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Subject[PATCH 19/21] nd: infrastructure for btt devices
From
Date
Block devices from an nd bus, in addition to accepting "struct bio"
based requests, also have the capability to perform byte-aligned
accesses. By default only the bio/block interface is used. However, if
another driver can make effective use of the byte-aligned capability it
can claim/disable the block interface and use the byte-aligned "nd_io"
interface.

The BTT driver is the intended first consumer of this mechanism to allow
layering atomic sector update guarantees on top of nd_io capable
nd-bus-block-devices.

Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/block/nd/Kconfig | 3
drivers/block/nd/Makefile | 2
drivers/block/nd/btt.h | 45 ++++
drivers/block/nd/btt_devs.c | 442 +++++++++++++++++++++++++++++++++++++++++
drivers/block/nd/bus.c | 128 ++++++++++++
drivers/block/nd/core.c | 80 +++++++
drivers/block/nd/nd-private.h | 28 +++
drivers/block/nd/nd.h | 94 +++++++++
drivers/block/nd/pmem.c | 30 +++
include/uapi/linux/ndctl.h | 2
10 files changed, 850 insertions(+), 4 deletions(-)
create mode 100644 drivers/block/nd/btt.h
create mode 100644 drivers/block/nd/btt_devs.c

diff --git a/drivers/block/nd/Kconfig b/drivers/block/nd/Kconfig
index 38eae5f0ae4b..faa756841773 100644
--- a/drivers/block/nd/Kconfig
+++ b/drivers/block/nd/Kconfig
@@ -89,4 +89,7 @@ config BLK_DEV_PMEM

Say Y if you want to use a NVDIMM described by NFIT

+config ND_BTT_DEVS
+ def_bool y
+
endif
diff --git a/drivers/block/nd/Makefile b/drivers/block/nd/Makefile
index 93856f1c9dbd..3e4878e0fe1d 100644
--- a/drivers/block/nd/Makefile
+++ b/drivers/block/nd/Makefile
@@ -29,4 +29,6 @@ nd-y += region.o
nd-y += namespace_devs.o
nd-y += label.o

