allow UUID changes on V5/CRC filesystems

index 4daaa66..88c38df 100644
@@ -100,7 +100,7 @@ typedef struct xfs_sb {
 	xfs_rfsblock_t	sb_dblocks;	/* number of data blocks */
 	xfs_rfsblock_t	sb_rblocks;	/* number of realtime blocks */
 	xfs_rtblock_t	sb_rextents;	/* number of realtime extents */
-	uuid_t		sb_uuid;	/* file system unique id */
+	uuid_t		sb_uuid;	/* user-visible file system unique id */
 	xfs_fsblock_t	sb_logstart;	/* starting block of log if internal */
 	xfs_ino_t	sb_rootino;	/* root inode number */
 	xfs_ino_t	sb_rbmino;	/* bitmap inode for realtime extents */

@@ -174,6 +174,7 @@ typedef struct xfs_sb {
 
 	xfs_ino_t	sb_pquotino;	/* project quota inode */
 	xfs_lsn_t	sb_lsn;		/* last write sequence */
+	uuid_t		sb_meta_uuid;	/* metadata file system unique id */
 
 	/* must be padded to 64 bit alignment */
 } xfs_sb_t;

@@ -190,7 +191,7 @@ typedef struct xfs_dsb {
 	__be64		sb_dblocks;	/* number of data blocks */
 	__be64		sb_rblocks;	/* number of realtime blocks */
 	__be64		sb_rextents;	/* number of realtime extents */
-	uuid_t		sb_uuid;	/* file system unique id */
+	uuid_t		sb_uuid;	/* user-visible file system unique id */
 	__be64		sb_logstart;	/* starting block of log if internal */
 	__be64		sb_rootino;	/* root inode number */
 	__be64		sb_rbmino;	/* bitmap inode for realtime extents */

@@ -260,6 +261,7 @@ typedef struct xfs_dsb {
 
 	__be64		sb_pquotino;	/* project quota inode */
 	__be64		sb_lsn;		/* last write sequence */
+	uuid_t		sb_meta_uuid;	/* metadata file system unique id */
 
 	/* must be padded to 64 bit alignment */
 } xfs_dsb_t;

@@ -457,8 +459,10 @@ xfs_sb_has_ro_compat_feature(
 }
 
 #define XFS_SB_FEAT_INCOMPAT_FTYPE	(1 << 0)	/* filetype in dirent */
+#define XFS_SB_FEAT_INCOMPAT_META_UUID	(1 << 1)	/* metadata UUID */
 #define XFS_SB_FEAT_INCOMPAT_ALL \
-		(XFS_SB_FEAT_INCOMPAT_FTYPE)
+		(XFS_SB_FEAT_INCOMPAT_FTYPE | \
+		 XFS_SB_FEAT_INCOMPAT_META_UUID)
 
 #define XFS_SB_FEAT_INCOMPAT_UNKNOWN	~XFS_SB_FEAT_INCOMPAT_ALL
 static inline bool

@@ -507,6 +511,18 @@ static inline int xfs_sb_version_hasfinobt(xfs_sb_t *sbp)
 }
 
 /*
+ * XFS_SB_FEAT_INCOMPAT_META_UUID indicates that the metadata UUID
+ * is stored separately from the user-visible UUID; this allows the
+ * user-visible UUID to be changed on V5 filesystems which have a
+ * filesystem UUID stamped into every piece of metadata.
+ */
+static inline int xfs_sb_version_hasmetauuid(xfs_sb_t *sbp)
+{
+	return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) &&
+		(sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_META_UUID);
+}
+
+/*
  * end of superblock version macros
  */
 

index dc4bfc5..547230f 100644
@@ -377,6 +377,13 @@ __xfs_sb_from_disk(
 	to->sb_pad = 0;
 	to->sb_pquotino = be64_to_cpu(from->sb_pquotino);
 	to->sb_lsn = be64_to_cpu(from->sb_lsn);
+	if (xfs_sb_version_hasmetauuid(to)) {
+		memcpy(&to->sb_meta_uuid, &from->sb_meta_uuid,
+					sizeof(to->sb_meta_uuid));
+	} else {
+		memcpy(&to->sb_meta_uuid, &from->sb_uuid,
+					sizeof(to->sb_meta_uuid));
+	}
 	/* Convert on-disk flags to in-memory flags? */
 	if (convert_xquota)
 		xfs_sb_quota_from_disk(to);

@@ -518,6 +525,10 @@ xfs_sb_to_disk(
 				cpu_to_be32(from->sb_features_log_incompat);
 		to->sb_pad = 0;
 		to->sb_lsn = cpu_to_be64(from->sb_lsn);
+		if (xfs_sb_version_hasmetauuid(from)) {
+			memcpy(&to->sb_meta_uuid, &from->sb_meta_uuid,
+						sizeof(to->sb_meta_uuid));
+		}
 	}
 }
 

index 516162b..27f76ca 100644
@@ -450,7 +450,7 @@ xfs_agfl_verify(
 	struct xfs_agfl	*agfl = XFS_BUF_TO_AGFL(bp);
 	int		i;
 
-	if (!uuid_equal(&agfl->agfl_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	if (be32_to_cpu(agfl->agfl_magicnum) != XFS_AGFL_MAGIC)
 		return false;

@@ -2203,7 +2203,7 @@ xfs_agf_verify(
 	struct xfs_agf	*agf = XFS_BUF_TO_AGF(bp);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
-	    !uuid_equal(&agf->agf_uuid, &mp->m_sb.sb_uuid))
+	    !uuid_equal(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 
 	if (!(agf->agf_magicnum == cpu_to_be32(XFS_AGF_MAGIC) &&

index 59d521c..90de071 100644
@@ -295,7 +295,7 @@ xfs_allocbt_verify(
 	case cpu_to_be32(XFS_ABTB_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (block->bb_u.s.bb_blkno != cpu_to_be64(bp->b_bn))
 			return false;

@@ -313,7 +313,7 @@ xfs_allocbt_verify(
 	case cpu_to_be32(XFS_ABTC_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (block->bb_u.s.bb_blkno != cpu_to_be64(bp->b_bn))
 			return false;

index 04e79d5..6755762 100644
@@ -262,7 +262,7 @@ xfs_attr3_leaf_verify(
 		if (ichdr.magic != XFS_ATTR3_LEAF_MAGIC)
 			return false;
 
-		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->info.blkno) != bp->b_bn)
 			return false;

@@ -1056,7 +1056,7 @@ xfs_attr3_leaf_create(
 
 		hdr3->blkno = cpu_to_be64(bp->b_bn);
 		hdr3->owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);
 
 		ichdr.freemap[0].base = sizeof(struct xfs_attr3_leaf_hdr);
 	} else {

index 20de88d..eba0d1e 100644
@@ -100,7 +100,7 @@ xfs_attr3_rmt_verify(
 		return false;
 	if (rmt->rm_magic != cpu_to_be32(XFS_ATTR3_RMT_MAGIC))
 		return false;
-	if (!uuid_equal(&rmt->rm_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	if (be64_to_cpu(rmt->rm_blkno) != bno)
 		return false;

@@ -217,7 +217,7 @@ xfs_attr3_rmt_hdr_set(
 	rmt->rm_magic = cpu_to_be32(XFS_ATTR3_RMT_MAGIC);
 	rmt->rm_offset = cpu_to_be32(offset);
 	rmt->rm_bytes = cpu_to_be32(size);
-	uuid_copy(&rmt->rm_uuid, &mp->m_sb.sb_uuid);
+	uuid_copy(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid);
 	rmt->rm_owner = cpu_to_be64(ino);
 	rmt->rm_blkno = cpu_to_be64(bno);
 

index 2c44c8e..6b0cf65 100644
@@ -349,7 +349,8 @@ xfs_bmbt_to_bmdr(
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		ASSERT(rblock->bb_magic == cpu_to_be32(XFS_BMAP_CRC_MAGIC));
-		ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid));
+		ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid,
+		       &mp->m_sb.sb_meta_uuid));
 		ASSERT(rblock->bb_u.l.bb_blkno ==
 		       cpu_to_be64(XFS_BUF_DADDR_NULL));
 	} else

@@ -647,7 +648,7 @@ xfs_bmbt_verify(
 	case cpu_to_be32(XFS_BMAP_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(block->bb_u.l.bb_blkno) != bp->b_bn)
 			return false;

index c72283d..f7d7ee7 100644
@@ -65,7 +65,8 @@ xfs_btree_check_lblock(
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		lblock_ok = lblock_ok &&
-			uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid) &&
+			uuid_equal(&block->bb_u.l.bb_uuid,
+				   &mp->m_sb.sb_meta_uuid) &&
 			block->bb_u.l.bb_blkno == cpu_to_be64(
 				bp ? bp->b_bn : XFS_BUF_DADDR_NULL);
 	}

@@ -115,7 +116,8 @@ xfs_btree_check_sblock(
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		sblock_ok = sblock_ok &&
-			uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid) &&
+			uuid_equal(&block->bb_u.s.bb_uuid,
+				   &mp->m_sb.sb_meta_uuid) &&
 			block->bb_u.s.bb_blkno == cpu_to_be64(
 				bp ? bp->b_bn : XFS_BUF_DADDR_NULL);
 	}

@@ -1000,7 +1002,7 @@ xfs_btree_init_block_int(
 		if (flags & XFS_BTREE_CRC_BLOCKS) {
 			buf->bb_u.l.bb_blkno = cpu_to_be64(blkno);
 			buf->bb_u.l.bb_owner = cpu_to_be64(owner);
-			uuid_copy(&buf->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&buf->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid);
 			buf->bb_u.l.bb_pad = 0;
 			buf->bb_u.l.bb_lsn = 0;
 		}

@@ -1013,7 +1015,7 @@ xfs_btree_init_block_int(
 		if (flags & XFS_BTREE_CRC_BLOCKS) {
 			buf->bb_u.s.bb_blkno = cpu_to_be64(blkno);
 			buf->bb_u.s.bb_owner = cpu_to_be32(__owner);
-			uuid_copy(&buf->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&buf->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid);
 			buf->bb_u.s.bb_lsn = 0;
 		}
 	}

index 2385f8c..e9f6709 100644
@@ -146,7 +146,7 @@ xfs_da3_node_verify(
 		if (ichdr.magic != XFS_DA3_NODE_MAGIC)
 			return false;
 
