| Message ID | 20200207202652.1439-4-vgoyal@redhat.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
| Series | dax, pmem: Provide a dax operation to zero range of memory | expand |
> + int rc; > + struct pmem_device *pmem = dax_get_private(dax_dev); > + struct page *page = ZERO_PAGE(0); Nit: I tend to find code easier to read if variable declarations with assignments are above those without. Also I don't think we need the page variable here. > + rc = pmem_do_write(pmem, page, 0, offset, len); > + if (rc > 0) > + return -EIO; pmem_do_write returns a blk_status_t, so the type of rc and the > check seem odd. But I think pmem_do_write (and pmem_do_read) might be better off returning a normal errno anyway. -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On Mon, Feb 17, 2020 at 05:26:07AM -0800, Christoph Hellwig wrote: > > + int rc; > > + struct pmem_device *pmem = dax_get_private(dax_dev); > > + struct page *page = ZERO_PAGE(0); > > Nit: I tend to find code easier to read if variable declarations > with assignments are above those without. Fixed in V4. > > Also I don't think we need the page variable here. Fixed in V4. > > > + rc = pmem_do_write(pmem, page, 0, offset, len); > > + if (rc > 0) > > + return -EIO; > > pmem_do_write returns a blk_status_t, so the type of rc and the > check > seem odd. But I think pmem_do_write (and pmem_do_read) might be better > off returning a normal errno anyway. Now I am using blk_status_to_errno() to convert error in V4. rc = pmem_do_write(pmem, ZERO_PAGE(0), 0, offset, len); return blk_status_to_errno(rc); Did not modify pmem_do_read()/pmem_do_write() to return errno as there is still one caller which expects to return blk_status_t and then that caller will have to do the converstion. Having said that, it probably is good idea to clean up functions called by pmem_do_read()/pmem_do_write() to return errno. I prefer not to take that work in that patch series as that seems like a nice to have thing and can be handled in a separate patch series. Thanks Vivek -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 26a654dbc69a..31ee0b47b4ed 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -344,6 +344,25 @@ size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, } EXPORT_SYMBOL_GPL(dax_copy_to_iter); +int dax_zero_page_range(struct dax_device *dax_dev, u64 offset, size_t len) +{ + if (!dax_alive(dax_dev)) + return -ENXIO; + + if (!dax_dev->ops->zero_page_range) + return -EOPNOTSUPP; + /* + * There are no callers that want to zero across a page boundary as of + * now. Once users are there, this check can be removed after the + * device mapper code has been updated to split ranges across targets. + */ + if (offset_in_page(offset) + len > PAGE_SIZE) + return -EIO; + + return dax_dev->ops->zero_page_range(dax_dev, offset, len); +} +EXPORT_SYMBOL_GPL(dax_zero_page_range); + #ifdef CONFIG_ARCH_HAS_PMEM_API void arch_wb_cache_pmem(void *addr, size_t size); void dax_flush(struct dax_device *dax_dev, void *addr, size_t size) diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index 281fe04d25fd..0def7dc8e487 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -299,6 +299,20 @@ static const struct block_device_operations pmem_fops = { .revalidate_disk = nvdimm_revalidate_disk, }; +static int pmem_dax_zero_page_range(struct dax_device *dax_dev, u64 offset, + size_t len) +{ + int rc; + struct pmem_device *pmem = dax_get_private(dax_dev); + struct page *page = ZERO_PAGE(0); + + rc = pmem_do_write(pmem, page, 0, offset, len); + if (rc > 0) + return -EIO; + + return 0; +} + static long pmem_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn) { @@ -330,6 +344,7 @@ static const struct dax_operations pmem_dax_ops = { .dax_supported = generic_fsdax_supported, .copy_from_iter = pmem_copy_from_iter, .copy_to_iter = pmem_copy_to_iter, + .zero_page_range = pmem_dax_zero_page_range, }; static const struct attribute_group *pmem_attribute_groups[] = { diff --git a/include/linux/dax.h b/include/linux/dax.h index 9bd8528bd305..a555f0aeb7bd 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -34,6 +34,8 @@ struct dax_operations { /* copy_to_iter: required operation for fs-dax direct-i/o */ size_t (*copy_to_iter)(struct dax_device *, pgoff_t, void *, size_t, struct iov_iter *); + /* zero_page_range: required operation. Zero range with-in a page */ + int (*zero_page_range)(struct dax_device *, u64, size_t); }; extern struct attribute_group dax_attribute_group; @@ -209,6 +211,7 @@ size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i); size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i); +int dax_zero_page_range(struct dax_device *dax_dev, u64 offset, size_t len); void dax_flush(struct dax_device *dax_dev, void *addr, size_t size); ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
Add a dax operation zero_page_range, to zero a range of memory. This will also clear any poison in the range being zeroed. As of now, zeroing of up to one page is allowed in a single call. There are no callers which are trying to zero more than a page in a single call. Once we grow the callers which zero more than a page in single call, we can add that support. Primary reason for not doing that yet is that this will add little complexity in dm implementation where a range might be spanning multiple underlying targets and one will have to split the range into multiple sub ranges and call zero_page_range() on individual targets. Suggested-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> --- drivers/dax/super.c | 19 +++++++++++++++++++ drivers/nvdimm/pmem.c | 15 +++++++++++++++ include/linux/dax.h | 3 +++ 3 files changed, 37 insertions(+)