+nd-$(CONFIG_ND_BTT_DEVS) += btt_devs.o
+
nd_pmem-y := pmem.o
diff --git a/drivers/block/nd/btt.h b/drivers/block/nd/btt.h
new file mode 100644
index 000000000000..e8f6d8e0ddd3
--- /dev/null
+++ b/drivers/block/nd/btt.h
@@ -0,0 +1,45 @@
+/*
+ * Block Translation Table library
+ * Copyright (c) 2014-2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef _LINUX_BTT_H
+#define _LINUX_BTT_H
+
+#include <linux/types.h>
+
+#define BTT_SIG_LEN 16
+#define BTT_SIG "BTT_ARENA_INFO\0"
+
+struct btt_sb {
+ u8 signature[BTT_SIG_LEN];
+ u8 uuid[16];
+ u8 parent_uuid[16];
+ __le32 flags;
+ __le16 version_major;
+ __le16 version_minor;
+ __le32 external_lbasize;
+ __le32 external_nlba;
+ __le32 internal_lbasize;
+ __le32 internal_nlba;
+ __le32 nfree;
+ __le32 infosize;
+ __le64 nextoff;
+ __le64 dataoff;
+ __le64 mapoff;
+ __le64 logoff;
+ __le64 info2off;
+ u8 padding[3968];
+ __le64 checksum;
+};
+
+#endif
diff --git a/drivers/block/nd/btt_devs.c b/drivers/block/nd/btt_devs.c
new file mode 100644
index 000000000000..746d582910b6
--- /dev/null
+++ b/drivers/block/nd/btt_devs.c
@@ -0,0 +1,442 @@
+/*
+ * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#include <linux/device.h>
+#include <linux/genhd.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include "nd-private.h"
+#include "btt.h"
+#include "nd.h"
+
+static DEFINE_IDA(btt_ida);
+
+static void nd_btt_release(struct device *dev)
+{
+ struct nd_btt *nd_btt = to_nd_btt(dev);
+
+ dev_dbg(dev, "%s\n", __func__);
+ WARN_ON(nd_btt->backing_dev);
+ ndio_del_claim(nd_btt->ndio_claim);
+ ida_simple_remove(&btt_ida, nd_btt->id);
+ kfree(nd_btt->uuid);
+ kfree(nd_btt);
+}
+
+static struct device_type nd_btt_device_type = {
+ .name = "nd_btt",
+ .release = nd_btt_release,
+};
+
+bool is_nd_btt(struct device *dev)
+{
+ return dev->type == &nd_btt_device_type;
+}
+
+struct nd_btt *to_nd_btt(struct device *dev)
+{
+ struct nd_btt *nd_btt = container_of(dev, struct nd_btt, dev);
+
+ WARN_ON(!is_nd_btt(dev));
+ return nd_btt;
+}
+EXPORT_SYMBOL(to_nd_btt);
+
+static const unsigned long btt_lbasize_supported[] = { 512, 4096, 0 };
+
+static ssize_t sector_size_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct nd_btt *nd_btt = to_nd_btt(dev);
+
+ return nd_sector_size_show(nd_btt->lbasize, btt_lbasize_supported, buf);
+}
+
+static ssize_t sector_size_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ struct nd_btt *nd_btt = to_nd_btt(dev);
+ ssize_t rc;
+
+ device_lock(dev);
+ nd_bus_lock(dev);
+ rc = nd_sector_size_store(dev, buf, &nd_btt->lbasize,
+ btt_lbasize_supported);
+ dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
+ rc, buf, buf[len - 1] == '\n' ? "" : "\n");
+ nd_bus_unlock(dev);
+ device_unlock(dev);
+
+ return rc ? rc : len;
+}
+static DEVICE_ATTR_RW(sector_size);
+
+static ssize_t uuid_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct nd_btt *nd_btt = to_nd_btt(dev);
+
+ if (nd_btt->uuid)
+ return sprintf(buf, "%pUb\n", nd_btt->uuid);
+ return sprintf(buf, "\n");
+}
+
+static ssize_t uuid_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ struct nd_btt *nd_btt = to_nd_btt(dev);
+ ssize_t rc;
+
+ device_lock(dev);
+ rc = nd_uuid_store(dev, &nd_btt->uuid, buf, len);
+ dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
+ rc, buf, buf[len - 1] == '\n' ? "" : "\n");
+ device_unlock(dev);
+
+ return rc ? rc : len;
+}
+static DEVICE_ATTR_RW(uuid);
+
+static ssize_t backing_dev_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct nd_btt *nd_btt = to_nd_btt(dev);
+ char name[BDEVNAME_SIZE];
+
+ if (nd_btt->backing_dev)
+ return sprintf(buf, "/dev/%s\n",
+ bdevname(nd_btt->backing_dev, name));
+ else
+ return sprintf(buf, "\n");
+}
+
+static const fmode_t nd_btt_devs_mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
+
+static void nd_btt_ndio_notify_remove(struct nd_io_claim *ndio_claim)
+{
+ char bdev_name[BDEVNAME_SIZE];
+ struct nd_btt *nd_btt;
+
+ if (!ndio_claim || !ndio_claim->holder)
+ return;
+
+ nd_btt = to_nd_btt(ndio_claim->holder);
+ WARN_ON_ONCE(!is_nd_bus_locked(&nd_btt->dev));
+ dev_dbg(&nd_btt->dev, "%pf: %s: release /dev/%s\n",
+ __builtin_return_address(0), __func__,
+ bdevname(nd_btt->backing_dev, bdev_name));
+ blkdev_put(nd_btt->backing_dev, nd_btt_devs_mode);
+ nd_btt->backing_dev = NULL;
+
+ /*
+ * Once we've had our backing device removed we need to be fully
+ * reconfigured. The bus will have already created a new seed
+ * for this purpose, so now is a good time to clean up this
+ * stale nd_btt instance.
+ */
+ if (nd_btt->dev.driver)
+ nd_device_unregister(&nd_btt->dev, ND_ASYNC);
+ else {
+ ndio_del_claim(ndio_claim);
+ nd_btt->ndio_claim = NULL;
+ }
+}
+
+static ssize_t __backing_dev_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ struct nd_bus *nd_bus = walk_to_nd_bus(dev);
+ struct nd_btt *nd_btt = to_nd_btt(dev);
+ char bdev_name[BDEVNAME_SIZE];
+ struct block_device *bdev;
+ struct nd_io *ndio;
+ char *path;
+
+ if (dev->driver) {
+ dev_dbg(dev, "%s: -EBUSY\n", __func__);
+ return -EBUSY;
+ }
+
+ path = kstrndup(buf, len, GFP_KERNEL);
+ if (!path)
+ return -ENOMEM;
+
+ /* detach the backing device */
+ if (strcmp(strim(path), "") == 0) {
+ if (!nd_btt->backing_dev)
+ goto out;
+ nd_btt_ndio_notify_remove(nd_btt->ndio_claim);
+ goto out;
+ } else if (nd_btt->backing_dev) {
+ dev_dbg(dev, "backing_dev already set\n");
+ len = -EBUSY;
+ goto out;
+ }
+
+ bdev = blkdev_get_by_path(strim(path), nd_btt_devs_mode, nd_btt);
+ if (IS_ERR(bdev)) {
+ dev_dbg(dev, "open '%s' failed: %ld\n", strim(path),
+ PTR_ERR(bdev));
+ len = PTR_ERR(bdev);
+ goto out;
+ }
+
+ if (get_capacity(bdev->bd_disk) < SZ_16M / 512) {
+ blkdev_put(bdev, nd_btt_devs_mode);
+ len = -ENXIO;
+ goto out;
+ }
+
+ ndio = ndio_lookup(nd_bus, bdevname(bdev->bd_contains, bdev_name));
+ if (!ndio) {
+ dev_dbg(dev, "%s does not have an ndio interface\n",
+ strim(path));
+ blkdev_put(bdev, nd_btt_devs_mode);
+ len = -ENXIO;
+ goto out;
+ }
+
+ nd_btt->ndio_claim = ndio_add_claim(ndio, &nd_btt->dev,
+ nd_btt_ndio_notify_remove);
+ if (!nd_btt->ndio_claim) {
