-/*
- * This is a little more tricky than the file -> pipe splicing. There are
- * basically three cases:
- *
- * - Destination page already exists in the address space and there
- * are users of it. For that case we have no other option that
- * copying the data. Tough luck.
- * - Destination page already exists in the address space, but there
- * are no users of it. Make sure it's uptodate, then drop it. Fall
- * through to last case.
- * - Destination page does not exist, we can add the pipe page to
- * the page cache and avoid the copy.
- *
- * If asked to move pages to the output file (SPLICE_F_MOVE is set in
- * sd->flags), we attempt to migrate pages from the pipe to the output
- * file address space page cache. This is possible if no one else has
- * the pipe page referenced outside of the pipe and page cache. If
- * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
- * a new page in the output file page cache and fill/dirty that.
- */
-int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
- struct splice_desc *sd)
-{
- struct file *file = sd->u.file;
- struct address_space *mapping = file->f_mapping;
- unsigned int offset, this_len;
- struct page *page;
- void *fsdata;
- int ret;
-
- offset = sd->pos & ~PAGE_CACHE_MASK;
-
- this_len = sd->len;
- if (this_len + offset > PAGE_CACHE_SIZE)
- this_len = PAGE_CACHE_SIZE - offset;
-
- ret = pagecache_write_begin(file, mapping, sd->pos, this_len,
- AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
- if (unlikely(ret))
- goto out;
-
- if (buf->page != page) {
- char *src = kmap_atomic(buf->page);
- char *dst = kmap_atomic(page);
-
- memcpy(dst + offset, src + buf->offset, this_len);
- flush_dcache_page(page);
- kunmap_atomic(dst);
- kunmap_atomic(src);
- }
- ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len,
- page, fsdata);
-out:
- return ret;
-}
-EXPORT_SYMBOL(pipe_to_file);
-