-		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->info.blkno) != bp->b_bn)
 			return false;

@@ -324,7 +324,7 @@ xfs_da3_node_create(
 		ichdr.magic = XFS_DA3_NODE_MAGIC;
 		hdr3->info.blkno = cpu_to_be64(bp->b_bn);
 		hdr3->info.owner = cpu_to_be64(args->dp->i_ino);
-		uuid_copy(&hdr3->info.uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->info.uuid, &mp->m_sb.sb_meta_uuid);
 	} else {
 		ichdr.magic = XFS_DA_NODE_MAGIC;
 	}

index 9354e19..4778d1d 100644
@@ -67,7 +67,7 @@ xfs_dir3_block_verify(
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		if (hdr3->magic != cpu_to_be32(XFS_DIR3_BLOCK_MAGIC))
 			return false;
-		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;

@@ -157,7 +157,7 @@ xfs_dir3_block_init(
 		hdr3->magic = cpu_to_be32(XFS_DIR3_BLOCK_MAGIC);
 		hdr3->blkno = cpu_to_be64(bp->b_bn);
 		hdr3->owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);
 		return;
 
 	}

index de1ea16..6a57fdb 100644
@@ -220,7 +220,7 @@ xfs_dir3_data_verify(
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		if (hdr3->magic != cpu_to_be32(XFS_DIR3_DATA_MAGIC))
 			return false;
-		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;

@@ -604,7 +604,7 @@ xfs_dir3_data_init(
 		hdr3->magic = cpu_to_be32(XFS_DIR3_DATA_MAGIC);
 		hdr3->blkno = cpu_to_be64(bp->b_bn);
 		hdr3->owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);
 
 	} else
 		hdr->magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);

index 1061199..f300240 100644
@@ -160,7 +160,7 @@ xfs_dir3_leaf_verify(
 
 		if (leaf3->info.hdr.magic != cpu_to_be16(magic3))
 			return false;
-		if (!uuid_equal(&leaf3->info.uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&leaf3->info.uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(leaf3->info.blkno) != bp->b_bn)
 			return false;

@@ -310,7 +310,7 @@ xfs_dir3_leaf_init(
 					 : cpu_to_be16(XFS_DIR3_LEAFN_MAGIC);
 		leaf3->info.blkno = cpu_to_be64(bp->b_bn);
 		leaf3->info.owner = cpu_to_be64(owner);
-		uuid_copy(&leaf3->info.uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&leaf3->info.uuid, &mp->m_sb.sb_meta_uuid);
 	} else {
 		memset(leaf, 0, sizeof(*leaf));
 		leaf->hdr.info.magic = cpu_to_be16(type);

index 41b80d3..527b733 100644
@@ -93,7 +93,7 @@ xfs_dir3_free_verify(
 
 		if (hdr3->magic != cpu_to_be32(XFS_DIR3_FREE_MAGIC))
 			return false;
-		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;

@@ -226,7 +226,7 @@ xfs_dir3_free_get_buf(
 
 		hdr3->hdr.blkno = cpu_to_be64(bp->b_bn);
 		hdr3->hdr.owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->hdr.uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->hdr.uuid, &mp->m_sb.sb_meta_uuid);
 	} else
 		hdr.magic = XFS_DIR2_FREE_MAGIC;
 	dp->d_ops->free_hdr_to_disk(bp->b_addr, &hdr);

index 6fbf2d8..5331b7f 100644
@@ -163,7 +163,7 @@ xfs_dqcheck(
 	d->dd_diskdq.d_id = cpu_to_be32(id);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
-		uuid_copy(&d->dd_uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&d->dd_uuid, &mp->m_sb.sb_meta_uuid);
 		xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk),
 				 XFS_DQUOT_CRC_OFF);
 	}

@@ -198,7 +198,7 @@ xfs_dquot_buf_verify_crc(
 		if (!xfs_verify_cksum((char *)d, sizeof(struct xfs_dqblk),
 				 XFS_DQUOT_CRC_OFF))
 			return false;
-		if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 	}
 	return true;

index 07349a1..d9b90c0 100644
@@ -307,7 +307,8 @@ xfs_ialloc_inode_init(
 			if (version == 3) {
 				free->di_ino = cpu_to_be64(ino);
 				ino++;
-				uuid_copy(&free->di_uuid, &mp->m_sb.sb_uuid);
+				uuid_copy(&free->di_uuid,
+					  &mp->m_sb.sb_meta_uuid);
 				xfs_dinode_calc_crc(mp, free);
 			} else if (tp) {
 				/* just log the inode core */

@@ -2049,7 +2050,7 @@ xfs_agi_verify(
 	struct xfs_agi	*agi = XFS_BUF_TO_AGI(bp);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
-	    !uuid_equal(&agi->agi_uuid, &mp->m_sb.sb_uuid))
+	    !uuid_equal(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 	/*
 	 * Validate the magic number of the agi block.

index 964c465..0fa2a27 100644
@@ -230,7 +230,7 @@ xfs_inobt_verify(
 	case cpu_to_be32(XFS_FIBT_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (block->bb_u.s.bb_blkno != cpu_to_be64(bp->b_bn))
 			return false;

index 002b6b3..0f9563e 100644
@@ -306,7 +306,7 @@ xfs_dinode_verify(
 		return false;
 	if (be64_to_cpu(dip->di_ino) != ip->i_ino)
 		return false;
-	if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	return true;
 }

@@ -368,7 +368,7 @@ xfs_iread(
 		if (xfs_sb_version_hascrc(&mp->m_sb)) {
 			ip->i_d.di_version = 3;
 			ip->i_d.di_ino = ip->i_ino;
-			uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid);
 		} else
 			ip->i_d.di_version = 2;
 		return 0;

index e7e26bd..8f8af05 100644
@@ -63,7 +63,7 @@ xfs_symlink_hdr_set(
 	dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
 	dsl->sl_offset = cpu_to_be32(offset);
 	dsl->sl_bytes = cpu_to_be32(size);
-	uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
+	uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
 	dsl->sl_owner = cpu_to_be64(ino);
 	dsl->sl_blkno = cpu_to_be64(bp->b_bn);
 	bp->b_ops = &xfs_symlink_buf_ops;

@@ -107,7 +107,7 @@ xfs_symlink_verify(
 		return false;
 	if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 		return false;
-	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 		return false;

index 02c01bb..e0c7e15 100644
@@ -251,7 +251,7 @@ xfs_qm_init_dquot_blk(
 		d->dd_diskdq.d_id = cpu_to_be32(curid);
 		d->dd_diskdq.d_flags = type;
 		if (xfs_sb_version_hascrc(&mp->m_sb)) {
-			uuid_copy(&d->dd_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&d->dd_uuid, &mp->m_sb.sb_meta_uuid);
 			xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk),
 					 XFS_DQUOT_CRC_OFF);
 		}

index cb7e8a2..9c892cd 100644
@@ -248,7 +248,7 @@ xfs_growfs_data_private(
 		agf->agf_freeblks = cpu_to_be32(tmpsize);
 		agf->agf_longest = cpu_to_be32(tmpsize);
 		if (xfs_sb_version_hascrc(&mp->m_sb))
-			uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid);
 
 		error = xfs_bwrite(bp);
 		xfs_buf_relse(bp);

@@ -271,7 +271,7 @@ xfs_growfs_data_private(
 		if (xfs_sb_version_hascrc(&mp->m_sb)) {
 			agfl->agfl_magicnum = cpu_to_be32(XFS_AGFL_MAGIC);
 			agfl->agfl_seqno = cpu_to_be32(agno);
-			uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid);
 		}
 
 		agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, bp);

@@ -307,7 +307,7 @@ xfs_growfs_data_private(
 		agi->agi_newino = cpu_to_be32(NULLAGINO);
 		agi->agi_dirino = cpu_to_be32(NULLAGINO);
 		if (xfs_sb_version_hascrc(&mp->m_sb))
-			uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid);
 		if (xfs_sb_version_hasfinobt(&mp->m_sb)) {
 			agi->agi_free_root = cpu_to_be32(XFS_FIBT_BLOCK(mp));
 			agi->agi_free_level = cpu_to_be32(1);

index d6ebc85..9a2ecb7 100644
@@ -787,7 +787,7 @@ xfs_ialloc(
 
 	if (ip->i_d.di_version == 3) {
 		ASSERT(ip->i_d.di_ino == ino);
-		ASSERT(uuid_equal(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid));
+		ASSERT(uuid_equal(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid));
 		ip->i_d.di_crc = 0;
 		ip->i_d.di_changecount = 1;
 		ip->i_d.di_lsn = 0;

index 950d1ea..c27c294 100644
@@ -107,7 +107,7 @@ typedef struct xfs_sb {
 	xfs_drfsbno_t	sb_dblocks;	/* number of data blocks */
 	xfs_drfsbno_t	sb_rblocks;	/* number of realtime blocks */
 	xfs_drtbno_t	sb_rextents;	/* number of realtime extents */
-	uuid_t		sb_uuid;	/* file system unique id */
+	uuid_t		sb_uuid;	/* user-visible file system unique id */
 	xfs_dfsbno_t	sb_logstart;	/* starting block of log if internal */
 	xfs_ino_t	sb_rootino;	/* root inode number */
 	xfs_ino_t	sb_rbmino;	/* bitmap inode for realtime extents */

@@ -178,6 +178,7 @@ typedef struct xfs_sb {
 
 	xfs_ino_t	sb_pquotino;	/* project quota inode */
 	xfs_lsn_t	sb_lsn;		/* last write sequence */
+	uuid_t		sb_meta_uuid;	/* metadata file system unique id */
 
 	/* must be padded to 64 bit alignment */
 } xfs_sb_t;

