Commit 1e32d34c authored Jan 30, 2013 by Alex Elder Committed by Sage Weil Feb 13, 2013

rbd: don't take extra bio reference for osd client

Currently, if the OSD client finds an osd request has had a bio list
attached to it, it drops a reference to it (or rather, to the first
entry on that list) when the request is released.

The code that added that reference (i.e., the rbd client) is
therefore required to take an extra reference to that first bio
structure.

The osd client doesn't really do anything with the bio pointer other
than transfer it from the osd request structure to outgoing (for
writes) and ingoing (for reads) messages.  So it really isn't the
right place to be taking or dropping references.

Furthermore, the rbd client already holds references to all bio
structures it passes to the osd client, and holds them until the
request is completed.  So there's no need for this extra reference
whatsoever.

So remove the bio_put() call in ceph_osdc_release_request(), as
well as its matching bio_get() call in rbd_osd_req_create().

This change could lead to a crash if old libceph.ko was used with
new rbd.ko.  Add a compatibility check at rbd initialization time to
avoid this possibilty.

This resolves:
    http://tracker.ceph.com/issues/3798    and
    http://tracker.ceph.com/issues/3799



Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

parent 72fe25e3

drivers/block/rbd.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -1342,7 +1342,6 @@ static struct ceph_osd_request *rbd_osd_req_create(
		case OBJ_REQUEST_BIO:
		rbd_assert(obj_request->bio_list != NULL);
		osd_req->r_bio = obj_request->bio_list;
		bio_get(osd_req->r_bio);
		/* osd client requires "num pages" even for bio */
		osd_req->r_num_pages = calc_pages_for(offset, length);
		break;
		@@ -4149,6 +4148,11 @@ int __init rbd_init(void)
		{
		int rc;

		if (!libceph_compatible(NULL)) {
		rbd_warn(NULL, "libceph incompatibility (quitting)");

		return -EINVAL;
		}
		rc = rbd_sysfs_init();
		if (rc)
		return rc;

net/ceph/ceph_common.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -39,7 +39,7 @@
		*/
		bool libceph_compatible(void *data)
		{
		return false;
		return true;
		}
		EXPORT_SYMBOL(libceph_compatible);

net/ceph/osd_client.c

+0 −4

Original line number	Diff line number	Diff line
		@@ -147,10 +147,6 @@ void ceph_osdc_release_request(struct kref *kref)
		if (req->r_own_pages)
		ceph_release_page_vector(req->r_pages,
		req->r_num_pages);
		#ifdef CONFIG_BLOCK
		if (req->r_bio)
		bio_put(req->r_bio);
		#endif
		ceph_put_snap_context(req->r_snapc);
		ceph_pagelist_release(&req->r_trail);
		if (req->r_mempool)

Admin message