[XFS] Make use of the init-once slab optimisation.

To avoid having to initialise some fields of the XFS inode on every
allocation, we can use the slab init-once feature to initialise them. All
we have to guarantee is that when we free the inode, all it's entries are
in the initial state. Add asserts where possible to ensure debug kernels
check this initial state before freeing and after allocation.

SGI-PV: 981498

SGI-Modid: xfs-linux-melb:xfs-kern:31925a

Signed-off-by: David Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>

1 files changed, 36 insertions, 1 deletions

diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 37ebe36056eb..d1c4dec51a3b 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -887,6 +887,41 @@ xfs_fs_inode_init_once(
 	inode_init_once((struct inode *)vnode);
 }
 
+
+/*
+ * Slab object creation initialisation for the XFS inode.
+ * This covers only the idempotent fields in the XFS inode;
+ * all other fields need to be initialised on allocation
+ * from the slab. This avoids the need to repeatedly intialise
+ * fields in the xfs inode that left in the initialise state
+ * when freeing the inode.
+ */
+void
+xfs_inode_init_once(
+	kmem_zone_t		*zone,
+	void			*inode)
+{
+	struct xfs_inode	*ip = inode;
+
+	memset(ip, 0, sizeof(struct xfs_inode));
+	atomic_set(&ip->i_iocount, 0);
+	atomic_set(&ip->i_pincount, 0);
+	spin_lock_init(&ip->i_flags_lock);
+	INIT_LIST_HEAD(&ip->i_reclaim);
+	init_waitqueue_head(&ip->i_ipin_wait);
+	/*
+	 * Because we want to use a counting completion, complete
+	 * the flush completion once to allow a single access to
+	 * the flush completion without blocking.
+	 */
+	init_completion(&ip->i_flush);
+	complete(&ip->i_flush);
+
+	mrlock_init(&ip->i_lock, MRLOCK_ALLOW_EQUAL_PRI|MRLOCK_BARRIER,
+		     "xfsino", ip->i_ino);
+	mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
+}
+
 /*
  * Attempt to flush the inode, this will actually fail
  * if the inode is pinned, but we dirty the inode again
@@ -2018,7 +2053,7 @@ xfs_init_zones(void)
 	xfs_inode_zone =
 		kmem_zone_init_flags(sizeof(xfs_inode_t), "xfs_inode",
 					KM_ZONE_HWALIGN | KM_ZONE_RECLAIM |
-					KM_ZONE_SPREAD, NULL);
+					KM_ZONE_SPREAD, xfs_inode_init_once);
 	if (!xfs_inode_zone)
 		goto out_destroy_efi_zone;