fs: iomap: use bio_add_folio_nofail where possible

When the iomap buffered-io code can't add a folio to a bio, it allocates a
new bio and adds the folio to that one. This is done using bio_add_folio(),
but doesn't check for errors.

As adding a folio to a newly created bio can't fail, use the newly
introduced bio_add_folio_nofail() function.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/58fa893c24c67340a63323f09a179fefdca07f2a.1685532726.git.johannes.thumshirn@wdc.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/iomap/buffered-io.c

@@ -312,7 +312,7 @@ static loff_t iomap_readpage_iter(const struct iomap_iter *iter,
 			ctx->bio->bi_opf |= REQ_RAHEAD;
 		ctx->bio->bi_iter.bi_sector = sector;
 		ctx->bio->bi_end_io = iomap_read_end_io;
-		bio_add_folio(ctx->bio, folio, plen, poff);
+		bio_add_folio_nofail(ctx->bio, folio, plen, poff);
 	}
 
 done:
@@ -539,7 +539,7 @@ static int iomap_read_folio_sync(loff_t block_start, struct folio *folio,
 
 	bio_init(&bio, iomap->bdev, &bvec, 1, REQ_OP_READ);
 	bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
-	bio_add_folio(&bio, folio, plen, poff);
+	bio_add_folio_nofail(&bio, folio, plen, poff);
 	return submit_bio_wait(&bio);
 }
 
@@ -1582,7 +1582,7 @@ iomap_add_to_ioend(struct inode *inode, loff_t pos, struct folio *folio,
 
 	if (!bio_add_folio(wpc->ioend->io_bio, folio, len, poff)) {
 		wpc->ioend->io_bio = iomap_chain_bio(wpc->ioend->io_bio);
-		bio_add_folio(wpc->ioend->io_bio, folio, len, poff);
+		bio_add_folio_nofail(wpc->ioend->io_bio, folio, len, poff);
 	}
 
 	if (iop)