[SCSI] libosd: Fix blk_put_request locking again
So libosd has decided to sacrifice some code simplicity for the sake of
a clean API. One of these things is the possibility for users to call
osd_end_request, in any condition at any state. This opens up some
problems with calling blk_put_request when out-side of the completion
callback but calling __blk_put_request when detecting a from-completion
state.
The current hack was working just fine until exofs decided to operate on
all devices in parallel and wait for the sum of the requests, before
deallocating all osd-requests at once. There are two new possible cases
1. All request in a group are deallocated as part of the last request's
async-done, request_queue is locked.
2. All request in a group where executed asynchronously, but
de-allocation was delayed to after the async-done, in the context of
another thread. Async execution but request_queue is not locked.
The solution I chose was to separate the deallocation of the osd_request
which has the information users need, from the deallocation of the
internal(2) requests which impose the locking problem. The internal
block-requests are freed unconditionally inside the async-done-callback,
when we know the queue is always locked. If at osd_end_request time we
still have a bock-request, then we know it did not come from within an
async-done-callback and we can call the regular blk_put_request.
The internal requests were used for carrying error information after
execution. This information is now copied to osd_request members for
later analysis by user code.
The external API and behaviour was unchanged, except now it really
supports what was previously advertised.
Reported-by: Vineet Agarwal <checkout.vineet@gmail.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Cc: Stable Tree <stable@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/scsi/osd/osd_initiator.c b/drivers/scsi/osd/osd_initiator.c
index 950202a..2422347 100644
--- a/drivers/scsi/osd/osd_initiator.c
+++ b/drivers/scsi/osd/osd_initiator.c
@@ -432,30 +432,23 @@
seg->alloc_size = 0;
}
-static void _put_request(struct request *rq , bool is_async)
+static void _put_request(struct request *rq)
{
- if (is_async) {
- WARN_ON(rq->bio);
- __blk_put_request(rq->q, rq);
- } else {
- /*
- * If osd_finalize_request() was called but the request was not
- * executed through the block layer, then we must release BIOs.
- * TODO: Keep error code in or->async_error. Need to audit all
- * code paths.
- */
- if (unlikely(rq->bio))
- blk_end_request(rq, -ENOMEM, blk_rq_bytes(rq));
- else
- blk_put_request(rq);
- }
+ /*
+ * If osd_finalize_request() was called but the request was not
+ * executed through the block layer, then we must release BIOs.
+ * TODO: Keep error code in or->async_error. Need to audit all
+ * code paths.
+ */
+ if (unlikely(rq->bio))
+ blk_end_request(rq, -ENOMEM, blk_rq_bytes(rq));
+ else
+ blk_put_request(rq);
}
void osd_end_request(struct osd_request *or)
{
struct request *rq = or->request;
- /* IMPORTANT: make sure this agrees with osd_execute_request_async */
- bool is_async = (or->request->end_io_data == or);
_osd_free_seg(or, &or->set_attr);
_osd_free_seg(or, &or->enc_get_attr);
@@ -463,20 +456,34 @@
if (rq) {
if (rq->next_rq) {
- _put_request(rq->next_rq, is_async);
+ _put_request(rq->next_rq);
rq->next_rq = NULL;
}
- _put_request(rq, is_async);
+ _put_request(rq);
}
_osd_request_free(or);
}
EXPORT_SYMBOL(osd_end_request);
+static void _set_error_resid(struct osd_request *or, struct request *req,
+ int error)
+{
+ or->async_error = error;
+ or->req_errors = req->errors ? : error;
+ or->sense_len = req->sense_len;
+ if (or->out.req)
+ or->out.residual = or->out.req->resid_len;
+ if (or->in.req)
+ or->in.residual = or->in.req->resid_len;
+}
+
int osd_execute_request(struct osd_request *or)
{
- return or->async_error =
- blk_execute_rq(or->request->q, NULL, or->request, 0);
+ int error = blk_execute_rq(or->request->q, NULL, or->request, 0);
+
+ _set_error_resid(or, or->request, error);
+ return error;
}
EXPORT_SYMBOL(osd_execute_request);
@@ -484,15 +491,17 @@
{
struct osd_request *or = req->end_io_data;
- or->async_error = error;
-
- if (unlikely(error)) {
- OSD_DEBUG("osd_request_async_done error recieved %d "
- "errors 0x%x\n", error, req->errors);
- if (!req->errors) /* don't miss out on this one */
- req->errors = error;
+ _set_error_resid(or, req, error);
+ if (req->next_rq) {
+ __blk_put_request(req->q, req->next_rq);
+ req->next_rq = NULL;
}
+ __blk_put_request(req->q, req);
+ or->request = NULL;
+ or->in.req = NULL;
+ or->out.req = NULL;
+
if (or->async_done)
or->async_done(or, or->async_private);
else
@@ -1489,21 +1498,18 @@
#endif
int ret;
- if (likely(!or->request->errors)) {
- osi->out_resid = 0;
- osi->in_resid = 0;
+ if (likely(!or->req_errors))
return 0;
- }
osi = osi ? : &local_osi;
memset(osi, 0, sizeof(*osi));
- ssdb = or->request->sense;
- sense_len = or->request->sense_len;
+ ssdb = (typeof(ssdb))or->sense;
+ sense_len = or->sense_len;
if ((sense_len < (int)sizeof(*ssdb) || !ssdb->sense_key)) {
OSD_ERR("Block-layer returned error(0x%x) but "
"sense_len(%u) || key(%d) is empty\n",
- or->request->errors, sense_len, ssdb->sense_key);
+ or->req_errors, sense_len, ssdb->sense_key);
goto analyze;
}
@@ -1525,7 +1531,7 @@
"additional_code=0x%x async_error=%d errors=0x%x\n",
osi->key, original_sense_len, sense_len,
osi->additional_code, or->async_error,
- or->request->errors);
+ or->req_errors);
if (original_sense_len < sense_len)
sense_len = original_sense_len;
@@ -1695,10 +1701,10 @@
ret = -EIO;
}
- if (or->out.req)
- osi->out_resid = or->out.req->resid_len ?: or->out.total_bytes;
- if (or->in.req)
- osi->in_resid = or->in.req->resid_len ?: or->in.total_bytes;
+ if (!or->out.residual)
+ or->out.residual = or->out.total_bytes;
+ if (!or->in.residual)
+ or->in.residual = or->in.total_bytes;
return ret;
}