biotop compilation error on 4.9-rc3

[goldshtn]

This is from Ubuntu 16.04 with Linux 4.9-rc3:

/usr/share/bcc/tools# ./biotop
In file included from /virtual/main.c:3:
In file included from include/linux/blkdev.h:9:
In file included from include/linux/genhd.h:64:
In file included from include/linux/device.h:24:
In file included from include/linux/pinctrl/devinfo.h:21:
In file included from include/linux/pinctrl/consumer.h:17:
In file included from include/linux/seq_file.h:10:
include/linux/fs.h:2693:9: warning: comparison of unsigned enum expression < 0 is always false [-Wtautological-compare]
        if (id < 0 || id >= READING_MAX_ID)
            ~~ ^ ~
/virtual/main.c:74:34: error: use of undeclared identifier 'REQ_WRITE'; did you mean 'REQ_OP_WRITE'?
    info.type = req->cmd_flags & REQ_WRITE;
                                 ^~~~~~~~~
                                 REQ_OP_WRITE
include/linux/blk_types.h:241:2: note: 'REQ_OP_WRITE' declared here
        REQ_OP_WRITE,
        ^
1 warning and 1 error generated.
Traceback (most recent call last):
  File "./biotop", line 152, in <module>
    """, debug=0)
  File "/usr/lib/python2.7/dist-packages/bcc/__init__.py", line 240, in __init__
    raise Exception("Failed to compile BPF module %s" % src_file)
Exception: Failed to compile BPF module 

/cc @brendangregg

[ghost]

Same here.

[ghost]

The fix is also very simple. Just replace REQ_WRITE with REQ_OP_WRITE in biotop tool.

[goldshtn]

Indeed, except we probably want to support both pre-4.9 and post-4.9 kernels.

[goldshtn]

I think that if we can move this tool (and some others) to use tracepoints it would be truly great, and break much less often.

[4ast]

in the mean time, let's fix biotop the same way biosnoop fixed this issue.

[syg00]

Looks like 4.10 is breaking things again (at least biotop and biosnoop).
REQ_OP_SHIFT has disappeared from blkdev.h