xfs: ensure btree root split sets blkno correctly
For CRC enabled filesystems, the BMBT is rooted in an inode, so it passes through a different code path on root splits than the freespace and inode btrees. This is much less traversed by xfstests than the other trees. When testing on a 1k block size filesystem, I've been seeing ASSERT failures in generic/234 like: XFS: Assertion failed: cur->bc_btnum != XFS_BTNUM_BMAP || cur->bc_private.b.allocated == 0, file: fs/xfs/xfs_btree.c, line: 317 which are generally preceded by a lblock check failure. I noticed this in the bmbt stats: $ pminfo -f xfs.btree.block_map xfs.btree.block_map.lookup value 39135 xfs.btree.block_map.compare value 268432 xfs.btree.block_map.insrec value 15786 xfs.btree.block_map.delrec value 13884 xfs.btree.block_map.newroot value 2 xfs.btree.block_map.killroot value 0 ..... Very little coverage of root splits and merges. Indeed, on a 4k filesystem, block_map.newroot and block_map.killroot are both zero. i.e. the code is not exercised at all, and it's the only generic btree infrastructure operation that is not exercised by a default run of xfstests. Turns out that on a 1k filesystem, generic/234 accounts for one of those two root splits, and that is somewhat of a smoking gun. In fact, 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> Reviewed-by:
Ben Myers <bpm@sgi.com> Signed-off-by:
Ben Myers <bpm@sgi.com> (cherry picked from commit ade1335a)
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5170711d
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