vmsplice: relax alignement requirements for SPLICE_F_GIFT

It seems there is no fundamental reason to limit vmsplice()
SPLICE_F_GIFT to page aligned chunks.

All helpers are prepared to cope with offsets in page.

This limitation makes vmsplice() API very impractical in the zero-copy
land.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: Changli Gao <xiaosuo@gmail.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/splice.c b/fs/splice.c
index 5f883de7ef3ad0bd8dfe9392356725660f9a69b3..5417aa320dc7a540a8acacd9ae2e75f3d39b63ec 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1385,7 +1385,7 @@ 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, int aligned,
+                               struct partial_page *partial, bool aligned,
                                unsigned int pipe_buffers)
 {
        int buffers = 0, error = 0;
@@ -1623,7 +1623,7 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
                return -ENOMEM;
 
        spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
-                                           spd.partial, flags & SPLICE_F_GIFT,
+                                           spd.partial, false,
                                            pipe->buffers);
        if (spd.nr_pages <= 0)
                ret = spd.nr_pages;