朴泊斋

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http://damocles.blogbus.com/logs/45423624.html

After changing emulator to qemu, I find that the file flush in file system seems not work correctly. The data I wrote to disk lost after rebooting the machine. Finally I find that the dirty bit is not set in file_write because the address space of fs and user env is different. Copy the content of memory will only make the address of current env dirty. But the memory of fs is still clean. Add two lines after memmove in file_write

    for (i = 0; i < n; i += BLKSIZE)
        fsipc_dirty(fd->fd_file.id, offset + i);

To send request to the file system server to mark the page dirty directly.

Another thing to mention is that, it seems that *blk=*blk has no effect for the dirty bit. I Just map the page using syscall to modify its perm. Also please remember in the sys_map_page, you needs to modify the condition of returning invalid parameter. Add PTE_D to the reasonable parameter to perm.