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mapfile: optionally store map file in /dev 

During early boot, /var/run may not exist or be writable.
If that happens, sore the mapfile (which is very important for
incremental assembly) in /dev (which should exist for udev).

Thanks to Doug Ledford <dledford@redhat.com> for identify this
problem and suggesting a solution.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2009-04-14 10:49:40 +10:00
parent 78e3d2a376
commit cf3a3d7888
1 changed files with 52 additions and 45 deletions
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97
mapfile.c
View File

@ -2,7 +2,7 @@
* mapfile - manage /var/run/mdadm.map. Part of:
* mdadm - manage Linux "md" devices aka RAID arrays.
*
* Copyright (C) 2006 Neil Brown <neilb@suse.de>
* Copyright (C) 2006-2009 Neil Brown <neilb@suse.de>
*
*
* This program is free software; you can redistribute it and/or modify
@ -38,23 +38,48 @@
* UUID - uuid of the array
* path - path where device created: /dev/md/home
*
* The preferred location for the map file is /var/run/mdadm.map.
* However /var/run may not exist or be writable in early boot. And if
* no-one has created /var/run/mdadm, we still want to survive.
* So possible locations are:
* /var/run/mdadm/map /var/run/mdadm.map /dev/.mdadm.map
* the last, because udev requires a writable /dev very early.
* We read from the first one that exists and write to the first
* one that we can.
*/
#include "mdadm.h"
#define mapnames(base) { #base, #base ".new", #base ".lock"}
char *mapname[3][3] = {
mapnames(/var/run/mdadm/map),
mapnames(/var/run/mdadm.map),
mapnames(/dev/.mdadm.map)
};
int mapmode[3] = { O_RDONLY, O_RDWR|O_CREAT, O_RDWR|O_CREAT | O_TRUNC };
char *mapsmode[3] = { "r", "w", "w"};
FILE *open_map(int modenum, int *choice)
{
int i;
for (i = 0 ; i < 3 ; i++) {
int fd = open(mapname[i][modenum], mapmode[modenum], 0600);
if (fd >= 0) {
*choice = i;
return fdopen(fd, mapsmode[modenum]);
}
}
return NULL;
}
int map_write(struct map_ent *mel)
{
FILE *f;
int err;
int subdir = 1;
int which;
f = open_map(1, &which);
f = fopen("/var/run/mdadm/map.new", "w");
if (!f) {
f = fopen("/var/run/mdadm.map.new", "w");
subdir = 0;
}
if (!f)
return 0;
for (; mel; mel = mel->next) {
@ -73,37 +98,25 @@ int map_write(struct map_ent *mel)
err = ferror(f);
fclose(f);
if (err) {
if (subdir)
unlink("/var/run/mdadm/map.new");
else
unlink("/var/run/mdadm.map.new");
unlink(mapname[which][1]);
return 0;
}
if (subdir)
return rename("/var/run/mdadm/map.new",
"/var/run/mdadm/map") == 0;
else
return rename("/var/run/mdadm.map.new",
"/var/run/mdadm.map") == 0;
return rename(mapname[which][1],
mapname[which][0]) == 0;
}
static int lfd = -1;
static int lsubdir = 0;
static FILE *lf = NULL;
static int lwhich = 0;
int map_lock(struct map_ent **melp)
{
if (lfd < 0) {
lfd = open("/var/run/mdadm/map.lock", O_CREAT|O_RDWR, 0600);
if (lfd < 0) {
lfd = open("/var/run/mdadm.map.lock", O_CREAT|O_RDWR, 0600);
lsubdir = 0;
} else
lsubdir = 1;
if (lfd < 0)
if (lf == NULL) {
lf = open_map(2, &lwhich);
if (lf == NULL)
return -1;
if (lockf(lfd, F_LOCK, 0) != 0) {
close(lfd);
lfd = -1;
if (lockf(fileno(lf), F_LOCK, 0) != 0) {
fclose(lf);
lf = NULL;
return -1;
}
}
@ -115,13 +128,10 @@ int map_lock(struct map_ent **melp)
void map_unlock(struct map_ent **melp)
{
if (lfd >= 0)
close(lfd);
if (lsubdir)
unlink("/var/run/mdadm/map.lock");
else
unlink("/var/run/mdadm.map.lock");
lfd = -1;
if (lf)
fclose(lf);
unlink(mapname[lwhich][2]);
lf = NULL;
}
void map_add(struct map_ent **melp,
@ -146,18 +156,15 @@ void map_read(struct map_ent **melp)
int devnum, uuid[4];
char metadata[30];
char nam[4];
int which;
*melp = NULL;
f = fopen("/var/run/mdadm/map", "r");
if (!f)
f = fopen("/var/run/mdadm.map", "r");
f = open_map(0, &which);
if (!f) {
RebuildMap();
f = fopen("/var/run/mdadm/map", "r");
f = open_map(0, &which);
}
if (!f)
f = fopen("/var/run/mdadm.map", "r");
if (!f)
return;