+ blkdev_put(bdev, nd_btt_devs_mode);
+ len = -ENOMEM;
+ goto out;
+ }
+
+ WARN_ON_ONCE(!is_nd_bus_locked(&nd_btt->dev));
+ nd_btt->backing_dev = bdev;
+
+ out:
+ kfree(path);
+ return len;
+}
+
+static ssize_t backing_dev_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ ssize_t rc;
+
+ nd_bus_lock(dev);
+ device_lock(dev);
+ rc = __backing_dev_store(dev, attr, buf, len);
+ dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
+ rc, buf, buf[len - 1] == '\n' ? "" : "\n");
+ device_unlock(dev);
+ nd_bus_unlock(dev);
+
+ return rc;
+}
+static DEVICE_ATTR_RW(backing_dev);
+
+static bool is_nd_btt_idle(struct device *dev)
+{
+ struct nd_bus *nd_bus = walk_to_nd_bus(dev);
+ struct nd_btt *nd_btt = to_nd_btt(dev);
+
+ if (nd_bus->nd_btt == nd_btt || dev->driver || nd_btt->backing_dev)
+ return false;
+ return true;
+}
+
+static ssize_t delete_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ /* return 1 if can be deleted */
+ return sprintf(buf, "%d\n", is_nd_btt_idle(dev));
+}
+
+static ssize_t delete_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ unsigned long val;
+
+ /* write 1 to delete */
+ if (kstrtoul(buf, 0, &val) != 0 || val != 1)
+ return -EINVAL;
+
+ /* prevent deletion while this btt is active, or is the current seed */
+ if (!is_nd_btt_idle(dev))
+ return -EBUSY;
+
+ /*
+ * userspace raced itself if device goes active here and it gets
+ * to keep the pieces
+ */
+ nd_device_unregister(dev, ND_ASYNC);
+
+ return len;
+}
+static DEVICE_ATTR_RW(delete);
+
+static struct attribute *nd_btt_attributes[] = {
+ &dev_attr_sector_size.attr,
+ &dev_attr_backing_dev.attr,
+ &dev_attr_delete.attr,
+ &dev_attr_uuid.attr,
+ NULL,
+};
+
+static struct attribute_group nd_btt_attribute_group = {
+ .attrs = nd_btt_attributes,
+};
+
+static const struct attribute_group *nd_btt_attribute_groups[] = {
+ &nd_btt_attribute_group,
+ &nd_device_attribute_group,
+ NULL,
+};
+
+static struct nd_btt *__nd_btt_create(struct nd_bus *nd_bus,
+ unsigned long lbasize, u8 *uuid)
+{
+ struct nd_btt *nd_btt = kzalloc(sizeof(*nd_btt), GFP_KERNEL);
+ struct device *dev;
+
+ if (!nd_btt)
+ return NULL;
+ nd_btt->id = ida_simple_get(&btt_ida, 0, 0, GFP_KERNEL);
+ if (nd_btt->id < 0) {
+ kfree(nd_btt);
+ return NULL;
+ }
+
+ nd_btt->lbasize = lbasize;
+ if (uuid)
+ uuid = kmemdup(uuid, 16, GFP_KERNEL);
+ nd_btt->uuid = uuid;
+ dev = &nd_btt->dev;
+ dev_set_name(dev, "btt%d", nd_btt->id);
+ dev->parent = &nd_bus->dev;
+ dev->type = &nd_btt_device_type;
+ dev->groups = nd_btt_attribute_groups;
+ return nd_btt;
+}
+
+struct nd_btt *nd_btt_create(struct nd_bus *nd_bus)
+{
+ struct nd_btt *nd_btt = __nd_btt_create(nd_bus, 0, NULL);
+
+ if (!nd_btt)
+ return NULL;
+ nd_device_register(&nd_btt->dev);
+ return nd_btt;
+}
+
+/*
+ * btt_sb_checksum: compute checksum for btt info block
+ *
+ * Returns a fletcher64 checksum of everything in the given info block
+ * except the last field (since that's where the checksum lives).
+ */
+u64 btt_sb_checksum(struct btt_sb *btt_sb)
+{
+ u64 sum, sum_save;
+
+ sum_save = btt_sb->checksum;
+ btt_sb->checksum = 0;
+ sum = nd_fletcher64(btt_sb, sizeof(*btt_sb));
+ btt_sb->checksum = sum_save;
+ return sum;
+}
+EXPORT_SYMBOL(btt_sb_checksum);
+
+static int nd_btt_autodetect(struct nd_bus *nd_bus, struct nd_io *ndio,
+ struct block_device *bdev)
+{
+ char name[BDEVNAME_SIZE];
+ struct nd_btt *nd_btt;
+ struct btt_sb *btt_sb;
+ u64 offset, checksum;
+ u32 lbasize;
+ u8 *uuid;
+ int rc;
+
+ btt_sb = kzalloc(sizeof(*btt_sb), GFP_KERNEL);
+ if (!btt_sb)
+ return -ENODEV;
+
+ offset = nd_partition_offset(bdev);
+ rc = ndio->rw_bytes(ndio, btt_sb, offset + SZ_4K, sizeof(*btt_sb), READ);
+ if (rc)
+ goto out_free_sb;
+
+ if (get_capacity(bdev->bd_disk) < SZ_16M / 512)
+ goto out_free_sb;
+
+ if (memcmp(btt_sb->signature, BTT_SIG, BTT_SIG_LEN) != 0)
+ goto out_free_sb;
+
+ checksum = le64_to_cpu(btt_sb->checksum);
+ btt_sb->checksum = 0;
+ if (checksum != btt_sb_checksum(btt_sb))
+ goto out_free_sb;
+ btt_sb->checksum = cpu_to_le64(checksum);
+
+ uuid = kmemdup(btt_sb->uuid, 16, GFP_KERNEL);
+ if (!uuid)
+ goto out_free_sb;
+
+ lbasize = le32_to_cpu(btt_sb->external_lbasize);
+ nd_btt = __nd_btt_create(nd_bus, lbasize, uuid);
+ if (!nd_btt)
+ goto out_free_uuid;
+
+ device_initialize(&nd_btt->dev);
+ nd_btt->ndio_claim = ndio_add_claim(ndio, &nd_btt->dev,
+ nd_btt_ndio_notify_remove);
+ if (!nd_btt->ndio_claim)
+ goto out_free_btt;
+
+ nd_btt->backing_dev = bdev;
+ dev_dbg(&nd_btt->dev, "%s: activate %s\n", __func__,
+ bdevname(bdev, name));
+ __nd_device_register(&nd_btt->dev);
+ kfree(btt_sb);
+ return 0;
+
+ out_free_btt:
+ kfree(nd_btt);
+ out_free_uuid:
+ kfree(uuid);
+ out_free_sb:
+ kfree(btt_sb);
+
+ return -ENODEV;
+}
+
+void nd_btt_notify_ndio(struct nd_bus *nd_bus, struct nd_io *ndio)
+{
+ struct disk_part_iter piter;
+ struct hd_struct *part;
+
+ disk_part_iter_init(&piter, ndio->disk, DISK_PITER_INCL_PART0);
+ while ((part = disk_part_iter_next(&piter))) {
+ struct block_device *bdev;
+ int rc;
+
+ bdev = bdget_disk(ndio->disk, part->partno);
+ if (!bdev)
+ continue;
+ if (blkdev_get(bdev, nd_btt_devs_mode, nd_bus) != 0)
+ continue;
+ rc = nd_btt_autodetect(nd_bus, ndio, bdev);
+ if (rc)
+ blkdev_put(bdev, nd_btt_devs_mode);
+ /* no need to scan further in the case of whole disk btt */
+ if (rc == 0 && part->partno == 0)
+ break;
+ }
+ disk_part_iter_exit(&piter);
+}
diff --git a/drivers/block/nd/bus.c b/drivers/block/nd/bus.c
index cb619d70166d..7fbac49faad2 100644
--- a/drivers/block/nd/bus.c
+++ b/drivers/block/nd/bus.c
@@ -16,6 +16,7 @@
#include <linux/module.h>
#include <linux/fcntl.h>
#include <linux/async.h>
+#include <linux/genhd.h>
#include <linux/ndctl.h>
#include <linux/sched.h>
#include <linux/slab.h>
@@ -41,6 +42,8 @@ static int to_nd_device_type(struct device *dev)
return ND_DEVICE_REGION_BLOCK;
else if (is_nd_pmem(dev->parent) || is_nd_blk(dev->parent))
return nd_region_to_namespace_type(to_nd_region(dev->parent));
+ else if (is_nd_btt(dev))
+ return ND_DEVICE_BTT;

