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Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r--drivers/scsi/scsi_lib.c39
1 files changed, 34 insertions, 5 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 4e42acbb3f32..88cac92fc153 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -978,6 +978,14 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
scsi_io_completion_action(cmd, result);
}
+static inline bool scsi_cmd_needs_dma_drain(struct scsi_device *sdev,
+ struct request *rq)
+{
+ return sdev->dma_drain_len && blk_rq_is_passthrough(rq) &&
+ !op_is_write(req_op(rq)) &&
+ sdev->host->hostt->dma_need_drain(rq);
+}
+
/*
* Function: scsi_init_io()
*
@@ -991,26 +999,47 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
*/
blk_status_t scsi_init_io(struct scsi_cmnd *cmd)
{
+ struct scsi_device *sdev = cmd->device;
struct request *rq = cmd->request;
+ unsigned short nr_segs = blk_rq_nr_phys_segments(rq);
+ struct scatterlist *last_sg = NULL;
blk_status_t ret;
+ bool need_drain = scsi_cmd_needs_dma_drain(sdev, rq);
int count;
- if (WARN_ON_ONCE(!blk_rq_nr_phys_segments(rq)))
+ if (WARN_ON_ONCE(!nr_segs))
return BLK_STS_IOERR;
/*
+ * Make sure there is space for the drain. The driver must adjust
+ * max_hw_segments to be prepared for this.
+ */
+ if (need_drain)
+ nr_segs++;
+
+ /*
* If sg table allocation fails, requeue request later.
*/
- if (unlikely(sg_alloc_table_chained(&cmd->sdb.table,
- blk_rq_nr_phys_segments(rq), cmd->sdb.table.sgl,
- SCSI_INLINE_SG_CNT)))
+ if (unlikely(sg_alloc_table_chained(&cmd->sdb.table, nr_segs,
+ cmd->sdb.table.sgl, SCSI_INLINE_SG_CNT)))
return BLK_STS_RESOURCE;
/*
* Next, walk the list, and fill in the addresses and sizes of
* each segment.
*/
- count = blk_rq_map_sg(rq->q, rq, cmd->sdb.table.sgl);
+ count = __blk_rq_map_sg(rq->q, rq, cmd->sdb.table.sgl, &last_sg);
+
+ if (need_drain) {
+ sg_unmark_end(last_sg);
+ last_sg = sg_next(last_sg);
+ sg_set_buf(last_sg, sdev->dma_drain_buf, sdev->dma_drain_len);
+ sg_mark_end(last_sg);
+
+ rq->extra_len += sdev->dma_drain_len;
+ count++;
+ }
+
BUG_ON(count > cmd->sdb.table.nents);
cmd->sdb.table.nents = count;
cmd->sdb.length = blk_rq_payload_bytes(rq);