Linux 内核使用register_filesystem添加自定义文件系统deanfs

内核版本：3.0.35

先上码：

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/backing-dev.h>
#include <linux/ramfs.h>
#include <linux/sched.h>
#include <linux/parser.h>
#include <linux/magic.h>
#include <linux/slab.h>
#include <asm/uaccess.h>


static struct dentry *deanfs_mount(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *data)
{
    printk(KERN_INFO"dean: %s =>> %s ==>>%d\n",__FILE__,__FUNCTION__,__LINE__);
    return 0;
}

void kill_dean_super(struct super_block *sb)
{
    printk(KERN_INFO"dean: %s =>> %s ==>>%d\n",__FILE__,__FUNCTION__,__LINE__);
}



static struct file_system_type deanfs_fs_type = {
    .name		= "deanfs",
    .mount		= deanfs_mount,  // mount -t deanfs /mnt /mnt 执行此函数
    .kill_sb	= kill_dean_super,
};

static int __init init_deanfs_fs(void)
{
    printk(KERN_INFO"dean: %s =>> %s ==>>%d\n",__FILE__,__FUNCTION__,__LINE__);
    return register_filesystem(&deanfs_fs_type);
}

static void __exit exit_deanfs_fs(void)
{
    printk(KERN_INFO"dean: %s =>> %s ==>>%d\n",__FILE__,__FUNCTION__,__LINE__);
    unregister_filesystem(&deanfs_fs_type);
}

module_init(init_deanfs_fs)
module_exit(exit_deanfs_fs)

MODULE_LICENSE("GPL");
           

编译，执行：

/tmp # insmod deanfs.ko 

[ 2219.088567] dean: /home/dawu/network/filesystem/deanfs/deanfs.c =>> init_deanfs_fs ==>>39

/tmp # 

/tmp # cat /proc/filesystems 

nodev   sysfs

nodev   rootfs

nodev   bdev

nodev   proc

nodev   tmpfs

nodev   debugfs

nodev   sockfs

nodev   pipefs

nodev   anon_inodefs

nodev   rpc_pipefs

nodev   devpts

        ext3

        ext2

        ext4

        cramfs

        squashfs

nodev   ramfs

        vfat

        msdos

nodev   nfs

        ntfs

nodev   autofs

nodev   fuse

        fuseblk

nodev   fusectl

nodev   mqueue

nodev   oprofilefs

nodev   deanfs          //我们新添加的文件系统

/tmp # 

/tmp # mount -t deanfs /mnt /mnt

[ 2313.598446] dean: /home/dawu/network/filesystem/deanfs/deanfs.c =>> deanfs_mount ==>>20   //这里调用mount回调函数

[ 2313.607580] Unable to handle kernel NULL pointer dereference at virtual address 00000058

[ 2313.615776] pgd = e40ec000

[ 2313.618532] [00000058] *pgd=39ed7831, *pte=00000000, *ppte=00000000

[ 2313.625088] Internal error: Oops: 17 [#2] PREEMPT SMP

[ 2313.630144] Modules linked in: deanfs [last unloaded: deanfs]

[ 2313.635941] CPU: 0    Tainted: G      D      (3.0.35 #3)

[ 2313.641271] PC is at mount_fs+0x30/0xdc

[ 2313.645123] LR is at __schedule+0x2cc/0x79c

[ 2313.649313] pc : [<c0771c94>]    lr : [<c0b22d88>]    psr: 00000013

[ 2313.649318] sp : e9cb9ea0  ip : e9cb9cf8  fp : e9cb9ecc

[ 2313.660809] r10: e9ee17e0  r9 : e9ee1a60  r8 : 00000000

[ 2313.666038] r7 : 00008000  r6 : bf0081c8  r5 : 00000000  r4 : e9fc9a80

[ 2313.672570] r3 : 00000002  r2 : 00000001  r1 : e9ec8be0  r0 : 00000000

[ 2313.679104] Flags: nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user

[ 2313.686245] Control: 10c53c7d  Table: 340ec04a  DAC: 00000015

[ 2313.691996] Process mount (pid: 633, stack limit = 0xe9cb82f0)

[ 2313.697834] Stack: (0xe9cb9ea0 to 0xe9cba000)

[ 2313.702199] 9ea0: 00000000 bf0081c8 bf0081c8 e9fc9a80 bf0081c8 e9ee17e0 00000000 e9ee1a60

[ 2313.710384] 9ec0: e9cb9ef4 e9cb9ed0 c078b52c c0771c70 00000000 bf0081c8 e9ee1a60 00000000

[ 2313.718570] 9ee0: e9ee17e0 00008000 e9cb9f1c e9cb9ef8 c078b9e4 c078b4dc 00000000 00000020

[ 2313.726756] 9f00: 00000000 00008000 00000000 00008000 e9cb9f6c e9cb9f20 c078d2a4 c078b9ac

[ 2313.734940] 9f20: be8e8f88 00001000 e9fc9940 e60c4f70 c07493bc c07492b0 e9cb9f80 be8e8f88

[ 2313.743125] 9f40: 00000000 e9e36000 be8e8f88 00000000 00008000 c0683104 e9cb8000 00000000

[ 2313.751310] 9f60: e9cb9fa4 e9cb9f70 c078d96c c078ce98 00000000 00000000 00000000 e9ee1a60

[ 2313.759494] 9f80: e9ee17e0 00000000 00000000 00000000 be8e8f88 00000015 00000000 e9cb9fa8

[ 2313.767679] 9fa0: c0682ec0 c078d8e4 00000000 00000000 be8e8f88 be8e8f8d be8e8f81 00008000

[ 2313.775864] 9fc0: 00000000 00000000 be8e8f88 00000015 be8e8f8d 00000000 be8e8f81 00000000

[ 2313.784050] 9fe0: 00008000 be8e8b6c 0007e4f8 4028fb64 60000010 be8e8f88 7bfdffff 6ff9fcff

[ 2313.792254] [<c0771c94>] (mount_fs+0x30/0xdc) from [<c078b52c>] (vfs_kern_mount+0x5c/0x9c)

[ 2313.800533] [<c078b52c>] (vfs_kern_mount+0x5c/0x9c) from [<c078b9e4>] (do_kern_mount+0x44/0xe4)

[ 2313.809245] [<c078b9e4>] (do_kern_mount+0x44/0xe4) from [<c078d2a4>] (do_mount+0x418/0x708)

[ 2313.817609] [<c078d2a4>] (do_mount+0x418/0x708) from [<c078d96c>] (sys_mount+0x94/0xd4)

[ 2313.825628] [<c078d96c>] (sys_mount+0x94/0xd4) from [<c0682ec0>] (ret_fast_syscall+0x0/0x30)

[ 2313.834077] Code: e12fff3c e3700a01 e1a05000 8a000011 (e5904058) 

[ 2313.840401] ---[ end trace 6fbf4607db252efa ]---

Segmentation fault

/tmp # 

注：这里出现oops是因为这个只是不完整的文件系统，还差很多东西填充，接下去有空会慢慢完善。