《ORANGE’S：一个操作系统的实现》读书笔记（三十五）内存管理（三）文章代码

#include "type.h" #include "config.h" #include "const.h" #include "protect.h" #include "console.h" #include "tty.h" #include "proc.h" #include "proto.h" #include "string.h" #include "fs.h" #include "hd.h" #include "global.h" PRIVATE void init_fs(); PRIVATE void mkfs(); PRIVATE void read_super_block(int dev); PRIVATE int fs_fork(); PRIVATE int fs_exit(); /** * <Ring 1> The main loop of TASK FS. */ PUBLIC void task_fs() { printl("Task FS begins.\n"); init_fs(); while (1) { send_recv(RECEIVE, ANY, &fs_msg); int src = fs_msg.source; pcaller = &proc_table[src]; switch (fs_msg.type) { case OPEN: fs_msg.FD = do_open(); break; case CLOSE: fs_msg.RETVAL = do_close(); break; case READ: case WRITE: fs_msg.CNT = do_rdwt(); break; case UNLINK: fs_msg.RETVAL = do_unlink(); break; case RESUME_PROC: src = fs_msg.PROC_NR; break; case FORK: fs_msg.RETVAL = fs_fork(); break; case EXIT: fs_msg.RETVAL = fs_exit(); break; case STAT: fs_msg.RETVAL = do_stat(); break; default: dump_msg("FS::unknown message:", &fs_msg); assert(0); break; } /* reply */ if (fs_msg.type != SUSPEND_PROC) { fs_msg.type = SYSCALL_RET; send_recv(SEND, src, &fs_msg); } } } /** * <Ring 1> Do some preparation. */ PRIVATE void init_fs() { int i; /* f_desc_table[] */ for (i = 0; i < NR_FILE_DESC; i++) { memset(&f_desc_table[i], 0, sizeof(struct file_desc)); } /* inode_table[] */ for (i = 0; i < NR_INODE; i++) { memset(&inode_table[i], 0, sizeof(struct inode)); } /* super_block[] */ struct super_block * sb = super_block; for (; sb < &super_block[NR_SUPER_BLOCK]; sb++) { sb->sb_dev = NO_DEV; } /* open the device: hard disk */ MESSAGE driver_msg; driver_msg.type = DEV_OPEN; driver_msg.DEVICE = MINOR(ROOT_DEV); assert(dd_map[MAJOR(ROOT_DEV)].driver_nr != INVALID_DRIVER); send_recv(BOTH, dd_map[MAJOR(ROOT_DEV)].driver_nr, &driver_msg); /* make FS */ mkfs(); /* load super block of ROOT */ read_super_block(ROOT_DEV); sb = get_super_block(ROOT_DEV); assert(sb->magic == MAGIC_V1); root_inode = get_inode(ROOT_DEV, ROOT_INODE); } /** * <Ring 1> Make a available Orange'S FS in the disk. it will * - Write a super block to sector 1. * - Create three special files: dev_tty0, dev_tty1, dev_tty2 * - Create a file cmd.tar * - Create the inode map * - Create the sector map * - Create the inodes of the files * - Create '/' the root directory */ PRIVATE void mkfs() { MESSAGE driver_msg; int i, j; int bits_per_sect = SECTOR_SIZE * 8; /* 8 bits per byte */ /* get the geometry of ROOTDEV */ struct part_info geo; driver_msg.type = DEV_IOCTL; driver_msg.DEVICE = MINOR(ROOT_DEV); driver_msg.REQUEST = DIOCTL_GET_GEO; driver_msg.BUF = &geo; driver_msg.PROC_NR = TASK_FS; assert(dd_map[MAJOR(ROOT_DEV)].driver_nr != INVALID_DRIVER); send_recv(BOTH, dd_map[MAJOR(ROOT_DEV)].driver_nr, &driver_msg); printl("dev size: 0x%x sectors\n", geo.size); /* super block */ struct super_block sb; sb.magic = MAGIC_V1; sb.nr_inodes = bits_per_sect; sb.nr_inode_sects = sb.nr_inodes * INODE_SIZE / SECTOR_SIZE; sb.nr_sects = geo.size; /* partition size in sector */ sb.nr_imap_sects = 1; sb.nr_smap_sects = sb.nr_sects / bits_per_sect + 1; sb.n_1st_sect = 1 + 1 + /* boot sector & super block */ sb.nr_imap_sects + sb.nr_smap_sects + sb.nr_inode_sects; sb.root_inode = ROOT_INODE; sb.inode_size = INODE_SIZE; struct inode x; sb.inode_isize_off = (int)&x.i_size - (int)&x; sb.inode_start_off = (int)&x.i_start_sect - (int)&x; sb.dir_ent_size = DIR_ENTRY_SIZE; struct dir_entry de; sb.dir_ent_inode_off = (int)&de.inode_nr - (int)&de; sb.dir_ent_fname_off = (int)&de.name - (int)&de; memset(fsbuf, 0x90, SECTOR_SIZE); memcpy(fsbuf, &sb, SUPER_BLOCK_SIZE); /* write the super block */ WR_SECT(ROOT_DEV, 1); printl("devbase:0x%x00, sb:0x%x00, imap:0x%x00, smap:0x%x00\n", geo.base * 2, (geo.base + 1) * 2, (geo.base + 1 + 1) * 2, (geo.base + 1 + 1 + sb.nr_imap_sects) * 2); printl(" inodes:0x%x00, 1st_sector:0x%x00\n", (geo.base + 1 + 1 + sb.nr_imap_sects + sb.nr_smap_sects) * 2, (geo.base + sb.n_1st_sect) * 2); /* inode map */ memset(fsbuf, 0, SECTOR_SIZE); for (i = 0; i < (NR_CONSOLES + 3); i++) { fsbuf[0] |= 1 << i; } assert(fsbuf[0] == 0x3F); /* 0011 1111 : * || |||| * || |||`--- bit 0 : reserved * || ||`---- bit 1 : the first inode, * || || which indicates `/' * || |`----- bit 2 : /dev_tty0 * || `------ bit 3 : /dev_tty1 * |`-------- bit 4 : /dev_tty2 * `--------- bit 5 : /cmd.tar */ WR_SECT(ROOT_DEV, 2); /* sector map */ memset(fsbuf, 0, SECTOR_SIZE); int nr_sects = NR_DEFAULT_FILE_SECTS + 1; /* ~~~~~~~~~~~~~~~~~~~|~ | * | `--- bit 0 is reserved * `-------- for `/' */ for (i = 0; i < nr_sects / 8; i++) { fsbuf[i] = 0xFF; } for (j = 0; j < nr_sects % 8; j++) { fsbuf[i] |= (1 << j); } WR_SECT(ROOT_DEV, 2 + sb.nr_imap_sects); /* zeromemory the rest sector-map */ memset(fsbuf, 0, SECTOR_SIZE); for (i = 1; i < sb.nr_smap_sects; i++) { WR_SECT(ROOT_DEV, 2 + sb.nr_imap_sects + i); } /* cmd.tar */ int bit_offset = INSTALL_START_SECT - sb.n_1st_sect + 1; /* sect M <-> bit (M - sb.n_1st_sect + 1) */ int bit_off_in_sect = bit_offset % (SECTOR_SIZE * 8); int bit_left = INSTALL_NR_SECTS; int cur_sect = bit_offset / (SECTOR_SIZE * 8); RD_SECT(ROOT_DEV, 2 + sb.nr_imap_sects + cur_sect); while (bit_left) { int byte_off = bit_off_in_sect / 8; /* this line is ineffecient in a loop, but I don't care */ fsbuf[byte_off] |= 1 << (bit_off_in_sect % 8); bit_left--; bit_off_in_sect++; if (bit_off_in_sect == (SECTOR_SIZE * 8)) { WR_SECT(ROOT_DEV, 2 + sb.nr_imap_sects + cur_sect); cur_sect++; RD_SECT(ROOT_DEV, 2 + sb.nr_imap_sects + cur_sect); bit_off_in_sect = 0; } } WR_SECT(ROOT_DEV, 2 + sb.nr_imap_sects + cur_sect); /* inodes */ /* inode of '/' */ memset(fsbuf, 0, SECTOR_SIZE); struct inode * pi = (struct inode*)fsbuf; pi->i_mode = I_DIRECTORY; pi->i_size = DIR_ENTRY_SIZE * 5; /* 5 files: * '.' * 'dev_tty0', 'dev_tty1', 'dev_tty2', * 'cmd.tar' */ pi->i_start_sect = sb.n_1st_sect; pi->i_nr_sects = NR_DEFAULT_FILE_SECTS; /* inod