mm: buffered write iterator
Add an iterator data structure to operate over an iovec. Add usercopy
operators needed by generic_file_buffered_write, and convert that function
over.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 500ffc0..86ce27c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -401,6 +401,39 @@
struct address_space;
struct writeback_control;
+struct iov_iter {
+ const struct iovec *iov;
+ unsigned long nr_segs;
+ size_t iov_offset;
+ size_t count;
+};
+
+size_t iov_iter_copy_from_user_atomic(struct page *page,
+ struct iov_iter *i, unsigned long offset, size_t bytes);
+size_t iov_iter_copy_from_user(struct page *page,
+ struct iov_iter *i, unsigned long offset, size_t bytes);
+void iov_iter_advance(struct iov_iter *i, size_t bytes);
+int iov_iter_fault_in_readable(struct iov_iter *i);
+size_t iov_iter_single_seg_count(struct iov_iter *i);
+
+static inline void iov_iter_init(struct iov_iter *i,
+ const struct iovec *iov, unsigned long nr_segs,
+ size_t count, size_t written)
+{
+ i->iov = iov;
+ i->nr_segs = nr_segs;
+ i->iov_offset = 0;
+ i->count = count + written;
+
+ iov_iter_advance(i, written);
+}
+
+static inline size_t iov_iter_count(struct iov_iter *i)
+{
+ return i->count;
+}
+
+
struct address_space_operations {
int (*writepage)(struct page *page, struct writeback_control *wbc);
int (*readpage)(struct file *, struct page *);
