[v2,01/17] block: Tighter assertions on bdrv_aligned_pwritev()

Commit Message

Eric Blake June 14, 2016, 9:30 p.m. UTC

For symmetry with bdrv_aligned_preadv(), assert that the caller
really has aligned things properly. This requires adding an align
parameter, which is used now only in the new asserts, but will
come in handy in a later patch that adds auto-fragmentation to the
max transfer size, since that value need not always be a multiple
of the alignment, and therefore must be rounded down.

Signed-off-by: Eric Blake <[e-mail]>

---
v2: new patch
---
 block/io.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

Comments

Fam Zheng June 16, 2016, 5:05 a.m. UTC | #1

On Tue, 06/14 15:30, Eric Blake wrote:
> For symmetry with bdrv_aligned_preadv(), assert that the caller
> really has aligned things properly. This requires adding an align
> parameter, which is used now only in the new asserts, but will
> come in handy in a later patch that adds auto-fragmentation to the
> max transfer size, since that value need not always be a multiple
> of the alignment, and therefore must be rounded down.
> 
> Signed-off-by: Eric Blake <[e-mail]>

Reviewed-by: Fam Zheng <[e-mail]>

Stefan Hajnoczi June 20, 2016, 12:09 p.m. UTC | #2

On Tue, Jun 14, 2016 at 03:30:23PM -0600, Eric Blake wrote:
> For symmetry with bdrv_aligned_preadv(), assert that the caller
> really has aligned things properly. This requires adding an align
> parameter, which is used now only in the new asserts, but will
> come in handy in a later patch that adds auto-fragmentation to the
> max transfer size, since that value need not always be a multiple
> of the alignment, and therefore must be rounded down.
> 
> Signed-off-by: Eric Blake <[e-mail]>
> 
> ---
> v2: new patch
> ---
>  block/io.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)

Reviewed-by: Stefan Hajnoczi <[e-mail]>

Patch

diff --git a/block/io.c b/block/io.c
index 42e63f7..056a101 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1242,7 +1242,7 @@  fail:
  */
 static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
     BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
-    QEMUIOVector *qiov, int flags)
+    int64_t align, QEMUIOVector *qiov, int flags)
 {
     BlockDriver *drv = bs->drv;
     bool waited;
@@ -1251,6 +1251,9 @@  static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
     int64_t start_sector = offset >> BDRV_SECTOR_BITS;
     int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);

+    assert(is_power_of_2(align));
+    assert((offset & (align - 1)) == 0);
+    assert((bytes & (align - 1)) == 0);
     assert(!qiov || bytes == qiov->size);
     assert((bs->open_flags & BDRV_O_NO_IO) == 0);
     assert(!(flags & ~BDRV_REQ_MASK));
@@ -1337,7 +1340,7 @@  static int coroutine_fn bdrv_co_do_zero_pwritev(BlockDriverState *bs,

         memset(buf + head_padding_bytes, 0, zero_bytes);
         ret = bdrv_aligned_pwritev(bs, req, offset & ~(align - 1), align,
-                                   &local_qiov,
+                                   align, &local_qiov,
                                    flags & ~BDRV_REQ_ZERO_WRITE);
         if (ret < 0) {
             goto fail;
@@ -1350,7 +1353,7 @@  static int coroutine_fn bdrv_co_do_zero_pwritev(BlockDriverState *bs,
     if (bytes >= align) {
         /* Write the aligned part in the middle. */
         uint64_t aligned_bytes = bytes & ~(align - 1);
-        ret = bdrv_aligned_pwritev(bs, req, offset, aligned_bytes,
+        ret = bdrv_aligned_pwritev(bs, req, offset, aligned_bytes, align,
                                    NULL, flags);
         if (ret < 0) {
             goto fail;
@@ -1374,7 +1377,7 @@  static int coroutine_fn bdrv_co_do_zero_pwritev(BlockDriverState *bs,
         bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL);

         memset(buf, 0, bytes);
-        ret = bdrv_aligned_pwritev(bs, req, offset, align,
+        ret = bdrv_aligned_pwritev(bs, req, offset, align, align,
                                    &local_qiov, flags & ~BDRV_REQ_ZERO_WRITE);
     }
 fail:
@@ -1499,7 +1502,7 @@  int coroutine_fn bdrv_co_pwritev(BlockDriverState *bs,
         bytes = ROUND_UP(bytes, align);
     }

-    ret = bdrv_aligned_pwritev(bs, &req, offset, bytes,
+    ret = bdrv_aligned_pwritev(bs, &req, offset, bytes, align,
                                use_local_qiov ? &local_qiov : qiov,
                                flags);