zdtm: Add filesystem specific helpers

In particular we have to find out if we're
running on btrfs filesystem for proper device
number mangling.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@odin.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm/lib/Makefile

@@ -6,7 +6,7 @@ CFLAGS	+= $(USERCFLAGS)
 LIBDIR	= .
 LIB	= libzdtmtst.a
 
-LIBSRC	= datagen.c msg.c parseargs.c test.c streamutil.c lock.c ns.c tcp.c
+LIBSRC	= datagen.c msg.c parseargs.c test.c streamutil.c lock.c ns.c tcp.c fs.c
 LIBOBJ	= $(LIBSRC:%.c=%.o)
 LIBDEP	= $(LIBSRC:%.c=%.d)
 

test/zdtm/lib/fs.c

+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <errno.h>
+#include <unistd.h>
+#include <limits.h>
+
+#include "zdtmtst.h"
+#include "fs.h"
+
+mnt_info_t *mnt_info_alloc(void)
+{
+	mnt_info_t *m = malloc(sizeof(*m));
+	if (m)
+		memset(m, 0, sizeof(*m));
+	return m;
+}
+
+void mnt_info_free(mnt_info_t **m)
+{
+	if (m && *m) {
+		free(*m);
+		*m = NULL;
+	}
+}
+
+mnt_info_t *get_cwd_mnt_info(void)
+{
+	int mnt_id, parent_mnt_id;
+	unsigned int kmaj, kmin;
+	char str[1024], *cwd;
+	int ret;
+	FILE *f;
+
+	mnt_info_t *m = NULL;
+
+	char mountpoint[PATH_MAX];
+	char root[PATH_MAX];
+
+	char *fsname = NULL;
+	size_t len = 0, best_len = 0;
+
+	f = fopen("/proc/self/mountinfo", "r");
+	if (!f)
+		return NULL;
+
+	cwd = get_current_dir_name();
+	if (!cwd)
+		goto err;
+
+	m = mnt_info_alloc();
+	if (!m)
+		goto err;
+
+	while (fgets(str, sizeof(str), f)) {
+		char *hyphen = strchr(str, '-');
+		ret = sscanf(str, "%i %i %u:%u %s %s",
+			     &mnt_id, &parent_mnt_id,
+			     &kmaj, &kmin,
+			     root, mountpoint);
+		if (ret != 6 || !hyphen)
+			goto err;
+		ret = sscanf(hyphen + 1, " %ms", &fsname);
+		if (ret != 1)
+			goto err;
+
+		len = strlen(mountpoint);
+		if (!strncmp(mountpoint, cwd, len)) {
+			if (len > best_len) {
+				best_len = len;
+
+				m->mnt_id = mnt_id;
+				m->parent_mnt_id = parent_mnt_id;
+				m->s_dev = MKKDEV(kmaj, kmin);
+
+				strncpy(m->root, root, sizeof(m->root));
+				strncpy(m->mountpoint, mountpoint, sizeof(m->mountpoint));
+				strncpy(m->fsname, fsname, sizeof(m->fsname));
+			}
+		}
+
+		free(fsname);
+		fsname = NULL;
+	}
+
+out:
+	free(cwd);
+	fclose(f);
+
+	return m;
+
+err:
+	mnt_info_free(&m);
+	goto out;
+}

test/zdtm/lib/fs.h

+#ifndef ZDTM_FS_H_
+#define ZDTM_FS_H_
+
+#define _BSD_SOURCE
+#include <sys/types.h>
+
+#include <limits.h>
+
+#define KDEV_MINORBITS	20
+#define KDEV_MINORMASK	((1UL << KDEV_MINORBITS) - 1)
+#define MKKDEV(ma, mi)	(((ma) << KDEV_MINORBITS) | (mi))
+
+static inline unsigned int kdev_major(unsigned int kdev)
+{
+	return kdev >> KDEV_MINORBITS;
+}
+
+static inline unsigned int kdev_minor(unsigned int kdev)
+{
+	return kdev & KDEV_MINORMASK;
+}
+
+static inline dev_t kdev_to_odev(unsigned int kdev)
+{
+	/*
+	 * New kernels encode devices in a new form.
+	 * See kernel's fs/stat.c for details, there
+	 * choose_32_64 helpers which are the key.
+	 */
+	unsigned major = kdev_major(kdev);
+	unsigned minor = kdev_minor(kdev);
+
+	return makedev(major, minor);
+}
+
+typedef struct {
+	int			mnt_id;
+	int			parent_mnt_id;
+	unsigned int		s_dev;
+	char			root[PATH_MAX];
+	char			mountpoint[PATH_MAX];
+	char			fsname[64];
+} mnt_info_t;
+
+extern mnt_info_t *mnt_info_alloc(void);
+extern void mnt_info_free(mnt_info_t **m);
+extern mnt_info_t *get_cwd_mnt_info(void);
+
+#endif /* ZDTM_FS_H_ */