implement qemu_blockalign (Stefano Stabellini)

this patch adds a buffer_alignment field to BlockDriverState and
implements a qemu_blockalign function that uses that field to allocate a
memory aligned buffer to be used by the block driver.
buffer_alignment is initialized to 512 but each block driver can set
a different value (at the moment none of them do).
This patch modifies ide.c, block-qcow.c, block-qcow2.c and block.c to
use qemu_blockalign instead of qemu_memalign.
There is only one place left that still uses qemu_memalign to allocate
buffers used by block drivers that is posix-aio-compat:handle_aiocb_rw
because it is not possible to get the BlockDriverState from that
function. However I think it is not important because posix-aio-compat
already deals with driver specific code so it is supposed to know its
own needs.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7229 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 8 insertions, 1 deletions

diff --git a/block.c b/block.c
index 8348cf2..3d1223d 100644
--- a/block.c
+++ b/block.c
@@ -362,6 +362,8 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
     bs->is_temporary = 0;
     bs->encrypted = 0;
     bs->valid_key = 0;
+    /* buffer_alignment defaulted to 512, drivers can change this value */
+    bs->buffer_alignment = 512;
 
     if (flags & BDRV_O_SNAPSHOT) {
         BlockDriverState *bs1;
@@ -1390,7 +1392,7 @@ static BlockDriverAIOCB *bdrv_aio_rw_vector(BlockDriverState *bs,
     acb = qemu_aio_get(bs, cb, opaque);
     acb->is_write = is_write;
     acb->qiov = qiov;
-    acb->bounce = qemu_memalign(512, qiov->size);
+    acb->bounce = qemu_blockalign(bs, qiov->size);
 
     if (!acb->bh)
         acb->bh = qemu_bh_new(bdrv_aio_bh_cb, acb);
@@ -1640,3 +1642,8 @@ BlockDriverAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
         return drv->bdrv_aio_ioctl(bs, req, buf, cb, opaque);
     return NULL;
 }
+
+void *qemu_blockalign(BlockDriverState *bs, size_t size)
+{
+    return qemu_memalign((bs && bs->buffer_alignment) ? bs->buffer_alignment : 512, size);
+}