* s3: keep suspended-versioning conditional writes off the routed condition
A suspended PUT writes the null-version slot at the regular path while the
entry the conditional headers evaluate lives under .versions/. The routed
WriteCondition checked the request's etag against that empty slot, so a
correct If-Match failed with 412. Passing uniqueWritePath sends conditional
requests through the lock path, whose precondition resolves the same entry
the read path serves; unconditional writes still route.
Generated with [Devin](https://devin.ai)
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
* filer_pb: add condition_alt_key to ObjectTransactionRequest
* filer: evaluate a transaction condition against a fallback entry
condition_alt_key names the entry consulted when the primary is absent,
so a suspended-versioning write can check 'the null slot if present,
else the latest version' atomically under the lock.
* s3: route suspended-versioning conditional writes with a fallback key
The gateway names the latest version file as condition_alt_key, so the
transaction checks the entry the read path serves — null slot first,
latest version when it is absent — under the same lock that applies
the write. Conditional suspended PUTs route again instead of splitting
check and write across a gateway lock that routed writes skip.
* filer: resolve the condition fallback under the transaction lock
The gateway named the pointed-at version file as condition_alt_key,
resolved before the transaction ran: a concurrent version delete could
move the latest pointer between the gateway read and the locked check,
and a delete-marker latest read as an existing object. The alt key is
now the .versions directory and the filer resolves the latest-version
pointer under the same lock that serializes the write — a delete marker
resolves to absent, and unresolvable pointer state fails closed.
* filer: fail closed on alt-key lookups and skip directory primaries
A transient FindEntry error returning a nil entry read as "versions dir
absent" and let If-None-Match writes pass. Check the error before the
entry. And a bare directory at the object path satisfied the primary
lookup, so the .versions fallback never ran — directories are not the
object, treat them as an absent slot.
Generated with [Devin](https://devin.ai)
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
* filer: scope directory-as-absent conditions to alt-key callers
---------
Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
see https://blog.aqwari.net/xml-schema-go/
1. go get aqwari.net/xml/cmd/xsdgen
2. Add EncodingType element for ListBucketResult in AmazonS3.xsd
3. xsdgen -o s3api_xsd_generated.go -pkg s3api AmazonS3.xsd
4. Remove empty Grantee struct in s3api_xsd_generated.go
5. Remove xmlns: sed s'/http:\/\/s3.amazonaws.com\/doc\/2006-03-01\/\ //' s3api_xsd_generated.go
