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rbd: add code to get the size of a v2 rbd image 

The size of an rbd format 2 image is fetched from the server using a
"get_size" method.  The same method is used for getting the size of
a snapshot, so structure this addition with a generic helper routine
that we can get this information for either.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This commit is contained in:
Alex Elder 2012-07-03 16:01:19 -05:00
parent a30b71b999
commit 9d475de5d1
1 changed files with 53 additions and 0 deletions
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53
drivers/block/rbd.c
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@ -2127,6 +2127,47 @@ static char *rbd_dev_v1_snap_info(struct rbd_device *rbd_dev, u32 which,
return snap_name;
}
/*
* Get the size and object order for an image snapshot, or if
* snap_id is CEPH_NOSNAP, gets this information for the base
* image.
*/
static int _rbd_dev_v2_snap_size(struct rbd_device *rbd_dev, u64 snap_id,
u8 *order, u64 *snap_size)
{
__le64 snapid = cpu_to_le64(snap_id);
int ret;
struct {
u8 order;
__le64 size;
} __attribute__ ((packed)) size_buf = { 0 };
ret = rbd_req_sync_exec(rbd_dev, rbd_dev->header_name,
"rbd", "get_size",
(char *) &snapid, sizeof (snapid),
(char *) &size_buf, sizeof (size_buf),
CEPH_OSD_FLAG_READ, NULL);
dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret);
if (ret < 0)
return ret;
*order = size_buf.order;
*snap_size = le64_to_cpu(size_buf.size);
dout(" snap_id 0x%016llx order = %u, snap_size = %llu\n",
(unsigned long long) snap_id, (unsigned int) *order,
(unsigned long long) *snap_size);
return 0;
}
static int rbd_dev_v2_image_size(struct rbd_device *rbd_dev)
{
return _rbd_dev_v2_snap_size(rbd_dev, CEPH_NOSNAP,
&rbd_dev->header.obj_order,
&rbd_dev->header.image_size);
}
/*
* Scan the rbd device's current snapshot list and compare it to the
* newly-received snapshot context. Remove any existing snapshots
@ -2636,6 +2677,7 @@ out_err:
static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
{
size_t size;
int ret;
/*
* Image id was filled in by the caller. Record the header
@ -2647,12 +2689,23 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
return -ENOMEM;
sprintf(rbd_dev->header_name, "%s%s",
RBD_HEADER_PREFIX, rbd_dev->image_id);
/* Get the size and object order for the image */
ret = rbd_dev_v2_image_size(rbd_dev);
if (ret < 0)
goto out_err;
rbd_dev->image_format = 2;
dout("discovered version 2 image, header name is %s\n",
rbd_dev->header_name);
return -ENOTSUPP;
out_err:
kfree(rbd_dev->header_name);
rbd_dev->header_name = NULL;
return ret;
}
/*