If a previous partition power increase failed to cleanup all files in
their old partition locations, then during the next partition power
increase the relinker may find the same file to relink in more than
one source partition. This currently leads to an error log due to the
second relink attempt getting an EEXIST error.
With this patch, when an EEXIST is raised, the relinker will attempt
to create/verify a link from older partition power locations to the
next part power location, and if such a link is found then suppress
the error log.
During the relink step, if an alternative link is verified and if a
file is found that is neither linked to the next partition power
location nor in the current part power location, then the file is
removed during the relink step. That prevents the same EEXIST occuring
again during the cleanup step when it may no longer be possible to
verify that an alternative link exists.
For example, consider identical filenames in the N+1th, Nth and N-1th
partition power locations, with the N+1th being linked to the Nth:
- During relink, the Nth location is visited and its link is
verified. Then the N-1th location is visited and an EEXIST error
is encountered, but the new check verifies that a link exists to
the Nth location, which is OK.
- During cleanup the locations are visited in the same order, but
files are removed so that the Nth location file no longer exists
when the N-1th location is visited. If the N-1th location still
has a conflicting file then existence of an alternative link to
the Nth location can no longer be verified, so an error would be
raised. Therefore, the N-1th location file must be removed during
relink.
The error is only suppressed for tombstones. The number of partition
power location that the relinker will look back over may be configured
using the link_check_limit option in a conf file or --link-check-limit
on the command line, and defaults to 2.
Closes-Bug: 1921718
Change-Id: If9beb9efabdad64e81d92708f862146d5fafb16c
3bdd01cf4a