@@ -194,7 +195,7 @@ typedef struct xfs_dsb {
 	__be64		sb_dblocks;	/* number of data blocks */
 	__be64		sb_rblocks;	/* number of realtime blocks */
 	__be64		sb_rextents;	/* number of realtime extents */
-	uuid_t		sb_uuid;	/* file system unique id */
+	uuid_t		sb_uuid;	/* user-visible file system unique id */
 	__be64		sb_logstart;	/* starting block of log if internal */
 	__be64		sb_rootino;	/* root inode number */
 	__be64		sb_rbmino;	/* bitmap inode for realtime extents */

@@ -264,6 +265,7 @@ typedef struct xfs_dsb {
 
 	__be64		sb_pquotino;	/* project quota inode */
 	__be64		sb_lsn;		/* last write sequence */
+	uuid_t		sb_meta_uuid;	/* metadata file system unique id */
 
 	/* must be padded to 64 bit alignment */
 } xfs_dsb_t;

@@ -287,7 +289,7 @@ typedef enum {
 	XFS_SBS_FEATURES2, XFS_SBS_BAD_FEATURES2, XFS_SBS_FEATURES_COMPAT,
 	XFS_SBS_FEATURES_RO_COMPAT, XFS_SBS_FEATURES_INCOMPAT,
 	XFS_SBS_FEATURES_LOG_INCOMPAT, XFS_SBS_CRC, XFS_SBS_PAD,
-	XFS_SBS_PQUOTINO, XFS_SBS_LSN,
+	XFS_SBS_PQUOTINO, XFS_SBS_LSN, XFS_SBS_META_UUID,
 	XFS_SBS_FIELDCOUNT
 } xfs_sb_field_t;
 

@@ -319,6 +321,7 @@ typedef enum {
 #define XFS_SB_FEATURES_LOG_INCOMPAT XFS_SB_MVAL(FEATURES_LOG_INCOMPAT)
 #define XFS_SB_CRC		XFS_SB_MVAL(CRC)
 #define XFS_SB_PQUOTINO		XFS_SB_MVAL(PQUOTINO)
+#define	XFS_SB_META_UUID	XFS_SB_MVAL(META_UUID)
 #define	XFS_SB_NUM_BITS		((int)XFS_SBS_FIELDCOUNT)
 #define	XFS_SB_ALL_BITS		((1LL << XFS_SB_NUM_BITS) - 1)
 #define	XFS_SB_MOD_BITS		\

@@ -328,7 +331,7 @@ typedef enum {
 	 XFS_SB_ICOUNT | XFS_SB_IFREE | XFS_SB_FDBLOCKS | XFS_SB_FEATURES2 | \
 	 XFS_SB_BAD_FEATURES2 | XFS_SB_FEATURES_COMPAT | \
 	 XFS_SB_FEATURES_RO_COMPAT | XFS_SB_FEATURES_INCOMPAT | \
-	 XFS_SB_FEATURES_LOG_INCOMPAT | XFS_SB_PQUOTINO)
+	 XFS_SB_FEATURES_LOG_INCOMPAT | XFS_SB_PQUOTINO | XFS_SB_META_UUID)
 
 
 /*

@@ -600,8 +603,10 @@ xfs_sb_has_ro_compat_feature(
 }
 
 #define XFS_SB_FEAT_INCOMPAT_FTYPE	(1 << 0)	/* filetype in dirent */
+#define XFS_SB_FEAT_INCOMPAT_META_UUID (1 << 1)		/* metadata UUID */
 #define XFS_SB_FEAT_INCOMPAT_ALL \
-		(XFS_SB_FEAT_INCOMPAT_FTYPE)
+		(XFS_SB_FEAT_INCOMPAT_FTYPE | \
+		 XFS_SB_FEAT_INCOMPAT_META_UUID)
 
 #define XFS_SB_FEAT_INCOMPAT_UNKNOWN	~XFS_SB_FEAT_INCOMPAT_ALL
 static inline bool

@@ -650,6 +655,18 @@ static inline int xfs_sb_version_hasfinobt(xfs_sb_t *sbp)
 }
 
 /*
+ * XFS_SB_FEAT_INCOMPAT_META_UUID indicates that the metadata UUID
+ * is stored separately from the user-visible UUID; this allows the
+ * user-visible UUID to be changed on V5 filesystems which have a
+ * filesystem UUID stamped into every piece of metadata.
+ */
+static inline int xfs_sb_version_hasmetauuid(xfs_sb_t *sbp)
+{
+	return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) &&
+		(sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_META_UUID);
+}
+
+/*
  * end of superblock version macros
  */
 

index ea89367..c9ef019 100644
@@ -81,6 +81,7 @@ static const struct {
 	{ offsetof(xfs_sb_t, sb_pad),		0 },
 	{ offsetof(xfs_sb_t, sb_pquotino),	0 },
 	{ offsetof(xfs_sb_t, sb_lsn),		0 },
+	{ offsetof(xfs_sb_t, sb_meta_uuid),		1 },
 	{ sizeof(xfs_sb_t),			0 }
 };
 

@@ -413,6 +414,13 @@ xfs_sb_from_disk(
 	to->sb_pad = 0;
 	to->sb_pquotino = be64_to_cpu(from->sb_pquotino);
 	to->sb_lsn = be64_to_cpu(from->sb_lsn);
+	if (xfs_sb_version_hasmetauuid(to)) {
+		memcpy(&to->sb_meta_uuid, &from->sb_meta_uuid,
+					sizeof(to->sb_meta_uuid));
+	} else {
+		memcpy(&to->sb_meta_uuid, &from->sb_uuid,
+					sizeof(to->sb_meta_uuid));
+	}
 }
 
 static inline void

@@ -490,6 +498,13 @@ xfs_sb_to_disk(
 	/* We should never write the crc here, it's updated in the IO path */
 	fields &= ~XFS_SB_CRC;
 
+	/*
+	 * If the metadata-specific UUID feature isn't set, it's only set
+	 * in memory; don't write it out.
+	 */
+	if (!xfs_sb_version_hasmetauuid(from))
+		fields &= ~XFS_SB_UUID;
+
 	xfs_sb_quota_to_disk(to, from, &fields);
 	while (fields) {
 		f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);

59 lines not on this page · raw message

103 lines not on this page · raw message

index 49eb76d..ea698c4 100644
@@ -250,7 +250,7 @@ libxfs_ialloc(
 
 	if (ip->i_d.di_version == 3) {
 		ASSERT(ip->i_d.di_ino == ino);
-		ASSERT(uuid_equal(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid));
+		ASSERT(uuid_equal(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid));
 		ip->i_d.di_crc = 0;
 		ip->i_d.di_changecount = 1;
 		ip->i_d.di_lsn = 0;

index 6c82be0..06757c3 100644
@@ -426,7 +426,7 @@ xfs_agfl_verify(
 	struct xfs_agfl	*agfl = XFS_BUF_TO_AGFL(bp);
 	int		i;
 
-	if (!uuid_equal(&agfl->agfl_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	if (be32_to_cpu(agfl->agfl_magicnum) != XFS_AGFL_MAGIC)
 		return false;

@@ -2181,7 +2181,7 @@ xfs_agf_verify(
 	struct xfs_agf	*agf = XFS_BUF_TO_AGF(bp);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
-	    !uuid_equal(&agf->agf_uuid, &mp->m_sb.sb_uuid))
+	    !uuid_equal(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 
 	if (!(agf->agf_magicnum == cpu_to_be32(XFS_AGF_MAGIC) &&

index 215be7e..cefa18b 100644
@@ -279,7 +279,7 @@ xfs_allocbt_verify(
 	case cpu_to_be32(XFS_ABTB_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (block->bb_u.s.bb_blkno != cpu_to_be64(bp->b_bn))
 			return false;

@@ -297,7 +297,7 @@ xfs_allocbt_verify(
 	case cpu_to_be32(XFS_ABTC_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (block->bb_u.s.bb_blkno != cpu_to_be64(bp->b_bn))
 			return false;

index f7f02ae..e9f96ec 100644
@@ -161,7 +161,7 @@ xfs_attr3_leaf_verify(
 		if (ichdr.magic != XFS_ATTR3_LEAF_MAGIC)
 			return false;
 
-		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->info.blkno) != bp->b_bn)
 			return false;

@@ -952,7 +952,7 @@ xfs_attr3_leaf_create(
 
 		hdr3->blkno = cpu_to_be64(bp->b_bn);
 		hdr3->owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);
 
 		ichdr.freemap[0].base = sizeof(struct xfs_attr3_leaf_hdr);
 	} else {

index 08b983b..62abaec 100644
@@ -78,7 +78,7 @@ xfs_attr3_rmt_verify(
 		return false;
 	if (rmt->rm_magic != cpu_to_be32(XFS_ATTR3_RMT_MAGIC))
 		return false;
-	if (!uuid_equal(&rmt->rm_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	if (be64_to_cpu(rmt->rm_blkno) != bno)
 		return false;

@@ -194,7 +194,7 @@ xfs_attr3_rmt_hdr_set(
 	rmt->rm_magic = cpu_to_be32(XFS_ATTR3_RMT_MAGIC);
 	rmt->rm_offset = cpu_to_be32(offset);
 	rmt->rm_bytes = cpu_to_be32(size);
-	uuid_copy(&rmt->rm_uuid, &mp->m_sb.sb_uuid);
+	uuid_copy(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid);
 	rmt->rm_owner = cpu_to_be64(ino);
 	rmt->rm_blkno = cpu_to_be64(bno);
 

index a4bd69d..9913958 100644
@@ -412,7 +412,8 @@ xfs_bmbt_to_bmdr(
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		ASSERT(rblock->bb_magic == cpu_to_be32(XFS_BMAP_CRC_MAGIC));
-		ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid));
+		ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid,
+				  &mp->m_sb.sb_meta_uuid));
 		ASSERT(rblock->bb_u.l.bb_blkno ==
 		       cpu_to_be64(XFS_BUF_DADDR_NULL));
 	} else

@@ -712,7 +713,7 @@ xfs_bmbt_verify(
 	case cpu_to_be32(XFS_BMAP_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(block->bb_u.l.bb_blkno) != bp->b_bn)
 			return false;

index cc823f5..a8436f5 100644
@@ -50,7 +50,8 @@ xfs_btree_check_lblock(
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		lblock_ok = lblock_ok &&
-			uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid) &&
+			uuid_equal(&block->bb_u.l.bb_uuid,
+				   &mp->m_sb.sb_meta_uuid) &&
 			block->bb_u.l.bb_blkno == cpu_to_be64(
 				bp ? bp->b_bn : XFS_BUF_DADDR_NULL);
 	}

