docker容器中的blktrace输出错误

我的docker容器的基本形象是Ubuntu的，我运行它的完整权限选项，这意味着在运行命令我使用这些开关：

--cap-add=SYS_ADMIN --security-opt apparmor:unconfined

我想用下面的命令使用blktrce：

 sudo blktrace -d / -a issue -o - | blkparse -f "%p %T.%9t %D %S ^C %d\n" -i - >stream.out

但是，第一次使用这个命令时，我得到这个错误：

 Debugfs is not mounted at /sys/kernel/debug

我search，发现这个解决scheme ，导致使用这个命令：

 mount -t debugfs none /sys/kernel/debug

之后，当我再次使用blktrace命令，我得到这个错误：

 BLKTRACESETUP(2) / failed: 25/Inappropriate ioctl for device Thread 1 failed open /sys/kernel/debug/block/(null)/trace1: 2/No such file or directory Thread 0 failed open /sys/kernel/debug/block/(null)/trace0: 2/No such file or directory Thread 2 failed open /sys/kernel/debug/block/(null)/trace2: 2/No such file or directory Thread 4 failed open /sys/kernel/debug/block/(null)/trace4: 2/No such file or directory Thread 3 failed open /sys/kernel/debug/block/(null)/trace3: 2/No such file or directory Thread 5 failed open /sys/kernel/debug/block/(null)/trace5: 2/No such file or directory Thread 7 failed open /sys/kernel/debug/block/(null)/trace7: 2/No such file or directory Thread 8 failed open /sys/kernel/debug/block/(null)/trace8: 2/No such file or directory Thread 6 failed open /sys/kernel/debug/block/(null)/trace6: 2/No such file or directory Thread 12 failed open /sys/kernel/debug/block/(null)/trace12: 2/No such file or directory Thread 10 failed open /sys/kernel/debug/block/(null)/trace10: 2/No such file or directory Thread 13 failed open /sys/kernel/debug/block/(null)/trace13: 2/No such file or directory Thread 15 failed open /sys/kernel/debug/block/(null)/trace15: 2/No such file or directory Thread 14 failed open /sys/kernel/debug/block/(null)/trace14: 2/No such file or directory Thread 17 failed open /sys/kernel/debug/block/(null)/trace17: 2/No such file or directory Thread 16 failed open /sys/kernel/debug/block/(null)/trace16: 2/No such file or directory Thread 18 failed open /sys/kernel/debug/block/(null)/trace18: 2/No such file or directory Thread 11 failed open /sys/kernel/debug/block/(null)/trace11: 2/No such file or directory Thread 19 failed open /sys/kernel/debug/block/(null)/trace19: 2/No such file or directory Thread 20 failed open /sys/kernel/debug/block/(null)/trace20: 2/No such file or directory Thread 9 failed open /sys/kernel/debug/block/(null)/trace9: 2/No such file or directory Thread 21 failed open /sys/kernel/debug/block/(null)/trace21: 2/No such file or directory Thread 22 failed open /sys/kernel/debug/block/(null)/trace22: 2/No such file or directory Thread 23 failed open /sys/kernel/debug/block/(null)/trace23: 2/No such file or directory FAILED to start thread on CPU 0: 1/Operation not permitted FAILED to start thread on CPU 1: 1/Operation not permitted FAILED to start thread on CPU 2: 1/Operation not permitted FAILED to start thread on CPU 3: 1/Operation not permitted FAILED to start thread on CPU 4: 1/Operation not permitted FAILED to start thread on CPU 5: 1/Operation not permitted FAILED to start thread on CPU 6: 1/Operation not permitted FAILED to start thread on CPU 7: 1/Operation not permitted FAILED to start thread on CPU 8: 1/Operation not permitted FAILED to start thread on CPU 9: 1/Operation not permitted FAILED to start thread on CPU 10: 1/Operation not permitted FAILED to start thread on CPU 11: 1/Operation not permitted FAILED to start thread on CPU 12: 1/Operation not permitted FAILED to start thread on CPU 13: 1/Operation not permitted FAILED to start thread on CPU 14: 1/Operation not permitted FAILED to start thread on CPU 15: 1/Operation not permitted FAILED to start thread on CPU 16: 1/Operation not permitted FAILED to start thread on CPU 17: 1/Operation not permitted FAILED to start thread on CPU 18: 1/Operation not permitted FAILED to start thread on CPU 19: 1/Operation not permitted FAILED to start thread on CPU 20: 1/Operation not permitted FAILED to start thread on CPU 21: 1/Operation not permitted FAILED to start thread on CPU 22: 1/Operation not permitted FAILED to start thread on CPU 23: 1/Operation not permitted

