &num_bad);
The !! throws me off, I don't think it's necessary. You could just
make bb_present an int.
> + if (bb_present) {
> + dev_dbg(&nd_pfn->dev, "meta: %x badblocks at %lx\n",
> + num_bad, first_bad);
> + nsoff = (nd_region->ndr_start + (first_bad << 9)) -
> + nsio->res.start;
Perhaps this should be ALIGN_DOWN((nd_region->ndr_start + (first_bad
<< 9)) - nsio->res.start, PAGE_SIZE)...
> + zero_len = num_bad << 9;
...and then make this ALIGN(num_bad << 9, PAGE_SIZE), or otherwise a
comment about zero_len being zero...
> + while (zero_len) {
> + unsigned long chunk = min(zero_len,
> PAGE_SIZE);
...because the min(x, PAGE_SIZE) seems arbitrary.
Aligned clearing may be preferable considering we may be needing to
fixup page protections.
> +
> + rc = nvdimm_write_bytes(ndns, nsoff,
> zero_page,
> + chunk, 0);
> + if (rc)
> + break;
> +
> + zero_len -= chunk;
> + nsoff += chunk;
> + }
> + if (rc) {
> + dev_err(&nd_pfn->dev,
> + "error clearing %x badblocks at
> %lx\n",
> + num_bad, first_bad);
> + return rc;
> + }
> + }
> + } while (bb_present);
> +
> + return 0;
> +}
> +
> int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
> {
> + int rc;
> u64 checksum, offset;
> enum nd_pfn_mode mode;
> struct nd_namespace_io *nsio;
> @@ -477,6 +528,12 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char
> *sig)
> return -ENXIO;
> }
>
> + if (mode == PFN_MODE_PMEM) {
> + rc = nd_pfn_clear_meta_errors(nd_pfn);
> + if (rc)
> + return rc;
I think this can just be "return nd_pfn_clear_meta_errors()", and
maybe move the mode check inside nd_pfn_clear_meta_errors() to return
early if no volatile metadata to clear.
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