Re: [Qemu-devel] [PATCH v6 1/3] Revert "block: Fix unaligned zero write"

[Kevin Wolf]

Am 12.05.2015 um 08:09 hat Fam Zheng geschrieben:
> This reverts commit fc3959e4669a1c2149b91ccb05101cfc7ae1fc05.
> 
> The core write code already handles the case, so remove this
> duplication.
> 
> Because commit 61007b316 moved the touched code from block.c to
> block/io.c, the change is manually reverted.
> 
> Signed-off-by: Fam Zheng 
> Reviewed-by: Stefan Hajnoczi 

Reviewed-by: Kevin Wolf 

[Qemu-devel] [PATCH v6 1/3] Revert "block: Fix unaligned zero write"

[Fam Zheng]

This reverts commit fc3959e4669a1c2149b91ccb05101cfc7ae1fc05.

The core write code already handles the case, so remove this
duplication.

Because commit 61007b316 moved the touched code from block.c to
block/io.c, the change is manually reverted.

Signed-off-by: Fam Zheng 
Reviewed-by: Stefan Hajnoczi 
---
 block/io.c | 45 ++---
 1 file changed, 6 insertions(+), 39 deletions(-)

diff --git a/block/io.c b/block/io.c
index 1ce62c4..4e5a92e 100644
--- a/block/io.c
+++ b/block/io.c
@@ -929,19 +929,6 @@ out:
 return ret;
 }
 
-static inline uint64_t bdrv_get_align(BlockDriverState *bs)
-{
-/* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
-return MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
-}
-
-static inline bool bdrv_req_is_aligned(BlockDriverState *bs,
-   int64_t offset, size_t bytes)
-{
-int64_t align = bdrv_get_align(bs);
-return !(offset & (align - 1) || (bytes & (align - 1)));
-}
-
 /*
  * Handle a read request in coroutine context
  */
@@ -952,7 +939,8 @@ static int coroutine_fn bdrv_co_do_preadv(BlockDriverState 
*bs,
 BlockDriver *drv = bs->drv;
 BdrvTrackedRequest req;
 
-uint64_t align = bdrv_get_align(bs);
+/* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
+uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
 uint8_t *head_buf = NULL;
 uint8_t *tail_buf = NULL;
 QEMUIOVector local_qiov;
@@ -1194,7 +1182,8 @@ static int coroutine_fn 
bdrv_co_do_pwritev(BlockDriverState *bs,
 BdrvRequestFlags flags)
 {
 BdrvTrackedRequest req;
-uint64_t align = bdrv_get_align(bs);
+/* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
+uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
 uint8_t *head_buf = NULL;
 uint8_t *tail_buf = NULL;
 QEMUIOVector local_qiov;
@@ -1293,10 +1282,6 @@ static int coroutine_fn 
bdrv_co_do_pwritev(BlockDriverState *bs,
 bytes = ROUND_UP(bytes, align);
 }
 
-if (use_local_qiov) {
-/* Local buffer may have non-zero data. */
-flags &= ~BDRV_REQ_ZERO_WRITE;
-}
 ret = bdrv_aligned_pwritev(bs, &req, offset, bytes,
use_local_qiov ? &local_qiov : qiov,
flags);
@@ -1337,32 +1322,14 @@ int coroutine_fn bdrv_co_write_zeroes(BlockDriverState 
*bs,
   int64_t sector_num, int nb_sectors,
   BdrvRequestFlags flags)
 {
-int ret;
-
 trace_bdrv_co_write_zeroes(bs, sector_num, nb_sectors, flags);
 
 if (!(bs->open_flags & BDRV_O_UNMAP)) {
 flags &= ~BDRV_REQ_MAY_UNMAP;
 }
-if (bdrv_req_is_aligned(bs, sector_num << BDRV_SECTOR_BITS,
-nb_sectors << BDRV_SECTOR_BITS)) {
-ret = bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL,
-BDRV_REQ_ZERO_WRITE | flags);
-} else {
-uint8_t *buf;
-QEMUIOVector local_qiov;
-size_t bytes = nb_sectors << BDRV_SECTOR_BITS;
 
-buf = qemu_memalign(bdrv_opt_mem_align(bs), bytes);
-memset(buf, 0, bytes);
-qemu_iovec_init(&local_qiov, 1);
-qemu_iovec_add(&local_qiov, buf, bytes);
-
-ret = bdrv_co_do_writev(bs, sector_num, nb_sectors, &local_qiov,
-BDRV_REQ_ZERO_WRITE | flags);
-qemu_vfree(buf);
-}
-return ret;
+return bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL,
+ BDRV_REQ_ZERO_WRITE | flags);
 }
 
 int bdrv_flush_all(void)
-- 
2.1.0