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Protect against recursive slices creation in simlar way as it is done

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in BSD class, ie. if provider below us uses the same metadata, don't
create slices based on the metadata.
This allows to create slices on geoms with rank != 1 without hacks.

Discussed with:	phk
Approved by:	phk
MFC after:	2 weeks
This commit is contained in:
pjd 2005-01-20 22:14:05 +00:00
parent 45ddfd5fbb
commit 9e051a0e23
1 changed files with 33 additions and 7 deletions
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40
sys/geom/geom_mbr.c
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@ -43,6 +43,7 @@ __FBSDID("$FreeBSD$");
#include <sys/bio.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/md5.h>
#include <sys/diskmbr.h>
#include <sys/sbuf.h>
@ -82,6 +83,7 @@ struct g_mbr_softc {
int type [NDOSPART];
u_int sectorsize;
u_char sec0[512];
u_char slicesum[16];
};
static int
@ -90,6 +92,7 @@ g_mbr_modify(struct g_geom *gp, struct g_mbr_softc *ms, u_char *sec0)
int i, error;
off_t l[NDOSPART];
struct dos_partition ndp[NDOSPART], *dp;
MD5_CTX md5sum;
g_topology_assert();
@ -150,6 +153,15 @@ g_mbr_modify(struct g_geom *gp, struct g_mbr_softc *ms, u_char *sec0)
ms->sectorsize, "%ss%d", gp->name, 1 + i);
}
bcopy(sec0, ms->sec0, 512);
/*
* Calculate MD5 from the first sector and use it for avoiding
* recursive slices creation.
*/
MD5Init(&md5sum);
MD5Update(&md5sum, ms->sec0, sizeof(ms->sec0));
MD5Final(ms->slicesum, &md5sum);
return (0);
}
@ -215,6 +227,9 @@ g_mbr_start(struct bio *bp)
if (g_handleattr_off_t(bp, "MBR::offset",
gsp->slices[idx].offset))
return (1);
if (g_handleattr(bp, "MBR::slicesum", mp->slicesum,
sizeof(mp->slicesum)))
return (1);
}
return (0);
@ -247,6 +262,8 @@ g_mbr_taste(struct g_class *mp, struct g_provider *pp, int insist)
struct g_mbr_softc *ms;
u_int fwsectors, sectorsize;
u_char *buf;
u_char hash[16];
MD5_CTX md5sum;
g_trace(G_T_TOPOLOGY, "mbr_taste(%s,%s)", mp->name, pp->name);
g_topology_assert();
@ -255,13 +272,6 @@ g_mbr_taste(struct g_class *mp, struct g_provider *pp, int insist)
return (NULL);
g_topology_unlock();
do {
/* XXX: phk think about this! */
if (gp->rank != 2 &&
strcmp(pp->geom->class->name, "LABEL") != 0 &&
strcmp(pp->geom->class->name, "MIRROR") != 0 &&
strcmp(pp->geom->class->name, "NOP") != 0) {
break;
}
error = g_getattr("GEOM::fwsectors", cp, &fwsectors);
if (error)
fwsectors = 17;
@ -272,6 +282,22 @@ g_mbr_taste(struct g_class *mp, struct g_provider *pp, int insist)
buf = g_read_data(cp, 0, sectorsize, &error);
if (buf == NULL || error != 0)
break;
/*
* Calculate MD5 from the first sector and use it for avoiding
* recursive slices creation.
*/
bcopy(buf, ms->sec0, 512);
MD5Init(&md5sum);
MD5Update(&md5sum, ms->sec0, sizeof(ms->sec0));
MD5Final(ms->slicesum, &md5sum);
error = g_getattr("MBR::slicesum", cp, &hash);
if (!error && !bcmp(ms->slicesum, hash, sizeof(hash))) {
g_free(buf);
break;
}
g_topology_lock();
g_mbr_modify(gp, ms, buf);
g_topology_unlock();