Can Xv6 guarantee the write syscall is atomic?

It would cause serious problem that a user program try to write the large data to a file by a write system call.

#include "kernel/types.h"#include "kernel/stat.h"#include "user/user.h"#include "kernel/fs.h"#include "kernel/fcntl.h"void main(){    int fd = open("TEST2", O_CREATE | O_RDWR);    char buf[((10-1-1-2) / 2) * BSIZE + 10] = {0};    for (int i = 0; i < ((10-1-1-2) / 2) * BSIZE + 9; i++) {        buf[i] = 'x';    }    printf("%s\n", buf);    write(fd, buf, ((10-1-1-2) / 2) * BSIZE + 10);    exit(0);}

It's fine if nothing happend.

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If a crash happend after the first loop before the second.

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The TEST2 file is existing and it's 3072 bytes.Despite the fact that xv6-book claims that each syscall promises their writes would be atomic, the implementation cannot guarantee that the write syscall is atomic.

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