On Tue, Feb 18, 2020 at 09:09:28AM -0800, Christoph Hellwig wrote:
> On Mon, Feb 17, 2020 at 01:16:48PM -0500, Vivek Goyal wrote:
> > Currently pmem_do_write() is written with assumption that all I/O is
> > sector aligned. Soon I want to use this function in zero_page_range()
> > where range passed in does not have to be sector aligned.
> >
> > Modify this function to be able to deal with an arbitrary range. Which
> > is specified by pmem_off and len.
> >
> > Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
> > ---
> > drivers/nvdimm/pmem.c | 32 +++++++++++++++++++++++---------
> > 1 file changed, 23 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> > index 075b11682192..fae8f67da9de 100644
> > --- a/drivers/nvdimm/pmem.c
> > +++ b/drivers/nvdimm/pmem.c
> > @@ -154,15 +154,23 @@ static blk_status_t pmem_do_read(struct pmem_device *pmem,
> >
> > static blk_status_t pmem_do_write(struct pmem_device *pmem,
> > struct page *page, unsigned int page_off,
> > - sector_t sector, unsigned int len)
> > + u64 pmem_off, unsigned int len)
> > {
> > blk_status_t rc = BLK_STS_OK;
> > bool bad_pmem = false;
> > - phys_addr_t pmem_off = sector * 512 + pmem->data_offset;
> > - void *pmem_addr = pmem->virt_addr + pmem_off;
> > -
> > - if (unlikely(is_bad_pmem(&pmem->bb, sector, len)))
> > - bad_pmem = true;
> > + phys_addr_t pmem_real_off = pmem_off + pmem->data_offset;
> > + void *pmem_addr = pmem->virt_addr + pmem_real_off;
> > + sector_t sector_start, sector_end;
> > + unsigned nr_sectors;
> > +
> > + sector_start = DIV_ROUND_UP(pmem_off, SECTOR_SIZE);
> > + sector_end = (pmem_off + len) >> SECTOR_SHIFT;
> > + if (sector_end > sector_start) {
> > + nr_sectors = sector_end - sector_start;
> > + if (is_bad_pmem(&pmem->bb, sector_start,
> > + nr_sectors << SECTOR_SHIFT))
> > + bad_pmem = true;
> > + }
> >
> > /*
> > * Note that we write the data both before and after
> > @@ -181,7 +189,13 @@ static blk_status_t pmem_do_write(struct pmem_device *pmem,
> > flush_dcache_page(page);
> > write_pmem(pmem_addr, page, page_off, len);
> > if (unlikely(bad_pmem)) {
> > - rc = pmem_clear_poison(pmem, pmem_off, len);
> > + /*
> > + * Pass sector aligned offset and length. That seems
> > + * to work as of now. Other finer grained alignment
> > + * cases can be addressed later if need be.
> > + */
> > + rc = pmem_clear_poison(pmem, ALIGN(pmem_real_off, SECTOR_SIZE),
> > + nr_sectors << SECTOR_SHIFT);
> > write_pmem(pmem_addr, page, page_off, len);
>
> I'm still scared about the as of now commnet. If the interface to
> clearing poison is page aligned I think we should document that in the
> actual pmem_clear_poison function, and make that take the unaligned
> offset. I also think we want some feedback from Dan or other what the
> official interface is instead of "seems to work".
Ok, I am adding one more patch to series and enabling pmem_clear_poison()
to accept arbitrary offset and length and let it align offset and length
to sector boundary. Keeping it in a separate patch so that Dan can have
a close look at it and make sure I am doing things correctly.
Here is the new patch. I will post the V5 soon with this new patch.
Thanks
Vivek
Subject: drivers/pmem: Allow pmem_clear_poison() to accept arbitrary offset and len
Currently pmem_clear_poison() expects offset and len to be sector aligned.
Atleast that seems to be the assumption with which code has been written.
It is called only from pmem_do_bvec() which is called only from pmem_rw_page()
and pmem_make_request() which will only passe sector aligned offset and len.
Soon we want use this function from dax_zero_page_range() code path which
can try to zero arbitrary range of memory with-in a page. So update this
function to assume that offset and length can be arbitrary and do the
necessary alignments as needed.
nvdimm_clear_poison() seems to assume offset and len to be aligned to
clear_err_unit boundary. But this is currently internal detail and is
not exported for others to use. So for now, continue to align offset and
length to SECTOR_SIZE boundary. Improving it further and to align it
to clear_err_unit boundary is a TODO item for future.
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
drivers/nvdimm/pmem.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 075b11682192..e72959203253 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -74,14 +74,28 @@ static blk_status_t pmem_clear_poison(struct pmem_device *pmem,
sector_t sector;
long cleared;
blk_status_t rc = BLK_STS_OK;
+ phys_addr_t start_aligned, end_aligned;
+ unsigned int len_aligned;
- sector = (offset - pmem->data_offset) / 512;
+ /*
+ * Callers can pass arbitrary offset and len. But nvdimm_clear_poison()
+ * expects memory offset and length to meet certain alignment
+ * restrction (clear_err_unit). Currently nvdimm does not export
+ * required alignment. So align offset and length to sector boundary
+ * before passing it to nvdimm_clear_poison().
+ */
+ start_aligned = ALIGN(offset, SECTOR_SIZE);
+ end_aligned = ALIGN_DOWN((offset + len), SECTOR_SIZE) - 1;
+ len_aligned = end_aligned - start_aligned + 1;
+
+ sector = (start_aligned - pmem->data_offset) / 512;
- cleared = nvdimm_clear_poison(dev, pmem->phys_addr + offset, len);
- if (cleared < len)
+ cleared = nvdimm_clear_poison(dev, pmem->phys_addr + start_aligned,
+ len_aligned);
+ if (cleared < len_aligned)
rc = BLK_STS_IOERR;
if (cleared > 0 && cleared / 512) {
- hwpoison_clear(pmem, pmem->phys_addr + offset, cleared);
+ hwpoison_clear(pmem, pmem->phys_addr + start_aligned, cleared);
cleared /= 512;
dev_dbg(dev, "%#llx clear %ld sector%s\n",
(unsigned long long) sector, cleared,
--
2.20.1
