ocfs2: Limit inode allocation to 32bits.

ocfs2 inode numbers are block numbers.  For any filesystem with less
than 2^32 blocks, this is not a problem.  However, when ocfs2 starts
using JDB2, it will be able to support filesystems with more than 2^32
blocks.  This would result in inode numbers higher than 2^32.

The problem is that stat(2) can't handle those numbers on 32bit
machines.  The simple solution is to have ocfs2 allocate all inodes
below that boundary.

The suballoc code is changed to honor an optional block limit.  Only the
inode suballocator sets that limit - all other allocations stay unlimited.

The biggest trick is to grow the inode suballocator beneath that limit.
There's no point in allocating block groups that are above the limit,
then rejecting their elements later on.  We want to prevent the inode
allocator from ever having block groups above the limit.  This involves
a little gyration with the local alloc code.  If the local alloc window
is above the limit, it signals the caller to try the global bitmap but
does not disable the local alloc file (which can be used for other
allocations).

[ Minor cleanup - removed an ML_NOTICE comment. --Mark ]

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

1 files changed, 7 insertions, 4 deletions

diff --git a/fs/ocfs2/suballoc.h b/fs/ocfs2/suballoc.h
index dd0963695edc..4df159d8f450 100644
--- a/fs/ocfs2/suballoc.h
+++ b/fs/ocfs2/suballoc.h
@@ -28,10 +28,11 @@
 
 typedef int (group_search_t)(struct inode *,
 			     struct buffer_head *,
-			     u32,
-			     u32,
-			     u16 *,
-			     u16 *);
+			     u32,			/* bits_wanted */
+			     u32,			/* min_bits */
+			     u64,			/* max_block */
+			     u16 *,			/* *bit_off */
+			     u16 *);			/* *bits_found */
 
 struct ocfs2_alloc_context {
 	struct inode *ac_inode;    /* which bitmap are we allocating from? */
@@ -51,6 +52,8 @@ struct ocfs2_alloc_context {
 	group_search_t *ac_group_search;
 
 	u64    ac_last_group;
+	u64    ac_max_block;  /* Highest block number to allocate. 0 is
+				 is the same as ~0 - unlimited */
 };
 
 void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac);