f_mount();

 1 /*-----------------------------------------------------------------------*/
 2 /* Mount/Unmount a Logical Drive                                         */
 3 /*-----------------------------------------------------------------------*/
 4 //
 5 FRESULT f_mount (
 6     BYTE vol,        /* Logical drive number to be mounted/unmounted */
 7     FATFS *fs        /* Pointer to new file system object (NULL for unmount)*/
 8 )
 9 {
10     FATFS *rfs;  //
11 
12     if (vol >= _VOLUMES)        /* Check if the drive number is valid */
13         return FR_INVALID_DRIVE;
14     rfs = FatFs[vol];              /* Get current fs object */
15 
16     if (rfs) {  //
17 #if _FS_SHARE
18         clear_lock(rfs);
19 #endif
20 #if _FS_REENTRANT                /* Discard sync object of the current volume */
21         if (!ff_del_syncobj(rfs->sobj)) return FR_INT_ERR;
22 #endif
23         rfs->fs_type = 0;        /* Clear old fs object */
24     }
25 
26     if (fs) {
27         fs->fs_type = 0;        /* Clear new fs object */
28 #if _FS_REENTRANT                /* Create sync object for the new volume */
29         if (!ff_cre_syncobj(vol, &fs->sobj)) return FR_INT_ERR;
30 #endif
31     }
32     FatFs[vol] = fs;            /* Register new fs object */
33 
34     return FR_OK;
35 }

 5 FRESULT f_mount (
 6     BYTE vol,        /* Logical drive number to be mounted/unmounted */
 7     FATFS *fs        /* Pointer to new file system object (NULL for unmount)*/
 8 )
 9 {
10     FATFS *rfs;                     //定义一个FATFS类型的指针
14     rfs = FatFs[vol];               /* Get current fs object FatFs[vol]也是一个FATFS类型的指针，可以表示为之前挂载过的文件系统的头地址*/
16     if (rfs) {                      //表示之前有挂载过文件系统
23         rfs->fs_type = 0;           /* Clear old fs object 清除掉旧的文件系统*/
24     }
26     if (fs) {                      //fs指向分配内存的头地址，一般不为0
27         fs->fs_type = 0;           /* Clear new fs object 为什么要执行这条语句？0表示没有挂载，把0赋值过去，为什么呢？*/
31     }
32     FatFs[vol] = fs;               /* Register new fs object 把文件系统的头地址赋值，这就是挂载？？？感觉多此一举的？直接用也行的啊！？*/
34     return FR_OK;
35 }