[Qemu-devel] [PATCH 2/2] sheepdog: pass copy_policy in the request

[Liu Yuan]

Currently copy_policy isn't used. Recent sheepdog supports erasure coding, which
make use of copy_policy internally, but require client explicitly passing
copy_policy from base inode to newly creately inode for snapshot related
operations.

If connected sheep daemon doesn't utilize copy_policy, passing it to sheep
daemon is just one extra null effect operation. So no compatibility problem.

With this patch, sheepdog can provide erasure coded volume for QEMU VM.

Cc: Kevin Wolf <kw...@redhat.com>
Cc: Stefan Hajnoczi <stefa...@redhat.com>
Signed-off-by: Liu Yuan <namei.u...@gmail.com>
---
 block/sheepdog.c |   20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/block/sheepdog.c b/block/sheepdog.c
index ca4f98b..48b11da 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -126,7 +126,8 @@ typedef struct SheepdogObjReq {
     uint64_t oid;
     uint64_t cow_oid;
     uint8_t copies;
-    uint8_t reserved[3];
+    uint8_t copy_policy;
+    uint8_t reserved[2];
     uint32_t rsvd;
     uint64_t offset;
 } SheepdogObjReq;
@@ -140,7 +141,8 @@ typedef struct SheepdogObjRsp {
     uint32_t data_length;
     uint32_t result;
     uint8_t copies;
-    uint8_t reserved[3];
+    uint8_t copy_policy;
+    uint8_t reserved[2];
     uint32_t pad[6];
 } SheepdogObjRsp;
 
@@ -154,7 +156,8 @@ typedef struct SheepdogVdiReq {
     uint64_t vdi_size;
     uint32_t vdi_id;
     uint8_t copies;
-    uint8_t reserved[3];
+    uint8_t copy_policy;
+    uint8_t reserved[2];
     uint32_t snapid;
     uint32_t pad[3];
 } SheepdogVdiReq;
@@ -1347,7 +1350,8 @@ out:
 }
 
 static int do_sd_create(BDRVSheepdogState *s, char *filename, int64_t vdi_size,
-                        uint32_t base_vid, uint32_t *vdi_id, int snapshot)
+                        uint32_t base_vid, uint32_t *vdi_id, int snapshot,
+                        uint8_t copy_policy)
 {
     SheepdogVdiReq hdr;
     SheepdogVdiRsp *rsp = (SheepdogVdiRsp *)&hdr;
@@ -1377,6 +1381,7 @@ static int do_sd_create(BDRVSheepdogState *s, char 
*filename, int64_t vdi_size,
 
     hdr.data_length = wlen;
     hdr.vdi_size = vdi_size;
+    hdr.copy_policy = copy_policy;
 
     ret = do_req(fd, (SheepdogReq *)&hdr, buf, &wlen, &rlen);
 
@@ -1529,7 +1534,8 @@ static int sd_create(const char *filename, 
QEMUOptionParameter *options,
         bdrv_unref(bs);
     }
 
-    ret = do_sd_create(s, vdi, vdi_size, base_vid, &vid, 0);
+    /* TODO: allow users to specify copy number */
+    ret = do_sd_create(s, vdi, vdi_size, base_vid, &vid, 0, 0);
     if (!prealloc || ret) {
         goto out;
     }
@@ -1719,7 +1725,7 @@ static int sd_create_branch(BDRVSheepdogState *s)
      */
     deleted = sd_delete(s);
     ret = do_sd_create(s, s->name, s->inode.vdi_size, s->inode.vdi_id, &vid,
-                       !deleted);
+                       !deleted, s->inode.copy_policy);
     if (ret) {
         goto out;
     }
@@ -2009,7 +2015,7 @@ static int sd_snapshot_create(BlockDriverState *bs, 
QEMUSnapshotInfo *sn_info)
     }
 
     ret = do_sd_create(s, s->name, s->inode.vdi_size, s->inode.vdi_id, 
&new_vid,
-                       1);
+                       1, s->inode.copy_policy);
     if (ret < 0) {
         error_report("failed to create inode for snapshot. %s",
                      strerror(errno));
-- 
1.7.9.5