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Commit 12da58b0 authored by Chen Gong's avatar Chen Gong Committed by Linus Torvalds
Browse files

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: default avatarChen Gong <gong.chen@linux.intel.com>
Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: default avatarWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e06c3744

Documentation/vm/page-types.c

+101 −4
Original line number Diff line number Diff line
@@ -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 *page_flag_names[] = { 
};





static const char *debugfs_known_mountpoints[] = {

	"/sys/kernel/debug",

	"/debug",

	0,

};



/*

 * data structures

 */
@@ -184,7 +202,7 @@ static int kpageflags_fd; 
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 @@ static uint64_t kpageflags_flags(uint64_t flags) 
	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);

	}

}