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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 bf0d5f503d.

Reported-by: Dan van der Ster <dan@vanderster.com>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-off-by: Sage Weil <sage@inktank.com>
This commit is contained in:
Alex Elder 2013-03-27 09:16:30 -05:00 committed by Sage Weil
parent d6c0dd6b0c
commit 6e2a4505db
1 changed files with 30 additions and 17 deletions
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47
drivers/block/rbd.c
View File

@ -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,
@ -1284,23 +1310,10 @@ 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;
}
obj_request_done_set(obj_request);
if (obj_request->img_request)
rbd_img_obj_request_read_callback(obj_request);
else
obj_request_done_set(obj_request);
}
static void rbd_osd_write_callback(struct rbd_obj_request *obj_request)