1 files changed, 94 insertions, 0 deletions

diff --git a/mm/filemap.h b/mm/filemap.h
new file mode 100644
index 000000000000..13793ba0ce17
--- /dev/null
+++ b/mm/filemap.h
@@ -0,0 +1,94 @@
+/*
+ *      linux/mm/filemap.h
+ *
+ * Copyright (C) 1994-1999  Linus Torvalds
+ */
+
+#ifndef __FILEMAP_H
+#define __FILEMAP_H
+
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/uio.h>
+#include <linux/config.h>
+#include <asm/uaccess.h>
+
+size_t
+__filemap_copy_from_user_iovec(char *vaddr,
+                               const struct iovec *iov,
+                               size_t base,
+                               size_t bytes);
+
+/*
+ * Copy as much as we can into the page and return the number of bytes which
+ * were sucessfully copied.  If a fault is encountered then clear the page
+ * out to (offset+bytes) and return the number of bytes which were copied.
+ */
+static inline size_t
+filemap_copy_from_user(struct page *page, unsigned long offset,
+                        const char __user *buf, unsigned bytes)
+{
+        char *kaddr;
+        int left;
+
+        kaddr = kmap_atomic(page, KM_USER0);
+        left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
+        kunmap_atomic(kaddr, KM_USER0);
+
+        if (left != 0) {
+                /* Do it the slow way */
+                kaddr = kmap(page);
+                left = __copy_from_user(kaddr + offset, buf, bytes);
+                kunmap(page);
+        }
+        return bytes - left;
+}
+
+/*
+ * This has the same sideeffects and return value as filemap_copy_from_user().
+ * The difference is that on a fault we need to memset the remainder of the
+ * page (out to offset+bytes), to emulate filemap_copy_from_user()'s
+ * single-segment behaviour.
+ */
+static inline size_t
+filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
+                        const struct iovec *iov, size_t base, size_t bytes)
+{
+        char *kaddr;
+        size_t copied;
+
+        kaddr = kmap_atomic(page, KM_USER0);
+        copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
+                                                base, bytes);
+        kunmap_atomic(kaddr, KM_USER0);
+        if (copied != bytes) {
+                kaddr = kmap(page);
+                copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
+                                                        base, bytes);
+                kunmap(page);
+        }
+        return copied;
+}
+
+static inline void
+filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
+{
+        const struct iovec *iov = *iovp;
+        size_t base = *basep;
+
+        while (bytes) {
+                int copy = min(bytes, iov->iov_len - base);
+
+                bytes -= copy;
+                base += copy;
+                if (iov->iov_len == base) {
+                        iov++;
+                        base = 0;
+                }
+        }
+        *iovp = iov;
+        *basep = base;
+}
+#endif