@@ -100,7 +101,8 @@ xfs_btree_check_sblock(
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		sblock_ok = sblock_ok &&
-			uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid) &&
+			uuid_equal(&block->bb_u.s.bb_uuid,
+				   &mp->m_sb.sb_meta_uuid) &&
 			block->bb_u.s.bb_blkno == cpu_to_be64(
 				bp ? bp->b_bn : XFS_BUF_DADDR_NULL);
 	}

@@ -992,7 +994,7 @@ xfs_btree_init_block_int(
 		if (flags & XFS_BTREE_CRC_BLOCKS) {
 			buf->bb_u.l.bb_blkno = cpu_to_be64(blkno);
 			buf->bb_u.l.bb_owner = cpu_to_be64(owner);
-			uuid_copy(&buf->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&buf->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid);
 			buf->bb_u.l.bb_pad = 0;
 			buf->bb_u.l.bb_lsn = 0;
 		}

@@ -1005,7 +1007,7 @@ xfs_btree_init_block_int(
 		if (flags & XFS_BTREE_CRC_BLOCKS) {
 			buf->bb_u.s.bb_blkno = cpu_to_be64(blkno);
 			buf->bb_u.s.bb_owner = cpu_to_be32(__owner);
-			uuid_copy(&buf->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&buf->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid);
 			buf->bb_u.s.bb_lsn = 0;
 		}
 	}

index b731b54..0323dc7 100644
@@ -172,7 +172,7 @@ xfs_da3_node_verify(
 		if (ichdr.magic != XFS_DA3_NODE_MAGIC)
 			return false;
 
-		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->info.blkno) != bp->b_bn)
 			return false;

@@ -349,7 +349,7 @@ xfs_da3_node_create(
 		ichdr.magic = XFS_DA3_NODE_MAGIC;
 		hdr3->info.blkno = cpu_to_be64(bp->b_bn);
 		hdr3->info.owner = cpu_to_be64(args->dp->i_ino);
-		uuid_copy(&hdr3->info.uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->info.uuid, &mp->m_sb.sb_meta_uuid);
 	} else {
 		ichdr.magic = XFS_DA_NODE_MAGIC;
 	}

index cede01f..2a25059 100644
@@ -51,7 +51,7 @@ xfs_dir3_block_verify(
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		if (hdr3->magic != cpu_to_be32(XFS_DIR3_BLOCK_MAGIC))
 			return false;
-		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;

@@ -141,7 +141,7 @@ xfs_dir3_block_init(
 		hdr3->magic = cpu_to_be32(XFS_DIR3_BLOCK_MAGIC);
 		hdr3->blkno = cpu_to_be64(bp->b_bn);
 		hdr3->owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);
 		return;
 
 	}

index dc9df4d..4c79d7c 100644
@@ -186,7 +186,7 @@ xfs_dir3_data_verify(
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		if (hdr3->magic != cpu_to_be32(XFS_DIR3_DATA_MAGIC))
 			return false;
-		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;

@@ -573,7 +573,7 @@ xfs_dir3_data_init(
 		hdr3->magic = cpu_to_be32(XFS_DIR3_DATA_MAGIC);
 		hdr3->blkno = cpu_to_be64(bp->b_bn);
 		hdr3->owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);
 
 	} else
 		hdr->magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);

index 8e0cbc9..a918e15 100644
@@ -186,7 +186,7 @@ xfs_dir3_leaf_verify(
 
 		if (leaf3->info.hdr.magic != cpu_to_be16(magic3))
 			return false;
-		if (!uuid_equal(&leaf3->info.uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&leaf3->info.uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(leaf3->info.blkno) != bp->b_bn)
 			return false;

@@ -337,7 +337,7 @@ xfs_dir3_leaf_init(
 					 : cpu_to_be16(XFS_DIR3_LEAFN_MAGIC);
 		leaf3->info.blkno = cpu_to_be64(bp->b_bn);
 		leaf3->info.owner = cpu_to_be64(owner);
-		uuid_copy(&leaf3->info.uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&leaf3->info.uuid, &mp->m_sb.sb_meta_uuid);
 	} else {
 		memset(leaf, 0, sizeof(*leaf));
 		leaf->hdr.info.magic = cpu_to_be16(type);

index 3737e4e..309e7ce 100644
@@ -78,7 +78,7 @@ xfs_dir3_free_verify(
 
 		if (hdr3->magic != cpu_to_be32(XFS_DIR3_FREE_MAGIC))
 			return false;
-		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;

@@ -257,7 +257,7 @@ xfs_dir3_free_get_buf(
 
 		hdr3->hdr.blkno = cpu_to_be64(bp->b_bn);
 		hdr3->hdr.owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->hdr.uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->hdr.uuid, &mp->m_sb.sb_meta_uuid);
 	} else
 		hdr.magic = XFS_DIR2_FREE_MAGIC;
 	xfs_dir3_free_hdr_to_disk(bp->b_addr, &hdr);

index e089ec8..f75bfe3 100644
@@ -146,7 +146,7 @@ xfs_dqcheck(
 	d->dd_diskdq.d_id = cpu_to_be32(id);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
-		uuid_copy(&d->dd_uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&d->dd_uuid, &mp->m_sb.sb_meta_uuid);
 		xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk),
 				 XFS_DQUOT_CRC_OFF);
 	}

@@ -181,7 +181,7 @@ xfs_dquot_buf_verify_crc(
 		if (!xfs_verify_cksum((char *)d, sizeof(struct xfs_dqblk),
 				 XFS_DQUOT_CRC_OFF))
 			return false;
-		if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 	}
 	return true;

index b20a9ec..ae0804c 100644
@@ -295,7 +295,8 @@ xfs_ialloc_inode_init(
 			if (version == 3) {
 				free->di_ino = cpu_to_be64(ino);
 				ino++;
-				uuid_copy(&free->di_uuid, &mp->m_sb.sb_uuid);
+				uuid_copy(&free->di_uuid,
+					  &mp->m_sb.sb_meta_uuid);
 				xfs_dinode_calc_crc(mp, free);
 			} else if (tp) {
 				/* just log the inode core */

@@ -1947,7 +1948,7 @@ xfs_agi_verify(
 	struct xfs_agi	*agi = XFS_BUF_TO_AGI(bp);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
-	    !uuid_equal(&agi->agi_uuid, &mp->m_sb.sb_uuid))
+	    !uuid_equal(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 	/*
 	 * Validate the magic number of the agi block.

index c337389..320984f 100644
@@ -214,7 +214,7 @@ xfs_inobt_verify(
 	case cpu_to_be32(XFS_FIBT_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (block->bb_u.s.bb_blkno != cpu_to_be64(bp->b_bn))
 			return false;

index de16ed9..1c0047d 100644
@@ -295,7 +295,7 @@ xfs_dinode_verify(
 		return false;
 	if (be64_to_cpu(dip->di_ino) != ino)
 		return false;
-	if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	return true;
 }

index ebf60ac..3f8374e 100644
@@ -48,7 +48,7 @@ xfs_symlink_hdr_set(
 	dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
 	dsl->sl_offset = cpu_to_be32(offset);
 	dsl->sl_bytes = cpu_to_be32(size);
-	uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
+	uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
 	dsl->sl_owner = cpu_to_be64(ino);
 	dsl->sl_blkno = cpu_to_be64(bp->b_bn);
 	bp->b_ops = &xfs_symlink_buf_ops;

@@ -93,7 +93,7 @@ xfs_symlink_verify(
 		return false;
 	if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 		return false;
-	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 		return false;

index 949b79d..652d391 100644
@@ -28,8 +28,10 @@ header_check_uuid(xfs_mount_t *mp, xlog_rec_header_t *head)
 {
     char uu_log[64], uu_sb[64];
 
-    if (print_skip_uuid) return 0;
-    if (!platform_uuid_compare(&mp->m_sb.sb_uuid, &head->h_fs_uuid)) return 0;
+    if (print_skip_uuid)
+		return 0;
+    if (!platform_uuid_compare(&mp->m_sb.sb_uuid, &head->h_fs_uuid))
+		return 0;
 
     platform_uuid_unparse(&mp->m_sb.sb_uuid, uu_sb);
     platform_uuid_unparse(&head->h_fs_uuid, uu_log);

index 5084d75..a75e90c 100644
@@ -2755,7 +2755,8 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
 		agf->agf_freeblks = cpu_to_be32(nbmblocks);
 		agf->agf_longest = cpu_to_be32(nbmblocks);
 		if (xfs_sb_version_hascrc(&mp->m_sb))
-			platform_uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_uuid);
+			platform_uuid_copy(&agf->agf_uuid,
+					   &mp->m_sb.sb_meta_uuid);
 
 		if (loginternal && agno == logagno) {
 			be32_add_cpu(&agf->agf_freeblks, -logblocks);

@@ -2779,7 +2780,8 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
 		if (xfs_sb_version_hascrc(&mp->m_sb)) {
 			agfl->agfl_magicnum = cpu_to_be32(XFS_AGFL_MAGIC);
 			agfl->agfl_seqno = cpu_to_be32(agno);
-			platform_uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_uuid);
+			platform_uuid_copy(&agfl->agfl_uuid,
+					   &mp->m_sb.sb_meta_uuid);
 			for (bucket = 0; bucket < XFS_AGFL_SIZE(mp); bucket++)
 				agfl->agfl_bno[bucket] = cpu_to_be32(NULLAGBLOCK);
 		}

@@ -2810,7 +2812,8 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
 		agi->agi_newino = cpu_to_be32(NULLAGINO);
 		agi->agi_dirino = cpu_to_be32(NULLAGINO);
 		if (xfs_sb_version_hascrc(&mp->m_sb))
-			platform_uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_uuid);
+			platform_uuid_copy(&agi->agi_uuid,
+					   &mp->m_sb.sb_meta_uuid);
 		for (c = 0; c < XFS_AGI_UNLINKED_BUCKETS; c++)
 			agi->agi_unlinked[c] = cpu_to_be32(NULLAGINO);
 		libxfs_writebuf(buf, LIBXFS_EXIT_ON_FAILURE);

index 5dbf992..5200ff0 100644
@@ -112,7 +112,7 @@ verify_set_agf(xfs_mount_t *mp, xfs_agf_t *agf, xfs_agnumber_t i)
 	if (!xfs_sb_version_hascrc(&mp->m_sb))
 		return retval;
 
