iomap: remove unused private field from ioend

The only remaining user of ->io_private is the generic ioend merging
infrastructure. The only user of that is XFS, which no longer sets
->io_private or passes an associated merge callback. Remove the
unused parameter and the ->io_private field.

CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

fs/iomap/buffered-io.c

@@ -1134,9 +1134,7 @@ iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next)
 }
 
 void
-iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends,
-		void (*merge_private)(struct iomap_ioend *ioend,
-				struct iomap_ioend *next))
+iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends)
 {
 	struct iomap_ioend *next;
 
@@ -1148,8 +1146,6 @@ iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends,
 			break;
 		list_move_tail(&next->io_list, &ioend->io_list);
 		ioend->io_size += next->io_size;
-		if (next->io_private && merge_private)
-			merge_private(ioend, next);
 	}
 }
 EXPORT_SYMBOL_GPL(iomap_ioend_try_merge);
@@ -1236,7 +1232,6 @@ iomap_alloc_ioend(struct inode *inode, struct iomap_writepage_ctx *wpc,
 	ioend->io_inode = inode;
 	ioend->io_size = 0;
 	ioend->io_offset = offset;
-	ioend->io_private = NULL;
 	ioend->io_bio = bio;
 	return ioend;
 }

fs/xfs/xfs_aops.c

@@ -146,7 +146,7 @@ xfs_end_io(
 	while ((ioend = list_first_entry_or_null(&tmp, struct iomap_ioend,
 			io_list))) {
 		list_del_init(&ioend->io_list);
-		iomap_ioend_try_merge(ioend, &tmp, NULL);
+		iomap_ioend_try_merge(ioend, &tmp);
 		xfs_end_ioend(ioend);
 	}
 }

include/linux/iomap.h

@@ -198,7 +198,6 @@ struct iomap_ioend {
 	struct inode		*io_inode;	/* file being written to */
 	size_t			io_size;	/* size of the extent */
 	loff_t			io_offset;	/* offset in the file */
-	void			*io_private;	/* file system private data */
 	struct bio		*io_bio;	/* bio being built */
 	struct bio		io_inline_bio;	/* MUST BE LAST! */
 };
@@ -234,9 +233,7 @@ struct iomap_writepage_ctx {
 
 void iomap_finish_ioends(struct iomap_ioend *ioend, int error);
 void iomap_ioend_try_merge(struct iomap_ioend *ioend,
-		struct list_head *more_ioends,
-		void (*merge_private)(struct iomap_ioend *ioend,
-				struct iomap_ioend *next));
+		struct list_head *more_ioends);
 void iomap_sort_ioends(struct list_head *ioend_list);
 int iomap_writepage(struct page *page, struct writeback_control *wbc,
 		struct iomap_writepage_ctx *wpc,