[tip:perf/core] tools lib api fs: Add FSTYPE__mount() method

[tip-bot for Jiri Olsa]

Commit-ID:  73ca85ad364769ffa312b1d892816d8fa23a02bf
Gitweb:     http://git.kernel.org/tip/73ca85ad364769ffa312b1d892816d8fa23a02bf
Author:     Jiri Olsa <jolsa@xxxxxxxxxx>
AuthorDate: Wed, 2 Sep 2015 09:56:41 +0200
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Fri, 4 Sep 2015 12:01:00 -0300

tools lib api fs: Add FSTYPE__mount() method

Adding FSTYPE__mount (where FSTYPE is, as of now, one of sysfs, procfs,
debugfs, tracefs) method that tries to mount the filesystem in case no
mount of FSTYPE is found.

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Raphael Beamonte <raphael.beamonte@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1441180605-24737-12-git-send-email-jolsa@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/lib/api/fs/fs.c | 44 +++++++++++++++++++++++++++++++++++++++-----
 tools/lib/api/fs/fs.h | 15 +++++++++++----
 2 files changed, 50 insertions(+), 9 deletions(-)

diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
index ef16d2a..bc93baf 100644
--- a/tools/lib/api/fs/fs.c
+++ b/tools/lib/api/fs/fs.c
@@ -9,6 +9,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <sys/mount.h>
 
 #include "debugfs.h"
 #include "fs.h"
@@ -215,16 +216,49 @@ static const char *fs__mountpoint(int idx)
 	return fs__get_mountpoint(fs);
 }
 
-#define FS__MOUNTPOINT(name, idx)	\
+static const char *mount_overload(struct fs *fs)
+{
+	size_t name_len = strlen(fs->name);
+	/* "PERF_" + name + "_ENVIRONMENT" + '\0' */
+	char upper_name[5 + name_len + 12 + 1];
+
+	snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);
+	mem_toupper(upper_name, name_len);
+
+	return getenv(upper_name) ?: *fs->mounts;
+}
+
+static const char *fs__mount(int idx)
+{
+	struct fs *fs = &fs__entries[idx];
+	const char *mountpoint;
+
+	if (fs__mountpoint(idx))
+		return (const char *)fs->path;
+
+	mountpoint = mount_overload(fs);
+
+	if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)
+		return NULL;
+
+	return fs__check_mounts(fs) ? fs->path : NULL;
+}
+
+#define FS(name, idx)			\
 const char *name##__mountpoint(void)	\
 {					\
 	return fs__mountpoint(idx);	\
+}					\
+					\
+const char *name##__mount(void)		\
+{					\
+	return fs__mount(idx);		\
 }
 
-FS__MOUNTPOINT(sysfs,   FS__SYSFS);
-FS__MOUNTPOINT(procfs,  FS__PROCFS);
-FS__MOUNTPOINT(debugfs, FS__DEBUGFS);
-FS__MOUNTPOINT(tracefs, FS__TRACEFS);
+FS(sysfs,   FS__SYSFS);
+FS(procfs,  FS__PROCFS);
+FS(debugfs, FS__DEBUGFS);
+FS(tracefs, FS__TRACEFS);
 
 int filename__read_int(const char *filename, int *value)
 {
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
index 9013227..a9627ea 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -9,10 +9,17 @@
 #define PATH_MAX 4096
 #endif
 
-const char *sysfs__mountpoint(void);
-const char *procfs__mountpoint(void);
-const char *debugfs__mountpoint(void);
-const char *tracefs__mountpoint(void);
+#define FS(name)				\
+	const char *name##__mountpoint(void);	\
+	const char *name##__mount(void);
+
+FS(sysfs)
+FS(procfs)
+FS(debugfs)
+FS(tracefs)
+
+#undef FS
+
 
 int filename__read_int(const char *filename, int *value);
 int sysctl__read_int(const char *sysctl, int *value);
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