1 files changed, 25 insertions, 3 deletions

diff --git a/fs/splice.c b/fs/splice.c
index d4664a297bab..b150493b6fc3 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -141,7 +141,10 @@ static struct pipe_buf_operations page_cache_pipe_buf_ops = {
 static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
                                     struct pipe_buffer *buf)
 {
-        return 1;
+        if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
+                return 1;
+
+        return 0;
 }
 
 static struct pipe_buf_operations user_page_pipe_buf_ops = {
@@ -186,6 +189,9 @@ static ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
                         buf->offset = spd->partial[page_nr].offset;
                         buf->len = spd->partial[page_nr].len;
                         buf->ops = spd->ops;
+                        if (spd->flags & SPLICE_F_GIFT)
+                                buf->flags |= PIPE_BUF_FLAG_GIFT;
+
                         pipe->nrbufs++;
                         page_nr++;
                         ret += buf->len;
@@ -1073,7 +1079,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
  */
 static int get_iovec_page_array(const struct iovec __user *iov,
                                 unsigned int nr_vecs, struct page **pages,
-                                struct partial_page *partial)
+                                struct partial_page *partial, int aligned)
 {
         int buffers = 0, error = 0;
 
@@ -1113,6 +1119,15 @@ static int get_iovec_page_array(const struct iovec __user *iov,
                  * in the user pages.
                  */
                 off = (unsigned long) base & ~PAGE_MASK;
+
+                /*
+                 * If asked for alignment, the offset must be zero and the
+                 * length a multiple of the PAGE_SIZE.
+                 */
+                error = -EINVAL;
+                if (aligned && (off || len & ~PAGE_MASK))
+                        break;
+
                 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
                 if (npages > PIPE_BUFFERS - buffers)
                         npages = PIPE_BUFFERS - buffers;
@@ -1206,7 +1221,8 @@ static long do_vmsplice(struct file *file, const struct iovec __user *iov,
         else if (unlikely(!nr_segs))
                 return 0;
 
-        spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial);
+        spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
+                                            flags & SPLICE_F_GIFT);
         if (spd.nr_pages <= 0)
                 return spd.nr_pages;
 
@@ -1314,6 +1330,12 @@ static int link_pipe(struct pipe_inode_info *ipipe,
                                 obuf = opipe->bufs + nbuf;
                                 *obuf = *ibuf;
 
+                                /*
+                                 * Don't inherit the gift flag, we need to
+                                 * prevent multiple steals of this page.
+                                 */
+                                obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
+
                                 if (obuf->len > len)
                                         obuf->len = len;