Documentation/vm/page-types.c: auto debugfs mount for hwpoison operation
page-types.c doesn't supply a way to specify the debugfs path and the
original debugfs path is not usual on most machines. This patch supplies
a way to auto mount debugfs if needed.
This patch is heavily inspired by tools/perf/utils/debugfs.c
[akpm@linux-foundation.org: make functions static]
[akpm@linux-foundation.org: fix debugfs_mount() signature]
Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/vm/page-types.c b/Documentation/vm/page-types.c
index cc96ee2..7445caa 100644
--- a/Documentation/vm/page-types.c
+++ b/Documentation/vm/page-types.c
@@ -32,8 +32,20 @@
#include <sys/types.h>
#include <sys/errno.h>
#include <sys/fcntl.h>
+#include <sys/mount.h>
+#include <sys/statfs.h>
+#include "../../include/linux/magic.h"
+#ifndef MAX_PATH
+# define MAX_PATH 256
+#endif
+
+#ifndef STR
+# define _STR(x) #x
+# define STR(x) _STR(x)
+#endif
+
/*
* pagemap kernel ABI bits
*/
@@ -152,6 +164,12 @@
};
+static const char *debugfs_known_mountpoints[] = {
+ "/sys/kernel/debug",
+ "/debug",
+ 0,
+};
+
/*
* data structures
*/
@@ -184,7 +202,7 @@
static int opt_hwpoison;
static int opt_unpoison;
-static const char hwpoison_debug_fs[] = "/debug/hwpoison";
+static char hwpoison_debug_fs[MAX_PATH+1];
static int hwpoison_inject_fd;
static int hwpoison_forget_fd;
@@ -464,21 +482,100 @@
return flags;
}
+/* verify that a mountpoint is actually a debugfs instance */
+static int debugfs_valid_mountpoint(const char *debugfs)
+{
+ struct statfs st_fs;
+
+ if (statfs(debugfs, &st_fs) < 0)
+ return -ENOENT;
+ else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
+ return -ENOENT;
+
+ return 0;
+}
+
+/* find the path to the mounted debugfs */
+static const char *debugfs_find_mountpoint(void)
+{
+ const char **ptr;
+ char type[100];
+ FILE *fp;
+
+ ptr = debugfs_known_mountpoints;
+ while (*ptr) {
+ if (debugfs_valid_mountpoint(*ptr) == 0) {
+ strcpy(hwpoison_debug_fs, *ptr);
+ return hwpoison_debug_fs;
+ }
+ ptr++;
+ }
+
+ /* give up and parse /proc/mounts */
+ fp = fopen("/proc/mounts", "r");
+ if (fp == NULL)
+ perror("Can't open /proc/mounts for read");
+
+ while (fscanf(fp, "%*s %"
+ STR(MAX_PATH)
+ "s %99s %*s %*d %*d\n",
+ hwpoison_debug_fs, type) == 2) {
+ if (strcmp(type, "debugfs") == 0)
+ break;
+ }
+ fclose(fp);
+
+ if (strcmp(type, "debugfs") != 0)
+ return NULL;
+
+ return hwpoison_debug_fs;
+}
+
+/* mount the debugfs somewhere if it's not mounted */
+
+static void debugfs_mount(void)
+{
+ const char **ptr;
+
+ /* see if it's already mounted */
+ if (debugfs_find_mountpoint())
+ return;
+
+ ptr = debugfs_known_mountpoints;
+ while (*ptr) {
+ if (mount(NULL, *ptr, "debugfs", 0, NULL) == 0) {
+ /* save the mountpoint */
+ strcpy(hwpoison_debug_fs, *ptr);
+ break;
+ }
+ ptr++;
+ }
+
+ if (*ptr == NULL) {
+ perror("mount debugfs");
+ exit(EXIT_FAILURE);
+ }
+}
+
/*
* page actions
*/
static void prepare_hwpoison_fd(void)
{
- char buf[100];
+ char buf[MAX_PATH + 1];
+
+ debugfs_mount();
if (opt_hwpoison && !hwpoison_inject_fd) {
- sprintf(buf, "%s/corrupt-pfn", hwpoison_debug_fs);
+ snprintf(buf, MAX_PATH, "%s/hwpoison/corrupt-pfn",
+ hwpoison_debug_fs);
hwpoison_inject_fd = checked_open(buf, O_WRONLY);
}
if (opt_unpoison && !hwpoison_forget_fd) {
- sprintf(buf, "%s/unpoison-pfn", hwpoison_debug_fs);
+ snprintf(buf, MAX_PATH, "%s/hwpoison/unpoison-pfn",
+ hwpoison_debug_fs);
hwpoison_forget_fd = checked_open(buf, O_WRONLY);
}
}