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rbd: implement sync object read with new code 

Reimplement the synchronous read operation used for reading a
version 1 header using the new request tracking code.  Name the
resulting function rbd_obj_read_sync() to better reflect that
it's a full object operation, not an object request.  To do this,
implement a new OBJ_REQUEST_PAGES object request type.

This implements a new mechanism to allow the caller to wait for
completion for an rbd_obj_request by calling rbd_obj_request_wait().

This partially resolves:
    http://tracker.newdream.net/issues/3755

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This commit is contained in:
Alex Elder 2013-01-17 12:25:27 -06:00 committed by Sage Weil
parent 7d250b949a
commit 788e2df3b9
1 changed files with 92 additions and 4 deletions
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96
drivers/block/rbd.c
View File

@ -170,7 +170,7 @@ typedef void (*rbd_img_callback_t)(struct rbd_img_request *);
struct rbd_obj_request;
typedef void (*rbd_obj_callback_t)(struct rbd_obj_request *);
enum obj_request_type { OBJ_REQUEST_BIO }; /* More types to come */
enum obj_request_type { OBJ_REQUEST_BIO, OBJ_REQUEST_PAGES };
struct rbd_obj_request {
const char *object_name;
@ -182,7 +182,13 @@ struct rbd_obj_request {
u32 which; /* posn image request list */
enum obj_request_type type;
struct bio *bio_list;
union {
struct bio *bio_list;
struct {
struct page **pages;
u32 page_count;
};
};
struct ceph_osd_request *osd_req;
@ -192,6 +198,7 @@ struct rbd_obj_request {
atomic_t done;
rbd_obj_callback_t callback;
struct completion completion;
struct kref kref;
};
@ -1077,6 +1084,7 @@ static bool obj_request_type_valid(enum obj_request_type type)
{
switch (type) {
case OBJ_REQUEST_BIO:
case OBJ_REQUEST_PAGES:
return true;
default:
return false;
@ -1291,14 +1299,23 @@ static void rbd_img_request_complete(struct rbd_img_request *img_request)
rbd_img_request_put(img_request);
}
/* Caller is responsible for rbd_obj_request_destroy(obj_request) */
static int rbd_obj_request_wait(struct rbd_obj_request *obj_request)
{
return wait_for_completion_interruptible(&obj_request->completion);
}
static void rbd_obj_request_complete(struct rbd_obj_request *obj_request)
{
if (obj_request->callback)
obj_request->callback(obj_request);
else
complete_all(&obj_request->completion);
}
/*
* Request sync osd read
* Synchronously read a range from an object into a provided buffer
*/
static int rbd_req_sync_read(struct rbd_device *rbd_dev,
const char *object_name,
@ -1556,6 +1573,11 @@ static struct ceph_osd_request *rbd_osd_req_create(
/* osd client requires "num pages" even for bio */
osd_req->r_num_pages = calc_pages_for(offset, length);
break;
case OBJ_REQUEST_PAGES:
osd_req->r_pages = obj_request->pages;
osd_req->r_num_pages = obj_request->page_count;
osd_req->r_page_alignment = offset & ~PAGE_MASK;
break;
}
if (write_request) {
@ -1616,6 +1638,7 @@ static struct rbd_obj_request *rbd_obj_request_create(const char *object_name,
obj_request->type = type;
INIT_LIST_HEAD(&obj_request->links);
atomic_set(&obj_request->done, 0);
init_completion(&obj_request->completion);
kref_init(&obj_request->kref);
return obj_request;
@ -1639,6 +1662,11 @@ static void rbd_obj_request_destroy(struct kref *kref)
if (obj_request->bio_list)
bio_chain_put(obj_request->bio_list);
break;
case OBJ_REQUEST_PAGES:
if (obj_request->pages)
ceph_release_page_vector(obj_request->pages,
obj_request->page_count);
break;
}
kfree(obj_request);
@ -1987,6 +2015,65 @@ static void rbd_free_disk(struct rbd_device *rbd_dev)
put_disk(disk);
}
static int rbd_obj_read_sync(struct rbd_device *rbd_dev,
const char *object_name,
u64 offset, u64 length,
char *buf, u64 *version)
{
struct ceph_osd_req_op *op;
struct rbd_obj_request *obj_request;
struct ceph_osd_client *osdc;
struct page **pages = NULL;
u32 page_count;
int ret;
page_count = (u32) calc_pages_for(offset, length);
pages = ceph_alloc_page_vector(page_count, GFP_KERNEL);
if (IS_ERR(pages))
ret = PTR_ERR(pages);
ret = -ENOMEM;
obj_request = rbd_obj_request_create(object_name, offset, length,
OBJ_REQUEST_PAGES);
if (!obj_request)
goto out;
obj_request->pages = pages;
obj_request->page_count = page_count;
op = rbd_osd_req_op_create(CEPH_OSD_OP_READ, offset, length);
if (!op)
goto out;
obj_request->osd_req = rbd_osd_req_create(rbd_dev, false,
obj_request, op);
rbd_osd_req_op_destroy(op);
if (!obj_request->osd_req)
goto out;
osdc = &rbd_dev->rbd_client->client->osdc;
ret = rbd_obj_request_submit(osdc, obj_request);
if (ret)
goto out;
ret = rbd_obj_request_wait(obj_request);
if (ret)
goto out;
ret = obj_request->result;
if (ret < 0)
goto out;
ret = ceph_copy_from_page_vector(pages, buf, 0, obj_request->xferred);
if (version)
*version = obj_request->version;
out:
if (obj_request)
rbd_obj_request_put(obj_request);
else
ceph_release_page_vector(pages, page_count);
return ret;
}
/*
* Read the complete header for the given rbd device.
*
@ -2025,7 +2112,8 @@ rbd_dev_v1_header_read(struct rbd_device *rbd_dev, u64 *version)
if (!ondisk)
return ERR_PTR(-ENOMEM);
ret = rbd_req_sync_read(rbd_dev, rbd_dev->header_name,
(void) rbd_req_sync_read; /* avoid a warning */
ret = rbd_obj_read_sync(rbd_dev, rbd_dev->header_name,
0, size,
(char *) ondisk, version);