have been unlinked, but are still referenced by open file descriptors.
These inodes cannot be freed until the final file descriptor reference
has been closed. If the system crashes while they are still being
referenced, these inodes and their referenced blocks need to be
freed by fsck. By having them on a linked list with the head pointer
in the superblock, fsck can quickly find and process them rather
than having to check every inode in the filesystem to see if it is
unreferenced.
When updating the head pointer of this list of unlinked inodes in
the superblock, the superblock check-hash was not getting updated.
If the system crashed with the incorrect superblock check-hash, the
superblock would appear to be corrupted. This patch ensures that
the superblock check-hash is updated when updating the head pointer
of the unlinked inodes list.
There is no need to MFC as superblock check hashes first appeared in
13.0.
Tested by: Peter Holm
Sponsored by: Netflix
7792f70137