[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH 5/5] virtio-blk: add volatile writecache feature
From: |
Christoph Hellwig |
Subject: |
[Qemu-devel] [PATCH 5/5] virtio-blk: add volatile writecache feature |
Date: |
Fri, 4 Sep 2009 19:02:23 +0200 |
User-agent: |
Mutt/1.3.28i |
Add a new VIRTIO_BLK_F_WCACHE feature to virtio-blk to indicate that we have
a volatile write cache that needs controlled flushing. Implement a
VIRTIO_BLK_T_FLUSH operation to flush it.
Signed-off-by: Christoph Hellwig <address@hidden>
Index: qemu-kvm/hw/virtio-blk.c
===================================================================
--- qemu-kvm.orig/hw/virtio-blk.c
+++ qemu-kvm/hw/virtio-blk.c
@@ -129,6 +129,13 @@ static void virtio_blk_rw_complete(void
virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
}
+static void virtio_blk_flush_complete(void *opaque, int ret)
+{
+ VirtIOBlockReq *req = opaque;
+
+ virtio_blk_req_complete(req, ret ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK);
+}
+
static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
{
VirtIOBlockReq *req = qemu_mallocz(sizeof(*req));
@@ -252,6 +259,16 @@ static void virtio_blk_handle_scsi(VirtI
}
#endif /* __linux__ */
+static void virtio_blk_handle_flush(VirtIOBlockReq *req)
+{
+ BlockDriverAIOCB *acb;
+
+ acb = bdrv_aio_flush(req->dev->bs, virtio_blk_flush_complete, req);
+ if (!acb) {
+ virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
+ }
+}
+
static void virtio_blk_handle_write(VirtIOBlockReq *req)
{
BlockDriverAIOCB *acb;
@@ -294,7 +311,9 @@ static void virtio_blk_handle_output(Vir
req->out = (void *)req->elem.out_sg[0].iov_base;
req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
- if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
+ if (req->out->type & VIRTIO_BLK_T_FLUSH) {
+ virtio_blk_handle_flush(req);
+ } else if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
virtio_blk_handle_scsi(req);
} else if (req->out->type & VIRTIO_BLK_T_OUT) {
qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
@@ -382,6 +401,9 @@ static uint32_t virtio_blk_get_features(
features |= (1 << VIRTIO_BLK_F_SEG_MAX);
features |= (1 << VIRTIO_BLK_F_GEOMETRY);
+
+ if (bdrv_enable_write_cache(s->bs))
+ features |= (1 << VIRTIO_BLK_F_WCACHE);
#ifdef __linux__
features |= (1 << VIRTIO_BLK_F_SCSI);
#endif
Index: qemu-kvm/hw/virtio-blk.h
===================================================================
--- qemu-kvm.orig/hw/virtio-blk.h
+++ qemu-kvm/hw/virtio-blk.h
@@ -31,6 +31,7 @@
#define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/
#define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */
#define VIRTIO_BLK_F_IDENTIFY 8 /* ATA IDENTIFY supported */
+#define VIRTIO_BLK_F_WCACHE 9 /* write cache enabled */
#define VIRTIO_BLK_ID_LEN 256 /* length of identify u16 array */
#define VIRTIO_BLK_ID_SN 10 /* start of char * serial# */
@@ -55,6 +56,9 @@ struct virtio_blk_config
/* This bit says it's a scsi command, not an actual read or write. */
#define VIRTIO_BLK_T_SCSI_CMD 2
+/* Flush the volatile write cache */
+#define VIRTIO_BLK_T_FLUSH 4
+
/* Barrier before this op. */
#define VIRTIO_BLK_T_BARRIER 0x80000000