return 0;
}
@@ -85,6 +88,21 @@ static int nd_bus_probe(struct device *dev)

dev_dbg(&nd_bus->dev, "%s.probe(%s) = %d\n", dev->driver->name,
dev_name(dev), rc);
+
+ /* check if our btt-seed has sprouted, and plant another */
+ if (rc == 0 && is_nd_btt(dev) && dev == &nd_bus->nd_btt->dev) {
+ const char *sep = "", *name = "", *status = "failed";
+
+ nd_bus->nd_btt = nd_btt_create(nd_bus);
+ if (nd_bus->nd_btt) {
+ status = "succeeded";
+ sep = ": ";
+ name = dev_name(&nd_bus->nd_btt->dev);
+ }
+ dev_dbg(&nd_bus->dev, "btt seed creation %s%s%s\n",
+ status, sep, name);
+ }
+
if (rc != 0)
module_put(provider);
return rc;
@@ -173,14 +191,19 @@ static void nd_async_device_unregister(void *d, async_cookie_t cookie)
put_device(dev);
}

-void nd_device_register(struct device *dev)
+void __nd_device_register(struct device *dev)
{
dev->bus = &nd_bus_type;
- device_initialize(dev);
get_device(dev);
async_schedule_domain(nd_async_device_register, dev,
&nd_async_domain);
}
+
+void nd_device_register(struct device *dev)
+{
+ device_initialize(dev);
+ __nd_device_register(dev);
+}
EXPORT_SYMBOL(nd_device_register);

void nd_device_unregister(struct device *dev, enum nd_async_mode mode)
@@ -229,6 +252,107 @@ int __nd_driver_register(struct nd_device_driver *nd_drv, struct module *owner,
}
EXPORT_SYMBOL(__nd_driver_register);

