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/fs/overlayfs/file.c b/fs/overlayfs/file.c
index e235a63..ab5e928 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -9,6 +9,9 @@
 #include <linux/xattr.h>
 #include <linux/uio.h>
 #include <linux/uaccess.h>
+#include <linux/splice.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
 #include "overlayfs.h"
 
 static char ovl_whatisit(struct inode *inode, struct inode *realinode)
@@ -21,13 +24,16 @@
 		return 'm';
 }
 
+/* No atime modificaton nor notify on underlying */
+#define OVL_OPEN_FLAGS (O_NOATIME | FMODE_NONOTIFY)
+
 static struct file *ovl_open_realfile(const struct file *file,
 				      struct inode *realinode)
 {
 	struct inode *inode = file_inode(file);
 	struct file *realfile;
 	const struct cred *old_cred;
-	int flags = file->f_flags | O_NOATIME | FMODE_NONOTIFY;
+	int flags = file->f_flags | OVL_OPEN_FLAGS;
 
 	old_cred = ovl_override_creds(inode->i_sb);
 	realfile = open_with_fake_path(&file->f_path, flags, realinode,
@@ -48,8 +54,7 @@
 	struct inode *inode = file_inode(file);
 	int err;
 
-	/* No atime modificaton on underlying */
-	flags |= O_NOATIME | FMODE_NONOTIFY;
+	flags |= OVL_OPEN_FLAGS;
 
 	/* If some flag changed that cannot be changed then something's amiss */
 	if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
@@ -102,7 +107,7 @@
 	}
 
 	/* Did the flags change since open? */
-	if (unlikely((file->f_flags ^ real->file->f_flags) & ~O_NOATIME))
+	if (unlikely((file->f_flags ^ real->file->f_flags) & ~OVL_OPEN_FLAGS))
 		return ovl_change_flags(real->file, file->f_flags);
 
 	return 0;
@@ -146,7 +151,7 @@
 	struct inode *inode = file_inode(file);
 	struct fd real;
 	const struct cred *old_cred;
-	ssize_t ret;
+	loff_t ret;
 
 	/*
 	 * The two special cases below do not need to involve real fs,
@@ -291,6 +296,48 @@
 	return ret;
 }
 
+static ssize_t ovl_splice_read(struct file *in, loff_t *ppos,
+			 struct pipe_inode_info *pipe, size_t len,
+			 unsigned int flags)
+{
+	ssize_t ret;
+	struct fd real;
+	const struct cred *old_cred;
+
+	ret = ovl_real_fdget(in, &real);
+	if (ret)
+		return ret;
+
+	old_cred = ovl_override_creds(file_inode(in)->i_sb);
+	ret = generic_file_splice_read(real.file, ppos, pipe, len, flags);
+	revert_creds(old_cred);
+
+	ovl_file_accessed(in);
+	fdput(real);
+	return ret;
+}
+
+static ssize_t
+ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
+			  loff_t *ppos, size_t len, unsigned int flags)
+{
+	struct fd real;
+	const struct cred *old_cred;
+	ssize_t ret;
+
+	ret = ovl_real_fdget(out, &real);
+	if (ret)
+		return ret;
+
+	old_cred = ovl_override_creds(file_inode(out)->i_sb);
+	ret = iter_file_splice_write(pipe, real.file, ppos, len, flags);
+	revert_creds(old_cred);
+
+	ovl_file_accessed(out);
+	fdput(real);
+	return ret;
+}
+
 static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
 	struct fd real;
@@ -647,6 +694,8 @@
 	.fadvise	= ovl_fadvise,
 	.unlocked_ioctl	= ovl_ioctl,
 	.compat_ioctl	= ovl_compat_ioctl,
+	.splice_read    = ovl_splice_read,
+	.splice_write   = ovl_splice_write,
 
 	.copy_file_range	= ovl_copy_file_range,
 	.remap_file_range	= ovl_remap_file_range,