Linux-NVDIMM Archive on lore.kernel.org
 help / color / Atom feed
From: Vivek Goyal <vgoyal@redhat.com>
To: linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org,
	dan.j.williams@intel.com, hch@infradead.org
Cc: dm-devel@redhat.com
Subject: [PATCH 1/5] dax, pmem: Add a dax operation zero_page_range
Date: Mon,  3 Feb 2020 15:00:25 -0500
Message-ID: <20200203200029.4592-2-vgoyal@redhat.com> (raw)
In-Reply-To: <20200203200029.4592-1-vgoyal@redhat.com>

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   | 20 +++++++++++++++++
 drivers/nvdimm/pmem.c | 50 +++++++++++++++++++++++++++++++++++++++++++
 fs/dax.c              | 15 +++++++++++++
 include/linux/dax.h   |  6 ++++++
 4 files changed, 91 insertions(+)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 26a654dbc69a..371744256fe5 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -344,6 +344,26 @@ 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, pgoff_t pgoff,
+			unsigned offset, size_t len)
+{
+	if (!dax_alive(dax_dev))
+		return -ENXIO;
+
+	if (!dax_dev->ops->zero_page_range)
+		return -EOPNOTSUPP;
+
+	/*
+	 * There are no users as of now. Once users are there, fix dm code
+	 * to be able to split a long range across targets.
+	 */
+	if (offset + len > PAGE_SIZE)
+		return -EIO;
+
+	return dax_dev->ops->zero_page_range(dax_dev, pgoff, 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 ad8e4df1282b..8739244a72a4 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -268,6 +268,55 @@ 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, pgoff_t pgoff,
+				    unsigned int offset, size_t len)
+{
+	int rc = 0;
+	phys_addr_t phys_pos = pgoff * PAGE_SIZE + offset;
+	struct pmem_device *pmem = dax_get_private(dax_dev);
+	struct page *page = ZERO_PAGE(0);
+	unsigned bytes, nr_sectors = 0;
+	sector_t sector_start, sector_end;
+	bool bad_pmem = false;
+	phys_addr_t pmem_off = phys_pos + pmem->data_offset;
+	void *pmem_addr = pmem->virt_addr + pmem_off;
+
+	bytes = min_t(size_t, PAGE_SIZE - offset_in_page(phys_pos),
+		      len);
+	/*
+	 * As of now zeroing only with-in a page is supported. This can be
+	 * changed once there are users of zeroing across multiple pages
+	 */
+	if (WARN_ON(len > bytes))
+		return -EIO;
+
+	sector_start = ALIGN(phys_pos, 512)/512;
+	sector_end = ALIGN_DOWN(phys_pos + bytes, 512)/512;
+	if (sector_end > sector_start)
+		nr_sectors = sector_end - sector_start;
+
+	if (nr_sectors &&
+	    unlikely(is_bad_pmem(&pmem->bb, sector_start,
+				 nr_sectors * 512)))
+		bad_pmem = true;
+
+	write_pmem(pmem_addr, page, 0, bytes);
+	if (unlikely(bad_pmem)) {
+		/*
+		 * Pass block 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_off, 512),
+				       nr_sectors * 512);
+		write_pmem(pmem_addr, page, 0, bytes);
+	}
+	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)
 {
@@ -299,6 +348,7 @@ 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/fs/dax.c b/fs/dax.c
index 1f1f0201cad1..35631a4d0295 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1057,6 +1057,21 @@ static bool dax_range_is_aligned(struct block_device *bdev,
 	return true;
 }
 
+int generic_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
+				unsigned int offset, size_t len)
+{
+	long rc;
+	void *kaddr;
+
+	rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL);
+	if (rc < 0)
+		return rc;
+	memset(kaddr + offset, 0, len);
+	dax_flush(dax_dev, kaddr + offset, len);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(generic_dax_zero_page_range);
+
 int __dax_zero_page_range(struct block_device *bdev,
 		struct dax_device *dax_dev, sector_t sector,
 		unsigned int offset, unsigned int size)
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 9bd8528bd305..3356b874c55d 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 for fs-dax direct-i/o */
+	int (*zero_page_range)(struct dax_device *, pgoff_t, unsigned, size_t);
 };
 
 extern struct attribute_group dax_attribute_group;
@@ -209,6 +211,10 @@ 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, pgoff_t pgoff,
+			unsigned offset, size_t len);
+int generic_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
+				 unsigned int 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,
-- 
2.18.1
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org

  reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-03 20:00 [RFC PATCH 0/5][V2] dax,pmem: Provide a dax operation to zero range of memory Vivek Goyal
2020-02-03 20:00 ` Vivek Goyal [this message]
2020-02-05 18:30   ` [PATCH 1/5] dax, pmem: Add a dax operation zero_page_range Christoph Hellwig
2020-02-05 20:02     ` Vivek Goyal
2020-02-06  0:40       ` Dan Williams
2020-02-06  7:41         ` Christoph Hellwig
2020-02-07 16:57           ` Dan Williams
2020-02-07 17:01             ` Vivek Goyal
2020-02-07 17:06               ` Dan Williams
2020-02-06 14:34         ` Vivek Goyal
2020-02-07 16:58           ` Dan Williams
2020-02-03 20:00 ` [PATCH 2/5] s390,dax: Add dax zero_page_range operation to dcssblk driver Vivek Goyal
2020-02-05 18:32   ` Christoph Hellwig
2020-02-05 20:04     ` Vivek Goyal
2020-02-03 20:00 ` [PATCH 3/5] dm,dax: Add dax zero_page_range operation Vivek Goyal
2020-02-05 18:33   ` Christoph Hellwig
2020-02-07 16:34     ` Vivek Goyal
2020-02-03 20:00 ` [PATCH 4/5] dax,iomap: Start using dax native zero_page_range() Vivek Goyal
2020-02-05 18:33   ` Christoph Hellwig
2020-02-05 20:10     ` Vivek Goyal
2020-02-07 15:31     ` Vivek Goyal
2020-02-03 20:00 ` [PATCH 5/5] dax,iomap: Add helper dax_iomap_zero() to zero a range Vivek Goyal
2020-02-04  5:17   ` kbuild test robot
2020-02-05 18:36   ` Christoph Hellwig
2020-02-05 20:15     ` Vivek Goyal

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200203200029.4592-2-vgoyal@redhat.com \
    --to=vgoyal@redhat.com \
    --cc=dan.j.williams@intel.com \
    --cc=dm-devel@redhat.com \
    --cc=hch@infradead.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-nvdimm@lists.01.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-NVDIMM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-nvdimm/0 linux-nvdimm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-nvdimm linux-nvdimm/ https://lore.kernel.org/linux-nvdimm \
		linux-nvdimm@lists.01.org
	public-inbox-index linux-nvdimm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.01.lists.linux-nvdimm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git