A concurrent PutObject and DeleteObject on the same prefix directory
can race:
PutObject opens an O_TMPFILE in MetaTmpDir (not yet visible in the fs)
DeleteObject removes the last visible object in the prefix directory
and calls removeParents(), which rmdir's the now-empty prefix
directory
PutObject's link() tries to link the fd into a parent directory that
no longer exists
Fix by detecting ENOENT in the final link step (Linkat, Rename, and
MoveFile) and retrying after recreating the parent directory.
Also extract linkatOTmpfile() to consolidate the Linkat+EEXIST→Renameat
logic that was previously inline in link().
Fixes#1988
All the integration tests used to be in a single file, which had become large, messy, and difficult to maintain. These changes split `tests.go` into multiple files, organized by logical test groups.
Ben McClelland
niksis02