-	if (platform_uuid_compare(&agf->agf_uuid, &mp->m_sb.sb_uuid)) {
+	if (platform_uuid_compare(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid)) {
 		char uu[64];
 
 		retval = XR_AG_AGF;

@@ -120,7 +120,8 @@ verify_set_agf(xfs_mount_t *mp, xfs_agf_t *agf, xfs_agnumber_t i)
 		do_warn(_("bad uuid %s for agf %d\n"), uu, i);
 
 		if (!no_modify)
-			platform_uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_uuid);
+			platform_uuid_copy(&agf->agf_uuid,
+					   &mp->m_sb.sb_meta_uuid);
 	}
 	return retval;
 }

@@ -190,7 +191,7 @@ verify_set_agi(xfs_mount_t *mp, xfs_agi_t *agi, xfs_agnumber_t agno)
 	if (!xfs_sb_version_hascrc(&mp->m_sb))
 		return retval;
 
-	if (platform_uuid_compare(&agi->agi_uuid, &mp->m_sb.sb_uuid)) {
+	if (platform_uuid_compare(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid)) {
 		char uu[64];
 
 		retval = XR_AG_AGI;

@@ -198,7 +199,8 @@ verify_set_agi(xfs_mount_t *mp, xfs_agi_t *agi, xfs_agnumber_t agno)
 		do_warn(_("bad uuid %s for agi %d\n"), uu, agno);
 
 		if (!no_modify)
-			platform_uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_uuid);
+			platform_uuid_copy(&agi->agi_uuid,
+					   &mp->m_sb.sb_meta_uuid);
 	}
 
 	return retval;

@@ -245,7 +247,7 @@ compare_sb(xfs_mount_t *mp, xfs_sb_t *sb)
  * superblocks, not just the secondary superblocks.
  */
 static int
-secondary_sb_wack(
+secondary_sb_whack(
 	struct xfs_mount *mp,
 	struct xfs_buf	*sbuf,
 	struct xfs_sb	*sb,

@@ -267,7 +269,10 @@ secondary_sb_wack(
 	 *
 	 * size is the size of data which is valid for this sb.
 	 */
-	if (xfs_sb_version_hascrc(sb))
+	if (xfs_sb_version_hasmetauuid(sb))
+		size = offsetof(xfs_sb_t, sb_meta_uuid)
+			+ sizeof(sb->sb_meta_uuid);
+	else if (xfs_sb_version_hascrc(sb))
 		size = offsetof(xfs_sb_t, sb_lsn)
 			+ sizeof(sb->sb_lsn);
 	else if (xfs_sb_version_hasmorebits(sb))

@@ -526,7 +531,7 @@ verify_set_agheader(xfs_mount_t *mp, xfs_buf_t *sbuf, xfs_sb_t *sb,
 		rval |= XR_AG_SB;
 	}
 
-	rval |= secondary_sb_wack(mp, sbuf, sb, i);
+	rval |= secondary_sb_whack(mp, sbuf, sb, i);
 
 	rval |= verify_set_agf(mp, agf, i);
 	rval |= verify_set_agi(mp, agi, i);

index b5c10ec..fa6fc26 100644
@@ -24,7 +24,6 @@ typedef struct fs_geometry  {
 	xfs_drfsbno_t	sb_dblocks;	/* # data blocks */
 	xfs_drfsbno_t	sb_rblocks;	/* # realtime blocks */
 	xfs_drtbno_t	sb_rextents;	/* # realtime extents */
-	uuid_t		sb_uuid;	/* fs uuid */
 	xfs_dfsbno_t	sb_logstart;	/* starting log block # */
 	xfs_agblock_t	sb_rextsize;	/* realtime extent size (blocks )*/
 	xfs_agblock_t	sb_agblocks;	/* # of blocks per ag */

index 035212c..5d22652 100644
@@ -208,9 +208,9 @@ clear_dinode_core(struct xfs_mount *mp, xfs_dinode_t *dinoc, xfs_ino_t ino_num)
 		dinoc->di_ino = cpu_to_be64(ino_num);
 	}
 
-	if (platform_uuid_compare(&dinoc->di_uuid, &mp->m_sb.sb_uuid)) {
+	if (platform_uuid_compare(&dinoc->di_uuid, &mp->m_sb.sb_meta_uuid)) {
 		__dirty_no_modify_ret(dirty);
-		platform_uuid_copy(&dinoc->di_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&dinoc->di_uuid, &mp->m_sb.sb_meta_uuid);
 	}
 
 	for (i = 0; i < sizeof(dinoc->di_pad2)/sizeof(dinoc->di_pad2[0]); i++) {

@@ -2366,7 +2366,8 @@ _("inode identifier %llu mismatch on inode %" PRIu64 "\n"),
 				return 1;
 			goto clear_bad_out;
 		}
-		if (platform_uuid_compare(&dino->di_uuid, &mp->m_sb.sb_uuid)) {
+		if (platform_uuid_compare(&dino->di_uuid,
+					  &mp->m_sb.sb_meta_uuid)) {
 			if (!uncertain)
 				do_warn(
 			_("UUID mismatch on inode %" PRIu64 "\n"), lino);

index 3a2cdbb..d6f2ead 100644
@@ -1119,7 +1119,7 @@ build_agi(xfs_mount_t *mp, xfs_agnumber_t agno, bt_status_t *btree_curs,
 		agi->agi_unlinked[i] = cpu_to_be32(NULLAGINO);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb))
-		platform_uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid);
 
 	if (xfs_sb_version_hasfinobt(&mp->m_sb)) {
 		agi->agi_free_root = cpu_to_be32(finobt_curs->root);

@@ -1360,7 +1360,7 @@ build_agf_agfl(xfs_mount_t	*mp,
 #endif
 
 	if (xfs_sb_version_hascrc(&mp->m_sb))
-		platform_uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid);
 
 	/* initialise the AGFL, then fill it if there are blocks left over. */
 	agfl_buf = libxfs_getbuf(mp->m_dev,

@@ -1374,7 +1374,7 @@ build_agf_agfl(xfs_mount_t	*mp,
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		agfl->agfl_magicnum = cpu_to_be32(XFS_AGFL_MAGIC);
 		agfl->agfl_seqno = cpu_to_be32(agno);
-		platform_uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid);
 		for (i = 0; i < XFS_AGFL_SIZE(mp); i++)
 			agfl->agfl_bno[i] = cpu_to_be32(NULLAGBLOCK);
 	}

index c09b394..96204b9 100644
@@ -526,7 +526,7 @@ mk_rbmino(xfs_mount_t *mp)
 		ip->i_d.di_flags2 = 0;
 		ip->i_d.di_ino = mp->m_sb.sb_rbmino;
 		memset(&(ip->i_d.di_pad2[0]), 0, sizeof(ip->i_d.di_pad2));
-		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid);
 		times |= XFS_ICHGTIME_CREATE;
 	}
 	libxfs_trans_ichgtime(tp, ip, times);

@@ -782,7 +782,7 @@ mk_rsumino(xfs_mount_t *mp)
 		ip->i_d.di_flags2 = 0;
 		ip->i_d.di_ino = mp->m_sb.sb_rsumino;
 		memset(&(ip->i_d.di_pad2[0]), 0, sizeof(ip->i_d.di_pad2));
-		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid);
 		times |= XFS_ICHGTIME_CREATE;
 	}
 	libxfs_trans_ichgtime(tp, ip, times);

@@ -898,7 +898,7 @@ mk_root_dir(xfs_mount_t *mp)
 		ip->i_d.di_flags2 = 0;
 		ip->i_d.di_ino = mp->m_sb.sb_rootino;
 		memset(&(ip->i_d.di_pad2[0]), 0, sizeof(ip->i_d.di_pad2));
-		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid);
 		times |= XFS_ICHGTIME_CREATE;
 	}
 	libxfs_trans_ichgtime(tp, ip, times);

index 279527c..a58eee5 100644
@@ -466,6 +466,34 @@ write_wbuf(void)
 	sighold(SIGCHLD);
 }
 
+void
+sb_update_uuid(
+	xfs_sb_t	*sb,
+	ag_header_t	*ag_hdr,
+	thread_args	*tcarg)
+{
+	/*
+	 * If this filesystem has CRCs, the original UUID is stamped into
+	 * all metadata.  We need to copy the original UUID into the meta_uuid
+	 * slot and set the incompat flag if that hasn't already been done.
+	 */
+	if (xfs_sb_version_hascrc(sb) && !xfs_sb_version_hasmetauuid(sb)) {
+		__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);
+	}
+
+	platform_uuid_copy(&ag_hdr->xfs_sb->sb_uuid, &tcarg->uuid);
+
+	/* We changed the UUID, so update the superblock CRC if needed */
+	if (xfs_sb_version_hascrc(sb))
+		xfs_update_cksum((char *)&ag_hdr->xfs_sb, sb->sb_sectsize,
+							 XFS_SB_CRC_OFF);
+}
 
 int
 main(int argc, char **argv)

@@ -659,16 +687,6 @@ main(int argc, char **argv)
 	sb = &mbuf.m_sb;
 	libxfs_sb_from_disk(sb, XFS_BUF_TO_SBP(sbp));
 
-	/*
-	 * For now, V5 superblock filesystems are not supported without -d;
-	 * we do not have the infrastructure yet to fix CRCs when a new UUID
-	 * is generated.
-	 */
-	if (xfs_sb_version_hascrc(sb) && !duplicate) {
-		do_log(_("%s: Cannot yet copy V5 fs without '-d'\n"), progname);
-		exit(1);
-	}
-
 	mp = libxfs_mount(&mbuf, sb, xargs.ddev, xargs.logdev, xargs.rtdev, 0);
 	if (mp == NULL) {
 		do_log(_("%s: %s filesystem failed to initialize\n"

