xfs: set buffer ops when repair probes for btree type
In xrep_findroot_block, we work out the btree type and correctness of a given block by calling different btree verifiers on root block candidates. However, we leave the NULL b_ops while ->verify_read validates the block, which means that if the verifier calls xfs_buf_verifier_error it'll crash on the null b_ops. Fix it to set b_ops before calling the verifier and unsetting it if the verifier fails. Furthermore, improve the documentation around xfs_buf_ensure_ops, which is the function that is responsible for cleaning up the b_ops state of buffers that go through xrep_findroot_block but don't match anything. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Brian Foster <bfoster@redhat.com>
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@@ -768,18 +768,23 @@ xrep_findroot_block(
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if (!uuid_equal(&btblock->bb_u.s.bb_uuid,
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&mp->m_sb.sb_meta_uuid))
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goto out;
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/*
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* Read verifiers can reference b_ops, so we set the pointer
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* here. If the verifier fails we'll reset the buffer state
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* to what it was before we touched the buffer.
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*/
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bp->b_ops = fab->buf_ops;
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fab->buf_ops->verify_read(bp);
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if (bp->b_error) {
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bp->b_ops = NULL;
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bp->b_error = 0;
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goto out;
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}
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/*
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* Some read verifiers will (re)set b_ops, so we must be
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* careful not to blow away any such assignment.
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* careful not to change b_ops after running the verifier.
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*/
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if (!bp->b_ops)
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bp->b_ops = fab->buf_ops;
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}
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/*
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