[PATCH -next] iomap: fix inline data on buffered read

[Christoph Hellwig]

I'd move the iomap_iter_advance into iomap_read_inline_data, just like
we've pushed it down as far as possible elsewhere, e.g. something like
the patch below.  Although with that having size and length puzzles
me a bit, so maybe someone more familar with the code could figure
out why we need both, how they can be different and either document
or eliminate that.

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index d52cfdc299c4..7858c8834144 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -332,15 +332,15 @@ struct iomap_readpage_ctx {
  * Only a single IOMAP_INLINE extent is allowed at the end of each file.
  * Returns zero for success to complete the read, or the usual negative errno.
  */
-static int iomap_read_inline_data(const struct iomap_iter *iter,
-		struct folio *folio)
+static int iomap_read_inline_data(struct iomap_iter *iter, struct folio *folio)
 {
 	const struct iomap *iomap = iomap_iter_srcmap(iter);
 	size_t size = i_size_read(iter->inode) - iomap->offset;
+	loff_t length = iomap_length(iter);
 	size_t offset = offset_in_folio(folio, iomap->offset);
 
 	if (folio_test_uptodate(folio))
-		return 0;
+		goto advance;
 
 	if (WARN_ON_ONCE(size > iomap->length))
 		return -EIO;
@@ -349,7 +349,8 @@ static int iomap_read_inline_data(const struct iomap_iter *iter,
 
 	folio_fill_tail(folio, offset, iomap->inline_data, size);
 	iomap_set_range_uptodate(folio, offset, folio_size(folio) - offset);
-	return 0;
+advance:
+	return iomap_iter_advance(iter, &length);
 }
 
 static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter,