splice: switch get_iovec_page_array() to iov_iter

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/splice.c b/fs/splice.c
index 36e9353c19105c7e5e91a752e00b4573b1da1e30..31c52e0269c2cb82d263682f809b3f172c9c4007 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1434,106 +1434,32 @@ static long do_splice(struct file *in, loff_t __user *off_in,
        return -EINVAL;
 }
 
-/*
- * Map an iov into an array of pages and offset/length tupples. With the
- * partial_page structure, we can map several non-contiguous ranges into
- * our ones pages[] map instead of splitting that operation into pieces.
- * Could easily be exported as a generic helper for other users, in which
- * case one would probably want to add a 'max_nr_pages' parameter as well.
- */
-static int get_iovec_page_array(const struct iovec __user *iov,
-                               unsigned int nr_vecs, struct page **pages,
-                               struct partial_page *partial, bool aligned,
+static int get_iovec_page_array(struct iov_iter *from,
+                               struct page **pages,
+                               struct partial_page *partial,
                                unsigned int pipe_buffers)
 {
-       int buffers = 0, error = 0;
-
-       while (nr_vecs) {
-               unsigned long off, npages;
-               struct iovec entry;
-               void __user *base;
-               size_t len;
-               int i;
-
-               error = -EFAULT;
-               if (copy_from_user(&entry, iov, sizeof(entry)))
-                       break;
-
-               base = entry.iov_base;
-               len = entry.iov_len;
-
-               /*
-                * Sanity check this iovec. 0 read succeeds.
-                */
-               error = 0;
-               if (unlikely(!len))
-                       break;
-               error = -EFAULT;
-               if (!access_ok(VERIFY_READ, base, len))
-                       break;
-
-               /*
-                * Get this base offset and number of pages, then map
-                * 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;
-
-               error = get_user_pages_fast((unsigned long)base, npages,
-                                       0, &pages[buffers]);
-
-               if (unlikely(error <= 0))
-                       break;
-
-               /*
-                * Fill this contiguous range into the partial page map.
-                */
-               for (i = 0; i < error; i++) {
-                       const int plen = min_t(size_t, len, PAGE_SIZE - off);
-
-                       partial[buffers].offset = off;
-                       partial[buffers].len = plen;
-
-                       off = 0;
-                       len -= plen;
+       int buffers = 0;
+       while (iov_iter_count(from)) {
+               ssize_t copied;
+               size_t start;
+
+               copied = iov_iter_get_pages(from, pages + buffers, ~0UL,
+                                       pipe_buffers - buffers, &start);
+               if (copied <= 0)
+                       return buffers ? buffers : copied;
+
+               iov_iter_advance(from, copied);
+               while (copied) {
+                       int size = min_t(int, copied, PAGE_SIZE - start);
+                       partial[buffers].offset = start;
+                       partial[buffers].len = size;
+                       copied -= size;
+                       start = 0;
                        buffers++;
                }
-
-               /*
-                * We didn't complete this iov, stop here since it probably
-                * means we have to move some of this into a pipe to
-                * be able to continue.
-                */
-               if (len)
-                       break;
-
-               /*
-                * Don't continue if we mapped fewer pages than we asked for,
-                * or if we mapped the max number of pages that we have
-                * room for.
-                */
-               if (error < npages || buffers == pipe_buffers)
-                       break;
-
-               nr_vecs--;
-               iov++;
        }
-
-       if (buffers)
-               return buffers;
-
-       return error;
+       return buffers;
 }
 
 static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
@@ -1587,10 +1513,13 @@ static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
  * as splice-from-memory, where the regular splice is splice-from-file (or
  * to file). In both cases the output is a pipe, naturally.
  */
-static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
+static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov,
                             unsigned long nr_segs, unsigned int flags)
 {
        struct pipe_inode_info *pipe;
+       struct iovec iovstack[UIO_FASTIOV];
+       struct iovec *iov = iovstack;
+       struct iov_iter from;
        struct page *pages[PIPE_DEF_BUFFERS];
        struct partial_page partial[PIPE_DEF_BUFFERS];
        struct splice_pipe_desc spd = {
@@ -1607,11 +1536,18 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
        if (!pipe)
                return -EBADF;
 
-       if (splice_grow_spd(pipe, &spd))
+       ret = import_iovec(WRITE, uiov, nr_segs,
+                          ARRAY_SIZE(iovstack), &iov, &from);
+       if (ret < 0)
+               return ret;
+
+       if (splice_grow_spd(pipe, &spd)) {
+               kfree(iov);
                return -ENOMEM;
+       }
 
-       spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
-                                           spd.partial, false,
+       spd.nr_pages = get_iovec_page_array(&from, spd.pages,
+                                           spd.partial,
                                            spd.nr_pages_max);
        if (spd.nr_pages <= 0)
                ret = spd.nr_pages;
@@ -1619,6 +1555,7 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
                ret = splice_to_pipe(pipe, &spd);
 
        splice_shrink_spd(&spd);
+       kfree(iov);
        return ret;
 }