[PATCH v2 13/16] iomap: move read/readahead logic out of CONFIG_BLOCK guard

[Joanne Koong <joannelkoong@gmail.com>]

There is no longer a dependency on CONFIG_BLOCK in the iomap read and
readahead logic. Move this logic out of the CONFIG_BLOCK guard. This
allows non-block-based filesystems to use iomap for reads/readahead.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
---
 fs/iomap/buffered-io.c | 151 +++++++++++++++++++++--------------------
 1 file changed, 76 insertions(+), 75 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index f673e03f4ffb..c424e8c157dd 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -358,81 +358,6 @@ void iomap_finish_folio_read(struct folio *folio, size_t off, size_t len,
 }
 EXPORT_SYMBOL_GPL(iomap_finish_folio_read);
 
-#ifdef CONFIG_BLOCK
-static void iomap_read_end_io(struct bio *bio)
-{
-	int error = blk_status_to_errno(bio->bi_status);
-	struct folio_iter fi;
-
-	bio_for_each_folio_all(fi, bio)
-		iomap_finish_folio_read(fi.folio, fi.offset, fi.length, error);
-	bio_put(bio);
-}
-
-static int iomap_submit_read_bio(struct iomap_read_folio_ctx *ctx)
-{
-	struct bio *bio = ctx->private;
-
-	if (bio)
-		submit_bio(bio);
-
-	return 0;
-}
-
-/**
- * Read in a folio range asynchronously through bios.
- *
- * This should only be used for read/readahead, not for buffered writes.
- * Buffered writes must read in the folio synchronously.
- */
-static int iomap_read_folio_range_bio_async(const struct iomap_iter *iter,
-		struct iomap_read_folio_ctx *ctx, loff_t pos, size_t plen)
-{
-	struct folio *folio = ctx->cur_folio;
-	const struct iomap *iomap = &iter->iomap;
-	size_t poff = offset_in_folio(folio, pos);
-	loff_t length = iomap_length(iter);
-	sector_t sector;
-	struct bio *bio = ctx->private;
-
-	iomap_start_folio_read(folio, plen);
-
-	sector = iomap_sector(iomap, pos);
-	if (!bio || bio_end_sector(bio) != sector ||
-	    !bio_add_folio(bio, folio, plen, poff)) {
-		gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL);
-		gfp_t orig_gfp = gfp;
-		unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
-
-		iomap_submit_read_bio(ctx);
-
-		if (ctx->rac) /* same as readahead_gfp_mask */
-			gfp |= __GFP_NORETRY | __GFP_NOWARN;
-		bio = bio_alloc(iomap->bdev, bio_max_segs(nr_vecs),
-				     REQ_OP_READ, gfp);
-		/*
-		 * If the bio_alloc fails, try it again for a single page to
-		 * avoid having to deal with partial page reads.  This emulates
-		 * what do_mpage_read_folio does.
-		 */
-		if (!bio)
-			bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ, orig_gfp);
-		if (ctx->rac)
-			bio->bi_opf |= REQ_RAHEAD;
-		bio->bi_iter.bi_sector = sector;
-		bio->bi_end_io = iomap_read_end_io;
-		bio_add_folio_nofail(bio, folio, plen, poff);
-		ctx->private = bio;
-	}
-	return 0;
-}
-
-const struct iomap_read_ops iomap_read_bios_ops = {
-	.read_folio_range = iomap_read_folio_range_bio_async,
-	.read_submit = iomap_submit_read_bio,
-};
-EXPORT_SYMBOL_GPL(iomap_read_bios_ops);
-
 static int iomap_read_folio_iter(struct iomap_iter *iter,
 		struct iomap_read_folio_ctx *ctx, bool *cur_folio_owned)
 {
@@ -601,6 +526,82 @@ void iomap_readahead(const struct iomap_ops *ops,
 }
 EXPORT_SYMBOL_GPL(iomap_readahead);
 
+#ifdef CONFIG_BLOCK
+static void iomap_read_end_io(struct bio *bio)
+{
+	int error = blk_status_to_errno(bio->bi_status);
+	struct folio_iter fi;
+
+	bio_for_each_folio_all(fi, bio)
+		iomap_finish_folio_read(fi.folio, fi.offset, fi.length, error);
+	bio_put(bio);
+}
+
+static int iomap_submit_read_bio(struct iomap_read_folio_ctx *ctx)
+{
+	struct bio *bio = ctx->private;
+
+	if (bio)
+		submit_bio(bio);
+
+	return 0;
+}
+
+/**
+ * Read in a folio range asynchronously through bios.
+ *
+ * This should only be used for read/readahead, not for buffered writes.
+ * Buffered writes must read in the folio synchronously.
+ */
+static int iomap_read_folio_range_bio_async(const struct iomap_iter *iter,
+		struct iomap_read_folio_ctx *ctx, loff_t pos, size_t plen)
+{
+	struct folio *folio = ctx->cur_folio;
+	const struct iomap *iomap = &iter->iomap;
+	size_t poff = offset_in_folio(folio, pos);
+	loff_t length = iomap_length(iter);
+	sector_t sector;
+	struct bio *bio = ctx->private;
+
+	iomap_start_folio_read(folio, plen);
+
+	sector = iomap_sector(iomap, pos);
+	if (!bio || bio_end_sector(bio) != sector ||
+	    !bio_add_folio(bio, folio, plen, poff)) {
+		gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL);
+		gfp_t orig_gfp = gfp;
+		unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
+
+		if (bio)
+			submit_bio(bio);
+
+		if (ctx->rac) /* same as readahead_gfp_mask */
+			gfp |= __GFP_NORETRY | __GFP_NOWARN;
+		bio = bio_alloc(iomap->bdev, bio_max_segs(nr_vecs),
+				     REQ_OP_READ, gfp);
+		/*
+		 * If the bio_alloc fails, try it again for a single page to
+		 * avoid having to deal with partial page reads.  This emulates
+		 * what do_mpage_read_folio does.
+		 */
+		if (!bio)
+			bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ, orig_gfp);
+		if (ctx->rac)
+			bio->bi_opf |= REQ_RAHEAD;
+		bio->bi_iter.bi_sector = sector;
+		bio->bi_end_io = iomap_read_end_io;
+		bio_add_folio_nofail(bio, folio, plen, poff);
+		ctx->private = bio;
+	}
+	return 0;
+}
+
+const struct iomap_read_ops iomap_read_bios_ops = {
+	.read_folio_range = iomap_read_folio_range_bio_async,
+	.read_submit = iomap_submit_read_bio,
+};
+EXPORT_SYMBOL_GPL(iomap_read_bios_ops);
+
 static int iomap_read_folio_range(const struct iomap_iter *iter,
 		struct folio *folio, loff_t pos, size_t len)
 {
-- 
2.47.3