Commit 6e2a4505 authored by Alex Elder's avatar Alex Elder Committed by Sage Weil
Browse files

rbd: don't zero-fill non-image object requests 

A result of ENOENT from a read request for an object that's part of
an rbd image indicates that there is a hole in that portion of the
image.  Similarly, a short read for such an object indicates that
the remainder of the read should be interpreted a full read with
zeros filling out the end of the request.

This behavior is not correct for objects that are not backing rbd
image data.  Currently rbd_img_obj_request_callback() assumes it
should be done for all objects.

Change rbd_img_obj_request_callback() so it only does this zeroing
for image objects.  Encapsulate that special handling in its own
function.  Add an assertion that the image object request is a bio
request, since we assume that (and we currently don't support any
other types).

This resolves a problem identified here:
    http://tracker.ceph.com/issues/4559



The regression was introduced by bf0d5f50.

Reported-by: default avatarDan van der Ster <dan@vanderster.com>
Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-off-by: default avatarSage Weil <sage@inktank.com>
parent d6c0dd6b

drivers/block/rbd.c

+30 −17
Original line number Diff line number Diff line
@@ -1264,6 +1264,32 @@ static bool obj_request_done_test(struct rbd_obj_request *obj_request) 
	return atomic_read(&obj_request->done) != 0;

}



static void

rbd_img_obj_request_read_callback(struct rbd_obj_request *obj_request)

{

	dout("%s: obj %p img %p result %d %llu/%llu\n", __func__,

		obj_request, obj_request->img_request, obj_request->result,

		obj_request->xferred, obj_request->length);

	/*

	 * ENOENT means a hole in the image.  We zero-fill the

	 * entire length of the request.  A short read also implies

	 * zero-fill to the end of the request.  Either way we

	 * update the xferred count to indicate the whole request

	 * was satisfied.

	 */

	BUG_ON(obj_request->type != OBJ_REQUEST_BIO);

	if (obj_request->result == -ENOENT) {

		zero_bio_chain(obj_request->bio_list, 0);

		obj_request->result = 0;

		obj_request->xferred = obj_request->length;

	} else if (obj_request->xferred < obj_request->length &&

			!obj_request->result) {

		zero_bio_chain(obj_request->bio_list, obj_request->xferred);

		obj_request->xferred = obj_request->length;

	}

	obj_request_done_set(obj_request);

}



static void rbd_obj_request_complete(struct rbd_obj_request *obj_request)

{

	dout("%s: obj %p cb %p\n", __func__, obj_request,
@@ -1284,22 +1310,9 @@ static void rbd_osd_read_callback(struct rbd_obj_request *obj_request) 
{

	dout("%s: obj %p result %d %llu/%llu\n", __func__, obj_request,

		obj_request->result, obj_request->xferred, obj_request->length);

	/*

	 * ENOENT means a hole in the object.  We zero-fill the

	 * entire length of the request.  A short read also implies

	 * zero-fill to the end of the request.  Either way we

	 * update the xferred count to indicate the whole request

	 * was satisfied.

	 */

	if (obj_request->result == -ENOENT) {

		zero_bio_chain(obj_request->bio_list, 0);

		obj_request->result = 0;

		obj_request->xferred = obj_request->length;

	} else if (obj_request->xferred < obj_request->length &&

			!obj_request->result) {

		zero_bio_chain(obj_request->bio_list, obj_request->xferred);

		obj_request->xferred = obj_request->length;

	}

	if (obj_request->img_request)

		rbd_img_obj_request_read_callback(obj_request);

	else

		obj_request_done_set(obj_request);

}

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