Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 69d65d4..8d2bbcc 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -125,7 +125,7 @@
 	struct super_block *sb = inode->i_sb;
 	int blockmask = sb->s_blocksize - 1;
 
-	if (pos >= i_size_read(inode))
+	if (pos >= ALIGN(i_size_read(inode), sb->s_blocksize))
 		return 0;
 
 	if ((pos | iov_iter_alignment(from)) & blockmask)
@@ -165,6 +165,10 @@
 	ret = generic_write_checks(iocb, from);
 	if (ret <= 0)
 		return ret;
+
+	if (unlikely(IS_IMMUTABLE(inode)))
+		return -EPERM;
+
 	/*
 	 * If we have encountered a bitmap-format file, the size limit
 	 * is smaller than s_maxbytes, which is for extent-mapped files.
@@ -226,8 +230,6 @@
 	if (IS_DAX(inode))
 		return ext4_dax_write_iter(iocb, from);
 #endif
-	if (!o_direct && (iocb->ki_flags & IOCB_NOWAIT))
-		return -EOPNOTSUPP;
 
 	if (!inode_trylock(inode)) {
 		if (iocb->ki_flags & IOCB_NOWAIT)
@@ -264,6 +266,13 @@
 	}
 
 	ret = __generic_file_write_iter(iocb, from);
+	/*
+	 * Unaligned direct AIO must be the only IO in flight. Otherwise
+	 * overlapping aligned IO after unaligned might result in data
+	 * corruption.
+	 */
+	if (ret == -EIOCBQUEUED && unaligned_aio)
+		ext4_unwritten_wait(inode);
 	inode_unlock(inode);
 
 	if (ret > 0)
@@ -360,15 +369,17 @@
 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct inode *inode = file->f_mapping->host;
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct dax_device *dax_dev = sbi->s_daxdev;
 
-	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+	if (unlikely(ext4_forced_shutdown(sbi)))
 		return -EIO;
 
 	/*
-	 * We don't support synchronous mappings for non-DAX files. At least
-	 * until someone comes with a sensible use case.
+	 * We don't support synchronous mappings for non-DAX files and
+	 * for DAX files if underneath dax_device is not synchronous.
 	 */
-	if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC))
+	if (!daxdev_mapping_supported(vma, dax_dev))
 		return -EOPNOTSUPP;
 
 	file_accessed(file);
@@ -444,6 +455,10 @@
 	if (ret)
 		return ret;
 
+	ret = fsverity_file_open(inode, filp);
+	if (ret)
+		return ret;
+
 	/*
 	 * Set up the jbd2_inode if we are opening the inode for
 	 * writing and the journal is present