Revert "Don't ashift-align vdev read requests."

This reverts commit a5c20e2a0a9046c06d86615fbf51dc04f12bba14 which
accidentally introduced a regression for real 4k sector devices.
See issue #1065 for details.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1065

diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index ce76e01..ece3329 100644 (file)
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -2438,25 +2438,19 @@ zio_vdev_io_start(zio_t *zio)
 
        align = 1ULL << vd->vdev_top->vdev_ashift;
 
-       /*
-        * On Linux, we don't care about read alignment. The backing block
-        * device driver will take care of that for us.
-        * The only exception is raidz, which needs a full block for parity.
-        */
-       if (P2PHASE(zio->io_size, align) != 0 &&
-           (zio->io_type != ZIO_TYPE_READ ||
-            vd->vdev_ops == &vdev_raidz_ops)) {
+       if (P2PHASE(zio->io_size, align) != 0) {
                uint64_t asize = P2ROUNDUP(zio->io_size, align);
                char *abuf = zio_buf_alloc(asize);
+               ASSERT(vd == vd->vdev_top);
                if (zio->io_type == ZIO_TYPE_WRITE) {
                        bcopy(zio->io_data, abuf, zio->io_size);
                        bzero(abuf + zio->io_size, asize - zio->io_size);
                }
                zio_push_transform(zio, abuf, asize, asize, zio_subblock);
-               ASSERT(P2PHASE(zio->io_size, align) == 0);
        }
 
        ASSERT(P2PHASE(zio->io_offset, align) == 0);
+       ASSERT(P2PHASE(zio->io_size, align) == 0);
        VERIFY(zio->io_type != ZIO_TYPE_WRITE || spa_writeable(spa));
 
        /*