From b3a9a0c36e1f7b9e2e6cf965c2bb973624f2b3b9 Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@intel.com>
Date: Wed, 2 May 2018 06:46:33 -0700
Subject: [PATCH] dax: Introduce a ->copy_to_iter dax operation
Git-commit: b3a9a0c36e1f7b9e2e6cf965c2bb973624f2b3b9 (partial)
Patch-mainline: v4.18-rc1
References: bsc#1098782
Similar to the ->copy_from_iter() operation, a platform may want to
deploy an architecture or device specific routine for handling reads
from a dax_device like /dev/pmemX. On x86 this routine will point to a
machine check safe version of copy_to_iter(). For now, add the plumbing
to device-mapper and the dax core.
[JK: Partial backport only. Device mapper bits were ripped out to maintain
kABI.]
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Jan Kara <jack@suse.cz>
---
drivers/dax/super.c | 10 ++++++++++
drivers/md/dm.c | 7 +++++++
drivers/nvdimm/pmem.c | 7 +++++++
drivers/s390/block/dcssblk.c | 7 +++++++
fs/dax.c | 3 ++-
include/linux/dax.h | 5 +++++
6 files changed, 38 insertions(+), 1 deletion(-)
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -269,6 +269,16 @@ size_t dax_copy_from_iter(struct dax_dev
}
EXPORT_SYMBOL_GPL(dax_copy_from_iter);
+size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
+ size_t bytes, struct iov_iter *i)
+{
+ if (!dax_alive(dax_dev))
+ return 0;
+
+ return dax_dev->ops->copy_to_iter(dax_dev, pgoff, addr, bytes, i);
+}
+EXPORT_SYMBOL_GPL(dax_copy_to_iter);
+
#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)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1003,6 +1003,12 @@ static size_t dm_dax_copy_from_iter(stru
return ret;
}
+static size_t dm_dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
+ void *addr, size_t bytes, struct iov_iter *i)
+{
+ return copy_to_iter(addr, bytes, i);
+}
+
/*
* A target may call dm_accept_partial_bio only from the map routine. It is
* allowed for all bio types except REQ_PREFLUSH and REQ_OP_ZONE_RESET.
@@ -2978,6 +2984,7 @@ static const struct block_device_operati
static const struct dax_operations dm_dax_ops = {
.direct_access = dm_dax_direct_access,
.copy_from_iter = dm_dax_copy_from_iter,
+ .copy_to_iter = dm_dax_copy_to_iter,
};
/*
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -245,9 +245,16 @@ static size_t pmem_copy_from_iter(struct
return copy_from_iter_flushcache(addr, bytes, i);
}
+static size_t pmem_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
+ void *addr, size_t bytes, struct iov_iter *i)
+{
+ return copy_to_iter(addr, bytes, i);
+}
+
static const struct dax_operations pmem_dax_ops = {
.direct_access = pmem_dax_direct_access,
.copy_from_iter = pmem_copy_from_iter,
+ .copy_to_iter = pmem_copy_to_iter,
};
static const struct attribute_group *pmem_attribute_groups[] = {
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -50,9 +50,16 @@ static size_t dcssblk_dax_copy_from_iter
return copy_from_iter(addr, bytes, i);
}
+static size_t dcssblk_dax_copy_to_iter(struct dax_device *dax_dev,
+ pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
+{
+ return copy_to_iter(addr, bytes, i);
+}
+
static const struct dax_operations dcssblk_dax_ops = {
.direct_access = dcssblk_dax_direct_access,
.copy_from_iter = dcssblk_dax_copy_from_iter,
+ .copy_to_iter = dcssblk_dax_copy_to_iter,
};
struct dcssblk_dev_info {
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -979,7 +979,8 @@ dax_iomap_actor(struct inode *inode, lof
map_len = dax_copy_from_iter(dax_dev, pgoff, kaddr,
map_len, iter);
else
- map_len = copy_to_iter(kaddr, map_len, iter);
+ map_len = dax_copy_to_iter(dax_dev, pgoff, kaddr,
+ map_len, iter);
if (map_len <= 0) {
ret = map_len ? map_len : -EFAULT;
break;
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -19,6 +19,9 @@ struct dax_operations {
/* copy_from_iter: required operation for fs-dax direct-i/o */
size_t (*copy_from_iter)(struct dax_device *, pgoff_t, void *, size_t,
struct iov_iter *);
+ /* 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 *);
};
extern struct attribute_group dax_attribute_group;
@@ -89,6 +92,8 @@ long dax_direct_access(struct dax_device
void **kaddr, pfn_t *pfn);
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);
void dax_flush(struct dax_device *dax_dev, void *addr, size_t size);
void dax_write_cache(struct dax_device *dax_dev, bool wc);
bool dax_write_cache_enabled(struct dax_device *dax_dev);