[sheepdog] [PATCH] sheepdog: selectable object size support

[Hitoshi Mitake]

At Tue, 13 Jan 2015 17:41:12 +0900,
Teruaki Ishizaki wrote:
> 
> Previously, qemu block driver of sheepdog used hard-coded VDI object size.
> This patch enables users to handle "block_size_shift" value for
> calculating VDI object size.
> 
> When you start qemu, you don't need to specify additional command option.
> 
> But when you create the VDI which doesn't have default object size
> with qemu-img command, you specify block_size_shift option.
> 
> If you want to create a VDI of 8MB(1 << 23) object size,
> you need to specify following command option.
> 
>  # qemu-img create -o block_size_shift=23 sheepdog:test1 100M
> 
> In addition, when you don't specify qemu-img command option,
> a default value of sheepdog cluster is used for creating VDI.
> 
>  # qemu-img create sheepdog:test2 100M
> 
> Signed-off-by: Teruaki Ishizaki <ishizaki.teruaki at lab.ntt.co.jp>
> ---
>  block/sheepdog.c          |  138 +++++++++++++++++++++++++++++++++++++-------
>  include/block/block_int.h |    1 +
>  2 files changed, 117 insertions(+), 22 deletions(-)


> 
> @@ -1610,7 +1633,8 @@ out_with_err_set:
>      if (bs) {
>          bdrv_unref(bs);
>      }
> -    g_free(buf);
> +    if (buf) 

The above line has a style problem (white space).

> @@ -1669,6 +1693,17 @@ static int parse_redundancy(BDRVSheepdogState *s, const char *opt)
>      return 0;
>  }
>  
> +static int parse_block_size_shift(BDRVSheepdogState *s, const char *opt)
> +{
> +    struct SheepdogInode *inode = &s->inode;
> +    inode->block_size_shift = (uint8_t)atoi(opt);

This patch cannot create VDI with specified block size shift. Below is
the reason:

Initializing block_size_shift of the inode object here (in
parse_block_size_shift()) doesn't make sense. Because the
block_size_shift of newly created VDI is specified by block_size_shift
of SheepdogVdiReq (in sheepdog source code, sd_req.vdi). You need to
synchronize the struct and initialize the parameter. Below is a slack
solution:

diff --git a/block/sheepdog.c b/block/sheepdog.c
index 525254e..3dc3359 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -168,7 +168,8 @@ typedef struct SheepdogVdiReq {
     uint32_t base_vdi_id;
     uint8_t copies;
     uint8_t copy_policy;
-    uint8_t reserved[2];
+    uint8_t store_policy;
+    uint8_t block_size_shift;
     uint32_t snapid;
     uint32_t type;
     uint32_t pad[2];
@@ -1560,6 +1561,7 @@ static int do_sd_create(BDRVSheepdogState *s,
uint32_t *vdi_id, int snapshot,
     hdr.vdi_size = s->inode.vdi_size;
     hdr.copy_policy = s->inode.copy_policy;
     hdr.copies = s->inode.nr_copies;
+    hdr.block_size_shift = s->inode.block_size_shift;
 
     ret = do_req(fd, s->aio_context, (SheepdogReq *)&hdr, buf, &wlen,
     &rlen);

# This is a very slack solution. You need to avoid using inode as a
# temporal space of the parameter.

Thanks,
Hitoshi