block: stop setting ->direct_IO

Direct I/O on block devices now nevers goes through aops->direct_IO.
Stop setting it and set the FMODE_CAN_ODIRECT in ->open instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20230801172201.1923299-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Christoph Hellwig

block/fops.c

@@ -428,7 +428,6 @@ const struct address_space_operations def_blk_aops = {
 	.writepage	= blkdev_writepage,
 	.write_begin	= blkdev_write_begin,
 	.write_end	= blkdev_write_end,
-	.direct_IO	= blkdev_direct_IO,
 	.migrate_folio	= buffer_migrate_folio_norefs,
 	.is_dirty_writeback = buffer_check_dirty_writeback,
 };
@@ -505,7 +504,7 @@ static int blkdev_open(struct inode *inode, struct file *filp)
 	 * during an unstable branch.
 	 */
 	filp->f_flags |= O_LARGEFILE;
-	filp->f_mode |= FMODE_BUF_RASYNC;
+	filp->f_mode |= FMODE_BUF_RASYNC | FMODE_CAN_ODIRECT;
 
 	/*
 	 * Use the file private data to store the holder for exclusive openes.