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Commit c666601a authored by Josh Durgin's avatar Josh Durgin Committed by Alex Elder
Browse files

rbd: move snap_rwsem to the device, rename to header_rwsem 

A new temporary header is allocated each time the header changes, but
only the changed properties are copied over. We don't need a new
semaphore for each header update.

This addresses http://tracker.newdream.net/issues/2174



Signed-off-by: default avatarJosh Durgin <josh.durgin@dreamhost.com>
Reviewed-by: default avatarAlex Elder <elder@dreamhost.com>
parent 3489b42a

drivers/block/rbd.c

+11 −11
Original line number Diff line number Diff line
@@ -82,7 +82,6 @@ struct rbd_image_header { 
	__u8 obj_order;

	__u8 crypt_type;

	__u8 comp_type;

	struct rw_semaphore snap_rwsem;

	struct ceph_snap_context *snapc;

	size_t snap_names_len;

	u64 snap_seq;
@@ -173,6 +172,8 @@ struct rbd_device { 
	struct ceph_osd_event   *watch_event;

	struct ceph_osd_request *watch_request;



	/* protects updating the header */

	struct rw_semaphore     header_rwsem;

	char                    snap_name[RBD_MAX_SNAP_NAME_LEN];

	u32 cur_snap;	/* index+1 of current snapshot within snap context

			   0 - for the head */
@@ -502,7 +503,6 @@ static int rbd_header_from_disk(struct rbd_image_header *header, 
	if (!header->snapc)

		return -ENOMEM;



	init_rwsem(&header->snap_rwsem);

	header->snap_names_len = le64_to_cpu(ondisk->snap_names_len);

	if (snap_count) {

		header->snap_names = kmalloc(header->snap_names_len,
@@ -597,7 +597,7 @@ static int rbd_header_set_snap(struct rbd_device *dev, u64 *size) 


	BUILD_BUG_ON(sizeof (dev->snap_name) < sizeof (RBD_SNAP_HEAD_NAME));



	down_write(&header->snap_rwsem);

	down_write(&dev->header_rwsem);



	if (!memcmp(dev->snap_name, RBD_SNAP_HEAD_NAME,

		    sizeof (RBD_SNAP_HEAD_NAME))) {
@@ -620,7 +620,7 @@ static int rbd_header_set_snap(struct rbd_device *dev, u64 *size) 


	ret = 0;

done:

	up_write(&header->snap_rwsem);

	up_write(&dev->header_rwsem);

	return ret;

}
@@ -887,7 +887,6 @@ static int rbd_do_request(struct request *rq, 
	struct timespec mtime = CURRENT_TIME;

	struct rbd_request *req_data;

	struct ceph_osd_request_head *reqhead;

	struct rbd_image_header *header = &dev->header;

	struct ceph_osd_client *osdc;



	req_data = kzalloc(sizeof(*req_data), GFP_NOIO);
@@ -905,13 +904,13 @@ static int rbd_do_request(struct request *rq, 


	dout("rbd_do_request obj=%s ofs=%lld len=%lld\n", obj, len, ofs);



	down_read(&header->snap_rwsem);

	down_read(&dev->header_rwsem);



	osdc = &dev->rbd_client->client->osdc;

	req = ceph_osdc_alloc_request(osdc, flags, snapc, ops,

					false, GFP_NOIO, pages, bio);

	if (!req) {

		up_read(&header->snap_rwsem);

		up_read(&dev->header_rwsem);

		ret = -ENOMEM;

		goto done_pages;

	}
@@ -946,7 +945,7 @@ static int rbd_do_request(struct request *rq, 
				snapc,

				&mtime,

				req->r_oid, req->r_oid_len);

	up_read(&header->snap_rwsem);

	up_read(&dev->header_rwsem);



	if (linger_req) {

		ceph_osdc_set_request_linger(osdc, req);
@@ -1718,7 +1717,7 @@ static int __rbd_update_snaps(struct rbd_device *rbd_dev) 
	/* resized? */

	set_capacity(rbd_dev->disk, h.image_size / SECTOR_SIZE);



	down_write(&rbd_dev->header.snap_rwsem);

	down_write(&rbd_dev->header_rwsem);



	snap_seq = rbd_dev->header.snapc->seq;

	if (rbd_dev->header.total_snaps &&
@@ -1743,7 +1742,7 @@ static int __rbd_update_snaps(struct rbd_device *rbd_dev) 


	ret = __rbd_init_snaps_header(rbd_dev);



	up_write(&rbd_dev->header.snap_rwsem);

	up_write(&rbd_dev->header_rwsem);



	return ret;

}
@@ -2380,8 +2379,9 @@ static ssize_t rbd_add(struct bus_type *bus, 
	spin_lock_init(&rbd_dev->lock);

	INIT_LIST_HEAD(&rbd_dev->node);

	INIT_LIST_HEAD(&rbd_dev->snaps);

	init_rwsem(&rbd_dev->header_rwsem);



	init_rwsem(&rbd_dev->header.snap_rwsem);

	init_rwsem(&rbd_dev->header_rwsem);



	/* generate unique id: find highest unique id, add one */

	rbd_id_get(rbd_dev);