[PATCH 06/12] iomap: Introduce read_inline() function hook

[Goldwyn Rodrigues]

From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>

Introduce read_inline() function hook for reading inline extents. This
is performed for filesystems such as btrfs which may compress the data
in the inline extents.

This is added in struct iomap_folio_ops, since folio is available at
this point.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
 fs/iomap/buffered-io.c | 12 +++++++++---
 include/linux/iomap.h  |  7 +++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 4c734899a8e5..ef805730125a 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -359,6 +359,7 @@ static int iomap_read_inline_data(const struct iomap_iter *iter,
 	const struct iomap *iomap = iomap_iter_srcmap(iter);
 	size_t size = i_size_read(iter->inode) - iomap->offset;
 	size_t offset = offset_in_folio(folio, iomap->offset);
+	int ret = 0;
 
 	if (folio_test_uptodate(folio))
 		return 0;
@@ -368,9 +369,14 @@ static int iomap_read_inline_data(const struct iomap_iter *iter,
 	if (offset > 0)
 		ifs_alloc(iter->inode, folio, iter->flags);
 
-	folio_fill_tail(folio, offset, iomap->inline_data, size);
-	iomap_set_range_uptodate(folio, offset, folio_size(folio) - offset);
-	return 0;
+	if (iomap->folio_ops && iomap->folio_ops->read_inline)
+		ret = iomap->folio_ops->read_inline(iomap, folio);
+	else
+		folio_fill_tail(folio, offset, iomap->inline_data, size);
+
+	if (!ret)
+		iomap_set_range_uptodate(folio, offset, folio_size(folio) - offset);
+	return ret;
 }
 
 static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter,
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index a5cf00a01f23..82dabc0369cd 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -163,6 +163,13 @@ struct iomap_folio_ops {
 	 * locked by the iomap code.
 	 */
 	bool (*iomap_valid)(struct inode *inode, const struct iomap *iomap);
+
+	/*
+	 * Custom read_inline function for filesystem such as btrfs
+	 * that may store data in compressed form.
+	 */
+
+	int (*read_inline)(const struct iomap *iomap, struct folio *folio);
 };
 
 /*
-- 
2.46.1