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🆕 fat32_write (存在写入bug）

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This commit is contained in:
fslongjin
2022-04-29 23:57:36 +08:00
parent 3e101d71ff
commit 9db1c3f74e
4 changed files with 251 additions and 43 deletions
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174
kernel/filesystem/fat32/fat32.c
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@ -49,7 +49,7 @@ uint32_t fat32_read_FAT_entry(fat32_sb_info_t *fsbi, uint32_t cluster)
// 计算每个扇区内含有的FAT表项数
// FAT每项4bytes
uint32_t fat_ent_per_sec = (fsbi->bytes_per_sec >> 2); // 该值应为2的n次幂
uint32_t buf[256];
memset(buf, 0, fsbi->bytes_per_sec);
@ -551,7 +551,7 @@ long fat32_close(struct vfs_index_node_t *inode, struct vfs_file_t *file_ptr)
/**
* @brief 从fat32文件系统读取数据
*
*
* @param file_ptr 文件描述符
* @param buf 输出缓冲区
* @param count 要读取的字节数
@ -570,7 +570,7 @@ long fat32_read(struct vfs_file_t *file_ptr, char *buf, uint64_t count, long *po
// kdebug("fsbi->bytes_per_clus=%d", fsbi->bytes_per_clus);
// clus offset in file
uint64_t total_clus_of_file = (*position) / fsbi->bytes_per_clus;
uint64_t clus_offset_in_file = (*position) / fsbi->bytes_per_clus;
// bytes offset in clus
uint64_t bytes_offset = (*position) % fsbi->bytes_per_clus;
@ -578,7 +578,7 @@ long fat32_read(struct vfs_file_t *file_ptr, char *buf, uint64_t count, long *po
return -EFAULT;
// find the actual cluster on disk of the specified position
for (int i = 0; i < total_clus_of_file; ++i)
for (int i = 0; i < clus_offset_in_file; ++i)
cluster = fat32_read_FAT_entry(fsbi, cluster);
// 如果需要读取的数据边界大于文件大小
@ -615,7 +615,7 @@ long fat32_read(struct vfs_file_t *file_ptr, char *buf, uint64_t count, long *po
if (((uint64_t)buf) < USER_MAX_LINEAR_ADDR)
copy_to_user(buf, tmp_buffer + bytes_offset, step_trans_len);
else
memcpy(buf, tmp_buffer, step_trans_len);
memcpy(buf, tmp_buffer + bytes_offset, step_trans_len);
bytes_remain -= step_trans_len;
buf += step_trans_len;
@ -628,14 +628,174 @@ long fat32_read(struct vfs_file_t *file_ptr, char *buf, uint64_t count, long *po
kfree(tmp_buffer);
if(!bytes_remain)
if (!bytes_remain)
retval = count;
return retval;
}
// todo: write
/**
* @brief 在磁盘中寻找一个空闲的簇
*
* @param fsbi fat32超级块信息结构体
* @return uint64_t 空闲簇号（找不到则返回0）
*/
uint64_t fat32_find_available_cluster(fat32_sb_info_t *fsbi)
{
uint64_t sec_per_fat = fsbi->sec_per_FAT;
// 申请1扇区的缓冲区
uint32_t *buf = (uint32_t *)kmalloc(fsbi->bytes_per_sec, 0);
int ent_per_sec = (fsbi->bytes_per_sec >> 2);
for (int i = 0; i < sec_per_fat; ++i)
{
memset(buf, 0, fsbi->bytes_per_sec);
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);
// 依次检查簇是否空闲
for (int j = 0; j < ent_per_sec; ++j)
{
// 找到空闲簇
if ((buf[j] & 0x0fffffff) == 0)
return i * ent_per_sec + j;
}
}
return 0;
}
/**
* @brief 向fat32文件系统写入数据
*
* @param file_ptr 文件描述符
* @param buf 输入写入的字节数
* @param position 文件指针位置
* @return long 执行成功：传输的字节数量 执行失败：错误码（小于0）
*/
long fat32_write(struct vfs_file_t *file_ptr, char *buf, uint64_t count, long *position)
{
struct fat32_inode_info_t *finode = (struct fat32_inode_info_t *)file_ptr->dEntry->dir_inode->private_inode_info;
