linux内核读文件出现的错误。。。。。。。。。。。。。。。。。。。__kernel_ipshot_Aug_0x_02_

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linux内核读文件出现的错误。。。。。。。。。。。。。。。。。。。

来源: 互联网发布时间：2016-12-25

本文导语: 代码如下： int read_file(void) { char buf_read[1024]={0}; struct file *fp; mm_segment_t fs; loff_t pos; printk("hello entern"); fp = filp_open("/mnt/btr-test/file2", O_RDWR , 0644); if (IS_ERR(fp)) { p...

代码如下：

int read_file(void)

{

	char buf_read[1024]={0};

    struct file *fp;

    mm_segment_t fs;

    loff_t pos;

    printk("hello entern");

    fp = filp_open("/mnt/btr-test/file2", O_RDWR , 0644);

    if (IS_ERR(fp)) {

        printk("open flie faildn");

        return -1;

    }

	printk("open successn");

    fs = get_fs();

    set_fs(KERNEL_DS);

    pos = 0;

    vfs_read(fp, buf_read, sizeof(buf_read), &pos);

    printk("read: %sn", buf_read);

    filp_close(fp, NULL);

    set_fs(fs);

    return 0;

}

该函数在vfs下层的文件系统中被调用，然后问题是当文件被成功打开后，vfs_read操作时便没响应了，从/var/log/message中看到的信息是：

Aug 24 16:02:53 ipshot kernel: INFO: task btrfsctl:5714 blocked for more than 120 seconds.
Aug 24 16:02:53 ipshot kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Aug 24 16:02:53 ipshot kernel: btrfsctl D ffff88001500daf0 0 5714 3585 0x00000080
Aug 24 16:02:53 ipshot kernel: ffff88001387b328 0000000000000082 ffff88001387b298 0000000000000000
Aug 24 16:02:53 ipshot kernel: 0000000000014c80 ffff88001500d560 ffff88001500daf0 ffff88001387bfd8
Aug 24 16:02:53 ipshot kernel: ffff88001500daf8 0000000000014c80 ffff88001387a010 0000000000014c80
Aug 24 16:02:53 ipshot kernel: Call Trace:
Aug 24 16:02:53 ipshot kernel: [] btrfs_tree_lock+0x111/0x120 [btrfs]
Aug 24 16:02:53 ipshot kernel: [] ? btrfs_wake_function+0x0/0x20 [btrfs]
Aug 24 16:02:53 ipshot kernel: [] btrfs_search_slot+0x836/0x8a0 [btrfs]
Aug 24 16:02:53 ipshot kernel: [] btrfs_lookup_file_extent+0x3d/0x40 [btrfs]
Aug 24 16:02:53 ipshot kernel: [] btrfs_get_extent+0x147/0x9d0 [btrfs]
Aug 24 16:02:53 ipshot kernel: [] ? btrfs_lookup_ordered_extent+0x33/0x1e0 [btrfs]
Aug 24 16:02:53 ipshot kernel: [] __extent_read_full_page+0x190/0x670 [btrfs]
Aug 24 16:02:53 ipshot kernel: [] ? __mem_cgroup_commit_charge+0x5c/0xb0
Aug 24 16:02:53 ipshot kernel: [] ? mem_cgroup_charge_common+0x6d/0x90
Aug 24 16:02:53 ipshot kernel: [] ? btrfs_get_extent+0x0/0x9d0 [btrfs]
Aug 24 16:02:53 ipshot kernel: [] extent_read_full_page+0x2e/0x50 [btrfs]
Aug 24 16:02:53 ipshot kernel: [] btrfs_readpage+0x23/0x30 [btrfs]
Aug 24 16:02:53 ipshot kernel: [] generic_file_aio_read+0x1f1/0x6e0
Aug 24 16:02:53 ipshot kernel: [] do_sync_read+0xda/0x120
Aug 24 16:02:53 ipshot kernel: [] ? release_console_sem+0x1c1/0x200
Aug 24 16:02:53 ipshot kernel: [] ? security_file_permission+0x8b/0x90
Aug 24 16:02:53 ipshot kernel: [] vfs_read+0xc5/0x190

难道说不能在文件系统内部调用上层VFS的接口？

试试用.
fp->f_op->read