1 files changed, 17 insertions, 3 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 800f666c75a9..182ed1f788ff 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1919,6 +1919,7 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
         struct inode *bd_inode = bdev_file_inode(file);
         loff_t size = i_size_read(bd_inode);
         struct blk_plug plug;
+        size_t shorted = 0;
         ssize_t ret;
 
         if (bdev_read_only(I_BDEV(bd_inode)))
@@ -1936,12 +1937,17 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
         if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
                 return -EOPNOTSUPP;
 
-        iov_iter_truncate(from, size - iocb->ki_pos);
+        size -= iocb->ki_pos;
+        if (iov_iter_count(from) > size) {
+                shorted = iov_iter_count(from) - size;
+                iov_iter_truncate(from, size);
+        }
 
         blk_start_plug(&plug);
         ret = __generic_file_write_iter(iocb, from);
         if (ret > 0)
                 ret = generic_write_sync(iocb, ret);
+        iov_iter_reexpand(from, iov_iter_count(from) + shorted);
         blk_finish_plug(&plug);
         return ret;
 }
@@ -1953,13 +1959,21 @@ ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
         struct inode *bd_inode = bdev_file_inode(file);
         loff_t size = i_size_read(bd_inode);
         loff_t pos = iocb->ki_pos;
+        size_t shorted = 0;
+        ssize_t ret;
 
         if (pos >= size)
                 return 0;
 
         size -= pos;
-        iov_iter_truncate(to, size);
-        return generic_file_read_iter(iocb, to);
+        if (iov_iter_count(to) > size) {
+                shorted = iov_iter_count(to) - size;
+                iov_iter_truncate(to, size);
+        }
+
+        ret = generic_file_read_iter(iocb, to);
+        iov_iter_reexpand(to, iov_iter_count(to) + shorted);
+        return ret;
 }
 EXPORT_SYMBOL_GPL(blkdev_read_iter);