xfs: speed up free inode search

Don't search too far - abort if it is outside a certain radius and simply do
a linear search for the first free inode.  In AGs with a million inodes this
can speed up allocation speed by 3-4x.

[hch: ported to the new xfs_ialloc.c world order]

Signed-off-by: Dave Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Signed-off-by: Felix Blyakher <felixb@sgi.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h
index f24b50b68d03..a5d54bf4931b 100644
--- a/fs/xfs/xfs_ag.h
+++ b/fs/xfs/xfs_ag.h
@@ -198,6 +198,15 @@ typedef struct xfs_perag
         xfs_agino_t     pagi_count;     /* number of allocated inodes */
         int             pagb_count;     /* pagb slots in use */
         xfs_perag_busy_t *pagb_list;    /* unstable blocks */
+
+        /*
+         * Inode allocation search lookup optimisation.
+         * If the pagino matches, the search for new inodes
+         * doesn't need to search the near ones again straight away
+         */
+        xfs_agino_t     pagl_pagino;
+        xfs_agino_t     pagl_leftrec;
+        xfs_agino_t     pagl_rightrec;
 #ifdef __KERNEL__
         spinlock_t      pagb_lock;      /* lock for pagb_list */