FADVISE_KEEP_SIZE_BIT  654 fs/f2fs/f2fs.h #define file_keep_isize(inode)	is_file(inode, FADVISE_KEEP_SIZE_BIT)
FADVISE_KEEP_SIZE_BIT  655 fs/f2fs/f2fs.h #define file_set_keep_isize(inode) set_file(inode, FADVISE_KEEP_SIZE_BIT)