[PATCH 2/8] bsg-lib: handle bidi requests without block layer help

Christoph Hellwig
2019-02-01T07:56:14Z

We can just stash away the second request in struct bsg_job instead
of using the block layer req->next_rq field, allowing for the eventual
removal of the latter.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/bsg-lib.c | 44 +++++++++++++++++---
block/bsg.c | 68 +++++++------------------------
drivers/scsi/scsi_transport_sas.c | 1 -
include/linux/bsg-lib.h | 4 ++
4 files changed, 56 insertions(+), 61 deletions(-)

diff --git a/block/bsg-lib.c b/block/bsg-lib.c
index 192129856342..005e2b75d775 100644
--- a/block/bsg-lib.c
+++ b/block/bsg-lib.c
@@ -51,11 +51,40 @@ static int bsg_transport_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
fmode_t mode)
{
struct bsg_job *job = blk_mq_rq_to_pdu(rq);
+ int ret;

job->request_len = hdr->request_len;
job->request = memdup_user(uptr64(hdr->request), hdr->request_len);
+ if (IS_ERR(job->request))
+ return PTR_ERR(job->request);
+
+ if (hdr->dout_xfer_len && hdr->din_xfer_len) {
+ job->bidi_rq = blk_get_request(rq->q, REQ_OP_SCSI_IN, 0);
+ if (IS_ERR(job->bidi_rq)) {
+ ret = PTR_ERR(job->bidi_rq);
+ goto out;
+ }
+
+ ret = blk_rq_map_user(rq->q, job->bidi_rq, NULL,
+ uptr64(hdr->din_xferp), hdr->din_xfer_len,
+ GFP_KERNEL);
+ if (ret)
+ goto out_free_bidi_rq;
+
+ job->bidi_bio = job->bidi_rq->bio;
+ } else {
+ job->bidi_rq = NULL;
+ job->bidi_bio = NULL;
+ }

- return PTR_ERR_OR_ZERO(job->request);
+ return 0;
+
+out_free_bidi_rq:
+ if (job->bidi_rq)
+ blk_put_request(job->bidi_rq);
+out:
+ kfree(job->request);
+ return ret;
}

static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
@@ -93,7 +122,7 @@ static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
/* we assume all request payload was transferred, residual == 0 */
hdr->dout_resid = 0;

- if (rq->next_rq) {
+ if (job->bidi_rq) {
unsigned int rsp_len = job->reply_payload.payload_len;

if (WARN_ON(job->reply_payload_rcv_len > rsp_len))
@@ -111,6 +140,11 @@ static void bsg_transport_free_rq(struct request *rq)
{
struct bsg_job *job = blk_mq_rq_to_pdu(rq);

+ if (job->bidi_rq) {
+ blk_rq_unmap_user(job->bidi_bio);
+ blk_put_request(job->bidi_rq);
+ }
+
kfree(job->request);
}

@@ -200,7 +234,6 @@ static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
*/
static bool bsg_prepare_job(struct device *dev, struct request *req)
{
- struct request *rsp = req->next_rq;
struct bsg_job *job = blk_mq_rq_to_pdu(req);
int ret;

@@ -211,8 +244,8 @@ static bool bsg_prepare_job(struct device *dev, struct request *req)
if (ret)
goto failjob_rls_job;
}
- if (rsp && rsp->bio) {
- ret = bsg_map_buffer(&job->reply_payload, rsp);
+ if (job->bidi_rq) {
+ ret = bsg_map_buffer(&job->reply_payload, job->bidi_rq);
if (ret)
goto failjob_rls_rqst_payload;
}
@@ -369,7 +402,6 @@ struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
}

q->queuedata = dev;
- blk_queue_flag_set(QUEUE_FLAG_BIDI, q);
blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);

ret = bsg_register_queue(q, dev, name, &bsg_transport_ops);
diff --git a/block/bsg.c b/block/bsg.c
index a799b0ace55c..f306853c6b08 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -74,6 +74,11 @@ static int bsg_scsi_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
{
struct scsi_request *sreq = scsi_req(rq);

+ if (hdr->dout_xfer_len && hdr->din_xfer_len) {
+ pr_warn_once("BIDI support in bsg has been removed.\n");
+ return -EOPNOTSUPP;
+ }
+
sreq->cmd_len = hdr->request_len;
if (sreq->cmd_len > BLK_MAX_CDB) {
sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL);
@@ -114,14 +119,10 @@ static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
hdr->response_len = len;
}