@@ -1127,8 +1145,7 @@ main(int argc, char **argv)
 			/* do each thread in turn, each has its own UUID */
 
 			for (j = 0, tcarg = targ; j < num_targets; j++)  {
-				platform_uuid_copy(&ag_hdr.xfs_sb->sb_uuid,
-							&tcarg->uuid);
+				sb_update_uuid(sb, &ag_hdr, tcarg);
 				do_write(tcarg);
 				tcarg++;
 			}

103 lines not on this page · raw message

index c9ef019..ea30857 100644
@@ -503,7 +503,7 @@ xfs_sb_to_disk(
 	 * in memory; don't write it out.
 	 */
 	if (!xfs_sb_version_hasmetauuid(from))
-		fields &= ~XFS_SB_UUID;
+		fields &= ~XFS_SB_META_UUID;
 
 	xfs_sb_quota_to_disk(to, from, &fields);
 	while (fields) {

index 949b79d..652d391 100644
@@ -28,8 +28,10 @@ header_check_uuid(xfs_mount_t *mp, xlog_rec_header_t *head)
 {
     char uu_log[64], uu_sb[64];
 
-    if (print_skip_uuid) return 0;
-    if (!platform_uuid_compare(&mp->m_sb.sb_uuid, &head->h_fs_uuid)) return 0;
+    if (print_skip_uuid)
+		return 0;
+    if (!platform_uuid_compare(&mp->m_sb.sb_uuid, &head->h_fs_uuid))
+		return 0;
 
     platform_uuid_unparse(&mp->m_sb.sb_uuid, uu_sb);
     platform_uuid_unparse(&head->h_fs_uuid, uu_log);

index 5084d75..eb8b74d 100644
@@ -2598,6 +2598,8 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
 	sbp->sb_rextents = rtextents;
 	platform_uuid_generate(&uuid);
 	platform_uuid_copy(&sbp->sb_uuid, &uuid);
+	/* Only in memory; libxfs expects this */
+	platform_uuid_copy(&sbp->sb_meta_uuid, &uuid);
 	sbp->sb_logstart = logstart;
 	sbp->sb_rootino = sbp->sb_rbmino = sbp->sb_rsumino = NULLFSINO;
 	sbp->sb_rextsize = rtextblocks;

index 5dbf992..5200ff0 100644
@@ -112,7 +112,7 @@ verify_set_agf(xfs_mount_t *mp, xfs_agf_t *agf, xfs_agnumber_t i)
 	if (!xfs_sb_version_hascrc(&mp->m_sb))
 		return retval;
 
-	if (platform_uuid_compare(&agf->agf_uuid, &mp->m_sb.sb_uuid)) {
+	if (platform_uuid_compare(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid)) {
 		char uu[64];
 
 		retval = XR_AG_AGF;

@@ -120,7 +120,8 @@ verify_set_agf(xfs_mount_t *mp, xfs_agf_t *agf, xfs_agnumber_t i)
 		do_warn(_("bad uuid %s for agf %d\n"), uu, i);
 
 		if (!no_modify)
-			platform_uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_uuid);
+			platform_uuid_copy(&agf->agf_uuid,
+					   &mp->m_sb.sb_meta_uuid);
 	}
 	return retval;
 }

@@ -190,7 +191,7 @@ verify_set_agi(xfs_mount_t *mp, xfs_agi_t *agi, xfs_agnumber_t agno)
 	if (!xfs_sb_version_hascrc(&mp->m_sb))
 		return retval;
 
-	if (platform_uuid_compare(&agi->agi_uuid, &mp->m_sb.sb_uuid)) {
+	if (platform_uuid_compare(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid)) {
 		char uu[64];
 
 		retval = XR_AG_AGI;

@@ -198,7 +199,8 @@ verify_set_agi(xfs_mount_t *mp, xfs_agi_t *agi, xfs_agnumber_t agno)
 		do_warn(_("bad uuid %s for agi %d\n"), uu, agno);
 
 		if (!no_modify)
-			platform_uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_uuid);
+			platform_uuid_copy(&agi->agi_uuid,
+					   &mp->m_sb.sb_meta_uuid);
 	}
 
 	return retval;

@@ -245,7 +247,7 @@ compare_sb(xfs_mount_t *mp, xfs_sb_t *sb)
  * superblocks, not just the secondary superblocks.
  */
 static int
-secondary_sb_wack(
+secondary_sb_whack(
 	struct xfs_mount *mp,
 	struct xfs_buf	*sbuf,
 	struct xfs_sb	*sb,

@@ -267,7 +269,10 @@ secondary_sb_wack(
 	 *
 	 * size is the size of data which is valid for this sb.
 	 */
-	if (xfs_sb_version_hascrc(sb))
+	if (xfs_sb_version_hasmetauuid(sb))
+		size = offsetof(xfs_sb_t, sb_meta_uuid)
+			+ sizeof(sb->sb_meta_uuid);
+	else if (xfs_sb_version_hascrc(sb))
 		size = offsetof(xfs_sb_t, sb_lsn)
 			+ sizeof(sb->sb_lsn);
 	else if (xfs_sb_version_hasmorebits(sb))

@@ -526,7 +531,7 @@ verify_set_agheader(xfs_mount_t *mp, xfs_buf_t *sbuf, xfs_sb_t *sb,
 		rval |= XR_AG_SB;
 	}
 
-	rval |= secondary_sb_wack(mp, sbuf, sb, i);
+	rval |= secondary_sb_whack(mp, sbuf, sb, i);
 
 	rval |= verify_set_agf(mp, agf, i);
 	rval |= verify_set_agi(mp, agi, i);

index b5c10ec..fa6fc26 100644
@@ -24,7 +24,6 @@ typedef struct fs_geometry  {
 	xfs_drfsbno_t	sb_dblocks;	/* # data blocks */
 	xfs_drfsbno_t	sb_rblocks;	/* # realtime blocks */
 	xfs_drtbno_t	sb_rextents;	/* # realtime extents */
-	uuid_t		sb_uuid;	/* fs uuid */
 	xfs_dfsbno_t	sb_logstart;	/* starting log block # */
 	xfs_agblock_t	sb_rextsize;	/* realtime extent size (blocks )*/
 	xfs_agblock_t	sb_agblocks;	/* # of blocks per ag */

index 035212c..5d22652 100644
@@ -208,9 +208,9 @@ clear_dinode_core(struct xfs_mount *mp, xfs_dinode_t *dinoc, xfs_ino_t ino_num)
 		dinoc->di_ino = cpu_to_be64(ino_num);
 	}
 
-	if (platform_uuid_compare(&dinoc->di_uuid, &mp->m_sb.sb_uuid)) {
+	if (platform_uuid_compare(&dinoc->di_uuid, &mp->m_sb.sb_meta_uuid)) {
 		__dirty_no_modify_ret(dirty);
-		platform_uuid_copy(&dinoc->di_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&dinoc->di_uuid, &mp->m_sb.sb_meta_uuid);
 	}
 
 	for (i = 0; i < sizeof(dinoc->di_pad2)/sizeof(dinoc->di_pad2[0]); i++) {

@@ -2366,7 +2366,8 @@ _("inode identifier %llu mismatch on inode %" PRIu64 "\n"),
 				return 1;
 			goto clear_bad_out;
 		}
-		if (platform_uuid_compare(&dino->di_uuid, &mp->m_sb.sb_uuid)) {
+		if (platform_uuid_compare(&dino->di_uuid,
+					  &mp->m_sb.sb_meta_uuid)) {
 			if (!uncertain)
 				do_warn(
 			_("UUID mismatch on inode %" PRIu64 "\n"), lino);

index 3a2cdbb..d6f2ead 100644
@@ -1119,7 +1119,7 @@ build_agi(xfs_mount_t *mp, xfs_agnumber_t agno, bt_status_t *btree_curs,
 		agi->agi_unlinked[i] = cpu_to_be32(NULLAGINO);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb))
-		platform_uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid);
 
 	if (xfs_sb_version_hasfinobt(&mp->m_sb)) {
 		agi->agi_free_root = cpu_to_be32(finobt_curs->root);

@@ -1360,7 +1360,7 @@ build_agf_agfl(xfs_mount_t	*mp,
 #endif
 
 	if (xfs_sb_version_hascrc(&mp->m_sb))
-		platform_uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid);
 
 	/* initialise the AGFL, then fill it if there are blocks left over. */
 	agfl_buf = libxfs_getbuf(mp->m_dev,

@@ -1374,7 +1374,7 @@ build_agf_agfl(xfs_mount_t	*mp,
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		agfl->agfl_magicnum = cpu_to_be32(XFS_AGFL_MAGIC);
 		agfl->agfl_seqno = cpu_to_be32(agno);
-		platform_uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid);
 		for (i = 0; i < XFS_AGFL_SIZE(mp); i++)
 			agfl->agfl_bno[i] = cpu_to_be32(NULLAGBLOCK);
 	}

index c09b394..96204b9 100644
@@ -526,7 +526,7 @@ mk_rbmino(xfs_mount_t *mp)
 		ip->i_d.di_flags2 = 0;
 		ip->i_d.di_ino = mp->m_sb.sb_rbmino;
 		memset(&(ip->i_d.di_pad2[0]), 0, sizeof(ip->i_d.di_pad2));
-		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid);
 		times |= XFS_ICHGTIME_CREATE;
 	}
 	libxfs_trans_ichgtime(tp, ip, times);

@@ -782,7 +782,7 @@ mk_rsumino(xfs_mount_t *mp)
 		ip->i_d.di_flags2 = 0;
 		ip->i_d.di_ino = mp->m_sb.sb_rsumino;
 		memset(&(ip->i_d.di_pad2[0]), 0, sizeof(ip->i_d.di_pad2));
-		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid);
 		times |= XFS_ICHGTIME_CREATE;
 	}
 	libxfs_trans_ichgtime(tp, ip, times);

