Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/splice.c b/fs/splice.c
index b3daa97..9841272 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * "splice": joining two ropes together by interweaving their strands.
  *
@@ -138,7 +139,6 @@
 }
 
 const struct pipe_buf_operations page_cache_pipe_buf_ops = {
-	.can_merge = 0,
 	.confirm = page_cache_pipe_buf_confirm,
 	.release = page_cache_pipe_buf_release,
 	.steal = page_cache_pipe_buf_steal,
@@ -156,7 +156,6 @@
 }
 
 static const struct pipe_buf_operations user_page_pipe_buf_ops = {
-	.can_merge = 0,
 	.confirm = generic_pipe_buf_confirm,
 	.release = page_cache_pipe_buf_release,
 	.steal = user_page_pipe_buf_steal,
@@ -301,7 +300,7 @@
 	struct kiocb kiocb;
 	int idx, ret;
 
-	iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len);
+	iov_iter_pipe(&to, READ, pipe, len);
 	idx = to.idx;
 	init_sync_kiocb(&kiocb, in);
 	kiocb.ki_pos = *ppos;
@@ -326,22 +325,20 @@
 EXPORT_SYMBOL(generic_file_splice_read);
 
 const struct pipe_buf_operations default_pipe_buf_ops = {
-	.can_merge = 0,
 	.confirm = generic_pipe_buf_confirm,
 	.release = generic_pipe_buf_release,
 	.steal = generic_pipe_buf_steal,
 	.get = generic_pipe_buf_get,
 };
 
-static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
-				    struct pipe_buffer *buf)
+int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
+			     struct pipe_buffer *buf)
 {
 	return 1;
 }
 
 /* Pipe buffer operations for a socket and similar. */
 const struct pipe_buf_operations nosteal_pipe_buf_ops = {
-	.can_merge = 0,
 	.confirm = generic_pipe_buf_confirm,
 	.release = generic_pipe_buf_release,
 	.steal = generic_pipe_buf_nosteal,
@@ -357,7 +354,7 @@
 	ssize_t res;
 
 	old_fs = get_fs();
-	set_fs(get_ds());
+	set_fs(KERNEL_DS);
 	/* The cast to a user pointer is valid due to the set_fs() */
 	res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos, 0);
 	set_fs(old_fs);
@@ -386,7 +383,7 @@
 	 */
 	offset = *ppos & ~PAGE_MASK;
 
-	iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len + offset);
+	iov_iter_pipe(&to, READ, pipe, len + offset);
 
 	res = iov_iter_get_pages_alloc(&to, &pages, len + offset, &base);
 	if (res <= 0)
@@ -745,8 +742,7 @@
 			left -= this_len;
 		}
 
-		iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n,
-			      sd.total_len - left);
+		iov_iter_bvec(&from, WRITE, array, n, sd.total_len - left);
 		ret = vfs_iter_write(out, &from, &sd.pos, 0);
 		if (ret <= 0)
 			break;
@@ -946,11 +942,16 @@
 	sd->flags &= ~SPLICE_F_NONBLOCK;
 	more = sd->flags & SPLICE_F_MORE;
 
+	WARN_ON_ONCE(pipe->nrbufs != 0);
+
 	while (len) {
 		size_t read_len;
 		loff_t pos = sd->pos, prev_pos = pos;
 
-		ret = do_splice_to(in, &pos, pipe, len, flags);
+		/* Don't try to read more the pipe has space for. */
+		read_len = min_t(size_t, len,
+				 (pipe->buffers - pipe->nrbufs) << PAGE_SHIFT);
+		ret = do_splice_to(in, &pos, pipe, read_len, flags);
 		if (unlikely(ret <= 0))
 			goto out_release;
 
@@ -1119,6 +1120,9 @@
 		if (ipipe == opipe)
 			return -EINVAL;
 
+		if ((in->f_flags | out->f_flags) & O_NONBLOCK)
+			flags |= SPLICE_F_NONBLOCK;
+
 		return splice_pipe_to_pipe(ipipe, opipe, len, flags);
 	}
 
@@ -1144,6 +1148,9 @@
 		if (unlikely(ret < 0))
 			return ret;
 
+		if (in->f_flags & O_NONBLOCK)
+			flags |= SPLICE_F_NONBLOCK;
+
 		file_start_write(out);
 		ret = do_splice_from(ipipe, out, &offset, len, flags);
 		file_end_write(out);
@@ -1168,6 +1175,9 @@
 			offset = in->f_pos;
 		}
 
+		if (out->f_flags & O_NONBLOCK)
+			flags |= SPLICE_F_NONBLOCK;
+
 		pipe_lock(opipe);
 		ret = wait_for_space(opipe, flags);
 		if (!ret)
@@ -1346,7 +1356,7 @@
 	struct iovec iovstack[UIO_FASTIOV];
 	struct iovec *iov = iovstack;
 	struct iov_iter iter;
-	long error;
+	ssize_t error;
 	struct fd f;
 	int type;
 
@@ -1357,7 +1367,7 @@
 
 	error = import_iovec(type, uiov, nr_segs,
 			     ARRAY_SIZE(iovstack), &iov, &iter);
-	if (!error) {
+	if (error >= 0) {
 		error = do_vmsplice(f.file, &iter, flags);
 		kfree(iov);
 	}
@@ -1372,7 +1382,7 @@
 	struct iovec iovstack[UIO_FASTIOV];
 	struct iovec *iov = iovstack;
 	struct iov_iter iter;
-	long error;
+	ssize_t error;
 	struct fd f;
 	int type;
 
@@ -1383,7 +1393,7 @@
 
 	error = compat_import_iovec(type, iov32, nr_segs,
 			     ARRAY_SIZE(iovstack), &iov, &iter);
-	if (!error) {
+	if (error >= 0) {
 		error = do_vmsplice(f.file, &iter, flags);
 		kfree(iov);
 	}
@@ -1584,7 +1594,11 @@
 			 * Get a reference to this pipe buffer,
 			 * so we can copy the contents over.
 			 */
-			pipe_buf_get(ipipe, ibuf);
+			if (!pipe_buf_get(ipipe, ibuf)) {
+				if (ret == 0)
+					ret = -EFAULT;
+				break;
+			}
 			*obuf = *ibuf;
 
 			/*
@@ -1593,6 +1607,8 @@
 			 */
 			obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
 
+			pipe_buf_mark_unmergeable(obuf);
+
 			obuf->len = len;
 			opipe->nrbufs++;
 			ibuf->offset += obuf->len;
@@ -1656,7 +1672,11 @@
 		 * Get a reference to this pipe buffer,
 		 * so we can copy the contents over.
 		 */
-		pipe_buf_get(ipipe, ibuf);
+		if (!pipe_buf_get(ipipe, ibuf)) {
+			if (ret == 0)
+				ret = -EFAULT;
+			break;
+		}
 
 		obuf = opipe->bufs + nbuf;
 		*obuf = *ibuf;
@@ -1667,6 +1687,8 @@
 		 */
 		obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
 
+		pipe_buf_mark_unmergeable(obuf);
+
 		if (obuf->len > len)
 			obuf->len = len;
 
@@ -1713,6 +1735,9 @@
 	 * copying the data.
 	 */
 	if (ipipe && opipe && ipipe != opipe) {
+		if ((in->f_flags | out->f_flags) & O_NONBLOCK)
+			flags |= SPLICE_F_NONBLOCK;
+
 		/*
 		 * Keep going, unless we encounter an error. The ipipe/opipe
 		 * ordering doesn't really matter.