[PATCH 05/49] libxfs: ensure btree root split sets blkno correctly

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

For CRC enabled filesystems, the BMBT is rooted in an inode, so it
passes through a difference code path on root splits to the
freespace and inode btrees. The inode based btree root has a
corruption problem on split - it's the same problem we saw in the
directory/attr code where headers are memcpy()d from one block to
another without updating the self describing metadata.

Simple fix - when copying the header out of the root block, make
sure the block number is updated correctly.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 libxfs/xfs_btree.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/libxfs/xfs_btree.c b/libxfs/xfs_btree.c
index b11131c..3ac3330 100644
--- a/libxfs/xfs_btree.c
+++ b/libxfs/xfs_btree.c
@@ -2487,7 +2487,17 @@ xfs_btree_new_iroot(
 	if (error)
 		goto error0;
 
+	/*
+	 * we can't just memcpy() the root in for CRC enabled btree blocks.
+	 * In that case have to also ensure the blkno remains correct
+	 */
 	memcpy(cblock, block, xfs_btree_block_len(cur));
+	if (cur->bc_flags & XFS_BTREE_CRC_BLOCKS) {
+		if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
+			cblock->bb_u.l.bb_blkno = cpu_to_be64(cbp->b_bn);
+		else
+			cblock->bb_u.s.bb_blkno = cpu_to_be64(cbp->b_bn);
+	}
 
 	be16_add_cpu(&block->bb_level, 1);
 	xfs_btree_set_numrecs(block, 1);
-- 
1.8.3.2

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