spa: clear checkpoint information during retry #17319
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Shouldn't it be done in |
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@amotin Sounds like a better place. |
Signed-off-by: Mariusz Zaborski <[email protected]> Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc.
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Status: Code Review Needed
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Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc. Reviewed-by: Alexander Motin <[email protected]> Signed-off-by: Mariusz Zaborski <[email protected]> Closes openzfs#17319 (cherry picked from commit 8b9c4e6)
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Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc. Reviewed-by: Alexander Motin <[email protected]> Signed-off-by: Mariusz Zaborski <[email protected]> Closes openzfs#17319 (cherry picked from commit 8b9c4e6)
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Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc. Reviewed-by: Alexander Motin <[email protected]> Signed-off-by: Mariusz Zaborski <[email protected]> Closes #17319 (cherry picked from commit 8b9c4e6)
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Motivation and Context
During spa loading, the
spa_add()function allocates thespa_tstructure. The problematic rewind logic starts in
the spa_load_best() function:
spa_load()is called, which is a wrapper forspa_load_impl().One of the first actions in that function is to call
spa_ld_read_checkpoint_txg().
If a checkpoint exists, this function sets
spa->spa_checkpoint_txg.However, during
spa_load_impl(), many steps may fail after readingthe checkpoint, such as reading feature flags or MOS directories.
If one of these steps fails, the function returns an error.
If the failure is something other than
ZFS_ERR_NO_CHECKPOINT,a rewind is attempted in the loop shown above. But because
the checkpoint had already been read (and
spa_checkpoint_txgwas set), and nothing clears this state on failure,
another call to
spa_ld_read_checkpoint_txg()during rewind willcasue assertion:
And we might end with crash like:
Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Description
There are several potential ways to address this issue:
spa_checkpoint_txgduring retry (proposed in this PR).spa_ld_read_checkpoint_txg().spa_tstructure cleanup before retry.How Has This Been Tested?
I have hit this error during work on #16853. In that PR, we add one
additional TXG during export, which seems to trigger this loop during
import. This was triggered by the
checkpoint_zhack_feattest.However, I don't think that this bug is limited to this PR, and it's a
more generic problem that users can hit.
Types of changes
Checklist:
Signed-off-by.