blockdev: don't set S_DAX for misaligned partitions

The dax code doesn't currently support misaligned partitions, so disable O_DIRECT via dax until such time as that support materializes. Cc: <[email protected]> Suggested-by: Boaz Harrosh <[email protected]> Signed-off-by: Jeff Moyer <[email protected]> Signed-off-by: Dan Williams <[email protected]>
kyagi · Sep 16, 2015 · f0b2e56 · f0b2e56
1 parent e94f5a2
commit f0b2e56
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/fs/block_dev.c b/fs/block_dev.c
@@ -1242,6 +1242,13 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 				goto out_clear;
 			}
 			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
+			/*
+			 * If the partition is not aligned on a page
+			 * boundary, we can't do dax I/O to it.
+			 */
+			if ((bdev->bd_part->start_sect % (PAGE_SIZE / 512)) ||
+			    (bdev->bd_part->nr_sects % (PAGE_SIZE / 512)))
+				bdev->bd_inode->i_flags &= ~S_DAX;
 		}
 	} else {
 		if (bdev->bd_contains == bdev) {