PR/53949 CVS commit: src/sys/dev/scsipi

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

The following reply was made to PR kern/53949; it has been noted by GNATS.

From: "Frank Kardel" <kardel%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/53949 CVS commit: src/sys/dev/scsipi
Date: Tue, 12 Feb 2019 13:43:40 +0000

 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.