[patch] Fix orlov allocator boundary case

[Andrew Morton]

Stephen Hemminger <[e-mail]> wrote:
>
> Recent (post 2.5.67) versions of the kernel break the creation
> of the initial ram disk.

OK, here be the fix.

I'm a bit peeved that this wasn't discovered until it hit Linus's tree. 
Weren't these patches in -mjb as well?

In the interests of SMP scalability the ext2 free blocks and free inodes
counters are "approximate".  But there is a piece of code in the Orlov
allocator which fails due to boundary conditions on really small
filesystems.

Fix that up via a final allocation pass which simply uses first-fit for
allocation of a directory inode.

 fs/ext2/ialloc.c |    9 +++++++++
 1 files changed, 9 insertions(+)

diff -puN fs/ext2/ialloc.c~orlov-approx-counter-fix fs/ext2/ialloc.c
--- 25/fs/ext2/ialloc.c~orlov-approx-counter-fix	2003-04-17 12:12:33.000000000 -0700
+++ 25-akpm/fs/ext2/ialloc.c	2003-04-17 12:14:09.000000000 -0700
@@ -410,6 +410,15 @@ fallback:
 			goto found;
 	}
 
+	if (avefreei) {
+		/*
+		 * The free-inodes counter is approximate, and for really small
+		 * filesystems the above test can fail to find any blockgroups
+		 */
+		avefreei = 0;
+		goto fallback;
+	}
+
 	return -1;
 
 found:

_