By now everything _should_ be back to normal. Thanks for your patience.
This is what happened on the technical side:
18:37 maplebed: pushed out new db.php setting s4 to read-write
18:37 logmsgbot: ben synchronized wmf-config/db.php
18:35 maplebed: db31 made read-write as the new master for s4
18:31 maplebed: old master for s4 log file db22-bin.000106 log pos 631618956
18:30 maplebed: new master for s4: db31, log file db31-bin.000213
log pos is 205612709
18:24 logmsgbot: asher synchronized wmf-config/db.php 'setting s4
to read only, preparing to make db31 master'
18:21 Reedy: Commons having db issues, db22 (s4 master) has a disk issue
Daniel Zahn <dzahn(a)wikimedia.org>