--- zzzz-none-000/linux-2.6.28.10/fs/stack.c	2009-05-02 18:54:43.000000000 +0000
+++ puma5-6360-529/linux-2.6.28.10/fs/stack.c	2009-10-13 15:55:55.000000000 +0000
@@ -1,24 +1,82 @@
+/*
+ * Copyright (c) 2006-2009 Erez Zadok
+ * Copyright (c) 2006-2007 Josef 'Jeff' Sipek
+ * Copyright (c) 2006-2009 Stony Brook University
+ * Copyright (c) 2006-2009 The Research Foundation of SUNY
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/fs_stack.h>
 
-/* does _NOT_ require i_mutex to be held.
+/*
+ * does _NOT_ require i_mutex to be held.
  *
  * This function cannot be inlined since i_size_{read,write} is rather
  * heavy-weight on 32-bit systems
  */
-void fsstack_copy_inode_size(struct inode *dst, const struct inode *src)
+void fsstack_copy_inode_size(struct inode *dst, struct inode *src)
 {
-	i_size_write(dst, i_size_read((struct inode *)src));
-	dst->i_blocks = src->i_blocks;
+	loff_t i_size;
+	blkcnt_t i_blocks;
+
+	/*
+	 * i_size_read() includes its own seqlocking and protection from
+	 * preemption (see include/linux/fs.h): we need nothing extra for
+	 * that here, and prefer to avoid nesting locks than attempt to
+	 * keep i_size and i_blocks in synch together.
+	 */
+	i_size = i_size_read(src);
+
+	/*
+	 * But if CONFIG_LSF (on 32-bit), we ought to make an effort to keep
+	 * the two halves of i_blocks in synch despite SMP or PREEMPT - though
+	 * stat's generic_fillattr() doesn't bother, and we won't be applying
+	 * quotas (where i_blocks does become important) at the upper level.
+	 *
+	 * We don't actually know what locking is used at the lower level; but
+	 * if it's a filesystem that supports quotas, it will be using i_lock
+	 * as in inode_add_bytes().  tmpfs uses other locking, and its 32-bit
+	 * is (just) able to exceed 2TB i_size with the aid of holes; but its
+	 * i_blocks cannot carry into the upper long without almost 2TB swap -
+	 * let's ignore that case.
+	 */
+	if (sizeof(i_blocks) > sizeof(long))
+		spin_lock(&src->i_lock);
+	i_blocks = src->i_blocks;
+	if (sizeof(i_blocks) > sizeof(long))
+		spin_unlock(&src->i_lock);
+
+	/*
+	 * If CONFIG_SMP on 32-bit, it's vital for fsstack_copy_inode_size()
+	 * to hold some lock around i_size_write(), otherwise i_size_read()
+	 * may spin forever (see include/linux/fs.h).  We don't necessarily
+	 * hold i_mutex when this is called, so take i_lock for that case.
+	 *
+	 * And if CONFIG_LSF (on 32-bit), continue our effort to keep the
+	 * two halves of i_blocks in synch despite SMP or PREEMPT: use i_lock
+	 * for that case too, and do both at once by combining the tests.
+	 *
+	 * There is none of this locking overhead in the 64-bit case.
+	 */
+	if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long))
+		spin_lock(&dst->i_lock);
+	i_size_write(dst, i_size);
+	dst->i_blocks = i_blocks;
+	if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long))
+		spin_unlock(&dst->i_lock);
 }
 EXPORT_SYMBOL_GPL(fsstack_copy_inode_size);
 
-/* copy all attributes; get_nlinks is optional way to override the i_nlink
+/*
+ * copy all attributes; get_nlinks is optional way to override the i_nlink
  * copying
  */
-void fsstack_copy_attr_all(struct inode *dest, const struct inode *src,
-				int (*get_nlinks)(struct inode *))
+void fsstack_copy_attr_all(struct inode *dest, const struct inode *src)
 {
 	dest->i_mode = src->i_mode;
 	dest->i_uid = src->i_uid;
@@ -29,14 +87,6 @@
 	dest->i_ctime = src->i_ctime;
 	dest->i_blkbits = src->i_blkbits;
 	dest->i_flags = src->i_flags;
-
-	/*
-	 * Update the nlinks AFTER updating the above fields, because the
-	 * get_links callback may depend on them.
-	 */
-	if (!get_nlinks)
-		dest->i_nlink = src->i_nlink;
-	else
-		dest->i_nlink = (*get_nlinks)(dest);
+	dest->i_nlink = src->i_nlink;
 }
 EXPORT_SYMBOL_GPL(fsstack_copy_attr_all);