MFC r293680

ext4: add support for reading sparse files

Add support for sparse files in ext4. Also implement read-ahead, which
greatly increases the performance when transferring files from ext4.
The sparse file support has become very common in ext4.

Both features implemented by Damjan Jovanovic.

PR:		205816

1 files changed, 5 insertions, 1 deletions

diff --git a/sys/fs/ext2fs/ext2_extents.h b/sys/fs/ext2fs/ext2_extents.h
index 94ded83..4ce16f3 100644
--- a/sys/fs/ext2fs/ext2_extents.h
+++ b/sys/fs/ext2fs/ext2_extents.h
@@ -84,7 +84,11 @@ struct ext4_extent_cache {
 struct ext4_extent_path {
 	uint16_t ep_depth;
 	struct buf *ep_bp;
-	struct ext4_extent *ep_ext;
+	int ep_is_sparse;
+	union {
+		struct ext4_extent ep_sparse_ext;
+		struct ext4_extent *ep_ext;
+	};
 	struct ext4_extent_index *ep_index;
 	struct ext4_extent_header *ep_header;
 };