dm exception store: fix misordered writes
We must zero the next chunk on disk *before* writing out the current chunk, not after. Otherwise if the machine crashes at the wrong time, the "end of metadata" marker may be missing. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: stable@kernel.org
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@ -610,18 +610,23 @@ static void persistent_commit(struct exception_store *store,
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(ps->current_committed != ps->exceptions_per_area))
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return;
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/*
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* If we completely filled the current area, then wipe the next one.
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*/
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if ((ps->current_committed == ps->exceptions_per_area) &&
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zero_disk_area(ps, ps->current_area + 1))
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ps->valid = 0;
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/*
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* Commit exceptions to disk.
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*/
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if (area_io(ps, WRITE))
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if (ps->valid && area_io(ps, WRITE))
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ps->valid = 0;
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/*
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* Advance to the next area if this one is full.
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*/
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if (ps->current_committed == ps->exceptions_per_area) {
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if (zero_disk_area(ps, ps->current_area + 1))
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ps->valid = 0;
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ps->current_committed = 0;
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ps->current_area++;
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zero_memory_area(ps);
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