Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 639d5e7..41b06af 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -422,7 +422,7 @@
 	int err;
 	struct iovec v;
 
-	if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
+	if (iter_is_iovec(i)) {
 		iterate_iovec(i, bytes, v, iov, skip, ({
 			err = fault_in_pages_readable(v.iov_base, v.iov_len);
 			if (unlikely(err))
@@ -570,12 +570,13 @@
 }
 
 static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
-				__wsum *csum, struct iov_iter *i)
+					 struct csum_state *csstate,
+					 struct iov_iter *i)
 {
 	struct pipe_inode_info *pipe = i->pipe;
+	__wsum sum = csstate->csum;
+	size_t off = csstate->off;
 	size_t n, r;
-	size_t off = 0;
-	__wsum sum = *csum;
 	int idx;
 
 	if (!sanity(i))
@@ -596,7 +597,8 @@
 		addr += chunk;
 	}
 	i->count -= bytes;
-	*csum = sum;
+	csstate->csum = sum;
+	csstate->off = off;
 	return bytes;
 }
 
@@ -894,9 +896,12 @@
 		size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
 		kunmap_atomic(kaddr);
 		return wanted;
-	} else if (unlikely(iov_iter_is_discard(i)))
+	} else if (unlikely(iov_iter_is_discard(i))) {
+		if (unlikely(i->count < bytes))
+			bytes = i->count;
+		i->count -= bytes;
 		return bytes;
-	else if (likely(!iov_iter_is_pipe(i)))
+	} else if (likely(!iov_iter_is_pipe(i)))
 		return copy_page_to_iter_iovec(page, offset, bytes, i);
 	else
 		return copy_page_to_iter_pipe(page, offset, bytes, i);
@@ -1484,18 +1489,19 @@
 }
 EXPORT_SYMBOL(csum_and_copy_from_iter_full);
 
-size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump,
+size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
 			     struct iov_iter *i)
 {
+	struct csum_state *csstate = _csstate;
 	const char *from = addr;
-	__wsum *csum = csump;
 	__wsum sum, next;
-	size_t off = 0;
+	size_t off;
 
 	if (unlikely(iov_iter_is_pipe(i)))
-		return csum_and_copy_to_pipe_iter(addr, bytes, csum, i);
+		return csum_and_copy_to_pipe_iter(addr, bytes, _csstate, i);
 
-	sum = *csum;
+	sum = csstate->csum;
+	off = csstate->off;
 	if (unlikely(iov_iter_is_discard(i))) {
 		WARN_ON(1);	/* for now */
 		return 0;
@@ -1524,7 +1530,8 @@
 		off += v.iov_len;
 	})
 	)
-	*csum = sum;
+	csstate->csum = sum;
+	csstate->off = off;
 	return bytes;
 }
 EXPORT_SYMBOL(csum_and_copy_to_iter);