Improve AF hard disk detection

[zfs.git] / include / linux / blkdev_compat.h

diff --git a/include/linux/blkdev_compat.h b/include/linux/blkdev_compat.h
index 56a1baf..1ff8eea 100644 (file)
--- 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
@@ -425,6 +439,29 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
 #endif
 
 /*
+ * 2.6.32 API change
+ * Use the normal I/O patch for discards.
+ */
+#ifdef REQ_DISCARD
+# define VDEV_REQ_DISCARD              REQ_DISCARD
+#endif
+
+/*
+ * 2.6.33 API change
+ * Discard granularity and alignment restrictions may now be set.  For
+ * older kernels which do not support this it is safe to skip it.
+ */
+#ifdef HAVE_DISCARD_GRANULARITY
+static inline void
+blk_queue_discard_granularity(struct request_queue *q, unsigned int dg)
+{
+       q->limits.discard_granularity = dg;
+}
+#else
+#define blk_queue_discard_granularity(x, dg)   ((void)0)
+#endif /* HAVE_DISCARD_GRANULARITY */
+
+/*
  * Default Linux IO Scheduler,
  * Setting the scheduler to noop will allow the Linux IO scheduler to
  * still perform front and back merging, while leaving the request