block: remove blkdev_writepages

While the block device code should switch to implementing
->writepages instead of ->writepage eventually, the current
implementation is entirely pointless as it does the same looping over
->writepage as the generic code if no ->writepages is present.

Remove blkdev_writepages so that we can eventually unexport
generic_writepages.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221116132035.2192924-1-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/fops.c

@@ -405,12 +405,6 @@ static int blkdev_write_end(struct file *file, struct address_space *mapping,
 	return ret;
 }
 
-static int blkdev_writepages(struct address_space *mapping,
-			     struct writeback_control *wbc)
-{
-	return generic_writepages(mapping, wbc);
-}
-
 const struct address_space_operations def_blk_aops = {
 	.dirty_folio	= block_dirty_folio,
 	.invalidate_folio = block_invalidate_folio,
@@ -419,7 +413,6 @@ const struct address_space_operations def_blk_aops = {
 	.writepage	= blkdev_writepage,
 	.write_begin	= blkdev_write_begin,
 	.write_end	= blkdev_write_end,
-	.writepages	= blkdev_writepages,
 	.direct_IO	= blkdev_direct_IO,
 	.migrate_folio	= buffer_migrate_folio_norefs,
 	.is_dirty_writeback = buffer_check_dirty_writeback,