linux-kernel - Re: [PATCH 10/20] perf data: Add directory support

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Date:   Mon, 25 Feb 2019 14:56:51 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Stephane Eranian <eranian@...gle.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>
Subject: Re: [PATCH 10/20] perf data: Add directory support

On Mon, Feb 25, 2019 at 10:45:48AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Sun, Feb 24, 2019 at 08:06:46PM +0100, Jiri Olsa escreveu:
> > Adding support to have directory as perf.data.
> > 
> > The caller needs to set 'struct perf_data::is_dir flag
> > and the path will be treated as directory.
> > 
> > The 'struct perf_data::file' is initialized and open
> > as 'path/header' file.
> > 
> > Adding check to direcory interface functions to check
> > on is_dir flag.
> > 
> > Link: http://lkml.kernel.org/n/tip-pvot1aywiem9epgqpfi1agaj@git.kernel.org
> > Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> > ---
> >  tools/perf/util/data.c    | 41 ++++++++++++++++++++++++++++++++++++++-
> >  tools/perf/util/data.h    |  6 ++++++
> >  tools/perf/util/session.c |  4 ++++
> >  3 files changed, 50 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
> > index 7bd5ddeb7a41..72ac4dbb5c69 100644
> > --- a/tools/perf/util/data.c
> > +++ b/tools/perf/util/data.c
> > @@ -34,6 +34,9 @@ int perf_data__create_dir(struct perf_data *data, int nr)
> >  	struct perf_data_file *files = NULL;
> >  	int i, ret = -1;
> >  
> > +	if (WARN_ON(!data->is_dir))
> > +		return -EINVAL;
> > +
> >  	files = zalloc(nr * sizeof(*files));
> >  	if (!files)
> >  		return -ENOMEM;
> > @@ -69,6 +72,9 @@ int perf_data__open_dir(struct perf_data *data)
> >  	DIR *dir;
> >  	int nr = 0;
> >  
> > +	if (WARN_ON(!data->is_dir))
> > +		return -EINVAL;
> > +
> >  	dir = opendir(data->path);
> >  	if (!dir)
> >  		return -EINVAL;
> > @@ -173,6 +179,16 @@ static int check_backup(struct perf_data *data)
> >  	return 0;
> >  }
> >  
> > +static bool is_dir(struct perf_data *data)
> > +{
> > +	struct stat st;
> > +
> > +	if (stat(data->path, &st))
> > +		return false;
> > +
> > +	return (st.st_mode & S_IFMT) == S_IFDIR;
> > +}
> > +
> >  static int open_file_read(struct perf_data *data)
> >  {
> >  	struct stat st;
> > @@ -254,6 +270,22 @@ static int open_file_dup(struct perf_data *data)
> >  	return open_file(data);
> >  }
> >  
> > +static int open_dir(struct perf_data *data)
> > +{
> > +	if (perf_data__is_write(data) &&
> > +	    mkdir(data->path, S_IRWXU) < 0)
> > +		return -1;
> > +
> > +	/*
> > +	 * So far we open only the header, so we
> > +	 * can read the data version and layout.
> > +	 */
> > +	if (asprintf(&data->file.path, "%s/header", data->path) < 0)
> > +		return -ENOMEM;
> 
> so, if this fails, then we should unwind the mkdir, if it was
> performed, so that we leave things as they were before calling
> open_dir(), right?

I think we need to some global solution on this,
currently we also leve halfway screwed perf.data
if we fail in the middle

I think maybe we need to add something on upper (session)
layer to cleanup if we screw up

jirka