add offset to iov_iteriov

2 files changed, 21 insertions, 29 deletions

diff --git a/fs/iov-iter.c b/fs/iov-iter.c
index 6cecab49b7ca..edc5d1ce535f 100644
--- a/fs/iov-iter.c
+++ b/fs/iov-iter.c
@@ -180,35 +180,25 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes)
 {
 	BUG_ON(i->count < bytes);
 
-	if (likely(i->nr_segs == 1)) {
-		i->iov_offset += bytes;
-		i->count -= bytes;
-	} else {
-		const struct iovec *iov = i->iov;
-		size_t base = i->iov_offset;
-		unsigned long nr_segs = i->nr_segs;
-
-		/*
-		 * The !iov->iov_len check ensures we skip over unlikely
-		 * zero-length segments (without overruning the iovec).
-		 */
-		while (bytes || unlikely(i->count && !iov->iov_len)) {
-			int copy;
-
-			copy = min(bytes, iov->iov_len - base);
-			BUG_ON(!i->count || i->count < copy);
-			i->count -= copy;
-			bytes -= copy;
-			base += copy;
-			if (iov->iov_len == base) {
-				iov++;
-				nr_segs--;
-				base = 0;
-			}
+	i->count -= bytes;
+	i->offset += bytes;
+
+	while (bytes) {
+		size_t len;
+
+		BUG_ON(!i->nr_segs);
+
+		len = i->iov->iov_len - i->iov_offset;
+
+		if (bytes < len) {
+			i->iov_offset += bytes;
+			bytes = 0;
+		} else {
+			bytes -= len;
+			i->iov++;
+			i->nr_segs--;
+			i->iov_offset = 0;
 		}
-		i->iov = iov;
-		i->iov_offset = base;
-		i->nr_segs = nr_segs;
 	}
 }
 EXPORT_SYMBOL(iov_iter_advance);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e5ea8b38da14..3fc25679467e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -293,6 +293,7 @@ struct iov_iter {
 	unsigned long nr_segs;
 	size_t iov_offset;
 	size_t count;
+	loff_t offset;
 };
 
 size_t __iov_iter_copy_to_user_atomic(struct page *page,
@@ -311,12 +312,13 @@ size_t iov_iter_single_seg_count(const 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 count, loff_t offset)
 {
 	i->iov = iov;
 	i->nr_segs = nr_segs;
 	i->iov_offset = 0;
 	i->count = count;
+	i->offset = offset;
 }
 
 static inline size_t iov_iter_count(struct iov_iter *i)