freebsd-skq/sys/geom/mirror
markj 6266e5e4ec Fix some I/O ordering issues in gmirror.
- BIO_FLUSH requests were dispatched to the disks directly from
  g_mirror_start() rather than going through the mirror's I/O request
  queue, so they could have been reordered with preceding writes.
  Address this by processing such requests from the queue, avoiding
  direct dispatch.
- Handling for collisions with synchronization requests was too
  fine-grained and could cause reordering of writes. In particular,
  BIO_ORDERED was not being honoured. Address this by effectively
  freezing the request queue any time a collision with a synchronization
  request occurs. The queue is unfrozen once the collision with the
  first frozen request is over.
- The above-mentioned collision handling allowed reads to jump ahead
  of writes to the same offset. Address this by freezing all request
  types when a collision occurs, not just BIO_WRITEs and BIO_DELETEs.

Also add some more fail points for use in testing error handling.

Reviewed by:	imp
MFC after:	3 weeks
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D13559
2018-01-02 18:11:54 +00:00
..
g_mirror_ctl.c sys/geom: adoption of SPDX licensing ID tags. 2017-11-27 15:17:37 +00:00
g_mirror.c Fix some I/O ordering issues in gmirror. 2018-01-02 18:11:54 +00:00
g_mirror.h Avoid using bioq_* in gmirror. 2017-12-19 17:13:04 +00:00