2 files changed, 50 insertions, 9 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 37fba001bdcf..527d43e982bb 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1806,6 +1806,22 @@ void end_request(struct request *req, int uptodate)
 }
 EXPORT_SYMBOL(end_request);
 
+static int end_that_request_data(struct request *rq, int error,
+                                 unsigned int nr_bytes, unsigned int bidi_bytes)
+{
+        if (rq->bio) {
+                if (__end_that_request_first(rq, error, nr_bytes))
+                        return 1;
+
+                /* Bidi request must be completed as a whole */
+                if (blk_bidi_rq(rq) &&
+                    __end_that_request_first(rq->next_rq, error, bidi_bytes))
+                        return 1;
+        }
+
+        return 0;
+}
+
 /**
  * blk_end_io - Generic end_io function to complete a request.
  * @rq:           the request being processed
@@ -1832,15 +1848,8 @@ static int blk_end_io(struct request *rq, int error, unsigned int nr_bytes,
         struct request_queue *q = rq->q;
         unsigned long flags = 0UL;
 
-        if (rq->bio) {
-                if (__end_that_request_first(rq, error, nr_bytes))
-                        return 1;
-
-                /* Bidi request must be completed as a whole */
-                if (blk_bidi_rq(rq) &&
-                    __end_that_request_first(rq->next_rq, error, bidi_bytes))
-                        return 1;
-        }
+        if (end_that_request_data(rq, error, nr_bytes, bidi_bytes))
+                return 1;
 
         /* Special feature for tricky drivers */
         if (drv_callback && drv_callback(rq))
@@ -1923,6 +1932,36 @@ int blk_end_bidi_request(struct request *rq, int error, unsigned int nr_bytes,
 EXPORT_SYMBOL_GPL(blk_end_bidi_request);
 
 /**
+ * blk_update_request - Special helper function for request stacking drivers
+ * @rq:           the request being processed
+ * @error:        %0 for success, < %0 for error
+ * @nr_bytes:     number of bytes to complete @rq
+ *
+ * Description:
+ *     Ends I/O on a number of bytes attached to @rq, but doesn't complete
+ *     the request structure even if @rq doesn't have leftover.
+ *     If @rq has leftover, sets it up for the next range of segments.
+ *
+ *     This special helper function is only for request stacking drivers
+ *     (e.g. request-based dm) so that they can handle partial completion.
+ *     Actual device drivers should use blk_end_request instead.
+ */
+void blk_update_request(struct request *rq, int error, unsigned int nr_bytes)
+{
+        if (!end_that_request_data(rq, error, nr_bytes, 0)) {
+                /*
+                 * These members are not updated in end_that_request_data()
+                 * when all bios are completed.
+                 * Update them so that the request stacking driver can find
+                 * how many bytes remain in the request later.
+                 */
+                rq->nr_sectors = rq->hard_nr_sectors = 0;
+                rq->current_nr_sectors = rq->hard_cur_sectors = 0;
+        }
+}
+EXPORT_SYMBOL_GPL(blk_update_request);
+
+/**
  * blk_end_request_callback - Special helper function for tricky drivers
  * @rq:           the request being processed
  * @error:        %0 for success, < %0 for error
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e23b838825bd..e82a84c9f37a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -791,6 +791,8 @@ extern void blk_complete_request(struct request *);
 extern void __blk_complete_request(struct request *);
 extern void blk_abort_request(struct request *);
 extern void blk_abort_queue(struct request_queue *);
+extern void blk_update_request(struct request *rq, int error,
+                               unsigned int nr_bytes);
 
 /*
  * blk_end_request() takes bytes instead of sectors as a complete size.