+/**
+ * nd_register_ndio() - register byte-aligned access capability for an nd-bdev
+ * @disk: child gendisk of the ndio namepace device
+ * @ndio: initialized ndio instance to register
+ *
+ * LOCKING: hold nd_bus_lock() over the creation of ndio->disk and the
+ * subsequent nd_region_ndio event
+ */
+int nd_register_ndio(struct nd_io *ndio)
+{
+ struct nd_bus *nd_bus;
+ struct device *dev;
+
+ if (!ndio || !ndio->dev || !ndio->disk || !list_empty(&ndio->list)
+ || !ndio->rw_bytes || !list_empty(&ndio->claims)) {
+ pr_debug("%s bad parameters from %pf\n", __func__,
+ __builtin_return_address(0));
+ return -EINVAL;
+ }
+
+ dev = ndio->dev;
+ nd_bus = walk_to_nd_bus(dev);
+ if (!nd_bus)
+ return -EINVAL;
+
+ WARN_ON_ONCE(!is_nd_bus_locked(&nd_bus->dev));
+ list_add(&ndio->list, &nd_bus->ndios);
+
+ /* TODO: generic infrastructure for 3rd party ndio claimers */
+ nd_btt_notify_ndio(nd_bus, ndio);
+
+ return 0;
+}
+EXPORT_SYMBOL(nd_register_ndio);
+
+/**
+ * __nd_unregister_ndio() - try to remove an ndio interface
+ * @ndio: interface to remove
+ */
+static int __nd_unregister_ndio(struct nd_io *ndio)
+{
+ struct nd_io_claim *ndio_claim, *_n;
+ struct nd_bus *nd_bus;
+ LIST_HEAD(claims);
+
+ nd_bus = walk_to_nd_bus(ndio->dev);
+ if (!nd_bus || list_empty(&ndio->list))
+ return -ENXIO;
+
+ spin_lock(&ndio->lock);
+ list_splice_init(&ndio->claims, &claims);
+ spin_unlock(&ndio->lock);
+
+ list_for_each_entry_safe(ndio_claim, _n, &claims, list)
+ ndio_claim->notify_remove(ndio_claim);
+
+ list_del_init(&ndio->list);
+
+ return 0;
+}
+
+int nd_unregister_ndio(struct nd_io *ndio)
+{
+ struct device *dev = ndio->dev;
+ int rc;
+
+ nd_bus_lock(dev);
+ rc = __nd_unregister_ndio(ndio);
+ nd_bus_unlock(dev);
+
+ /*
+ * Flush in case ->notify_remove() kicked off asynchronous device
+ * unregistration
+ */
+ nd_synchronize();
+
+ return rc;
+}
+EXPORT_SYMBOL(nd_unregister_ndio);
+
+static struct nd_io *__ndio_lookup(struct nd_bus *nd_bus, const char *diskname)
+{
+ struct nd_io *ndio;
+
+ list_for_each_entry(ndio, &nd_bus->ndios, list)
+ if (strcmp(diskname, ndio->disk->disk_name) == 0)
+ return ndio;
+
+ return NULL;
+}
+
+struct nd_io *ndio_lookup(struct nd_bus *nd_bus, const char *diskname)
+{
+ struct nd_io *ndio;
+
+ WARN_ON_ONCE(!is_nd_bus_locked(&nd_bus->dev));
+ ndio = __ndio_lookup(nd_bus, diskname);
+
+ return ndio;
+}
+
static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
diff --git a/drivers/block/nd/core.c b/drivers/block/nd/core.c
index 880aef08f919..a093c6468a53 100644
--- a/drivers/block/nd/core.c
+++ b/drivers/block/nd/core.c
@@ -62,6 +62,62 @@ bool is_nd_bus_locked(struct device *dev)
}
EXPORT_SYMBOL(is_nd_bus_locked);

