tmpfs(Temporary File System,临时文件系统)是一种基于内存的文件系统,它将文件存储在内存中,而不是磁盘上,当文件被创建或访问时,它们会暂时存储在内存中,直到被关闭或删除,tmpfs可以提高文件系统的性能,特别是在处理大量小文件时,在Linux系统中,tmpfs通常用于挂载点,以便用户可以将临时文件存储在内存中,而不是磁盘上。
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1、创建一个空的tmpfs挂载点
要使用tmpfs,首先需要创建一个空的挂载点,可以使用mkdir
命令创建一个目录,并使用mount
命令将其挂载到tmpfs。
sudo mkdir /mnt/tmpfs sudo mount -t tmpfs tmpfs /mnt/tmpfs
2、格式化tmpfs文件系统
如果需要对tmpfs进行格式化,可以使用mkfs
命令,要将tmpfs格式化为ext4文件系统,可以使用以下命令:
sudo mkfs.ext4 /dev/sdb1
注意:请根据实际情况替换/dev/sdb1
。
3、将设备挂载到tmpfs
要将设备挂载到tmpfs,可以使用mount
命令,要将U盘挂载到tmpfs,可以使用以下命令:
sudo mount /dev/sdb1 /mnt/tmpfs
注意:请根据实际情况替换/dev/sdb1
和/mnt/tmpfs
。
4、在程序中使用tmpfs
要在程序中使用tmpfs,可以使用fopen
函数打开一个指向内存中的文件。
includeinclude include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include include define TMPFS_NAME "tmpfs" /* Name of the tmpfs device */ static int major_number; /* Device number (set by module_init() function) */ static struct cdev tmpfs_cdev; /* The character device structure */ /* Create a new tmpfs device */ /* and add it to the list of registered devices */ int tmpfs_init(void); /* Unregister the tmpfs device */ int tmpfs_cleanup(void); /* Register the tmpfs device */ static struct file_operations tmpfs_fops = { /* Open, read, write and release functions */ int (*open)(struct inode *inode, struct file *file); int (*release)(struct inode *inode, struct file *file); ssize_t (*read)(struct file *file, char __user *buf, size_t count, loff_t *ppos); ssize_t (*write)(struct file *file, const char __user *buf, size_t count, loff_t *ppos);}; /* Set up the device operations for this class */ struct class *tmpfs_class = NULL; int major_number; int tmpfs_init(void) { int result; char name[32]; result = register_chrdev(0, TMPFS_NAME, &tmpfs_fops); if (result < 0) printk("Failed to register tmpfs device "); else { major_number = result; strcpy(name, TMPFS_NAME); tmpfs_class = class_create(THIS_MODULE, name); } return result; } void tmpfs_cleanup(void) { unregister_chrdev(major_number, TMPFS_NAME); class_destroy(tmpfs_class); } /* The actual open function for the tmpfs device */ int open(struct inode *inode, struct file *file) { char path[256]; sprintf(path, "/%d", getpid()); int res = syscall(__NR_shmat, (void *)getpid(), (void *)path, OBJAT | SHM_RDONLY | SHM_ANON | SHM_CREAT | SHM_PERMS, 0777 & ~IPC_LOCK); if (res == -1) return -1; file->f_mode = 4200755; file->f_pos = 0; file->f_flags = O_RDONLY; return res; } /* The actual read function for the tmpfs device */ ssize_t read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { char path[256]; char *ptr; int res = syscall(__NR_shmat, (void *)getpid(), (void *)path, OBJAT | SHM_RDONLY | SHM_ANON | SHM_CREAT | SHM_PERMS, 0777 & ~IPC_LOCK); if (res == -1) return -1; ptr = mmap((void *)path + offsetof(struct shmid_ds, shm_addr), count, PROT_READ, MAP_SHARED, (unsigned long)file->f_mapping); if (ptr == MAP_FAILED) return -1; memcpy(buf, ptr + *ppos % count, count); *ppos += count; munmap((void *)path + offsetof(struct shmid_ds, shm_addr), count); return count; } /* The actual write function for the tmpfs device */ ssize_t write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { char path[256]; char *ptr; int res = syscall(__NR_shmat, (void *)getpid(), (void *)path, OBJAT | SHM_RDONLY | SHM_ANON | SHM_CREAT | SHM_PERMS, 0777 & ~IPC_LOCK); if (res == -1) return -1; ptr = mmap((void *)path + offsetof(struct shmid_ds, shm_addr), count, PROT_WRITE | PROT_READ, MAP_SHARED, (unsigned long)file->f_mapping); if (ptr == MAP_FAILED) return -1; memcpy((void *)ptr + *ppos % count, buf, count); *ppos += count; munmap((void *)path + offsetof(struct shmid_ds, shm_addr), count); return count
本文名称:Linux中如何使用tmpfs内存文件系统
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