fs/aio.c: eliminate redundant loads in put_aio_ring_file

Using a local variable we can prevent gcc from reloading
aio_ring_file->f_inode->i_mapping twice, eliminating 2x2 dependent
loads.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 6 insertions, 3 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 4fe81d1c60f9..1157e13a36d6 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -274,14 +274,17 @@ __initcall(aio_setup);
 static void put_aio_ring_file(struct kioctx *ctx)
 {
         struct file *aio_ring_file = ctx->aio_ring_file;
+        struct address_space *i_mapping;
+
         if (aio_ring_file) {
                 truncate_setsize(aio_ring_file->f_inode, 0);
 
                 /* Prevent further access to the kioctx from migratepages */
-                spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock);
-                aio_ring_file->f_inode->i_mapping->private_data = NULL;
+                i_mapping = aio_ring_file->f_inode->i_mapping;
+                spin_lock(&i_mapping->private_lock);
+                i_mapping->private_data = NULL;
                 ctx->aio_ring_file = NULL;
-                spin_unlock(&aio_ring_file->f_inode->i_mapping->private_lock);
+                spin_unlock(&i_mapping->private_lock);
 
                 fput(aio_ring_file);
         }