+void nd_init_ndio(struct nd_io *ndio, nd_rw_bytes_fn rw_bytes,
+ struct device *dev, struct gendisk *disk, unsigned long align)
+{
+ memset(ndio, 0, sizeof(*ndio));
+ INIT_LIST_HEAD(&ndio->claims);
+ INIT_LIST_HEAD(&ndio->list);
+ spin_lock_init(&ndio->lock);
+ ndio->dev = dev;
+ ndio->disk = disk;
+ ndio->align = align;
+ ndio->rw_bytes = rw_bytes;
+}
+EXPORT_SYMBOL(nd_init_ndio);
+
+void ndio_del_claim(struct nd_io_claim *ndio_claim)
+{
+ struct nd_io *ndio;
+ struct device *holder;
+
+ if (!ndio_claim)
+ return;
+ ndio = ndio_claim->parent;
+ holder = ndio_claim->holder;
+
+ dev_dbg(holder, "%s: drop %s\n", __func__, dev_name(ndio->dev));
+ spin_lock(&ndio->lock);
+ list_del(&ndio_claim->list);
+ spin_unlock(&ndio->lock);
+ put_device(ndio->dev);
+ kfree(ndio_claim);
+ put_device(holder);
+}
+
+struct nd_io_claim *ndio_add_claim(struct nd_io *ndio, struct device *holder,
+ ndio_notify_remove_fn notify_remove)
+{
+ struct nd_io_claim *ndio_claim = kzalloc(sizeof(*ndio_claim), GFP_KERNEL);
+
+ if (!ndio_claim)
+ return NULL;
+
+ INIT_LIST_HEAD(&ndio_claim->list);
+ ndio_claim->parent = ndio;
+ get_device(ndio->dev);
+
+ spin_lock(&ndio->lock);
+ list_add(&ndio_claim->list, &ndio->claims);
+ spin_unlock(&ndio->lock);
+
+ ndio_claim->holder = holder;
+ ndio_claim->notify_remove = notify_remove;
+ get_device(holder);
+
+ return ndio_claim;
+}
+
/**
* nd_dimm_by_handle - lookup an nd_dimm by its corresponding nfit_handle
* @nd_bus: parent bus of the dimm
@@ -125,6 +181,8 @@ static void nd_bus_release(struct device *dev)
kfree(nd_mem);
}

+ WARN_ON(!list_empty(&nd_bus->ndios));
+
ida_simple_remove(&nd_ida, nd_bus->id);
kfree(nd_bus);
}
@@ -323,11 +381,29 @@ static ssize_t wait_probe_show(struct device *dev,
}
static DEVICE_ATTR_RO(wait_probe);

+static ssize_t btt_seed_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct nd_bus *nd_bus = to_nd_bus(dev);
+ ssize_t rc;
+
+ nd_bus_lock(dev);
+ if (nd_bus->nd_btt)
+ rc = sprintf(buf, "%s\n", dev_name(&nd_bus->nd_btt->dev));
+ else
+ rc = sprintf(buf, "\n");
+ nd_bus_unlock(dev);
+
+ return rc;
+}
+static DEVICE_ATTR_RO(btt_seed);
+
static struct attribute *nd_bus_attributes[] = {
&dev_attr_commands.attr,
&dev_attr_wait_probe.attr,
&dev_attr_provider.attr,
&dev_attr_revision.attr,
+ &dev_attr_btt_seed.attr,
NULL,
};

@@ -353,6 +429,7 @@ static void *nd_bus_new(struct device *parent,
INIT_LIST_HEAD(&nd_bus->bdws);
INIT_LIST_HEAD(&nd_bus->memdevs);
INIT_LIST_HEAD(&nd_bus->dimms);
+ INIT_LIST_HEAD(&nd_bus->ndios);
INIT_LIST_HEAD(&nd_bus->list);
init_waitqueue_head(&nd_bus->probe_wait);
INIT_RADIX_TREE(&nd_bus->dimm_radix, GFP_KERNEL);
@@ -737,6 +814,9 @@ static struct nd_bus *nd_bus_probe(struct nd_bus *nd_bus)
if (rc)
goto err_child;

+ nd_bus->nd_btt = nd_btt_create(nd_bus);
+ nd_synchronize();
+
mutex_lock(&nd_bus_list_mutex);
list_add_tail(&nd_bus->list, &nd_bus_list);
mutex_unlock(&nd_bus_list_mutex);
diff --git a/drivers/block/nd/nd-private.h b/drivers/block/nd/nd-private.h
index f88140dceea7..5f58e8e96a41 100644
--- a/drivers/block/nd/nd-private.h
+++ b/drivers/block/nd/nd-private.h
@@ -31,6 +31,11 @@ enum {
DPA_RESOURCE_ADJUSTED = 1 << 0,
};

+struct block_device;
+struct nd_io_claim;
+struct nd_btt;
+struct nd_io;
+
/*
* List manipulation is protected by nd_bus_list_mutex, except for the
* deferred probe tracking list which nests under instances where
@@ -46,10 +51,12 @@ struct nd_bus {
struct list_head spas;
struct list_head dcrs;
struct list_head bdws;
+ struct list_head ndios;
struct list_head list;
struct device dev;
int id, probe_active;
struct mutex reconfig_mutex;
+ struct nd_btt *nd_btt;
};

struct nd_dimm {
@@ -100,12 +107,32 @@ struct nd_mem {
struct list_head list;
};

