ocfs2: Define data structures for discontiguous block groups.
Defines the OCFS2_FEATURE_INCOMPAT_DISCONTIG_BG feature bit and modifies
struct ocfs2_group_desc for the feature.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Tao Ma <tao.ma@oracle.com>
diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
index d61a152..448aa8d 100644
--- a/fs/ocfs2/ocfs2_fs.h
+++ b/fs/ocfs2/ocfs2_fs.h
@@ -165,6 +165,9 @@
/* Refcount tree support */
#define OCFS2_FEATURE_INCOMPAT_REFCOUNT_TREE 0x1000
+/* Discontigous block groups */
+#define OCFS2_FEATURE_INCOMPAT_DISCONTIG_BG 0x2000
+
/*
* backup superblock flag is used to indicate that this volume
* has backup superblocks.
@@ -832,6 +835,13 @@
};
/*
+ * Largest bitmap for a block (suballocator) group in bytes. This limit
+ * does not affect cluster groups (global allocator). Cluster group
+ * bitmaps run to the end of the block.
+ */
+#define OCFS2_MAX_BG_BITMAP_SIZE 256
+
+/*
* On disk allocator group structure for OCFS2
*/
struct ocfs2_group_desc
@@ -852,7 +862,29 @@
__le64 bg_blkno; /* Offset on disk, in blocks */
/*30*/ struct ocfs2_block_check bg_check; /* Error checking */
__le64 bg_reserved2;
-/*40*/ __u8 bg_bitmap[0];
+/*40*/ union {
+ __u8 bg_bitmap[0];
+ struct {
+ /*
+ * Block groups may be discontiguous when
+ * OCFS2_FEATURE_INCOMPAT_DISCONTIG_BG is set.
+ * The extents of a discontigous block group are
+ * stored in bg_list. It is a flat list.
+ * l_tree_depth must always be zero. A
+ * discontiguous group is signified by a non-zero
+ * bg_list->l_next_free_rec. Only block groups
+ * can be discontiguous; Cluster groups cannot.
+ * We've never made a block group with more than
+ * 2048 blocks (256 bytes of bg_bitmap). This
+ * codifies that limit so that we can fit bg_list.
+ * bg_size of a discontiguous block group will
+ * be 256 to match bg_bitmap_filler.
+ */
+ __u8 bg_bitmap_filler[OCFS2_MAX_BG_BITMAP_SIZE];
+/*140*/ struct ocfs2_extent_list bg_list;
+ };
+ };
+/* Actual on-disk size is one block */
};
struct ocfs2_refcount_rec {
@@ -1276,12 +1308,16 @@
return size;
}
-static inline int ocfs2_group_bitmap_size(struct super_block *sb)
+static inline int ocfs2_group_bitmap_size(struct super_block *sb,
+ int suballocator)
{
int size;
- size = sb->s_blocksize -
- offsetof(struct ocfs2_group_desc, bg_bitmap);
+ if (suballocator)
+ size = OCFS2_MAX_BG_BITMAP_SIZE;
+ else
+ size = sb->s_blocksize -
+ offsetof(struct ocfs2_group_desc, bg_bitmap);
return size;
}
@@ -1404,12 +1440,15 @@
return size;
}
-static inline int ocfs2_group_bitmap_size(int blocksize)
+static inline int ocfs2_group_bitmap_size(int blocksize, int suballocator)
{
int size;
- size = blocksize -
- offsetof(struct ocfs2_group_desc, bg_bitmap);
+ if (suballocator)
+ size = OCFS2_MAX_BG_BITMAP_SIZE;
+ else
+ size = blocksize -
+ offsetof(struct ocfs2_group_desc, bg_bitmap);
return size;
}