ocfs2: New slot map format

The old slot map had a few limitations:

- It was limited to one block, so the maximum slot count was 255.
- Each slot was signed 16bits, limiting node numbers to INT16_MAX.
- An empty slot was marked by the magic 0xFFFF (-1).

The new slot map format provides 32bit node numbers (UINT32_MAX), a
separate space to mark a slot in use, and extra room to grow.  The slot
map is now bounded by i_size, not a block.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 95f783dbe8b2..f78e9ed53249 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -374,6 +374,13 @@ static inline int ocfs2_mount_local(struct ocfs2_super *osb)
         return (osb->s_feature_incompat & OCFS2_FEATURE_INCOMPAT_LOCAL_MOUNT);
 }
 
+static inline int ocfs2_uses_extended_slot_map(struct ocfs2_super *osb)
+{
+        return (osb->s_feature_incompat &
+                OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP);
+}
+
+
 #define OCFS2_IS_VALID_DINODE(ptr)                                      \
         (!strcmp((ptr)->i_signature, OCFS2_INODE_SIGNATURE))