[Libguestfs] [PATCH v3 2/2] New API: btrfs_device_stats

[Pino Toscano]

In data venerdì 19 giugno 2015 14:18:22, Cao jin ha scritto:
> Signed-off-by: Cao jin <caoj.fnst at cn.fujitsu.com>
> ---
>  daemon/btrfs.c       | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  generator/actions.ml | 10 ++++++++
>  2 files changed, 81 insertions(+)
> 
> diff --git a/daemon/btrfs.c b/daemon/btrfs.c
> index caa28ca..4288fc9 100644
> --- a/daemon/btrfs.c
> +++ b/daemon/btrfs.c
> @@ -2083,3 +2083,74 @@ do_btrfs_image (char *const *sources, const char *image,
>    return 0;
>  }
>  
> +char **
> +do_btrfs_device_stats (const char *path)
> +{
> +  const size_t MAX_ARGS = 64;
> +  const char *argv[MAX_ARGS];
> +  size_t i = 0;
> +  CLEANUP_FREE char *buf = NULL;
> +  CLEANUP_FREE char *err = NULL;
> +  CLEANUP_FREE char *out = NULL;
> +  char *p, *key = NULL, *value = NULL;
> +  DECLARE_STRINGSBUF (ret);

Now that my stringsbuf improvements in the daemon are in, you can make
use of them to avoid leaking stringsbuf's. Declare the stringsbuf as:

 CLEANUP_FREE_STRINGSBUF DECLARE_STRINGSBUF (ret);

and then when you want to return the strings in it, call e.g.:

 return take_stringsbuf (&ret);

> +  int r;
> +  int is_dev;
> +
> +  is_dev = STREQLEN (path, "/dev/", 5);
> +  buf = is_dev ? strdup (path) : sysroot_path (path);
> +  if (buf == NULL) {
> +    reply_with_perror ("malloc");
> +    return NULL;
> +  }
> +
> +  ADD_ARG (argv, i, str_btrfs);
> +  ADD_ARG (argv, i, "device");
> +  ADD_ARG (argv, i, "stats");
> +  ADD_ARG (argv, i, buf);
> +  ADD_ARG (argv, i, NULL);
> +
> +  r = commandv (&out, &err, argv);
> +  if (r == -1) {
> +    reply_with_error ("%s: %s", path, err);
> +    return NULL;
> +  }
> +
> +  /* Output pattern is:
> +   *   [/dev/sda].write_io_errs   0
> +   *   [/dev/sda].read_io_errs    0
> +   *   [/dev/sda].flush_io_errs   0
> +   *   [/dev/sda].corruption_errs 0
> +   *   [/dev/sda].generation_errs 0
> +   *   [/dev/sdb].write_io_errs   0
> +   *   [/dev/sdb].read_io_errs    0
> +   *   [/dev/sdb].flush_io_errs   0
> +   *   [/dev/sdb].corruption_errs 0
> +   *   [/dev/sdb].generation_errs 0
> +   *   [/dev/sdc]...
> +   *   ...
> +   */
> +
> +  /* Read the lines and split into "key: value". */
> +  p = analyze_line(out, &key, &value, ' ');
> +  while (key) {
> +    if (add_string (&ret, key) == -1)
> +      goto error;
> +
> +    if (add_string (&ret, value) == -1)
> +      goto error;
> +
> +    p = analyze_line(p, &key, &value, ' ');
> +  }
> +
> +  if (end_stringsbuf (&ret) == -1)
> +    goto error;
> +
> +  return ret.argv;
> +
> +error:
> +  if (ret.argv != NULL)
> +    free_stringslen (ret.argv, ret.size);

With the above changes, this label is no more needed.

> +
> +  return NULL;
> +}
> diff --git a/generator/actions.ml b/generator/actions.ml
> index d5e5ccf..8d279fd 100644
> --- a/generator/actions.ml
> +++ b/generator/actions.ml
> @@ -12593,6 +12593,16 @@ numbered C<partnum> on device C<device>.
>  
>  It returns C<primary>, C<logical>, or C<extended>." };
>  
> +  { defaults with
> +    name = "btrfs_device_stats"; added = (1, 29, 47);
> +    style = RHashtable "devicestats", [Dev_or_Path "path"], [];
> +    proc_nr = Some 456;
> +    optional = Some "btrfs"; camel_name = "BTRFSDeviceStats";
> +    shortdesc = "read and print the device IO stats for mounted btrfs device";
> +    longdesc = "\
> +Read and print the device IO stats for all mounted devices of the filesystem
> +identified by C<path>, or for a single device identified by C<path>." };

"I/O"

I'm still not convinced that the return value of this new API is good,
leaving its users to parse again strings that may change because of
changes in future outputs of `btrfs device stats`.
I understand that you want/need it, but we have to find an acceptable
structure for it.

-- 
Pino Toscano