ocfs2: Local alloc window size changeable via mount option

Local alloc is a performance optimization in ocfs2 in which a node
takes a window of bits from the global bitmap and then uses that for
all small local allocations. This window size is fixed to 8MB currently.
This patch allows users to specify the window size in MB including
disabling it by passing in 0. If the number specified is too large,
the fs will use the default value of 8MB.

mount -o localalloc=X /dev/sdX /mntpoint

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 4391744e80f..7e397e2c25d 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -1516,8 +1516,9 @@ int __ocfs2_claim_clusters(struct ocfs2_super *osb,
                 if (min_clusters > (osb->bitmap_cpg - 1)) {
                         /* The only paths asking for contiguousness
                          * should know about this already. */
-                        mlog(ML_ERROR, "minimum allocation requested exceeds "
-                                       "group bitmap size!");
+                        mlog(ML_ERROR, "minimum allocation requested %u exceeds "
+                             "group bitmap size %u!\n", min_clusters,
+                             osb->bitmap_cpg);
                         status = -ENOSPC;
                         goto bail;
                 }