[PATCH v4 6/7] dax: add recovery_write to dax_iomap_iter in failure path

[Jane Chu <jane.chu@oracle.com>]

dax_iomap_iter() fails if the destination range contains poison.
Add recovery_write to the failure code path.

Signed-off-by: Jane Chu <jane.chu@oracle.com>
---
 fs/dax.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index cd03485867a7..236675bd5946 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1199,6 +1199,8 @@ int dax_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
 }
 EXPORT_SYMBOL_GPL(dax_truncate_page);
 
+typedef size_t (*iter_func_t)(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
 static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
 		struct iov_iter *iter)
 {
@@ -1210,6 +1212,7 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
 	ssize_t ret = 0;
 	size_t xfer;
 	int id;
+	iter_func_t write_func = dax_copy_from_iter;
 
 	if (iov_iter_rw(iter) == READ) {
 		end = min(end, i_size_read(iomi->inode));
@@ -1249,6 +1252,17 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
 
 		map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size),
 				&kaddr, NULL);
+		if ((map_len == -EIO) && (iov_iter_rw(iter) == WRITE)) {
+			if (dax_prep_recovery(dax_dev, &kaddr) < 0) {
+				ret = map_len;
+				break;
+			}
+			map_len = dax_direct_access(dax_dev, pgoff,
+					PHYS_PFN(size), &kaddr, NULL);
+			if (map_len > 0)
+				write_func = dax_recovery_write;
+		}
+
 		if (map_len < 0) {
 			ret = map_len;
 			break;
@@ -1261,12 +1275,17 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
 			map_len = end - pos;
 
 		if (iov_iter_rw(iter) == WRITE)
-			xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr,
-					map_len, iter);
+			xfer = write_func(dax_dev, pgoff, kaddr, map_len, iter);
 		else
 			xfer = dax_copy_to_iter(dax_dev, pgoff, kaddr,
 					map_len, iter);
 
+		if (xfer == (ssize_t) -EIO) {
+			pr_warn("dax_ioma_iter: write_func returns -EIO\n");
+			ret = -EIO;
+			break;
+		}
+
 		pos += xfer;
 		length -= xfer;
 		done += xfer;
-- 
2.18.4