+struct nd_io *ndio_lookup(struct nd_bus *nd_bus, const char *diskname);
const char *spa_type_name(u16 type);
int nfit_spa_type(struct nfit_spa __iomem *nfit_spa);
struct nd_dimm *nd_dimm_by_handle(struct nd_bus *nd_bus, u32 nfit_handle);
bool is_nd_dimm(struct device *dev);
bool is_nd_blk(struct device *dev);
bool is_nd_pmem(struct device *dev);
+#if IS_ENABLED(CONFIG_ND_BTT_DEVS)
+bool is_nd_btt(struct device *dev);
+struct nd_btt *nd_btt_create(struct nd_bus *nd_bus);
+void nd_btt_notify_ndio(struct nd_bus *nd_bus, struct nd_io *ndio);
+#else
+static inline bool is_nd_btt(struct device *dev)
+{
+ return false;
+}
+
+static inline struct nd_btt *nd_btt_create(struct nd_bus *nd_bus)
+{
+ return NULL;
+}
+
+static inline void nd_btt_notify_ndio(struct nd_bus *nd_bus, struct nd_io *ndio)
+{
+}
+#endif
struct nd_bus *to_nd_bus(struct device *dev);
struct nd_dimm *to_nd_dimm(struct device *dev);
struct nd_bus *walk_to_nd_bus(struct device *nd_dev);
@@ -127,6 +154,7 @@ void nd_bus_destroy_ndctl(struct nd_bus *nd_bus);
int nd_bus_register_dimms(struct nd_bus *nd_bus);
int nd_bus_register_regions(struct nd_bus *nd_bus);
int nd_bus_init_interleave_sets(struct nd_bus *nd_bus);
+void __nd_device_register(struct device *dev);
int nd_match_dimm(struct device *dev, void *data);
struct nd_label_id;
char *nd_label_gen_id(struct nd_label_id *label_id, u8 *uuid, u32 flags);
diff --git a/drivers/block/nd/nd.h b/drivers/block/nd/nd.h
index 91f61e952003..b4f95ccc0252 100644
--- a/drivers/block/nd/nd.h
+++ b/drivers/block/nd/nd.h
@@ -12,12 +12,18 @@
*/
#ifndef __ND_H__
#define __ND_H__
+#include <linux/genhd.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/ndctl.h>
#include <linux/types.h>
+#include <linux/fs.h>
#include "label.h"

+enum {
+ SECTOR_SHIFT = 9,
+};
+
struct nd_dimm_drvdata {
struct device *dev;
int nsindex_size;
@@ -116,6 +122,84 @@ static inline unsigned nd_inc_seq(unsigned seq)
return next[seq & 3];
}

+struct nd_io;
+/**
+ * nd_rw_bytes_fn() - access bytes relative to the "whole disk" namespace device
+ * @ndio: per-namespace context
+ * @buf: source / target for the write / read
+ * @offset: offset relative to the start of the namespace device
+ * @n: num bytes to access
+ * @flags: READ, WRITE, and other REQ_* flags
+ *
+ * Note: Implementations may assume that offset + n never crosses ndio->align
+ */
+typedef int (*nd_rw_bytes_fn)(struct nd_io *ndio, void *buf, size_t offset,
+ size_t n, unsigned long flags);
+#define nd_data_dir(flags) (flags & 1)
+
+/**
+ * struct nd_io - info for byte-aligned access to nd devices
+ * @rw_bytes: operation to perform byte-aligned access
+ * @align: a single ->rw_bytes() request may not cross this alignment
+ * @gendisk: whole disk block device for the namespace
+ * @list: for the core to cache a list of "ndio"s for later association
+ * @dev: namespace device
+ * @claims: list of clients using this interface
+ * @lock: protect @claims mutation
+ */
+struct nd_io {
+ nd_rw_bytes_fn rw_bytes;
+ unsigned long align;
+ struct gendisk *disk;
+ struct list_head list;
+ struct device *dev;
+ struct list_head claims;
+ spinlock_t lock;
+};
+
+struct nd_io_claim;
+typedef void (*ndio_notify_remove_fn)(struct nd_io_claim *ndio_claim);
+
+/**
+ * struct nd_io_claim - instance of a claim on a parent ndio
+ * @notify_remove: ndio is going away, release resources
+ * @holder: object that has claimed this ndio
+ * @parent: ndio in use
+ * @holder: holder device
+ * @list: claim peers
+ *
+ * An ndio may be claimed multiple times, consider the case of a btt
+ * instance per partition on a namespace.
+ */
+struct nd_io_claim {
+ struct nd_io *parent;
+ ndio_notify_remove_fn notify_remove;
+ struct list_head list;
+ struct device *holder;
+};
+
+struct nd_btt {
+ struct device dev;
+ struct nd_io *ndio;
+ struct block_device *backing_dev;
+ unsigned long lbasize;
+ u8 *uuid;
+ u64 offset;
+ int id;
+ struct nd_io_claim *ndio_claim;
+};
+
+static inline u64 nd_partition_offset(struct block_device *bdev)
+{
+ struct hd_struct *p;
+
+ if (bdev == bdev->bd_contains)
+ return 0;
+
+ p = bdev->bd_part;
+ return ((u64) p->start_sect) << SECTOR_SHIFT;
+}
+
enum nd_async_mode {
ND_SYNC,
ND_ASYNC,
@@ -131,6 +215,13 @@ ssize_t nd_sector_size_show(unsigned long current_lbasize,
const unsigned long *supported, char *buf);
ssize_t nd_sector_size_store(struct device *dev, const char *buf,
unsigned long *current_lbasize, const unsigned long *supported);
+int nd_register_ndio(struct nd_io *ndio);
+int nd_unregister_ndio(struct nd_io *ndio);
+void nd_init_ndio(struct nd_io *ndio, nd_rw_bytes_fn rw_bytes,
+ struct device *dev, struct gendisk *disk, unsigned long align);
+void ndio_del_claim(struct nd_io_claim *ndio_claim);
+struct nd_io_claim *ndio_add_claim(struct nd_io *ndio, struct device *holder,
+ ndio_notify_remove_fn notify_remove);
extern struct attribute_group nd_device_attribute_group;
struct nd_dimm;
struct nd_dimm_drvdata *to_ndd(struct nd_mapping *nd_mapping);
@@ -144,6 +235,9 @@ int nd_dimm_init_config_data(struct nd_dimm_drvdata *ndd);
int nd_dimm_firmware_status(struct device *dev);
int nd_dimm_set_config_data(struct nd_dimm_drvdata *ndd, size_t offset,
void *buf, size_t len);
+struct nd_btt *to_nd_btt(struct device *dev);
+struct btt_sb;
+u64 btt_sb_checksum(struct btt_sb *btt_sb);
struct nd_region *to_nd_region(struct device *dev);
int nd_region_to_namespace_type(struct nd_region *nd_region);
int nd_region_register_namespaces(struct nd_region *nd_region, int *err);
diff --git a/drivers/block/nd/pmem.c b/drivers/block/nd/pmem.c
index aa2b4fb1f140..c902e74f10a7 100644
--- a/drivers/block/nd/pmem.c
+++ b/drivers/block/nd/pmem.c
@@ -31,6 +31,7 @@
struct pmem_device {
struct request_queue *pmem_queue;
struct gendisk *pmem_disk;
+ struct nd_io ndio;

