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Documentation/vm/page-types.c: auto debugfs mount for hwpoison operation

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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>
This commit is contained in:
Chen Gong 2011-03-22 16:35:03 -07:00 committed by Linus Torvalds
parent e06c374400
commit 12da58b0c8
1 changed files with 101 additions and 4 deletions
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105
Documentation/vm/page-types.c
View file

@ -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);
}
}