fsdax: switch dax_iomap_rw to use iomap_iter

Switch the dax_iomap_rw implementation to use iomap_iter.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

fs/dax.c

@@ -1103,20 +1103,21 @@ s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap)
 	return size;
 }
 
-static loff_t
-dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
-		struct iomap *iomap, struct iomap *srcmap)
+static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
+		struct iov_iter *iter)
 {
+	const struct iomap *iomap = &iomi->iomap;
+	loff_t length = iomap_length(iomi);
+	loff_t pos = iomi->pos;
 	struct block_device *bdev = iomap->bdev;
 	struct dax_device *dax_dev = iomap->dax_dev;
-	struct iov_iter *iter = data;
 	loff_t end = pos + length, done = 0;
 	ssize_t ret = 0;
 	size_t xfer;
 	int id;
 
 	if (iov_iter_rw(iter) == READ) {
-		end = min(end, i_size_read(inode));
+		end = min(end, i_size_read(iomi->inode));
 		if (pos >= end)
 			return 0;
 
@@ -1133,7 +1134,7 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 	 * written by write(2) is visible in mmap.
 	 */
 	if (iomap->flags & IOMAP_F_NEW) {
-		invalidate_inode_pages2_range(inode->i_mapping,
+		invalidate_inode_pages2_range(iomi->inode->i_mapping,
 					      pos >> PAGE_SHIFT,
 					      (end - 1) >> PAGE_SHIFT);
 	}
@@ -1209,31 +1210,29 @@ ssize_t
 dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops)
 {
-	struct address_space *mapping = iocb->ki_filp->f_mapping;
-	struct inode *inode = mapping->host;
-	loff_t pos = iocb->ki_pos, ret = 0, done = 0;
-	unsigned flags = 0;
+	struct iomap_iter iomi = {
+		.inode		= iocb->ki_filp->f_mapping->host,
+		.pos		= iocb->ki_pos,
+		.len		= iov_iter_count(iter),
+	};
+	loff_t done = 0;
+	int ret;
 
 	if (iov_iter_rw(iter) == WRITE) {
-		lockdep_assert_held_write(&inode->i_rwsem);
-		flags |= IOMAP_WRITE;
+		lockdep_assert_held_write(&iomi.inode->i_rwsem);
+		iomi.flags |= IOMAP_WRITE;
 	} else {
-		lockdep_assert_held(&inode->i_rwsem);
+		lockdep_assert_held(&iomi.inode->i_rwsem);
 	}
 
 	if (iocb->ki_flags & IOCB_NOWAIT)
-		flags |= IOMAP_NOWAIT;
+		iomi.flags |= IOMAP_NOWAIT;
 
-	while (iov_iter_count(iter)) {
-		ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,
-				iter, dax_iomap_actor);
-		if (ret <= 0)
-			break;
-		pos += ret;
-		done += ret;
-	}
+	while ((ret = iomap_iter(&iomi, ops)) > 0)
+		iomi.processed = dax_iomap_iter(&iomi, iter);
 
-	iocb->ki_pos += done;
+	done = iomi.pos - iocb->ki_pos;
+	iocb->ki_pos = iomi.pos;
 	return done ? done : ret;
 }
 EXPORT_SYMBOL_GPL(dax_iomap_rw);
@@ -1307,7 +1306,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	}
 
 	/*
-	 * Note that we don't bother to use iomap_apply here: DAX required
+	 * Note that we don't bother to use iomap_iter here: DAX required
 	 * the file system block size to be equal the page size, which means
 	 * that we never have to deal with more than a single extent here.
 	 */
@@ -1561,7 +1560,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	}
 
 	/*
-	 * Note that we don't use iomap_apply here.  We aren't doing I/O, only
+	 * Note that we don't use iomap_iter here.  We aren't doing I/O, only
 	 * setting up a mapping, so really we're using iomap_begin() as a way
 	 * to look up our filesystem block.
 	 */