[PATCH 2/2] fsdax,xfs: port unshare to fsdax

Shiyang Ruan
2022-11-24T14:55:31Z

Implement unshare in fsdax mode: copy data from srcmap to iomap.

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
---
fs/dax.c | 52 ++++++++++++++++++++++++++++++++++++++++++++
fs/xfs/xfs_reflink.c | 8 +++++--
include/linux/dax.h | 2 ++
3 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 5ea7c0926b7f..3d0bf68ab6b0 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1235,6 +1235,58 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
}
#endif /* CONFIG_FS_DAX_PMD */

+static s64 dax_unshare_iter(struct iomap_iter *iter)
+{
+ struct iomap *iomap = &iter->iomap;
+ const struct iomap *srcmap = iomap_iter_srcmap(iter);
+ loff_t pos = iter->pos;
+ loff_t length = iomap_length(iter);
+ int id = 0;
+ s64 ret = 0;
+ void *daddr = NULL, *saddr = NULL;
+
+ /* don't bother with blocks that are not shared to start with */
+ if (!(iomap->flags & IOMAP_F_SHARED))
+ return length;
+ /* don't bother with holes or unwritten extents */
+ if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
+ return length;
+
+ id = dax_read_lock();
+ ret = dax_iomap_direct_access(iomap, pos, length, &daddr, NULL);
+ if (ret < 0)
+ goto out_unlock;
+
+ ret = dax_iomap_direct_access(srcmap, pos, length, &saddr, NULL);
+ if (ret < 0)
+ goto out_unlock;
+
+ ret = copy_mc_to_kernel(daddr, saddr, length);
+ if (ret)
+ ret = -EIO;
+
+out_unlock:
+ dax_read_unlock(id);
+ return ret;
+}
+
+int dax_file_unshare(struct inode *inode, loff_t pos, loff_t len,
+ const struct iomap_ops *ops)
+{
+ struct iomap_iter iter = {
+ .inode = inode,
+ .pos = pos,
+ .len = len,
+ .flags = IOMAP_WRITE | IOMAP_UNSHARE | IOMAP_DAX,
+ };
+ int ret;
+
+ while ((ret = iomap_iter(&iter, ops)) > 0)
+ iter.processed = dax_unshare_iter(&iter);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dax_file_unshare);
+
static int dax_memzero(struct iomap_iter *iter, loff_t pos, size_t size)
{
const struct iomap *iomap = &iter->iomap;
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 93bdd25680bc..fe46bce8cae6 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1693,8 +1693,12 @@ xfs_reflink_unshare(

inode_dio_wait(inode);

- error = iomap_file_unshare(inode, offset, len,
- &xfs_buffered_write_iomap_ops);
+ if (IS_DAX(inode))
+ error = dax_file_unshare(inode, offset, len,
+ &xfs_dax_write_iomap_ops);
+ else
+ error = iomap_file_unshare(inode, offset, len,
+ &xfs_buffered_write_iomap_ops);
if (error)
goto out;

diff --git a/include/linux/dax.h b/include/linux/dax.h
index ba985333e26b..2b5ecb591059 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -205,6 +205,8 @@ static inline void dax_unlock_mapping_entry(struct address_space *mapping,
}
#endif

+int dax_file_unshare(struct inode *inode, loff_t pos, loff_t len,
+ const struct iomap_ops *ops);
int dax_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
const struct iomap_ops *ops);
int dax_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
--
2.38.1