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Commit 788e2df3 authored by Alex Elder's avatar Alex Elder Committed by Sage Weil
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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: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent 7d250b94

drivers/block/rbd.c

+92 −4
Original line number Diff line number Diff line
@@ -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;

	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);