f2fs: support iflag change given the mask

In f2fs_fileattr_set(),

	if (!fa->flags_valid)
		mask &= FS_COMMON_FL;

In this case, we can set supported flags by mask only instead of BUG_ON.

/* Flags shared betwen flags/xflags */
	(FS_SYNC_FL | FS_IMMUTABLE_FL | FS_APPEND_FL | \
	 FS_NODUMP_FL |	FS_NOATIME_FL | FS_DAX_FL | \
	 FS_PROJINHERIT_FL)

Fixes: 9b1bb01c ("f2fs: convert to fileattr")
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -1817,7 +1817,8 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
 	struct f2fs_inode_info *fi = F2FS_I(inode);
 	u32 masked_flags = fi->i_flags & mask;
 
-	f2fs_bug_on(F2FS_I_SB(inode), (iflags & ~mask));
+	/* mask can be shrunk by flags_valid selector */
+	iflags &= mask;
 
 	/* Is it quota file? Do not allow user to mess with it */
 	if (IS_NOQUOTA(inode))