code:iowait - ikarishinjieva/unixV6-code-analyze-chs GitHub Wiki
- 等待 某缓存块的I/O操作完成
- 如有错误，将I/O错误返回给user结构
- 共传入一个参数 bp
- bp : 该缓存块的控制结构struct buf
4978
4979 /* Wait for I/O completion on the buffer; return errors
4980 * to the user.
4981 */
4982 iowait(bp)
4983 struct buf *bp;
4984 {
4985 register struct buf *rbp;
4986
4987 rbp = bp;
4988 spl6();
4989 while ((rbp->b_flags&B_DONE)==0)
- 处理机优先级设为6,防止其他进程对该缓存块进行操作
4990 sleep(rbp, PRIBIO);
4991 spl0();
- 若该缓存块未就绪，则进程睡眠
- 睡眠原因#struct buf
- 进程优先级置为PRIBIO
4992 geterror(rbp);
4993 }
- 检查该缓存块I/O错误
- 如有I/O错误，传递给user
4994 /* ------------------------- */