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From: John Groves <John@Groves.net>
To: John Groves <jgroves@micron.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Dan Williams <dan.j.williams@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
	Matthew Wilcox <willy@infradead.org>,
	linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	nvdimm@lists.linux.dev
Cc: John@Groves.net, john@jagalactic.com,
	Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@infradead.org>,
	dave.hansen@linux.intel.com, gregory.price@memverge.com,
	John Groves <john@groves.net>
Subject: [RFC PATCH 05/20] dev_dax_iomap: Add dax_operations for use by fs-dax on devdax
Date: Fri, 23 Feb 2024 11:41:49 -0600	[thread overview]
Message-ID: <5727b1be956278e3a6c4cf7b728ee4f8f037ae51.1708709155.git.john@groves.net> (raw)
In-Reply-To: <cover.1708709155.git.john@groves.net>

Notes about this commit:

* These methods are based somewhat loosely on pmem_dax_ops from
  drivers/nvdimm/pmem.c

* dev_dax_direct_access() is returns the hpa, pfn and kva. The kva was
  newly stored as dev_dax->virt_addr by dev_dax_probe().

* The hpa/pfn are used for mmap (dax_iomap_fault()), and the kva is used
  for read/write (dax_iomap_rw())

* dev_dax_recovery_write() and dev_dax_zero_page_range() have not been
  tested yet. I'm looking for suggestions as to how to test those.

Signed-off-by: John Groves <john@groves.net>
---
 drivers/dax/bus.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 664e8c1b9930..06fcda810674 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -10,6 +10,12 @@
 #include "dax-private.h"
 #include "bus.h"
 
+#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP)
+#include <linux/backing-dev.h>
+#include <linux/pfn_t.h>
+#include <linux/range.h>
+#endif
+
 static DEFINE_MUTEX(dax_bus_lock);
 
 #define DAX_NAME_LEN 30
@@ -1349,6 +1355,101 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
 }
 EXPORT_SYMBOL_GPL(dax_pgoff_to_phys);
 
+#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP)
+
+static void write_dax(void *pmem_addr, struct page *page,
+		unsigned int off, unsigned int len)
+{
+	unsigned int chunk;
+	void *mem;
+
+	while (len) {
+		mem = kmap_local_page(page);
+		chunk = min_t(unsigned int, len, PAGE_SIZE - off);
+		memcpy_flushcache(pmem_addr, mem + off, chunk);
+		kunmap_local(mem);
+		len -= chunk;
+		off = 0;
+		page++;
+		pmem_addr += chunk;
+	}
+}
+
+static long __dev_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
+			     long nr_pages, enum dax_access_mode mode, void **kaddr,
+			     pfn_t *pfn)
+{
+	struct dev_dax *dev_dax = dax_get_private(dax_dev);
+	size_t dax_size = dev_dax_size(dev_dax);
+	size_t size = nr_pages << PAGE_SHIFT;
+	size_t offset = pgoff << PAGE_SHIFT;
+	phys_addr_t phys;
+	u64 virt_addr = dev_dax->virt_addr + offset;
+	pfn_t local_pfn;
+	u64 flags = PFN_DEV|PFN_MAP;
+
+	WARN_ON(!dev_dax->virt_addr); /* virt_addr must be saved for direct_access */
+
+	phys = dax_pgoff_to_phys(dev_dax, pgoff, nr_pages << PAGE_SHIFT);
+
+	if (kaddr)
+		*kaddr = (void *)virt_addr;
+
+	local_pfn = phys_to_pfn_t(phys, flags); /* are flags correct? */
+	if (pfn)
+		*pfn = local_pfn;
+
+	/* This the valid size at the specified address */
+	return PHYS_PFN(min_t(size_t, size, dax_size - offset));
+}
+
+static int dev_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
+				    size_t nr_pages)
+{
+	long resid = nr_pages << PAGE_SHIFT;
+	long offset = pgoff << PAGE_SHIFT;
+
+	/* Break into one write per dax region */
+	while (resid > 0) {
+		void *kaddr;
+		pgoff_t poff = offset >> PAGE_SHIFT;
+		long len = __dev_dax_direct_access(dax_dev, poff,
+						   nr_pages, DAX_ACCESS, &kaddr, NULL);
+		len = min_t(long, len, PAGE_SIZE);
+		write_dax(kaddr, ZERO_PAGE(0), offset, len);
+
+		offset += len;
+		resid  -= len;
+	}
+	return 0;
+}
+
+static long dev_dax_direct_access(struct dax_device *dax_dev,
+		pgoff_t pgoff, long nr_pages, enum dax_access_mode mode,
+		void **kaddr, pfn_t *pfn)
+{
+	return __dev_dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
+}
+
+static size_t dev_dax_recovery_write(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	size_t len, off;
+
+	off = offset_in_page(addr);
+	len = PFN_PHYS(PFN_UP(off + bytes));
+
+	return _copy_from_iter_flushcache(addr, bytes, i);
+}
+
+static const struct dax_operations dev_dax_ops = {
+	.direct_access = dev_dax_direct_access,
+	.zero_page_range = dev_dax_zero_page_range,
+	.recovery_write = dev_dax_recovery_write,
+};
+
+#endif /* IS_ENABLED(CONFIG_DEV_DAX_IOMAP) */
+
 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
 {
 	struct dax_region *dax_region = data->dax_region;
@@ -1404,11 +1505,17 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
 		}
 	}
 
