CVS commit: src/sys/dev/scsipi

["Frank Kardel" <kardel%netbsd.org@localhost>]

Module Name:    src
Committed By:   kardel
Date:           Tue Feb 12 13:43:40 UTC 2019

Modified Files:
        src/sys/dev/scsipi: st.c

Log Message:
Fix PR kern/53949:

Fix inconsistent/incomplete file mark handling to conform again
to mtio(4) at close(2) time. This was necessary as the PREVENT/ALLOW
bracket was reduced from a whole mount session to cover only the
open(2)/close(2) time on ~2002-03-22. The rationale was to allow
robots and humans to change the media during a mount session.

Unfortunately this lead to file marks being written to potentially other
media at the beginning on drives that used the two file marks as EOM
pattern. In order for that to happen the media had to be removed after
data and at most one file mark had been written before removal.

The mount error message has been clarified and a warning about
potential data/file mark lossage on UNIT ATTENTION
during an active mount session with unfinished file marks has been
added.

While there, fix, but disable the commented SUN compatibility to write
final file marks by opening and immediately closing the device
in O_WRONLY mode. That code has not been working since around 1998.
It can now be enabled with options ST_SUNCOMPAT.

Additionally debug output coverage has been extended.


To generate a diff of this commit:
cvs rdiff -u -r1.235 -r1.236 src/sys/dev/scsipi/st.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.