mm: redefine address_space.assoc_mapping

Overhaul struct address_space.assoc_mapping renaming it to
address_space.private_data and its type is redefined to void*.  By this
approach we consistently name the .private_* elements from struct
address_space as well as allow extended usage for address_space
association with other data structures through ->private_data.

Also, all users of old ->assoc_mapping element are converted to reflect
its new name and type change (->private_data).
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/buffer.c

@@ -555,7 +555,7 @@ void emergency_thaw_all(void)
  */
 int sync_mapping_buffers(struct address_space *mapping)
 {
-	struct address_space *buffer_mapping = mapping->assoc_mapping;
+	struct address_space *buffer_mapping = mapping->private_data;
 
 	if (buffer_mapping == NULL || list_empty(&mapping->private_list))
 		return 0;
@@ -588,10 +588,10 @@ void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
 	struct address_space *buffer_mapping = bh->b_page->mapping;
 
 	mark_buffer_dirty(bh);
-	if (!mapping->assoc_mapping) {
-		mapping->assoc_mapping = buffer_mapping;
+	if (!mapping->private_data) {
+		mapping->private_data = buffer_mapping;
 	} else {
-		BUG_ON(mapping->assoc_mapping != buffer_mapping);
+		BUG_ON(mapping->private_data != buffer_mapping);
 	}
 	if (!bh->b_assoc_map) {
 		spin_lock(&buffer_mapping->private_lock);
@@ -788,7 +788,7 @@ void invalidate_inode_buffers(struct inode *inode)
 	if (inode_has_buffers(inode)) {
 		struct address_space *mapping = &inode->i_data;
 		struct list_head *list = &mapping->private_list;
-		struct address_space *buffer_mapping = mapping->assoc_mapping;
+		struct address_space *buffer_mapping = mapping->private_data;
 
 		spin_lock(&buffer_mapping->private_lock);
 		while (!list_empty(list))
@@ -811,7 +811,7 @@ int remove_inode_buffers(struct inode *inode)
 	if (inode_has_buffers(inode)) {
 		struct address_space *mapping = &inode->i_data;
 		struct list_head *list = &mapping->private_list;
-		struct address_space *buffer_mapping = mapping->assoc_mapping;
+		struct address_space *buffer_mapping = mapping->private_data;
 
 		spin_lock(&buffer_mapping->private_lock);
 		while (!list_empty(list)) {

fs/gfs2/glock.c

@@ -768,7 +768,7 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 		mapping->host = s->s_bdev->bd_inode;
 		mapping->flags = 0;
 		mapping_set_gfp_mask(mapping, GFP_NOFS);
-		mapping->assoc_mapping = NULL;
+		mapping->private_data = NULL;
 		mapping->backing_dev_info = s->s_bdi;
 		mapping->writeback_index = 0;
 	}

fs/inode.c

@@ -165,7 +165,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
 	mapping->host = inode;
 	mapping->flags = 0;
 	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
-	mapping->assoc_mapping = NULL;
+	mapping->private_data = NULL;
 	mapping->backing_dev_info = &default_backing_dev_info;
 	mapping->writeback_index = 0;
 

fs/nilfs2/page.c

@@ -431,7 +431,7 @@ void nilfs_mapping_init(struct address_space *mapping, struct inode *inode,
 	mapping->host = inode;
 	mapping->flags = 0;
 	mapping_set_gfp_mask(mapping, GFP_NOFS);
-	mapping->assoc_mapping = NULL;
+	mapping->private_data = NULL;
 	mapping->backing_dev_info = bdi;
 	mapping->a_ops = &empty_aops;
 }

include/linux/fs.h

@@ -418,7 +418,7 @@ struct address_space {
 	struct backing_dev_info *backing_dev_info; /* device readahead, etc */
 	spinlock_t		private_lock;	/* for use by the address_space */
 	struct list_head	private_list;	/* ditto */
-	struct address_space	*assoc_mapping;	/* ditto */
+	void			*private_data;	/* ditto */
 } __attribute__((aligned(sizeof(long))));
 	/*
 	 * On most architectures that alignment is already the case; but