@@ -898,7 +898,7 @@ mk_root_dir(xfs_mount_t *mp)
 		ip->i_d.di_flags2 = 0;
 		ip->i_d.di_ino = mp->m_sb.sb_rootino;
 		memset(&(ip->i_d.di_pad2[0]), 0, sizeof(ip->i_d.di_pad2));
-		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid);
+		platform_uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid);
 		times |= XFS_ICHGTIME_CREATE;
 	}
 	libxfs_trans_ichgtime(tp, ip, times);

index 950d1ea..c27c294 100644
@@ -107,7 +107,7 @@ typedef struct xfs_sb {
 	xfs_drfsbno_t	sb_dblocks;	/* number of data blocks */
 	xfs_drfsbno_t	sb_rblocks;	/* number of realtime blocks */
 	xfs_drtbno_t	sb_rextents;	/* number of realtime extents */
-	uuid_t		sb_uuid;	/* file system unique id */
+	uuid_t		sb_uuid;	/* user-visible file system unique id */
 	xfs_dfsbno_t	sb_logstart;	/* starting block of log if internal */
 	xfs_ino_t	sb_rootino;	/* root inode number */
 	xfs_ino_t	sb_rbmino;	/* bitmap inode for realtime extents */

@@ -178,6 +178,7 @@ typedef struct xfs_sb {
 
 	xfs_ino_t	sb_pquotino;	/* project quota inode */
 	xfs_lsn_t	sb_lsn;		/* last write sequence */
+	uuid_t		sb_meta_uuid;	/* metadata file system unique id */
 
 	/* must be padded to 64 bit alignment */
 } xfs_sb_t;

@@ -194,7 +195,7 @@ typedef struct xfs_dsb {
 	__be64		sb_dblocks;	/* number of data blocks */
 	__be64		sb_rblocks;	/* number of realtime blocks */
 	__be64		sb_rextents;	/* number of realtime extents */
-	uuid_t		sb_uuid;	/* file system unique id */
+	uuid_t		sb_uuid;	/* user-visible file system unique id */
 	__be64		sb_logstart;	/* starting block of log if internal */
 	__be64		sb_rootino;	/* root inode number */
 	__be64		sb_rbmino;	/* bitmap inode for realtime extents */

@@ -264,6 +265,7 @@ typedef struct xfs_dsb {
 
 	__be64		sb_pquotino;	/* project quota inode */
 	__be64		sb_lsn;		/* last write sequence */
+	uuid_t		sb_meta_uuid;	/* metadata file system unique id */
 
 	/* must be padded to 64 bit alignment */
 } xfs_dsb_t;

@@ -287,7 +289,7 @@ typedef enum {
 	XFS_SBS_FEATURES2, XFS_SBS_BAD_FEATURES2, XFS_SBS_FEATURES_COMPAT,
 	XFS_SBS_FEATURES_RO_COMPAT, XFS_SBS_FEATURES_INCOMPAT,
 	XFS_SBS_FEATURES_LOG_INCOMPAT, XFS_SBS_CRC, XFS_SBS_PAD,
-	XFS_SBS_PQUOTINO, XFS_SBS_LSN,
+	XFS_SBS_PQUOTINO, XFS_SBS_LSN, XFS_SBS_META_UUID,
 	XFS_SBS_FIELDCOUNT
 } xfs_sb_field_t;
 

@@ -319,6 +321,7 @@ typedef enum {
 #define XFS_SB_FEATURES_LOG_INCOMPAT XFS_SB_MVAL(FEATURES_LOG_INCOMPAT)
 #define XFS_SB_CRC		XFS_SB_MVAL(CRC)
 #define XFS_SB_PQUOTINO		XFS_SB_MVAL(PQUOTINO)
+#define	XFS_SB_META_UUID	XFS_SB_MVAL(META_UUID)
 #define	XFS_SB_NUM_BITS		((int)XFS_SBS_FIELDCOUNT)
 #define	XFS_SB_ALL_BITS		((1LL << XFS_SB_NUM_BITS) - 1)
 #define	XFS_SB_MOD_BITS		\

@@ -328,7 +331,7 @@ typedef enum {
 	 XFS_SB_ICOUNT | XFS_SB_IFREE | XFS_SB_FDBLOCKS | XFS_SB_FEATURES2 | \
 	 XFS_SB_BAD_FEATURES2 | XFS_SB_FEATURES_COMPAT | \
 	 XFS_SB_FEATURES_RO_COMPAT | XFS_SB_FEATURES_INCOMPAT | \
-	 XFS_SB_FEATURES_LOG_INCOMPAT | XFS_SB_PQUOTINO)
+	 XFS_SB_FEATURES_LOG_INCOMPAT | XFS_SB_PQUOTINO | XFS_SB_META_UUID)
 
 
 /*

@@ -600,8 +603,10 @@ xfs_sb_has_ro_compat_feature(
 }
 
 #define XFS_SB_FEAT_INCOMPAT_FTYPE	(1 << 0)	/* filetype in dirent */
+#define XFS_SB_FEAT_INCOMPAT_META_UUID (1 << 1)		/* metadata UUID */
 #define XFS_SB_FEAT_INCOMPAT_ALL \
-		(XFS_SB_FEAT_INCOMPAT_FTYPE)
+		(XFS_SB_FEAT_INCOMPAT_FTYPE | \
+		 XFS_SB_FEAT_INCOMPAT_META_UUID)
 
 #define XFS_SB_FEAT_INCOMPAT_UNKNOWN	~XFS_SB_FEAT_INCOMPAT_ALL
 static inline bool

@@ -650,6 +655,18 @@ static inline int xfs_sb_version_hasfinobt(xfs_sb_t *sbp)
 }
 
 /*
+ * XFS_SB_FEAT_INCOMPAT_META_UUID indicates that the metadata UUID
+ * is stored separately from the user-visible UUID; this allows the
+ * user-visible UUID to be changed on V5 filesystems which have a
+ * filesystem UUID stamped into every piece of metadata.
+ */
+static inline int xfs_sb_version_hasmetauuid(xfs_sb_t *sbp)
+{
+	return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) &&
+		(sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_META_UUID);
+}
+
+/*
  * end of superblock version macros
  */
 

index 49eb76d..ea698c4 100644
@@ -250,7 +250,7 @@ libxfs_ialloc(
 
 	if (ip->i_d.di_version == 3) {
 		ASSERT(ip->i_d.di_ino == ino);
-		ASSERT(uuid_equal(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid));
+		ASSERT(uuid_equal(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid));
 		ip->i_d.di_crc = 0;
 		ip->i_d.di_changecount = 1;
 		ip->i_d.di_lsn = 0;

index 6c82be0..06757c3 100644
@@ -426,7 +426,7 @@ xfs_agfl_verify(
 	struct xfs_agfl	*agfl = XFS_BUF_TO_AGFL(bp);
 	int		i;
 
-	if (!uuid_equal(&agfl->agfl_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	if (be32_to_cpu(agfl->agfl_magicnum) != XFS_AGFL_MAGIC)
 		return false;

@@ -2181,7 +2181,7 @@ xfs_agf_verify(
 	struct xfs_agf	*agf = XFS_BUF_TO_AGF(bp);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
-	    !uuid_equal(&agf->agf_uuid, &mp->m_sb.sb_uuid))
+	    !uuid_equal(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 
 	if (!(agf->agf_magicnum == cpu_to_be32(XFS_AGF_MAGIC) &&

index 215be7e..cefa18b 100644
@@ -279,7 +279,7 @@ xfs_allocbt_verify(
 	case cpu_to_be32(XFS_ABTB_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (block->bb_u.s.bb_blkno != cpu_to_be64(bp->b_bn))
 			return false;

@@ -297,7 +297,7 @@ xfs_allocbt_verify(
 	case cpu_to_be32(XFS_ABTC_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (block->bb_u.s.bb_blkno != cpu_to_be64(bp->b_bn))
 			return false;

index f7f02ae..e9f96ec 100644
@@ -161,7 +161,7 @@ xfs_attr3_leaf_verify(
 		if (ichdr.magic != XFS_ATTR3_LEAF_MAGIC)
 			return false;
 
-		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->info.blkno) != bp->b_bn)
 			return false;

@@ -952,7 +952,7 @@ xfs_attr3_leaf_create(
 
 		hdr3->blkno = cpu_to_be64(bp->b_bn);
 		hdr3->owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);
 
 		ichdr.freemap[0].base = sizeof(struct xfs_attr3_leaf_hdr);
 	} else {

index 08b983b..62abaec 100644
@@ -78,7 +78,7 @@ xfs_attr3_rmt_verify(
 		return false;
 	if (rmt->rm_magic != cpu_to_be32(XFS_ATTR3_RMT_MAGIC))
 		return false;
-	if (!uuid_equal(&rmt->rm_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	if (be64_to_cpu(rmt->rm_blkno) != bno)
 		return false;

@@ -194,7 +194,7 @@ xfs_attr3_rmt_hdr_set(
 	rmt->rm_magic = cpu_to_be32(XFS_ATTR3_RMT_MAGIC);
 	rmt->rm_offset = cpu_to_be32(offset);
 	rmt->rm_bytes = cpu_to_be32(size);
-	uuid_copy(&rmt->rm_uuid, &mp->m_sb.sb_uuid);
+	uuid_copy(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid);
 	rmt->rm_owner = cpu_to_be64(ino);
 	rmt->rm_blkno = cpu_to_be64(bno);
 

index a4bd69d..9913958 100644
@@ -412,7 +412,8 @@ xfs_bmbt_to_bmdr(
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		ASSERT(rblock->bb_magic == cpu_to_be32(XFS_BMAP_CRC_MAGIC));
-		ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid));
+		ASSERT(uuid_equal(&rblock->bb_u.l.bb_uuid,
+				  &mp->m_sb.sb_meta_uuid));
 		ASSERT(rblock->bb_u.l.bb_blkno ==
 		       cpu_to_be64(XFS_BUF_DADDR_NULL));
 	} else

@@ -712,7 +713,7 @@ xfs_bmbt_verify(
 	case cpu_to_be32(XFS_BMAP_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(block->bb_u.l.bb_blkno) != bp->b_bn)
 			return false;

index cc823f5..a8436f5 100644
@@ -50,7 +50,8 @@ xfs_btree_check_lblock(
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		lblock_ok = lblock_ok &&
-			uuid_equal(&block->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid) &&
+			uuid_equal(&block->bb_u.l.bb_uuid,
+				   &mp->m_sb.sb_meta_uuid) &&
 			block->bb_u.l.bb_blkno == cpu_to_be64(
 				bp ? bp->b_bn : XFS_BUF_DADDR_NULL);
 	}

