xfs: simplify and remove xfs_ireclaim

xfs_ireclaim has to get and put te pag structure because it is only
called with the inode to reclaim. The one caller of this function
already has a reference on the pag and a pointer to is, so move the
radix tree delete to the caller and remove xfs_ireclaim completely.
This avoids a xfs_perag_get/put on every inode being reclaimed.

The overhead was noticed in a bug report at:

https://bugzilla.kernel.org/show_bug.cgi?id=16348

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 30 insertions, 1 deletions

diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index 66cefb274385..dfcbd98d1599 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -855,7 +855,36 @@ out:
 reclaim:
         xfs_ifunlock(ip);
         xfs_iunlock(ip, XFS_ILOCK_EXCL);
-        xfs_ireclaim(ip);
+
+        XFS_STATS_INC(xs_ig_reclaims);
+        /*
+         * Remove the inode from the per-AG radix tree.
+         *
+         * Because radix_tree_delete won't complain even if the item was never
+         * added to the tree assert that it's been there before to catch
+         * problems with the inode life time early on.
+         */
+        write_lock(&pag->pag_ici_lock);
+        if (!radix_tree_delete(&pag->pag_ici_root,
+                                XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino)))
+                ASSERT(0);
+        write_unlock(&pag->pag_ici_lock);
+
+        /*
+         * Here we do an (almost) spurious inode lock in order to coordinate
+         * with inode cache radix tree lookups.  This is because the lookup
+         * can reference the inodes in the cache without taking references.
+         *
+         * We make that OK here by ensuring that we wait until the inode is
+         * unlocked after the lookup before we go ahead and free it.  We get
+         * both the ilock and the iolock because the code may need to drop the
+         * ilock one but will still hold the iolock.
+         */
+        xfs_ilock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
+        xfs_qm_dqdetach(ip);
+        xfs_iunlock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
+
+        xfs_inode_free(ip);
         return error;
 
 }