/* One contiguous memory region per device */
phys_addr_t phys_addr;
@@ -100,6 +101,26 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
return 0;
}

+static int pmem_rw_bytes(struct nd_io *ndio, void *buf, size_t offset,
+ size_t n, unsigned long flags)
+{
+ struct pmem_device *pmem = container_of(ndio, typeof(*pmem), ndio);
+ int rw = nd_data_dir(flags);
+
+ if (unlikely(offset + n > pmem->size)) {
+ dev_WARN_ONCE(ndio->dev, 1, "%s: request out of range\n",
+ __func__);
+ return -EFAULT;
+ }
+
+ if (rw == READ)
+ memcpy(buf, pmem->virt_addr + offset, n);
+ else
+ memcpy(pmem->virt_addr + offset, buf, n);
+
+ return 0;
+}
+
static long pmem_direct_access(struct block_device *bdev, sector_t sector,
void **kaddr, unsigned long *pfn, long size)
{
@@ -179,8 +200,6 @@ static struct pmem_device *pmem_alloc(struct device *dev, struct resource *res)
set_capacity(disk, pmem->size >> 9);
pmem->pmem_disk = disk;

- add_disk(disk);
-
return pmem;

out_free_queue:
@@ -224,6 +243,7 @@ static int pmem_probe(struct platform_device *pdev)
if (IS_ERR(pmem))
return PTR_ERR(pmem);

+ add_disk(pmem->pmem_disk);
platform_set_drvdata(pdev, pmem);

return 0;
@@ -273,7 +293,12 @@ static int nd_pmem_probe(struct device *dev)
if (IS_ERR(pmem))
return PTR_ERR(pmem);

+ nd_bus_lock(dev);
+ add_disk(pmem->pmem_disk);
dev_set_drvdata(dev, pmem);
+ nd_init_ndio(&pmem->ndio, pmem_rw_bytes, dev, pmem->pmem_disk, 0);
+ nd_register_ndio(&pmem->ndio);
+ nd_bus_unlock(dev);

return 0;
}
@@ -282,6 +307,7 @@ static int nd_pmem_remove(struct device *dev)
{
struct pmem_device *pmem = dev_get_drvdata(dev);

+ nd_unregister_ndio(&pmem->ndio);
pmem_free(pmem);
return 0;
}
diff --git a/include/uapi/linux/ndctl.h b/include/uapi/linux/ndctl.h
index 5f0cf00872e0..4156a0f816ca 100644
--- a/include/uapi/linux/ndctl.h
+++ b/include/uapi/linux/ndctl.h
@@ -181,6 +181,7 @@ static inline const char *nfit_dimm_cmd_name(unsigned cmd)
#define ND_DEVICE_NAMESPACE_IO 4 /* legacy persistent memory */
#define ND_DEVICE_NAMESPACE_PMEM 5 /* persistent memory namespace (may alias) */
#define ND_DEVICE_NAMESPACE_BLOCK 6 /* block-data-window namespace (may alias) */
+#define ND_DEVICE_BTT 7 /* block-translation table device */

enum nd_driver_flags {
ND_DRIVER_DIMM = 1 << ND_DEVICE_DIMM,
@@ -189,6 +190,7 @@ enum nd_driver_flags {
ND_DRIVER_NAMESPACE_IO = 1 << ND_DEVICE_NAMESPACE_IO,
ND_DRIVER_NAMESPACE_PMEM = 1 << ND_DEVICE_NAMESPACE_PMEM,
ND_DRIVER_NAMESPACE_BLOCK = 1 << ND_DEVICE_NAMESPACE_BLOCK,
+ ND_DRIVER_BTT = 1 << ND_DEVICE_BTT,
};

enum {


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