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rbd: add barriers near done flag operations

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Somehow, I missed this little item in Documentation/atomic_ops.txt:
    *** WARNING: atomic_read() and atomic_set() DO NOT IMPLY BARRIERS! ***

Create and use some helper functions that include the proper memory
barriers for manipulating the done field.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This commit is contained in:
Alex Elder 2013-02-05 23:41:50 -06:00 • committed by Sage Weil
commit 077413082f
1 changed files with 24 additions and 6 deletions
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30
drivers/block/rbd.c
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@ -1216,10 +1216,28 @@ static int rbd_obj_request_wait(struct rbd_obj_request *obj_request)
return wait_for_completion_interruptible(&obj_request->completion);
}
static void obj_request_done_init(struct rbd_obj_request *obj_request)
{
atomic_set(&obj_request->done, 0);
smp_wmb();
}
static void obj_request_done_set(struct rbd_obj_request *obj_request)
{
atomic_set(&obj_request->done, 1);
smp_wmb();
}
static bool obj_request_done_test(struct rbd_obj_request *obj_request)
{
smp_rmb();
return atomic_read(&obj_request->done) != 0;
}
static void rbd_osd_trivial_callback(struct rbd_obj_request *obj_request,
struct ceph_osd_op *op)
{
atomic_set(&obj_request->done, 1);
obj_request_done_set(obj_request);
}
static void rbd_obj_request_complete(struct rbd_obj_request *obj_request)
@ -1249,14 +1267,14 @@ static void rbd_osd_read_callback(struct rbd_obj_request *obj_request,
xferred = obj_request->length;
}
obj_request->xferred = xferred;
atomic_set(&obj_request->done, 1);
obj_request_done_set(obj_request);
}
static void rbd_osd_write_callback(struct rbd_obj_request *obj_request,
struct ceph_osd_op *op)
{
obj_request->xferred = le64_to_cpu(op->extent.length);
atomic_set(&obj_request->done, 1);
obj_request_done_set(obj_request);
}
static void rbd_osd_req_callback(struct ceph_osd_request *osd_req,
@ -1300,7 +1318,7 @@ static void rbd_osd_req_callback(struct ceph_osd_request *osd_req,
break;
}
if (atomic_read(&obj_request->done))
if (obj_request_done_test(obj_request))
rbd_obj_request_complete(obj_request);
}
@ -1407,7 +1425,7 @@ static struct rbd_obj_request *rbd_obj_request_create(const char *object_name,
obj_request->which = BAD_WHICH;
obj_request->type = type;
INIT_LIST_HEAD(&obj_request->links);
atomic_set(&obj_request->done, 0);
obj_request_done_init(obj_request);
init_completion(&obj_request->completion);
kref_init(&obj_request->kref);
@ -1611,7 +1629,7 @@ static void rbd_img_obj_callback(struct rbd_obj_request *obj_request)
rbd_assert(more);
rbd_assert(which < img_request->obj_request_count);
if (!atomic_read(&obj_request->done))
if (!obj_request_done_test(obj_request))
break;
rbd_assert(obj_request->xferred <= (u64) UINT_MAX);