@@ -100,7 +101,8 @@ xfs_btree_check_sblock(
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		sblock_ok = sblock_ok &&
-			uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid) &&
+			uuid_equal(&block->bb_u.s.bb_uuid,
+				   &mp->m_sb.sb_meta_uuid) &&
 			block->bb_u.s.bb_blkno == cpu_to_be64(
 				bp ? bp->b_bn : XFS_BUF_DADDR_NULL);
 	}

@@ -992,7 +994,7 @@ xfs_btree_init_block_int(
 		if (flags & XFS_BTREE_CRC_BLOCKS) {
 			buf->bb_u.l.bb_blkno = cpu_to_be64(blkno);
 			buf->bb_u.l.bb_owner = cpu_to_be64(owner);
-			uuid_copy(&buf->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&buf->bb_u.l.bb_uuid, &mp->m_sb.sb_meta_uuid);
 			buf->bb_u.l.bb_pad = 0;
 			buf->bb_u.l.bb_lsn = 0;
 		}

@@ -1005,7 +1007,7 @@ xfs_btree_init_block_int(
 		if (flags & XFS_BTREE_CRC_BLOCKS) {
 			buf->bb_u.s.bb_blkno = cpu_to_be64(blkno);
 			buf->bb_u.s.bb_owner = cpu_to_be32(__owner);
-			uuid_copy(&buf->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid);
+			uuid_copy(&buf->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid);
 			buf->bb_u.s.bb_lsn = 0;
 		}
 	}

index b731b54..0323dc7 100644
@@ -172,7 +172,7 @@ xfs_da3_node_verify(
 		if (ichdr.magic != XFS_DA3_NODE_MAGIC)
 			return false;
 
-		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->info.uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->info.blkno) != bp->b_bn)
 			return false;

@@ -349,7 +349,7 @@ xfs_da3_node_create(
 		ichdr.magic = XFS_DA3_NODE_MAGIC;
 		hdr3->info.blkno = cpu_to_be64(bp->b_bn);
 		hdr3->info.owner = cpu_to_be64(args->dp->i_ino);
-		uuid_copy(&hdr3->info.uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->info.uuid, &mp->m_sb.sb_meta_uuid);
 	} else {
 		ichdr.magic = XFS_DA_NODE_MAGIC;
 	}

index cede01f..2a25059 100644
@@ -51,7 +51,7 @@ xfs_dir3_block_verify(
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		if (hdr3->magic != cpu_to_be32(XFS_DIR3_BLOCK_MAGIC))
 			return false;
-		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;

@@ -141,7 +141,7 @@ xfs_dir3_block_init(
 		hdr3->magic = cpu_to_be32(XFS_DIR3_BLOCK_MAGIC);
 		hdr3->blkno = cpu_to_be64(bp->b_bn);
 		hdr3->owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);
 		return;
 
 	}

index dc9df4d..4c79d7c 100644
@@ -186,7 +186,7 @@ xfs_dir3_data_verify(
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
 		if (hdr3->magic != cpu_to_be32(XFS_DIR3_DATA_MAGIC))
 			return false;
-		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;

@@ -573,7 +573,7 @@ xfs_dir3_data_init(
 		hdr3->magic = cpu_to_be32(XFS_DIR3_DATA_MAGIC);
 		hdr3->blkno = cpu_to_be64(bp->b_bn);
 		hdr3->owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);
 
 	} else
 		hdr->magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);

index 8e0cbc9..a918e15 100644
@@ -186,7 +186,7 @@ xfs_dir3_leaf_verify(
 
 		if (leaf3->info.hdr.magic != cpu_to_be16(magic3))
 			return false;
-		if (!uuid_equal(&leaf3->info.uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&leaf3->info.uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(leaf3->info.blkno) != bp->b_bn)
 			return false;

@@ -337,7 +337,7 @@ xfs_dir3_leaf_init(
 					 : cpu_to_be16(XFS_DIR3_LEAFN_MAGIC);
 		leaf3->info.blkno = cpu_to_be64(bp->b_bn);
 		leaf3->info.owner = cpu_to_be64(owner);
-		uuid_copy(&leaf3->info.uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&leaf3->info.uuid, &mp->m_sb.sb_meta_uuid);
 	} else {
 		memset(leaf, 0, sizeof(*leaf));
 		leaf->hdr.info.magic = cpu_to_be16(type);

index 3737e4e..309e7ce 100644
@@ -78,7 +78,7 @@ xfs_dir3_free_verify(
 
 		if (hdr3->magic != cpu_to_be32(XFS_DIR3_FREE_MAGIC))
 			return false;
-		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (be64_to_cpu(hdr3->blkno) != bp->b_bn)
 			return false;

@@ -257,7 +257,7 @@ xfs_dir3_free_get_buf(
 
 		hdr3->hdr.blkno = cpu_to_be64(bp->b_bn);
 		hdr3->hdr.owner = cpu_to_be64(dp->i_ino);
-		uuid_copy(&hdr3->hdr.uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&hdr3->hdr.uuid, &mp->m_sb.sb_meta_uuid);
 	} else
 		hdr.magic = XFS_DIR2_FREE_MAGIC;
 	xfs_dir3_free_hdr_to_disk(bp->b_addr, &hdr);

index e089ec8..f75bfe3 100644
@@ -146,7 +146,7 @@ xfs_dqcheck(
 	d->dd_diskdq.d_id = cpu_to_be32(id);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb)) {
-		uuid_copy(&d->dd_uuid, &mp->m_sb.sb_uuid);
+		uuid_copy(&d->dd_uuid, &mp->m_sb.sb_meta_uuid);
 		xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk),
 				 XFS_DQUOT_CRC_OFF);
 	}

@@ -181,7 +181,7 @@ xfs_dquot_buf_verify_crc(
 		if (!xfs_verify_cksum((char *)d, sizeof(struct xfs_dqblk),
 				 XFS_DQUOT_CRC_OFF))
 			return false;
-		if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 	}
 	return true;

index b20a9ec..ae0804c 100644
@@ -295,7 +295,8 @@ xfs_ialloc_inode_init(
 			if (version == 3) {
 				free->di_ino = cpu_to_be64(ino);
 				ino++;
-				uuid_copy(&free->di_uuid, &mp->m_sb.sb_uuid);
+				uuid_copy(&free->di_uuid,
+					  &mp->m_sb.sb_meta_uuid);
 				xfs_dinode_calc_crc(mp, free);
 			} else if (tp) {
 				/* just log the inode core */

@@ -1947,7 +1948,7 @@ xfs_agi_verify(
 	struct xfs_agi	*agi = XFS_BUF_TO_AGI(bp);
 
 	if (xfs_sb_version_hascrc(&mp->m_sb) &&
-	    !uuid_equal(&agi->agi_uuid, &mp->m_sb.sb_uuid))
+	    !uuid_equal(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 	/*
 	 * Validate the magic number of the agi block.

index c337389..320984f 100644
@@ -214,7 +214,7 @@ xfs_inobt_verify(
 	case cpu_to_be32(XFS_FIBT_CRC_MAGIC):
 		if (!xfs_sb_version_hascrc(&mp->m_sb))
 			return false;
-		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid))
+		if (!uuid_equal(&block->bb_u.s.bb_uuid, &mp->m_sb.sb_meta_uuid))
 			return false;
 		if (block->bb_u.s.bb_blkno != cpu_to_be64(bp->b_bn))
 			return false;

index de16ed9..1c0047d 100644
@@ -295,7 +295,7 @@ xfs_dinode_verify(
 		return false;
 	if (be64_to_cpu(dip->di_ino) != ino)
 		return false;
-	if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	return true;
 }

index ea89367..c9ef019 100644
@@ -81,6 +81,7 @@ static const struct {
 	{ offsetof(xfs_sb_t, sb_pad),		0 },
 	{ offsetof(xfs_sb_t, sb_pquotino),	0 },
 	{ offsetof(xfs_sb_t, sb_lsn),		0 },
+	{ offsetof(xfs_sb_t, sb_meta_uuid),		1 },
 	{ sizeof(xfs_sb_t),			0 }
 };
 

@@ -413,6 +414,13 @@ xfs_sb_from_disk(
 	to->sb_pad = 0;
 	to->sb_pquotino = be64_to_cpu(from->sb_pquotino);
 	to->sb_lsn = be64_to_cpu(from->sb_lsn);
+	if (xfs_sb_version_hasmetauuid(to)) {
+		memcpy(&to->sb_meta_uuid, &from->sb_meta_uuid,
+					sizeof(to->sb_meta_uuid));
+	} else {
+		memcpy(&to->sb_meta_uuid, &from->sb_uuid,
+					sizeof(to->sb_meta_uuid));
+	}
 }
 
 static inline void

@@ -490,6 +498,13 @@ xfs_sb_to_disk(
 	/* We should never write the crc here, it's updated in the IO path */
 	fields &= ~XFS_SB_CRC;
 
+	/*
+	 * If the metadata-specific UUID feature isn't set, it's only set
+	 * in memory; don't write it out.
+	 */
+	if (!xfs_sb_version_hasmetauuid(from))
+		fields &= ~XFS_SB_UUID;
+
 	xfs_sb_quota_to_disk(to, from, &fields);
 	while (fields) {
 		f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);

index ebf60ac..3f8374e 100644
@@ -48,7 +48,7 @@ xfs_symlink_hdr_set(
 	dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
 	dsl->sl_offset = cpu_to_be32(offset);
 	dsl->sl_bytes = cpu_to_be32(size);
-	uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
+	uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
 	dsl->sl_owner = cpu_to_be64(ino);
 	dsl->sl_blkno = cpu_to_be64(bp->b_bn);
 	bp->b_ops = &xfs_symlink_buf_ops;

@@ -93,7 +93,7 @@ xfs_symlink_verify(
 		return false;
 	if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 		return false;
-	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
+	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
 		return false;
 	if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 		return false;