[Qemu-devel] make use of copy_policy

[Qemu-devel] make use of copy_policy

[Liu Yuan]

This patch set makes use of copy_policy in struct SheepdogInode in order to
support recently introduced erasure coding in sheepdog.

Thanks
Yuan

[Qemu-devel] [PATCH 1/2] sheepdog: explicitly set copies as type uint8_t

[Liu Yuan]

'copies' is actually uint8_t since day one, but request headers and some helper
functions parameterize it as uint32_t for unknown reasons and effectively
reserve 24 bytes for possible future use. This patch explicitly set the correct
for copies and reserve the left bytes.

This is a preparation patch that allow passing copy_policy in request header.

Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Liu Yuan <namei.unix@gmail.com>
---
 block/sheepdog.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/block/sheepdog.c b/block/sheepdog.c
index 5f81c93..ca4f98b 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -125,7 +125,8 @@ typedef struct SheepdogObjReq {
     uint32_t data_length;
     uint64_t oid;
     uint64_t cow_oid;
-    uint32_t copies;
+    uint8_t copies;
+    uint8_t reserved[3];
     uint32_t rsvd;
     uint64_t offset;
 } SheepdogObjReq;
@@ -138,7 +139,8 @@ typedef struct SheepdogObjRsp {
     uint32_t id;
     uint32_t data_length;
     uint32_t result;
-    uint32_t copies;
+    uint8_t copies;
+    uint8_t reserved[3];
     uint32_t pad[6];
 } SheepdogObjRsp;
 
@@ -151,7 +153,8 @@ typedef struct SheepdogVdiReq {
     uint32_t data_length;
     uint64_t vdi_size;
     uint32_t vdi_id;
-    uint32_t copies;
+    uint8_t copies;
+    uint8_t reserved[3];
     uint32_t snapid;
     uint32_t pad[3];
 } SheepdogVdiReq;
@@ -1081,7 +1084,7 @@ static int coroutine_fn add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
     return 0;
 }
 
-static int read_write_object(int fd, char *buf, uint64_t oid, int copies,
+static int read_write_object(int fd, char *buf, uint64_t oid, uint8_t copies,
                              unsigned int datalen, uint64_t offset,
                              bool write, bool create, uint32_t cache_flags)
 {
@@ -1129,7 +1132,7 @@ static int read_write_object(int fd, char *buf, uint64_t oid, int copies,
     }
 }
 
-static int read_object(int fd, char *buf, uint64_t oid, int copies,
+static int read_object(int fd, char *buf, uint64_t oid, uint8_t copies,
                        unsigned int datalen, uint64_t offset,
                        uint32_t cache_flags)
 {
@@ -1137,7 +1140,7 @@ static int read_object(int fd, char *buf, uint64_t oid, int copies,
                              false, cache_flags);
 }
 
-static int write_object(int fd, char *buf, uint64_t oid, int copies,
+static int write_object(int fd, char *buf, uint64_t oid, uint8_t copies,
                         unsigned int datalen, uint64_t offset, bool create,
                         uint32_t cache_flags)
 {
-- 
1.7.9.5

Re: [Qemu-devel] [sheepdog] [PATCH 1/2] sheepdog: explicitly set copies as type uint8_t

[MORITA Kazutaka]

At Wed, 16 Oct 2013 15:38:37 +0800,
Liu Yuan wrote:
> 
> 'copies' is actually uint8_t since day one, but request headers and some helper
> functions parameterize it as uint32_t for unknown reasons and effectively
> reserve 24 bytes for possible future use. This patch explicitly set the correct
> for copies and reserve the left bytes.
> 
> This is a preparation patch that allow passing copy_policy in request header.
> 
> Cc: Kevin Wolf <kwolf@redhat.com>
> Cc: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Liu Yuan <namei.unix@gmail.com>
> ---
>  block/sheepdog.c |   15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/block/sheepdog.c b/block/sheepdog.c
> index 5f81c93..ca4f98b 100644
> --- a/block/sheepdog.c
> +++ b/block/sheepdog.c
> @@ -125,7 +125,8 @@ typedef struct SheepdogObjReq {
>      uint32_t data_length;
>      uint64_t oid;
>      uint64_t cow_oid;
> -    uint32_t copies;
> +    uint8_t copies;
> +    uint8_t reserved[3];
>      uint32_t rsvd;
>      uint64_t offset;
>  } SheepdogObjReq;

Having both 'reserved' and 'rsvd' looks confusing.  I'd suggest
merging them into 'uint8_t reserved[7]'.

Thanks,

Kazutaka

[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 <kwolf@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Liu Yuan <namei.unix@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

Re: [Qemu-devel] make use of copy_policy

[Liu Yuan]

On Wed, Oct 16, 2013 at 03:38:36PM +0800, Liu Yuan wrote:
> This patch set makes use of copy_policy in struct SheepdogInode in order to
> support recently introduced erasure coding in sheepdog.
> 
> Thanks
> Yuan

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