Zorro reported that when making multiple copies of a V5
filesystem with xfs_copy while generating new UUIDs, all
but the first copy were corrupt.
Upon inspection, the corruption was related to incorrect UUIDs;
the original UUID, as stamped into every metadata structure,
was not preserved in the sb_meta_uuid field of the superblock
on any but the first copy.
This happened because sb_update_uuid was using the UUID present in
the ag_hdr structure as the unchanging meta-uuid which is to match
existing structures, but it also /updates/ that UUID with the
new identifying UUID present in tcarg. So the newly-generated
UUIDs moved transitively from tcarg->uuid to ag_hdr->xfs_sb->sb_uuid
to ag_hdr->xfs_sb->sb_meta_uuid each time the function got called.
Fix this by looking instead to the unchanging, original UUID
present in the xfs_sb_t we are given, which reflects the original
filesystem's metadata UUID, and copy /that/ UUID into each target
filesystem's meta_uuid field.
Most of this patch is changing comments and re-ordering tests
to match; the functional change is to simply use the *sb rather
than the *ag_hdr to identify the proper metadata UUID.
Reported-by: Zorro Lang <zlang@xxxxxxxxxx>
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
diff --git a/copy/xfs_copy.c b/copy/xfs_copy.c
index 3c8998c..d8edfdd 100644
--- a/copy/xfs_copy.c
+++ b/copy/xfs_copy.c
@@ -494,27 +494,29 @@ write_wbuf(void)
void
sb_update_uuid(
- xfs_sb_t *sb,
- ag_header_t *ag_hdr,
- thread_args *tcarg)
+ xfs_sb_t *sb, /* Original fs superblock */
+ ag_header_t *ag_hdr, /* AG hdr to update for this copy */
+ thread_args *tcarg) /* Args for this thread, with UUID */
{
/*
* If this filesystem has CRCs, the original UUID is stamped into
- * all metadata. If we are changing the UUID in the copy, we need
- * to copy the original UUID into the meta_uuid slot and set the
- * set the incompat flag if that hasn't already been done.
+ * all metadata. If we don't have an existing meta_uuid field in the
+ * the original filesystem and we are changing the UUID in this copy,
+ * we must copy the original sb_uuid to the sb_meta_uuid slot and set
+ * the incompat flag for the feature on this copy.
*/
- if (!uuid_equal(&tcarg->uuid, &ag_hdr->xfs_sb->sb_uuid) &&
- xfs_sb_version_hascrc(sb) && !xfs_sb_version_hasmetauuid(sb)) {
+ if (xfs_sb_version_hascrc(sb) && !xfs_sb_version_hasmetauuid(sb) &&
+ !uuid_equal(&tcarg->uuid, &sb->sb_uuid)) {
__be32 feat;
feat = be32_to_cpu(ag_hdr->xfs_sb->sb_features_incompat);
feat |= XFS_SB_FEAT_INCOMPAT_META_UUID;
ag_hdr->xfs_sb->sb_features_incompat = cpu_to_be32(feat);
platform_uuid_copy(&ag_hdr->xfs_sb->sb_meta_uuid,
- &ag_hdr->xfs_sb->sb_uuid);
+ &sb->sb_uuid);
}
+ /* Copy the (possibly new) fs-identifier UUID into sb_uuid */
platform_uuid_copy(&ag_hdr->xfs_sb->sb_uuid, &tcarg->uuid);
/* We may have changed the UUID, so update the superblock CRC */
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