block: switch bios to blk_status_t

Replace bi_error with a new bi_status to allow for a clear conversion.
Note that device mapper overloaded bi_error with a private value, which
we'll have to keep arround at least for now and thus propagate to a
proper blk_status_t value.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 1a82138..930ca0f 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -85,7 +85,7 @@
 		}
 #endif
 
-		if (bio->bi_error) {
+		if (bio->bi_status) {
 			SetPageError(page);
 			mapping_set_error(page->mapping, -EIO);
 		}
@@ -104,7 +104,7 @@
 				continue;
 			}
 			clear_buffer_async_write(bh);
-			if (bio->bi_error)
+			if (bio->bi_status)
 				buffer_io_error(bh);
 		} while ((bh = bh->b_this_page) != head);
 		bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
@@ -303,24 +303,25 @@
 		      bdevname(bio->bi_bdev, b),
 		      (long long) bio->bi_iter.bi_sector,
 		      (unsigned) bio_sectors(bio),
-		      bio->bi_error)) {
+		      bio->bi_status)) {
 		ext4_finish_bio(bio);
 		bio_put(bio);
 		return;
 	}
 	bio->bi_end_io = NULL;
 
-	if (bio->bi_error) {
+	if (bio->bi_status) {
 		struct inode *inode = io_end->inode;
 
 		ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
 			     "(offset %llu size %ld starting block %llu)",
-			     bio->bi_error, inode->i_ino,
+			     bio->bi_status, inode->i_ino,
 			     (unsigned long long) io_end->offset,
 			     (long) io_end->size,
 			     (unsigned long long)
 			     bi_sector >> (inode->i_blkbits - 9));
-		mapping_set_error(inode->i_mapping, bio->bi_error);
+		mapping_set_error(inode->i_mapping,
+				blk_status_to_errno(bio->bi_status));
 	}
 
 	if (io_end->flag & EXT4_IO_END_UNWRITTEN) {