- if (rq->next_rq) {
- hdr->dout_resid = sreq->resid_len;
- hdr->din_resid = scsi_req(rq->next_rq)->resid_len;
- } else if (rq_data_dir(rq) == READ) {
+ if (rq_data_dir(rq) == READ)
hdr->din_resid = sreq->resid_len;
- } else {
+ else
hdr->dout_resid = sreq->resid_len;
- }

return ret;
}
@@ -140,8 +141,8 @@ static const struct bsg_ops bsg_scsi_ops = {

static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)
{
- struct request *rq, *next_rq = NULL;
- struct bio *bio, *bidi_bio = NULL;
+ struct request *rq;
+ struct bio *bio;
struct sg_io_v4 hdr;
int ret;

@@ -164,7 +165,7 @@ static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)

ret = q->bsg_dev.ops->fill_hdr(rq, &hdr, mode);
if (ret)
- goto out;
+ return ret;

rq->timeout = msecs_to_jiffies(hdr.timeout);
if (!rq->timeout)
@@ -174,29 +175,6 @@ static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)
if (rq->timeout < BLK_MIN_SG_TIMEOUT)
rq->timeout = BLK_MIN_SG_TIMEOUT;

- if (hdr.dout_xfer_len && hdr.din_xfer_len) {
- if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
- ret = -EOPNOTSUPP;
- goto out;
- }
-
- pr_warn_once(
- "BIDI support in bsg has been deprecated and might be removed. "
- "Please report your use case to linux-scsi@vger.kernel.org\n");
-
- next_rq = blk_get_request(q, REQ_OP_SCSI_IN, 0);
- if (IS_ERR(next_rq)) {
- ret = PTR_ERR(next_rq);
- goto out;
- }
-
- rq->next_rq = next_rq;
- ret = blk_rq_map_user(q, next_rq, NULL, uptr64(hdr.din_xferp),
- hdr.din_xfer_len, GFP_KERNEL);
- if (ret)
- goto out_free_nextrq;
- }
-
if (hdr.dout_xfer_len) {
ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.dout_xferp),
hdr.dout_xfer_len, GFP_KERNEL);
@@ -206,38 +184,20 @@ static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)
}

if (ret)
- goto out_unmap_nextrq;
+ goto out_free_rq;

bio = rq->bio;
- if (rq->next_rq)
- bidi_bio = rq->next_rq->bio;

blk_execute_rq(q, NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL));
ret = rq->q->bsg_dev.ops->complete_rq(rq, &hdr);
-
- if (rq->next_rq) {
- blk_rq_unmap_user(bidi_bio);
- blk_put_request(rq->next_rq);
- }
-
blk_rq_unmap_user(bio);
+
+out_free_rq:
rq->q->bsg_dev.ops->free_rq(rq);
blk_put_request(rq);
-
- if (copy_to_user(uarg, &hdr, sizeof(hdr)))
+ if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
return -EFAULT;
return ret;
-
-out_unmap_nextrq:
- if (rq->next_rq)
- blk_rq_unmap_user(rq->next_rq->bio);
-out_free_nextrq:
- if (rq->next_rq)
- blk_put_request(rq->next_rq);
-out:
- q->bsg_dev.ops->free_rq(rq);
- blk_put_request(rq);
- return ret;
}

static struct bsg_device *bsg_alloc_device(void)
diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c
index 692b46937e52..60f1a81d2034 100644
--- a/drivers/scsi/scsi_transport_sas.c
+++ b/drivers/scsi/scsi_transport_sas.c
@@ -213,7 +213,6 @@ static int sas_bsg_initialize(struct Scsi_Host *shost, struct sas_rphy *rphy)
to_sas_host_attrs(shost)->q = q;
}

- blk_queue_flag_set(QUEUE_FLAG_BIDI, q);
return 0;
}

diff --git a/include/linux/bsg-lib.h b/include/linux/bsg-lib.h
index b356e0006731..7f14517a559b 100644
--- a/include/linux/bsg-lib.h
+++ b/include/linux/bsg-lib.h
@@ -69,6 +69,10 @@ struct bsg_job {
int result;
unsigned int reply_payload_rcv_len;

+ /* BIDI support */
+ struct request *bidi_rq;
+ struct bio *bidi_bio;
+
void *dd_data; /* Used for driver-specific storage */
};

--
2.20.1