* filer.remote.sync: confirm a missing RemoteEntry against the filer before re-uploading
The event is the entry as it was when the update was logged. A chmod or
utimes right after a write is logged while the sync is still uploading the
write, so it carries no RemoteEntry even though the object is on the remote
by the time it is processed. Gating on the event alone turned every such
update into a delete and a second upload of the same bytes; cp -p, rsync
and Django's FileSystemStorage all write that way.
Look up the filer's current entry when the event has no RemoteEntry: the
upload stamps it as soon as it completes, so the stamp is there for the
race and absent for a file that was never replicated. Skip the update when
the entry has since been deleted rather than upload from chunks that may be
gone; the delete event that follows removes the remote object.
Tests build entries from chunks, which is what IsSameData compares in
production, and cover both no-RemoteEntry cases through a stub filer.
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* filer.remote.sync: do not delete the remote object before overwriting it in place
The update write path deleted the old object and then wrote the new one,
even when both are the same key. S3, GCS and Azure all overwrite on write,
so the delete bought nothing and left the remote with no object between
the two calls, or at all if the write then failed and pinned the offset.
On a versioned remote bucket it also left a delete marker per rewrite.
Delete only when the key changes, which is what the delete was for.
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* filer.remote.sync: trim comments
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Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