我怎么解决这个问题？

UPDATE1：

在/sys/kernel/debug/block/有sda文件夹，并在这个文件夹中有这些文件：

 trace0 trace1 trace2 etc.

UPDATE2：

@abligh谢谢你的回答，但没有帮助。关于ioctl的strace输出是：

 ioctl(3, BLKTRACESETUP, {act_mask=64, buf_size=524288, buf_nr=4, start_lba=0, end_lba=0, pid=0}, 0x7ffe8a4ceac0) = -1 ENOTTY (Inappropriate ioctl for device) write(2, "BLKTRACESETUP(2) / failed: 25/Inappropriate ioctl for device\n", 61) = 61 ioctl(3, BLKTRACESTOP, 0x7f6fd19789d0) = -1 ENOTTY (Inappropriate ioctl for device) ioctl(3, BLKTRACESTOP, 0x7ffe8a4ce540) = -1 ENOTTY (Inappropriate ioctl for device) ioctl(3, BLKTRACESTOP, 0x7f6fd19789e0) = -1 ENOTTY (Inappropriate ioctl for device)` ioctl(3, BLKTRACETEARDOWN, 0x7f6fd19789e0) = -1 ENOTTY (Inappropriate ioctl for device)

回答你为什么在容器中运行blktrace问题，我会说我使用容器作为集群，所以我需要每个节点的跟踪。

我没有足够的信息来debugging，但是你要求发布一个答案。

问题的根源似乎在这里：

 BLKTRACESETUP(2) / failed: 25/Inappropriate ioctl for device

这表示ioctl调用设置块跟踪失败。它在容器内部是失败的，但根据容器外部的评论作品。这将表明问题出在容器设置上，或者是内核中的一个限制，使得ioctl根本无法在容器中使用。

inappropriate ioctl for device错误是errno 25，即ENOTTY 。我不能立即看到什么将返回，除非找不到设备节点（因为你已经certificate了它的工作原理，它在块容器跟踪代码编译的容器之外）。我不记得这是否在一个模块，但它是值得首先尝试在容器外部的块跟踪（然后检查它在容器内），只是为了检查这不是一个模块加载问题。

debugging这个的第一步就是使用strace工具（如上面所build议的），这样你就可以确切地知道哪个系统调用正在使用什么参数。 EG运行：

 sudo strace -f -s2048 -o/tmp/trace blktrace -d / -a issue -o - | blkparse -f "%p %T.%9t %D %S ^C %d\n" -i - >stream.out

然后看看/tmp/trace 。 strace将列出所有系统调用。看看你能否确定哪个ioctl失败。

其次，我会确保你试图跟踪的块设备实际上出现在/proc/和/sys/的正确位置。这里发生了一些错误：

 Thread 0 failed open /sys/kernel/debug/block/(null)/trace0: 2/No such file or directory

注意debugging行中的(null) ，显然不应该存在 – 应该是块设备的名称。这可能是失败的ioctl的后果，或者可能表示/sys/层次结构中的问题。

BLKTRACESETUP在这里的内核中处理。这最终在这里调用doblktracesetup 。我不能立即看到任何理由，为什么这不会从一个适当的权限的容器，这使我怀疑你的/sys层次结构可能没有设置正确的工作。但strace的输出将会有所帮助。

另外，不可避免的评论：你为什么在一个容器中做这个？为什么不在容器外运行？

编辑：看起来这可能是一个内核的东西。见https://github.com/scaleway/kernel-tools/issues/107 – 这表明你（a）需要首先修改特定的模块，（b）可能需要一个特定的内核。