xfs_db: disallow sb UUID write on v5 filesystems

PATCH In review Eric Sandeen 3 participants 3 messages Apr 6, 2015 – Apr 7, 2015

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Eric Sandeen

author

2015-04-06 15:06 UTC #0 lore raw

PATCH 1/1 xfs_db: disallow sb UUID write on v5 filesystems

Do not allow xfs_db (or the xfs_admin frontend) to change the UUID of a V5 filesystem; this will cause UUID mismatches across the filesystem, and we currently have no mechanism to update them all. Changing only the superblock UUID makes all other metadata look invalid, and xfs_repair reacts by junking everything.

Addresses-Debian-Bug: 782012

Reported-by F. Stoyan <[email protected]>

Signed-off-by Eric Sandeen <[email protected]>

---

db/sb.c +12 -0

index 6cb665d..f31f4a2 100644
@@ -363,6 +363,18 @@ uuid_f(
 			return 0;
 		}
 
+		/*
+		* For now, changing the UUID of V5 superblock filesystems is
+		* not supported; we do not have the infrastructure to fix all
+		* other metadata when a new superblock UUID is generated.
+		*/
+		if (xfs_sb_version_hascrc(&mp->m_sb) &&
+		    strcasecmp(argv[1], "rewrite")) {
+			dbprintf(_("%s: only 'rewrite' supported on V5 fs\n"),
+				progname);
+			return 0;
+		}
+
 		if (!strcasecmp(argv[1], "generate")) {
 			platform_uuid_generate(&uu);
 		} else if (!strcasecmp(argv[1], "nil")) {

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Brian Foster

Reviewed-by on v1 1/1

2015-04-07 13:37 UTC #1 lore raw

Quoted 16 lines · Eric Sandeen

Do not allow xfs_db (or the xfs_admin frontend) to change the UUID of a V5 filesystem; this will cause UUID mismatches across the filesystem, and we currently have no mechanism to update them all. Changing only the superblock UUID makes all other metadata look invalid, and xfs_repair reacts by junking everything.
Addresses-Debian-Bug: 782012
Reported-by F. Stoyan <[email protected]>
Signed-off-by Eric Sandeen <[email protected]>
---
db/sb.c +0 -0
index 6cb665d..f31f4a2 100644

db/sb.c uuid_f( · line 370

Quoted 8 lines

db/sb.c +5 -0

@@ -363,6 +363,18 @@ uuid_f(
 			return 0;
 		}
 
+		/*
+		* For now, changing the UUID of V5 superblock filesystems is
+		* not supported; we do not have the infrastructure to fix all
+		* other metadata when a new superblock UUID is generated.
+		*/

Unaligned start of comment above. :) Otherwise looks fine to me:

Reviewed-by Brian Foster <[email protected]>

Quoted 11 lines

db/sb.c +7 -0

+		if (xfs_sb_version_hascrc(&mp->m_sb) &&
+		    strcasecmp(argv[1], "rewrite")) {
+			dbprintf(_("%s: only 'rewrite' supported on V5 fs\n"),
+				progname);
+			return 0;
+		}
+
 		if (!strcasecmp(argv[1], "generate")) {
 			platform_uuid_generate(&uu);
 		} else if (!strcasecmp(argv[1], "nil")) {

Quoted 4 lines

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Eric Sandeen

2015-04-07 13:58 UTC #2 lore raw

PATCH v2 1/1 xfs_db: disallow sb UUID write on v5 filesystems

In reply to Eric Sandeen

Addresses-Debian-Bug: 782012

Reported-by F. Stoyan <[email protected]>

Signed-off-by Eric Sandeen <[email protected]>

Reviewed-by Brian Foster <[email protected]>

---

V2, fix up comment whitespace :/
(and add brian's review for dave's convenience)

db/sb.c +12 -0

index 6cb665d..f31f4a2 100644
@@ -363,6 +363,18 @@ uuid_f(
 			return 0;
 		}
 
+		/*
+		 * For now, changing the UUID of V5 superblock filesystems is
+		 * not supported; we do not have the infrastructure to fix all
+		 * other metadata when a new superblock UUID is generated.
+		 */
+		if (xfs_sb_version_hascrc(&mp->m_sb) &&
+		    strcasecmp(argv[1], "rewrite")) {
+			dbprintf(_("%s: only 'rewrite' supported on V5 fs\n"),
+				progname);
+			return 0;
+		}
+
 		if (!strcasecmp(argv[1], "generate")) {
 			platform_uuid_generate(&uu);
 		} else if (!strcasecmp(argv[1], "nil")) {

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