[RFC PATCH 5/7] dax: memcpy before zeroing range

Shiyang Ruan
2019-07-31T11:50:05Z

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

However, this needed more iomap fields, so it was easier
to pass iomap and compute inside the function rather
than passing a log of arguments.

Note, there is subtle difference between iomap_sector and
dax_iomap_sector(). Can we replace dax_iomap_sector with
iomap_sector()? It would need pos & PAGE_MASK though or else
bdev_dax_pgoff() return -EINVAL.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
fs/dax.c | 17 ++++++++++++-----
fs/iomap.c | 9 +--------
include/linux/dax.h | 11 +++++------
include/linux/iomap.h | 6 ++++++
4 files changed, 24 insertions(+), 19 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 8111ba93f4d3..c92111950612 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1071,11 +1071,16 @@ static bool dax_range_is_aligned(struct block_device *bdev,
return true;
}

-int __dax_zero_page_range(struct block_device *bdev,
- struct dax_device *dax_dev, sector_t sector,
- unsigned int offset, unsigned int size)
+int __dax_zero_page_range(struct iomap *iomap, loff_t pos,
+ unsigned int offset, unsigned int size)
{
- if (dax_range_is_aligned(bdev, offset, size)) {
+ sector_t sector = dax_iomap_sector(iomap, pos & PAGE_MASK);
+ struct block_device *bdev = iomap->bdev;
+ struct dax_device *dax_dev = iomap->dax_dev;
+ int ret = 0;
+
+ if (!(iomap->type == IOMAP_COW) &&
+ dax_range_is_aligned(bdev, offset, size)) {
sector_t start_sector = sector + (offset >> 9);

return blkdev_issue_zeroout(bdev, start_sector,
@@ -1095,11 +1100,13 @@ int __dax_zero_page_range(struct block_device *bdev,
dax_read_unlock(id);
return rc;
}
+ if (iomap->type == IOMAP_COW)
+ ret = memcpy_mcsafe(kaddr, iomap->inline_data, offset);
memset(kaddr + offset, 0, size);
dax_flush(dax_dev, kaddr + offset, size);
dax_read_unlock(id);
}
- return 0;
+ return ret;
}
EXPORT_SYMBOL_GPL(__dax_zero_page_range);

diff --git a/fs/iomap.c b/fs/iomap.c
index 3377a7ec5b7d..b5662b5bac26 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -99,12 +99,6 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
return written ? written : ret;
}

-static sector_t
-iomap_sector(struct iomap *iomap, loff_t pos)
-{
- return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
-}
-
static struct iomap_page *
iomap_page_create(struct inode *inode, struct page *page)
{
@@ -993,8 +987,7 @@ static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
struct iomap *iomap)
{
- return __dax_zero_page_range(iomap->bdev, iomap->dax_dev,
- iomap_sector(iomap, pos & PAGE_MASK), offset, bytes);
+ return __dax_zero_page_range(iomap, pos, offset, bytes);
}

static loff_t
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 1370d39c91b6..c469d9ff54b4 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -9,6 +9,7 @@

typedef unsigned long dax_entry_t;

+struct iomap;
struct iomap_ops;
struct dax_device;
struct dax_operations {
@@ -163,13 +164,11 @@ int dax_file_range_compare(struct inode *src, loff_t srcoff,
const struct iomap_ops *ops);

#ifdef CONFIG_FS_DAX
-int __dax_zero_page_range(struct block_device *bdev,
- struct dax_device *dax_dev, sector_t sector,
- unsigned int offset, unsigned int length);
+int __dax_zero_page_range(struct iomap *iomap, loff_t pos,
+ unsigned int offset, unsigned int size);
#else
-static inline int __dax_zero_page_range(struct block_device *bdev,
- struct dax_device *dax_dev, sector_t sector,
- unsigned int offset, unsigned int length)
+static inline int __dax_zero_page_range(struct iomap *iomap, loff_t pos,
+ unsigned int offset, unsigned int size)
{
return -ENXIO;
}
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 75b78dd91c3c..3628e57954c6 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -7,6 +7,7 @@
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/mm_types.h>
+#include <linux/blkdev.h>

struct address_space;
struct fiemap_extent_info;
@@ -122,6 +123,11 @@ static inline struct iomap_page *to_iomap_page(struct page *page)
return NULL;
}

+static inline sector_t iomap_sector(struct iomap *iomap, loff_t pos)
+{
+ return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
+}
+
ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,
const struct iomap_ops *ops);
int iomap_readpage(struct page *page, const struct iomap_ops *ops);
--
2.17.0