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https://github.com/DragonOS-Community/DragonOS.git
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253 lines
8.6 KiB
C
253 lines
8.6 KiB
C
#include "fat_ent.h"
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#include <driver/disk/ahci/ahci.h>
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#include <common/errno.h>
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#include <mm/slab.h>
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/**
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* @brief 请求分配指定数量的簇
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*
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* @param inode 要分配簇的inode
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* @param clusters 返回的被分配的簇的簇号结构体
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* @param num_clusters 要分配的簇的数量
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* @return int 错误码
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*/
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int fat32_alloc_clusters(struct vfs_index_node_t *inode, uint32_t *clusters, int32_t num_clusters)
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{
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int retval = 0;
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fat32_sb_info_t *fsbi = (fat32_sb_info_t *)inode->sb->private_sb_info;
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struct fat32_inode_info_t *finode = (struct fat32_inode_info_t *)inode->private_inode_info;
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uint64_t sec_per_fat = fsbi->sec_per_FAT;
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// todo: 对alloc的过程加锁
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// 申请1扇区的缓冲区
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uint32_t *buf = (uint32_t *)kmalloc(fsbi->bytes_per_sec, 0);
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int ent_per_sec = (fsbi->bytes_per_sec >> 2);
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int clus_idx = 0;
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for (int i = 0; i < sec_per_fat; ++i)
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{
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if (clus_idx >= num_clusters)
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goto done;
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memset(buf, 0, fsbi->bytes_per_sec);
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ahci_operation.transfer(AHCI_CMD_READ_DMA_EXT, fsbi->FAT1_base_sector + i, 1, (uint64_t)buf, fsbi->ahci_ctrl_num, fsbi->ahci_port_num);
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// 依次检查簇是否空闲
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for (int j = 0; j < ent_per_sec; ++j)
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{
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if (clus_idx >= num_clusters)
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goto done;
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// 找到空闲簇
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if ((buf[j] & 0x0fffffff) == 0)
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{
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clusters[clus_idx] = i * ent_per_sec + j;
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++clus_idx;
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}
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}
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}
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// 空间不足
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retval = -ENOSPC;
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done:;
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kfree(buf);
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if (retval == 0) // 成功
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{
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int cluster, idx;
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if (finode->first_clus == 0)
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{
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// 空文件
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finode->first_clus = clusters[0];
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cluster = finode->first_clus;
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// 写入inode到磁盘
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inode->sb->sb_ops->write_inode(inode);
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idx = 1;
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}
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else
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{
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// todo: 跳转到文件当前的最后一个簇
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idx = 0;
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int tmp_clus = finode->first_clus;
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while (true)
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{
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tmp_clus = fat32_read_FAT_entry(fsbi, cluster);
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if (tmp_clus < 0x0ffffff7)
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cluster = tmp_clus;
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else
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break;
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}
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}
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// 写入fat表
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for (int i = idx; i < num_clusters; ++i)
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{
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fat32_write_FAT_entry(fsbi, cluster, clusters[i]);
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cluster = clusters[i];
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}
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fat32_write_FAT_entry(fsbi, cluster, 0x0ffffff8);
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return 0;
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}
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else // 出现错误
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{
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if (clus_idx < num_clusters)
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fat32_free_clusters(inode, clusters[0]);
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return retval;
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}
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return 0;
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}
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/**
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* @brief 释放从属于inode的,从cluster开始的所有簇
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*
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* @param inode 指定的文件的inode
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* @param cluster 指定簇
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* @return int 错误码
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*/
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int fat32_free_clusters(struct vfs_index_node_t *inode, int32_t cluster)
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{
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// todo: 释放簇
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return 0;
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}
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/**
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* @brief 读取指定簇的FAT表项
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*
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* @param fsbi fat32超级块私有信息结构体
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* @param cluster 指定簇
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* @return uint32_t 下一个簇的簇号
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*/
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uint32_t fat32_read_FAT_entry(fat32_sb_info_t *fsbi, uint32_t cluster)
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{
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// 计算每个扇区内含有的FAT表项数
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// FAT每项4bytes
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uint32_t fat_ent_per_sec = (fsbi->bytes_per_sec >> 2); // 该值应为2的n次幂
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uint32_t buf[256];
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memset(buf, 0, fsbi->bytes_per_sec);
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// 读取一个sector的数据,
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ahci_operation.transfer(AHCI_CMD_READ_DMA_EXT, fsbi->FAT1_base_sector + (cluster / fat_ent_per_sec), 1,
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(uint64_t)&buf, fsbi->ahci_ctrl_num, fsbi->ahci_port_num);
