[Ocfs2-tools-devel] [PATCH 1/6] libo2dlm: Provide capability queries

[Sunil Mushran]

Signed-off-by: Sunil Mushran <sunil.mushran at oracle.com>


Joel Becker wrote:
> ocfs2_dlmfs can now report added capabilities via a module parameter.
> libo2dlm now can query them before trying to use them.
>
> The two known capabilities at this time are 'bast' and 'stackglue'.
>
> Signed-off-by: Joel Becker <joel.becker at oracle.com>
> ---
>  include/o2dlm/o2dlm.h   |    7 +++
>  libo2dlm/.gitignore     |    1 +
>  libo2dlm/Makefile       |    2 +-
>  libo2dlm/capabilities.c |  131 +++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 140 insertions(+), 1 deletions(-)
>  create mode 100644 libo2dlm/capabilities.c
>
> diff --git a/include/o2dlm/o2dlm.h b/include/o2dlm/o2dlm.h
> index 99bee5f..eada3fb 100644
> --- a/include/o2dlm/o2dlm.h
> +++ b/include/o2dlm/o2dlm.h
> @@ -106,4 +106,11 @@ errcode_t o2dlm_write_lvb(struct o2dlm_ctxt *ctxt,
>   * Unlocks all pending locks and frees the lock context.
>   */
>  errcode_t o2dlm_destroy(struct o2dlm_ctxt *ctxt);
> +
> +/*
> + * Optional features that libo2dlm and dlmfs can support.
> + */
> +errcode_t o2dlm_supports_bast(int *supports);
> +errcode_t o2dlm_supports_stackglue(int *supports);
> +
>  #endif /* _O2DLM_H_ */
> diff --git a/libo2dlm/.gitignore b/libo2dlm/.gitignore
> index 944a5fb..91241ca 100644
> --- a/libo2dlm/.gitignore
> +++ b/libo2dlm/.gitignore
> @@ -4,3 +4,4 @@ o2dlm_err.*
>  *.d
>  o2dlm_test
>  libdlm.h
> +debug_*
> diff --git a/libo2dlm/Makefile b/libo2dlm/Makefile
> index 1bea796..92d6016 100644
> --- a/libo2dlm/Makefile
> +++ b/libo2dlm/Makefile
> @@ -30,7 +30,7 @@ debug_%: debug_%.o libo2dlm.a
>  
>  endif
>  
> -CFILES = o2dlm.c
> +CFILES = o2dlm.c capabilities.c
>  HFILES = libdlm-compat.h
>  
>  TESTING_CFILES = o2dlm_test.c
> diff --git a/libo2dlm/capabilities.c b/libo2dlm/capabilities.c
> new file mode 100644
> index 0000000..6840d61
> --- /dev/null
> +++ b/libo2dlm/capabilities.c
> @@ -0,0 +1,131 @@
> +/* -*- mode: c; c-basic-offset: 8; -*-
> + * vim: noexpandtab sw=8 ts=8 sts=0:
> + *
> + * capabilities.c
> + *
> + * Read dlmfs capabilities.
> + *
> + * Copyright (C) 2010 Oracle.  All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public
> + * License version 2 as published by the Free Software Foundation.
> + * 
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * General Public License for more details.
> + */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <errno.h>
> +#include <limits.h>
> +
> +#include "o2dlm/o2dlm.h"
> +
> +#define CAPABILITIES_FILE	"/sys/module/ocfs2_dlmfs/parameters/capabilities"
> +
> +static ssize_t read_single_line_file(const char *file, char *line,
> +				     size_t count)
> +{
> +	ssize_t ret = 0;
> +	FILE *f;
> +
> +	f = fopen(file, "r");
> +	if (f) {
> +		if (fgets(line, count, f))
> +			ret = strlen(line);
> +		fclose(f);
> +	} else
> +		ret = -errno;
> +
> +	return ret;
> +}
> +
> +static ssize_t o2dlm_read_capabilities(char *line, size_t count)
> +{
> +	ssize_t got;
> +
> +	got = read_single_line_file(CAPABILITIES_FILE, line, count);
> +	if ((got > 0) && (line[got - 1] == '\n')) {
> +		got--;
> +		line[got] = '\0';
> +	}
> +	return got;
> +}
> +
> +static errcode_t o2dlm_has_capability(const char *cap_name, int *found)
> +{
> +	char line[PATH_MAX];
> +	char *p;
> +	ssize_t got;
> +
> +	got = o2dlm_read_capabilities(line, PATH_MAX);
> +	if (got == -ENOENT) {
> +		got = 0;
> +		line[0] = '\0';
> +	}
> +	if (got < 0)
> +		return O2DLM_ET_SERVICE_UNAVAILABLE;
> +
> +	*found = 0;
> +	p = strstr(line, cap_name);
> +	if (p) {
> +		p += strlen(cap_name);
> +		if (!*p || (*p == ' '))
> +			*found = 1;
> +	}
> +	return 0;
> +}
> +
> +errcode_t o2dlm_supports_bast(int *supports)
> +{
> +	return o2dlm_has_capability("bast", supports);
> +}
> +
> +errcode_t o2dlm_supports_stackglue(int *supports)
> +{
> +	return o2dlm_has_capability("stackglue", supports);
> +}
> +
> +#ifdef DEBUG_EXE
> +int main(int argc, char *argv[])
> +{
> +	errcode_t ret;
> +	int i, rc = 0;
> +	char **caps;
> +
> +	initialize_o2dl_error_table();
> +
> +	ret = o2dlm_supports_bast(&i);
> +	if (!ret)
> +		fprintf(stdout, "bast: %s\n", i ? "yes" : "no");
> +	else {
> +		rc = 1;
> +		com_err("debug_capabilities", ret,
> +			"while testing bast capability");
> +	}
> +
> +	ret = o2dlm_supports_stackglue(&i);
> +	if (!ret)
> +		fprintf(stdout, "stackglue: %s\n", i ? "yes" : "no");
> +	else {
> +		rc = 1;
> +		com_err("debug_capabilities", ret,
> +			"while testing stackglue capability");
> +	}
> +
> +	ret = o2dlm_has_capability("invalid", &i);
> +	if (!ret)
> +		fprintf(stdout, "invalid: %s\n", i ? "yes" : "no");
> +	else {
> +		rc = 1;
> +		com_err("debug_capabilities", ret,
> +			"while testing invalid capability");
> +	}
> +
> +	return ret;
> +}
> +#endif
>