fsdax: factor out a dax_memzero helper

Factor out a helper for the "manual" zeroing of a DAX range to clean
up dax_iomap_zero a lot.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Dan Williams <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Dan Williams <[email protected]>

Author: Christoph Hellwig

fs/dax.c

@@ -1121,34 +1121,36 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
 }
 #endif /* CONFIG_FS_DAX_PMD */
 
+static int dax_memzero(struct dax_device *dax_dev, pgoff_t pgoff,
+		unsigned int offset, size_t size)
+{
+	void *kaddr;
+	long ret;
+
+	ret = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL);
+	if (ret > 0) {
+		memset(kaddr + offset, 0, size);
+		dax_flush(dax_dev, kaddr + offset, size);
+	}
+	return ret;
+}
+
 s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap)
 {
 	pgoff_t pgoff = dax_iomap_pgoff(iomap, pos);
 	long rc, id;
-	void *kaddr;
-	bool page_aligned = false;
 	unsigned offset = offset_in_page(pos);
 	unsigned size = min_t(u64, PAGE_SIZE - offset, length);
 
-	if (IS_ALIGNED(pos, PAGE_SIZE) && size == PAGE_SIZE)
-		page_aligned = true;
-
 	id = dax_read_lock();
-
-	if (page_aligned)
+	if (IS_ALIGNED(pos, PAGE_SIZE) && size == PAGE_SIZE)
 		rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1);
 	else
-		rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL);
-	if (rc < 0) {
-		dax_read_unlock(id);
-		return rc;
-	}
-
-	if (!page_aligned) {
-		memset(kaddr + offset, 0, size);
-		dax_flush(iomap->dax_dev, kaddr + offset, size);
-	}
+		rc = dax_memzero(iomap->dax_dev, pgoff, offset, size);
 	dax_read_unlock(id);
+
+	if (rc < 0)
+		return rc;
 	return size;
 }