+#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP)
+	/* holder_ops currently populated separately in a slightly hacky way */
+	dax_dev = alloc_dax(dev_dax, &dev_dax_ops);
+#else
 	/*
 	 * No dax_operations since there is no access to this device outside of
 	 * mmap of the resulting character device.
 	 */
 	dax_dev = alloc_dax(dev_dax, NULL);
+#endif
+
 	if (IS_ERR(dax_dev)) {
 		rc = PTR_ERR(dax_dev);
 		goto err_alloc_dax;
-- 
2.43.0


  parent reply	other threads:[~2024-02-23 17:42 UTC|newest]

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-23 17:41 [RFC PATCH 00/20] Introduce the famfs shared-memory file system John Groves
2024-02-23 17:41 ` [RFC PATCH 01/20] famfs: Documentation John Groves
2024-02-23 17:41 ` [RFC PATCH 02/20] dev_dax_iomap: Add fs_dax_get() func to prepare dax for fs-dax usage John Groves
2024-02-26 12:05   ` Jonathan Cameron
2024-02-26 15:00     ` John Groves
2024-02-23 17:41 ` [RFC PATCH 03/20] dev_dax_iomap: Move dax_pgoff_to_phys from device.c to bus.c since both need it now John Groves
2024-02-26 12:10   ` Jonathan Cameron
2024-02-26 15:13     ` John Groves
2024-02-23 17:41 ` [RFC PATCH 04/20] dev_dax_iomap: Save the kva from memremap John Groves
2024-02-26 12:21   ` Jonathan Cameron
2024-02-26 15:48     ` John Groves
2024-02-23 17:41 ` John Groves [this message]
2024-02-26 12:32   ` [RFC PATCH 05/20] dev_dax_iomap: Add dax_operations for use by fs-dax on devdax Jonathan Cameron
2024-02-26 16:09     ` John Groves
2024-02-23 17:41 ` [RFC PATCH 06/20] dev_dax_iomap: Add CONFIG_DEV_DAX_IOMAP kernel build parameter John Groves
2024-02-26 12:34   ` Jonathan Cameron
2024-02-26 16:12     ` John Groves
2024-02-23 17:41 ` [RFC PATCH 07/20] famfs: Add include/linux/famfs_ioctl.h John Groves
2024-02-24  1:39   ` Randy Dunlap
2024-02-24  2:23     ` John Groves
2024-02-24  3:27       ` Randy Dunlap
2024-02-24 23:32         ` John Groves
2024-02-24 23:40           ` Randy Dunlap
2024-02-26 12:39   ` Jonathan Cameron
2024-02-26 16:44     ` John Groves
2024-02-26 16:56       ` Jonathan Cameron
2024-02-26 18:04         ` John Groves
2024-02-23 17:41 ` [RFC PATCH 08/20] famfs: Add famfs_internal.h John Groves
2024-02-26 12:48   ` Jonathan Cameron
2024-02-26 17:35     ` John Groves
2024-02-27 10:28       ` Jonathan Cameron
2024-02-28  1:06         ` John Groves
2024-02-27 13:38   ` Christian Brauner
2024-02-27 14:12     ` John Groves
2024-02-23 17:41 ` [RFC PATCH 09/20] famfs: Add super_operations John Groves
2024-02-26 12:51   ` Jonathan Cameron
2024-02-26 21:47     ` John Groves
2024-02-27 10:34       ` Jonathan Cameron
2024-02-27 17:48     ` John Groves
2024-02-23 17:41 ` [RFC PATCH 10/20] famfs: famfs_open_device() & dax_holder_operations John Groves
2024-02-26 12:56   ` Jonathan Cameron
2024-02-26 22:22     ` John Groves
2024-02-27 13:39   ` Christian Brauner
2024-02-27 18:38     ` John Groves
2024-02-23 17:41 ` [RFC PATCH 11/20] famfs: Add fs_context_operations John Groves