fat32_sb_info_t *fsbi = (fat32_sb_info_t *)(file_ptr->dEntry->dir_inode->sb->private_sb_info);
// First cluster num of the file
uint64_t cluster = finode->first_clus;
int64_t flags = 0;
kdebug("fsbi->bytes_per_clus=%d", fsbi->bytes_per_clus);
// clus offset in file
uint64_t clus_offset_in_file = (*position) / fsbi->bytes_per_clus;
// bytes offset in clus
uint64_t bytes_offset = (*position) % fsbi->bytes_per_clus;
if (!cluster) // 起始簇号为0，说明是空文件
{
// 找一个可用的簇
cluster = fat32_find_available_cluster(fsbi);
flags = 1;
}
else
{
// 跳转到position所在的簇
for (uint64_t i = 0; i < clus_offset_in_file; ++i)
cluster = fat32_read_FAT_entry(fsbi, cluster);
}
kdebug("hhhhhhhh");
// 没有可用的磁盘空间
if (!cluster)
return -ENOSPC;
if (flags) // 空文件
{
finode->first_clus = cluster;
// 写入目录项
file_ptr->dEntry->dir_inode->sb->sb_ops->write_inode(file_ptr->dEntry->dir_inode);
fat32_write_FAT_entry(fsbi, cluster, 0x0fffffff8); // 写入fat表项
}
uint64_t bytes_remain = count;
uint64_t sector;
int64_t retval = 0;
void *tmp_buffer = kmalloc(fsbi->bytes_per_clus, 0);
kdebug("ggggg");
do
{
memset(tmp_buffer, 0, fsbi->bytes_per_clus);
sector = fsbi->first_data_sector + (cluster - 2) * fsbi->sec_per_clus; // 计算对应的扇区
if (!flags) // 当前簇已分配
{
// 读取一个簇的数据
int errno = ahci_operation.transfer(AHCI_CMD_READ_DMA_EXT, sector, fsbi->sec_per_clus, (uint64_t)tmp_buffer, fsbi->ahci_ctrl_num, fsbi->ahci_port_num);
if (errno != AHCI_SUCCESS)
{
kerror("FAT32 FS(write) read disk error!");
retval = -EIO;
break;
}
}
int64_t step_trans_len = 0; // 当前循环传输的字节数
if (bytes_remain > (fsbi->bytes_per_clus - bytes_offset))
step_trans_len = (fsbi->bytes_per_clus - bytes_offset);
else
step_trans_len = bytes_remain;
if (((uint64_t)buf) < USER_MAX_LINEAR_ADDR)
copy_from_user(tmp_buffer + bytes_offset, buf, step_trans_len);
else
memcpy(tmp_buffer + bytes_offset, buf, step_trans_len);
// 写入数据到对应的簇
int errno = ahci_operation.transfer(AHCI_CMD_WRITE_DMA_EXT, sector, fsbi->sec_per_clus, (uint64_t)tmp_buffer, fsbi->ahci_ctrl_num, fsbi->ahci_port_num);
if (errno != AHCI_SUCCESS)
{
kerror("FAT32 FS(write) read disk error!");
retval = -EIO;
break;
}
bytes_remain -= step_trans_len;
buf += step_trans_len;
bytes_offset -= bytes_offset;
*position += step_trans_len; // 更新文件指针
kdebug("step_trans_len=%d", step_trans_len);
int next_clus = 0;
if (bytes_remain)
next_clus = fat32_read_FAT_entry(fsbi, cluster);
else
break;
if (next_clus >= 0x0ffffff8) // 已经到达了最后一个簇，需要分配新簇
{
next_clus = fat32_find_available_cluster(fsbi);
if (!next_clus) // 没有空闲簇
{
kfree(tmp_buffer);
return -ENOSPC;
}
// 将簇加入到文件末尾
fat32_write_FAT_entry(fsbi, cluster, next_clus);
fat32_write_FAT_entry(fsbi, next_clus, 0x0ffffff8);
cluster = next_clus; // 切换当前簇
flags = 1; // 标记当前簇是新分配的簇
}
} while (bytes_remain);
// 文件大小有增长
if (*position > (file_ptr->dEntry->dir_inode->file_size))
{
file_ptr->dEntry->dir_inode->file_size = *position;
file_ptr->dEntry->dir_inode->sb->sb_ops->write_inode(file_ptr->dEntry->dir_inode);
kdebug("new file size=%ld", *position);
}
kfree(tmp_buffer);
if (!bytes_remain)
retval = count;
kdebug("retval=%lld", retval);
return retval;
}
// todo: lseek
long fat32_lseek(struct vfs_file_t *file_ptr, long offset, long origin)