fix: rollback snapshot to prevent bolt deadlock #1326
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ktock
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Jul 27, 2023
snapshot/snapshot.go
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| @@ -331,7 +331,8 @@ func (o *snapshotter) commit(ctx context.Context, isRemote bool, name, key strin | |||
| } | |||
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| if !isRemote { // skip diskusage for remote snapshots for allowing lazy preparation of nodes | |||
| du, err := fs.DiskUsage(ctx, o.upperPath(id)) | |||
| var du fs.Usage | |||
| du, err = fs.DiskUsage(ctx, o.upperPath(id)) | |||
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Could you add a comment line of notifying that we need to expose err to the outer scope?
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@ktock I went a bit further and used a pattern you used in the createSnapshot function. I like what you did there as it has an explicit variable rather than having an err with double duty.
stargz-snapshotter/snapshot/snapshot.go
Lines 517 to 524 in 9e9e7a5
Signed-off-by: Chris Goller <[email protected]>
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The defer function above checks for the err in the outer scope to determine if it should rollback.
The error in the inner-scope of isRemote is a shadow and when it is an error will not cause a rollback of the transaction.
This causes the bolt transaction to keep the write lock open forever. Any other attempts at taking a write lock will never succeed.
It is not uncommon for
fs.DiskUsageto be context canceled as it can take a long time to walk the filesystem.