2024-02-26 13:20   ` Jonathan Cameron
2024-02-26 22:43     ` John Groves
2024-02-27 13:41   ` Christian Brauner
2024-02-28  0:59     ` John Groves
2024-02-28  1:49       ` Randy Dunlap
2024-02-28  8:17         ` Christian Brauner
2024-02-28 10:07       ` Christian Brauner
2024-02-28 12:01         ` Christian Brauner
2024-02-23 17:41 ` [RFC PATCH 12/20] famfs: Add inode_operations and file_system_type John Groves
2024-02-26 13:25   ` Jonathan Cameron
2024-02-26 22:53     ` John Groves
2024-02-23 17:41 ` [RFC PATCH 13/20] famfs: Add iomap_ops John Groves
2024-02-26 13:30   ` Jonathan Cameron
2024-02-26 23:00     ` John Groves
2024-02-23 17:41 ` [RFC PATCH 14/20] famfs: Add struct file_operations John Groves
2024-02-26 13:32   ` Jonathan Cameron
2024-02-26 23:09     ` John Groves
2024-02-23 17:41 ` [RFC PATCH 15/20] famfs: Add ioctl to file_operations John Groves
2024-02-26 13:44   ` Jonathan Cameron
2024-02-23 17:42 ` [RFC PATCH 16/20] famfs: Add fault counters John Groves
2024-02-23 18:23   ` Dave Hansen
2024-02-23 19:56     ` John Groves
2024-02-23 20:04       ` Dan Williams
2024-02-23 20:39         ` John Groves
2024-02-23 21:19           ` Dave Hansen
2024-02-23 23:50             ` Dan Williams
2024-02-24  3:59               ` Matthew Wilcox
2024-02-24  4:30                 ` Dan Williams
2024-02-23 17:42 ` [RFC PATCH 17/20] famfs: Add module stuff John Groves
2024-02-26 13:47   ` Jonathan Cameron
2024-02-27 22:15     ` John Groves
2024-02-23 17:42 ` [RFC PATCH 18/20] famfs: Support character dax via the dev_dax_iomap patch John Groves
2024-02-26 13:52   ` Jonathan Cameron
2024-02-27 22:27     ` John Groves
2024-02-23 17:42 ` [RFC PATCH 19/20] famfs: Update MAINTAINERS file John Groves
2024-02-23 17:42 ` [RFC PATCH 20/20] famfs: Add Kconfig and Makefile plumbing John Groves
2024-02-24  1:50   ` Randy Dunlap
2024-02-24  2:24     ` John Groves
2024-02-24  0:07 ` [RFC PATCH 00/20] Introduce the famfs shared-memory file system Luis Chamberlain
2024-02-26 13:27   ` John Groves
2024-02-26 15:53     ` Luis Chamberlain
2024-02-26 21:16       ` John Groves
2024-02-27  0:58         ` Luis Chamberlain
2024-02-27  2:05           ` John Groves
2024-02-29  2:15             ` Dave Chinner
2024-02-29 14:52               ` John Groves
2024-03-11  1:29                 ` Dave Chinner
2024-02-29  6:52 ` Amir Goldstein
2024-02-29 22:16   ` John Groves
2024-05-17  9:55   ` Miklos Szeredi
2024-05-19  5:59     ` Amir Goldstein
2024-05-22  2:05       ` John Groves
2024-05-22  8:58         ` Miklos Szeredi
2024-05-22 10:16           ` Amir Goldstein
2024-05-22 11:28             ` Miklos Szeredi
2024-05-22 13:41               ` Amir Goldstein
2024-05-23  2:49           ` John Groves
2024-05-23 13:57             ` Miklos Szeredi
2024-05-24  0:47               ` John Groves
2024-05-24  7:55                 ` Miklos Szeredi
2024-05-25 22:54                   ` Dave Chinner

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