svn commit: r365477 - head/sys/geom/part

[Eugene Grosbein]

Author: eugen
Date: Tue Sep  8 22:23:53 2020
New Revision: 365477
URL: https://svnweb.freebsd.org/changeset/base/365477

Log:
  geom_part: extend kern.geom.part.check_integrity to work on GPT
  
  There are multiple USB/SATA bridges on the market that unconditionally
  cut some LBAs off connected media. This could be a problem
  for pre-partitioned drives so GEOM complains and does not create
  devices in /dev for slices/partitions preventing access to existing data.
  
  We have kern.geom.part.check_integrity that allows us to correct
  partitioning if changed from default 1 to 0 but it works for MBR only.
  If backup copy of GPT is unavailable due to decreases number of LBAs,
  kernel still does not give access to partitions and prints to dmesg:
  
  GEOM: md0: corrupt or invalid GPT detected.
  GEOM: md0: GPT rejected -- may not be recoverable.
  
  This change makes it work for GPT too, so it created partitions in /dev
  and prints to dmesg this instead:
  
  GEOM: md0: the secondary GPT table is corrupt or invalid.
  GEOM: md0: using the primary only -- recovery suggested.
  
  Then "gpart recover" re-created backup copy of GPT
  and allows further manipulations with partitions.
  
  This change is no-op for default configuration having
  kern.geom.part.check_integrity=1
  
  Reported by:	Alex Korchmar
  MFC after:	3 days.

Modified:
  head/sys/geom/part/g_part.c
  head/sys/geom/part/g_part_gpt.c

Modified: head/sys/geom/part/g_part.c
==============================================================================
--- head/sys/geom/part/g_part.c	Tue Sep  8 22:19:06 2020	(r365476)
+++ head/sys/geom/part/g_part.c	Tue Sep  8 22:23:53 2020	(r365477)
@@ -140,9 +140,9 @@ struct g_part_alias_list {
 SYSCTL_DECL(_kern_geom);
 SYSCTL_NODE(_kern_geom, OID_AUTO, part, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "GEOM_PART stuff");
-static u_int check_integrity = 1;
+u_int geom_part_check_integrity = 1;
 SYSCTL_UINT(_kern_geom_part, OID_AUTO, check_integrity,
-    CTLFLAG_RWTUN, &check_integrity, 1,
+    CTLFLAG_RWTUN, &geom_part_check_integrity, 1,
     "Enable integrity checking");
 static u_int auto_resize = 1;
 SYSCTL_UINT(_kern_geom_part, OID_AUTO, auto_resize,
@@ -428,7 +428,7 @@ g_part_check_integrity(struct g_part_table *table, str
 	if (failed != 0) {
 		printf("GEOM_PART: integrity check failed (%s, %s)\n",
 		    pp->name, table->gpt_scheme->name);
-		if (check_integrity != 0)
+		if (geom_part_check_integrity != 0)
 			return (EINVAL);
 		table->gpt_corrupt = 1;
 	}

Modified: head/sys/geom/part/g_part_gpt.c
==============================================================================
--- head/sys/geom/part/g_part_gpt.c	Tue Sep  8 22:19:06 2020	(r365476)
+++ head/sys/geom/part/g_part_gpt.c	Tue Sep  8 22:23:53 2020	(r365477)
@@ -66,6 +66,8 @@ SYSCTL_UINT(_kern_geom_part_gpt, OID_AUTO, allow_nesti
 CTASSERT(offsetof(struct gpt_hdr, padding) == 92);
 CTASSERT(sizeof(struct gpt_ent) == 128);
 
+extern u_int geom_part_check_integrity;
+
 #define	EQUUID(a,b)	(memcmp(a, b, sizeof(struct uuid)) == 0)
 
 #define	MBRSIZE		512
@@ -480,8 +482,9 @@ gpt_read_hdr(struct g_part_gpt_table *table, struct g_
 	if (hdr->hdr_lba_self != table->lba[elt])
 		goto fail;
 	hdr->hdr_lba_alt = le64toh(buf->hdr_lba_alt);
-	if (hdr->hdr_lba_alt == hdr->hdr_lba_self ||
-	    hdr->hdr_lba_alt > last)
+	if (hdr->hdr_lba_alt == hdr->hdr_lba_self)
+		goto fail;
+	if (hdr->hdr_lba_alt > last && geom_part_check_integrity)
 		goto fail;
 
 	/* Check the managed area. */