f2fs: fix to do sanity check on direct node in truncate_dnode()

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                        "fs/f2fs/node.c",
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{
                    "product": "Linux",
                    "vendor": "Linux",
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                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "fs/f2fs/f2fs.h",
                        "fs/f2fs/file.c",
                        "fs/f2fs/node.c",
                        "include/linux/f2fs_fs.h"
                    ],
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                        {
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