scsi: storvsc: Fix a bug in copy_from_bounce_buffer()

We may exit this function without properly freeing up the maapings
we may have acquired. Fix the bug.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index cdf048ba4d2d..f8e4dd925a9d 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -754,21 +754,22 @@ static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl,
                         if (bounce_sgl[j].length == PAGE_SIZE) {
                                 /* full..move to next entry */
                                 sg_kunmap_atomic(bounce_addr);
+                                bounce_addr = 0;
                                 j++;
+                        }
 
-                                /* if we need to use another bounce buffer */
-                                if (srclen || i != orig_sgl_count - 1)
-                                        bounce_addr = sg_kmap_atomic(bounce_sgl,j);
+                        /* if we need to use another bounce buffer */
+                        if (srclen && bounce_addr == 0)
+                                bounce_addr = sg_kmap_atomic(bounce_sgl, j);
 
-                        } else if (srclen == 0 && i == orig_sgl_count - 1) {
-                                /* unmap the last bounce that is < PAGE_SIZE */
-                                sg_kunmap_atomic(bounce_addr);
-                        }
                 }
 
                 sg_kunmap_atomic(src_addr - orig_sgl[i].offset);
         }
 
+        if (bounce_addr)
+                sg_kunmap_atomic(bounce_addr);
+
         local_irq_restore(flags);
 
         return total_copied;