diff options
Diffstat (limited to 'include/linux/blkdev_compat.h')
| -rw-r--r-- | include/linux/blkdev_compat.h | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/include/linux/blkdev_compat.h b/include/linux/blkdev_compat.h index a5294ceba..1ff8eeaf3 100644 --- a/include/linux/blkdev_compat.h +++ b/include/linux/blkdev_compat.h @@ -394,13 +394,27 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags) /* * 2.6.30 API change - * Change to make it explicit there this is the logical block size. + * To ensure good performance preferentially use the physical block size + * for proper alignment. The physical size is supposed to be the internal + * sector size used by the device. This is often 4096 byte for AF devices, + * while a smaller 512 byte logical size is supported for compatibility. + * + * Unfortunately, many drives still misreport their physical sector size. + * For devices which are known to lie you may need to manually set this + * at pool creation time with 'zpool create -o ashift=12 ...'. + * + * When the physical block size interface isn't available, we fall back to + * the logical block size interface and then the older hard sector size. */ -#ifdef HAVE_BDEV_LOGICAL_BLOCK_SIZE -# define vdev_bdev_block_size(bdev) bdev_logical_block_size(bdev) +#ifdef HAVE_BDEV_PHYSICAL_BLOCK_SIZE +# define vdev_bdev_block_size(bdev) bdev_physical_block_size(bdev) #else -# define vdev_bdev_block_size(bdev) bdev_hardsect_size(bdev) -#endif +# ifdef HAVE_BDEV_LOGICAL_BLOCK_SIZE +# define vdev_bdev_block_size(bdev) bdev_logical_block_size(bdev) +# else +# define vdev_bdev_block_size(bdev) bdev_hardsect_size(bdev) +# endif /* HAVE_BDEV_LOGICAL_BLOCK_SIZE */ +#endif /* HAVE_BDEV_PHYSICAL_BLOCK_SIZE */ /* * 2.6.37 API change |