btrfs: remove struct extent_io_ops

It's no longer used just remove the function and any related code which
was initialising it for inodes. No functional changes.

Removing 8 bytes from extent_io_tree in turn reduces size of other
structures where it is embedded, notably btrfs_inode where it reduces
size by 24 bytes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

@@ -3583,9 +3583,7 @@ static inline int btrfs_defrag_cancelled(struct btrfs_fs_info *fs_info)
 
 /* Sanity test specific functions */
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
-void btrfs_test_inode_set_ops(struct inode *inode);
 void btrfs_test_destroy_inode(struct inode *inode);
-
 static inline int btrfs_is_testing(struct btrfs_fs_info *fs_info)
 {
 	return test_bit(BTRFS_FS_STATE_DUMMY_FS_INFO, &fs_info->fs_state);

fs/btrfs/disk-io.c

@@ -50,7 +50,6 @@
 				 BTRFS_SUPER_FLAG_METADUMP |\
 				 BTRFS_SUPER_FLAG_METADUMP_V2)
 
-static const struct extent_io_ops btree_extent_io_ops;
 static void end_workqueue_fn(struct btrfs_work *work);
 static void btrfs_destroy_ordered_extents(struct btrfs_root *root);
 static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
@@ -2065,8 +2064,6 @@ static void btrfs_init_btree_inode(struct btrfs_fs_info *fs_info)
 	BTRFS_I(inode)->io_tree.track_uptodate = false;
 	extent_map_tree_init(&BTRFS_I(inode)->extent_tree);
 
-	BTRFS_I(inode)->io_tree.ops = &btree_extent_io_ops;
-
 	BTRFS_I(inode)->root = btrfs_grab_root(fs_info->tree_root);
 	memset(&BTRFS_I(inode)->location, 0, sizeof(struct btrfs_key));
 	set_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags);
@@ -4633,7 +4630,3 @@ static int btrfs_cleanup_transaction(struct btrfs_fs_info *fs_info)
 
 	return 0;
 }
-
-static const struct extent_io_ops btree_extent_io_ops = {
-	.submit_bio_hook = NULL
-};

fs/btrfs/extent-io-tree.h

@@ -63,7 +63,6 @@ struct extent_io_tree {
 	u8 owner;
 
 	spinlock_t lock;
-	const struct extent_io_ops *ops;
 };
 
 struct extent_state {

fs/btrfs/extent_io.c

@@ -281,7 +281,6 @@ void extent_io_tree_init(struct btrfs_fs_info *fs_info,
 {
 	tree->fs_info = fs_info;
 	tree->state = RB_ROOT;
-	tree->ops = NULL;
 	tree->dirty_bytes = 0;
 	spin_lock_init(&tree->lock);
 	tree->private_data = private_data;
@@ -3055,7 +3054,6 @@ static int submit_extent_page(unsigned int opf,
 		else
 			contig = bio_end_sector(bio) == sector;
 
-		ASSERT(tree->ops);
 		if (btrfs_bio_fits_in_stripe(page, page_size, bio, bio_flags))
 			can_merge = false;
 

fs/btrfs/extent_io.h

@@ -74,15 +74,6 @@ typedef blk_status_t (submit_bio_hook_t)(struct inode *inode, struct bio *bio,
 typedef blk_status_t (extent_submit_bio_start_t)(void *private_data,
 		struct bio *bio, u64 bio_offset);
 
-struct extent_io_ops {
-	/*
-	 * The following callback must be always defined, the function
-	 * pointer will be called unconditionally.
-	 */
-	submit_bio_hook_t *submit_bio_hook;
-};
-
-
 #define INLINE_EXTENT_BUFFER_PAGES 16
 #define MAX_INLINE_EXTENT_BUFFER_SIZE (INLINE_EXTENT_BUFFER_PAGES * PAGE_SIZE)
 struct extent_buffer {

fs/btrfs/inode.c

@@ -71,7 +71,6 @@ static const struct inode_operations btrfs_special_inode_operations;
 static const struct inode_operations btrfs_file_inode_operations;
 static const struct address_space_operations btrfs_aops;
 static const struct file_operations btrfs_dir_file_operations;
-static const struct extent_io_ops btrfs_extent_io_ops;
 
 static struct kmem_cache *btrfs_inode_cachep;
 struct kmem_cache *btrfs_trans_handle_cachep;
@@ -141,13 +140,6 @@ static inline void btrfs_cleanup_ordered_extents(struct btrfs_inode *inode,
 
 static int btrfs_dirty_inode(struct inode *inode);
 
-#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
-void btrfs_test_inode_set_ops(struct inode *inode)
-{
-	BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
-}
-#endif
-
 static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
 				     struct inode *inode,  struct inode *dir,
 				     const struct qstr *qstr)
@@ -3391,7 +3383,6 @@ static int btrfs_read_locked_inode(struct inode *inode,
 	switch (inode->i_mode & S_IFMT) {
 	case S_IFREG:
 		inode->i_mapping->a_ops = &btrfs_aops;
-		BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
 		inode->i_fop = &btrfs_file_operations;
 		inode->i_op = &btrfs_file_inode_operations;
 		break;
@@ -6307,7 +6298,6 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
 	if (err)
 		goto out_unlock;
 
-	BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
 	d_instantiate_new(dentry, inode);
 
 out_unlock:
@@ -9518,7 +9508,6 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
 	inode->i_fop = &btrfs_file_operations;
 	inode->i_op = &btrfs_file_inode_operations;
 	inode->i_mapping->a_ops = &btrfs_aops;
-	BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
 
 	err = btrfs_init_inode_security(trans, inode, dir, &dentry->d_name);
 	if (err)
@@ -9838,7 +9827,6 @@ static int btrfs_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 	inode->i_op = &btrfs_file_inode_operations;
 
 	inode->i_mapping->a_ops = &btrfs_aops;
-	BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
 
 	ret = btrfs_init_inode_security(trans, inode, dir, NULL);
 	if (ret)
@@ -10256,10 +10244,6 @@ static const struct file_operations btrfs_dir_file_operations = {
 	.fsync		= btrfs_sync_file,
 };
 
-static const struct extent_io_ops btrfs_extent_io_ops = {
-	.submit_bio_hook = NULL
-};
-
 /*
  * btrfs doesn't support the bmap operation because swapfiles
  * use bmap to make a mapping of extents in the file.  They assume

fs/btrfs/tests/inode-tests.c

@@ -949,7 +949,6 @@ static int test_extent_accounting(u32 sectorsize, u32 nodesize)
 	}
 
 	BTRFS_I(inode)->root = root;
-	btrfs_test_inode_set_ops(inode);
 
 	/* [BTRFS_MAX_EXTENT_SIZE] */
 	ret = btrfs_set_extent_delalloc(BTRFS_I(inode), 0,