iomap: switch iomap_fiemap to use iomap_iter

Rewrite the ->fiemap implementation based on 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/iomap/fiemap.c

 // SPDX-License-Identifier: GPL-2.0
 /*
- * Copyright (c) 2016-2018 Christoph Hellwig.
+ * Copyright (c) 2016-2021 Christoph Hellwig.
  */
 #include <linux/module.h>
 #include <linux/compiler.h>
@@ -8,13 +8,8 @@
 #include <linux/iomap.h>
 #include <linux/fiemap.h>
 
-struct fiemap_ctx {
-	struct fiemap_extent_info *fi;
-	struct iomap prev;
-};
-
 static int iomap_to_fiemap(struct fiemap_extent_info *fi,
-		struct iomap *iomap, u32 flags)
+		const struct iomap *iomap, u32 flags)
 {
 	switch (iomap->type) {
 	case IOMAP_HOLE:
@@ -43,24 +38,22 @@ static int iomap_to_fiemap(struct fiemap_extent_info *fi,
 			iomap->length, flags);
 }
 
-static loff_t
-iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
-		struct iomap *iomap, struct iomap *srcmap)
+static loff_t iomap_fiemap_iter(const struct iomap_iter *iter,
+		struct fiemap_extent_info *fi, struct iomap *prev)
 {
-	struct fiemap_ctx *ctx = data;
-	loff_t ret = length;
+	int ret;
 
-	if (iomap->type == IOMAP_HOLE)
-		return length;
+	if (iter->iomap.type == IOMAP_HOLE)
+		return iomap_length(iter);
 
-	ret = iomap_to_fiemap(ctx->fi, &ctx->prev, 0);
-	ctx->prev = *iomap;
+	ret = iomap_to_fiemap(fi, prev, 0);
+	*prev = iter->iomap;
 	switch (ret) {
 	case 0:		/* success */
-		return length;
+		return iomap_length(iter);
 	case 1:		/* extent array full */
 		return 0;
-	default:
+	default:	/* error */
 		return ret;
 	}
 }
@@ -68,38 +61,33 @@ iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
 		u64 start, u64 len, const struct iomap_ops *ops)
 {
-	struct fiemap_ctx ctx;
-	loff_t ret;
-
-	memset(&ctx, 0, sizeof(ctx));
-	ctx.fi = fi;
-	ctx.prev.type = IOMAP_HOLE;
+	struct iomap_iter iter = {
+		.inode		= inode,
+		.pos		= start,
+		.len		= len,
+		.flags		= IOMAP_REPORT,
+	};
+	struct iomap prev = {
+		.type		= IOMAP_HOLE,
+	};
+	int ret;
 
-	ret = fiemap_prep(inode, fi, start, &len, 0);
+	ret = fiemap_prep(inode, fi, start, &iter.len, 0);
 	if (ret)
 		return ret;
 
-	while (len > 0) {
-		ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx,
-				iomap_fiemap_actor);
-		/* inode with no (attribute) mapping will give ENOENT */
-		if (ret == -ENOENT)
-			break;
-		if (ret < 0)
-			return ret;
-		if (ret == 0)
-			break;
+	while ((ret = iomap_iter(&iter, ops)) > 0)
+		iter.processed = iomap_fiemap_iter(&iter, fi, &prev);
 
-		start += ret;
-		len -= ret;
-	}
-
-	if (ctx.prev.type != IOMAP_HOLE) {
-		ret = iomap_to_fiemap(fi, &ctx.prev, FIEMAP_EXTENT_LAST);
+	if (prev.type != IOMAP_HOLE) {
+		ret = iomap_to_fiemap(fi, &prev, FIEMAP_EXTENT_LAST);
 		if (ret < 0)
 			return ret;
 	}
 
+	/* inode with no (attribute) mapping will give ENOENT */
+	if (ret < 0 && ret != -ENOENT)
+		return ret;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(iomap_fiemap);