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// 返回下一个fat表项的值(也就是下一个cluster)
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return buf[cluster & (fat_ent_per_sec - 1)] & 0x0fffffff;
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}
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/**
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* @brief 写入指定簇的FAT表项
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*
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* @param fsbi fat32超级块私有信息结构体
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* @param cluster 指定簇
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* @param value 要写入该fat表项的值
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* @return uint32_t errcode
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*/
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uint32_t fat32_write_FAT_entry(fat32_sb_info_t *fsbi, uint32_t cluster, uint32_t value)
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{
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// 计算每个扇区内含有的FAT表项数
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// FAT每项4bytes
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uint32_t fat_ent_per_sec = (fsbi->bytes_per_sec >> 2); // 该值应为2的n次幂
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uint32_t *buf = kmalloc(fsbi->bytes_per_sec, 0);
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memset(buf, 0, fsbi->bytes_per_sec);
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ahci_operation.transfer(AHCI_CMD_READ_DMA_EXT, fsbi->FAT1_base_sector + (cluster / fat_ent_per_sec), 1,
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(uint64_t)buf, fsbi->ahci_ctrl_num, fsbi->ahci_port_num);
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buf[cluster & (fat_ent_per_sec - 1)] = (buf[cluster & (fat_ent_per_sec - 1)] & 0xf0000000) | (value & 0x0fffffff);
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// 向FAT1和FAT2写入数据
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ahci_operation.transfer(AHCI_CMD_WRITE_DMA_EXT, fsbi->FAT1_base_sector + (cluster / fat_ent_per_sec), 1,
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(uint64_t)buf, fsbi->ahci_ctrl_num, fsbi->ahci_port_num);
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ahci_operation.transfer(AHCI_CMD_WRITE_DMA_EXT, fsbi->FAT2_base_sector + (cluster / fat_ent_per_sec), 1,
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(uint64_t)buf, fsbi->ahci_ctrl_num, fsbi->ahci_port_num);
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kfree(buf);
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return 0;
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}
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/**
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* @brief 在父亲inode的目录项簇中,寻找连续num个空的目录项
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*
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* @param parent_inode 父inode
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* @param num 请求的目录项数量
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* @param mode 操作模式
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* @param res_sector 返回信息:缓冲区对应的扇区号
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* @param res_cluster 返回信息:缓冲区对应的簇号
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* @param res_data_buf_base 返回信息:缓冲区的内存基地址(记得要释放缓冲区内存!!!!)
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* @return struct fat32_Directory_t* 符合要求的entry的指针(指向地址高处的空目录项,也就是说,有连续num个≤这个指针的空目录项)
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*/
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struct fat32_Directory_t *fat32_find_empty_dentry(struct vfs_index_node_t *parent_inode, uint32_t num, uint32_t mode, uint32_t *res_sector, uint64_t *res_cluster, uint64_t *res_data_buf_base)
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{
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kdebug("find empty_dentry");
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struct fat32_inode_info_t *finode = (struct fat32_inode_info_t *)parent_inode->private_inode_info;
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fat32_sb_info_t *fsbi = (fat32_sb_info_t *)parent_inode->sb->private_sb_info;
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uint8_t *buf = kmalloc(fsbi->bytes_per_clus, 0);
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memset(buf, 0, fsbi->bytes_per_clus);
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// 计算父目录项的起始簇号
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uint32_t cluster = finode->first_clus;
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struct fat32_Directory_t *tmp_dEntry = NULL;
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// 指向最终的有用的dentry的指针
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struct fat32_Directory_t *result_dEntry = NULL;
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while (true)
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{
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// 计算父目录项的起始LBA扇区号
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uint64_t sector = fsbi->first_data_sector + (cluster - 2) * fsbi->sec_per_clus;
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// 读取父目录项的起始簇数据
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ahci_operation.transfer(AHCI_CMD_READ_DMA_EXT, sector, fsbi->sec_per_clus, (uint64_t)buf, fsbi->ahci_ctrl_num, fsbi->ahci_port_num);
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tmp_dEntry = (struct fat32_Directory_t *)buf;
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// 计数连续的空目录项
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uint32_t count_continuity = 0;
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// 查找连续num个空闲目录项
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for (int i = 0; (i < fsbi->bytes_per_clus) && count_continuity < num; i += 32, ++tmp_dEntry)
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{
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if (!(tmp_dEntry->DIR_Name[0] == 0xe5 || tmp_dEntry->DIR_Name[0] == 0x00))
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{
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count_continuity = 0;
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continue;
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}
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if (count_continuity == 0)
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result_dEntry = tmp_dEntry;
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++count_continuity;
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}
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// 成功查找到符合要求的目录项
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if (count_continuity == num)
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{
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result_dEntry += (num - 1);
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*res_sector = sector;
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*res_data_buf_base = (uint64_t)buf;
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*res_cluster = cluster;
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return result_dEntry;
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}
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// 当前簇没有发现符合条件的空闲目录项,寻找下一个簇
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uint64_t old_cluster = cluster;
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cluster = fat32_read_FAT_entry(fsbi, cluster);
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if (cluster >= 0x0ffffff7) // 寻找完父目录的所有簇,都没有找到符合要求的空目录项
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{
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// 新增一个簇
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if (fat32_alloc_clusters(parent_inode, &cluster, 1) != 0)
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{
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kerror("Cannot allocate a new cluster!");
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while (1)
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pause();
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}
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// 将这个新的簇清空
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sector = fsbi->first_data_sector + (cluster - 2) * fsbi->sec_per_clus;
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void *tmp_buf = kmalloc(fsbi->bytes_per_clus, 0);
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memset(tmp_buf, 0, fsbi->bytes_per_clus);
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ahci_operation.transfer(AHCI_CMD_WRITE_DMA_EXT, sector, fsbi->sec_per_clus, (uint64_t)tmp_buf, fsbi->ahci_ctrl_num, fsbi->ahci_port_num);
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kfree(tmp_buf);
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}
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}
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} |