From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
fs/btrfs/Makefile | 1 +
fs/btrfs/ctree.h | 5 ++++
fs/btrfs/dax.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/file.c | 13 ++++++++++-
4 files changed, 86 insertions(+), 1 deletion(-)
create mode 100644 fs/btrfs/dax.c
diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index ca693dd554e9..1fa77b875ae9 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -12,6 +12,7 @@ btrfs-y += super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
reada.o backref.o ulist.o qgroup.o send.o dev-replace.o raid56.o \
uuid-tree.o props.o free-space-tree.o tree-checker.o
+btrfs-$(CONFIG_FS_DAX) += dax.o
btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
btrfs-$(CONFIG_BTRFS_FS_CHECK_INTEGRITY) += check-integrity.o
btrfs-$(CONFIG_BTRFS_FS_REF_VERIFY) += ref-verify.o
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 5cc470fa6a40..038d64ecebe5 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3685,6 +3685,11 @@ int btrfs_reada_wait(void *handle);
void btrfs_reada_detach(void *handle);
int btree_readahead_hook(struct extent_buffer *eb, int err);
+#ifdef CONFIG_FS_DAX
+/* dax.c */
+ssize_t btrfs_file_dax_read(struct kiocb *iocb, struct iov_iter *to);
+#endif /* CONFIG_FS_DAX */
+
static inline int is_fstree(u64 rootid)
{
if (rootid == BTRFS_FS_TREE_OBJECTID ||
diff --git a/fs/btrfs/dax.c b/fs/btrfs/dax.c
new file mode 100644
index 000000000000..d614bf73bf8e
--- /dev/null
+++ b/fs/btrfs/dax.c
@@ -0,0 +1,68 @@
+#include <linux/dax.h>
+#include <linux/uio.h>
+#include "ctree.h"
+#include "btrfs_inode.h"
+
+static ssize_t em_dax_rw(struct inode *inode, struct extent_map *em, u64 pos,
+ u64 len, struct iov_iter *iter)
+{
+ struct dax_device *dax_dev = fs_dax_get_by_bdev(em->bdev);
+ ssize_t map_len;
+ pgoff_t blk_pg;
+ void *kaddr;
+ sector_t blk_start;
+ unsigned offset = pos & (PAGE_SIZE - 1);
+
+ len = min(len + offset, em->len - (pos - em->start));
+ len = ALIGN(len, PAGE_SIZE);
+ blk_start = (get_start_sect(em->bdev) << 9) + (em->block_start + (pos - em->start));
+ blk_pg = blk_start - offset;
+ map_len = dax_direct_access(dax_dev, PHYS_PFN(blk_pg), PHYS_PFN(len), &kaddr, NULL);
+ map_len = PFN_PHYS(map_len);
+ kaddr += offset;
+ map_len -= offset;
+ if (map_len > len)
+ map_len = len;
+ if (iov_iter_rw(iter) == WRITE)
+ return dax_copy_from_iter(dax_dev, blk_pg, kaddr, map_len, iter);
+ else
+ return dax_copy_to_iter(dax_dev, blk_pg, kaddr, map_len, iter);
+}
+
+ssize_t btrfs_file_dax_read(struct kiocb *iocb, struct iov_iter *to)
+{
+ size_t ret = 0, done = 0, count = iov_iter_count(to);
+ struct extent_map *em;
+ u64 pos = iocb->ki_pos;
+ u64 end = pos + count;
+ struct inode *inode = file_inode(iocb->ki_filp);
+
+ if (!count)
+ return 0;
+
+ end = i_size_read(inode) < end ? i_size_read(inode) : end;
+
+ while (pos < end) {
+ u64 len = end - pos;
+
+ em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, pos, len, 0);
+ if (IS_ERR(em)) {
+ if (!ret)
+ ret = PTR_ERR(em);
+ goto out;
+ }
+
+ BUG_ON(em->flags & EXTENT_FLAG_FS_MAPPING);
+
+ ret = em_dax_rw(inode, em, pos, len, to);
+ if (ret < 0)
+ goto out;
+ pos += ret;
+ done += ret;
+ }
+
+out:
+ iocb->ki_pos += done;
+ return done ? done : ret;
+}
+
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 58e93bce3036..ef6ed93f44d1 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3308,9 +3308,20 @@ static int btrfs_file_open(struct inode *inode, struct file *filp)
return generic_file_open(inode, filp);
}
+static ssize_t btrfs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+
+#ifdef CONFIG_FS_DAX
+ if (IS_DAX(inode))
+ return btrfs_file_dax_read(iocb, to);
+#endif
+ return generic_file_read_iter(iocb, to);
+}
+
const struct file_operations btrfs_file_operations = {
.llseek = btrfs_file_llseek,
- .read_iter = generic_file_read_iter,
+ .read_iter = btrfs_file_read_iter,
.splice_read = generic_file_splice_read,
.write_iter = btrfs_file_write_iter,
.mmap = btrfs_file_mmap,
--
2.16.4
