Date: Mon, 20 Sep 2010 23:39:00 +0000 (UTC) From: "Justin T. Gibbs" <gibbs@FreeBSD.org> To: cvs-src-old@freebsd.org Subject: cvs commit: src/sys/cam/ata ata_da.c src/sys/cam/scsi scsi_da.c src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs vdev_geom.c src/sys/geom geom_io.c src/sys/geom/sched subr_disk.c src/sys/kern subr_disk.c src/sys/sys bio.h Message-ID: <201009202339.o8KNdSIa083091@repoman.freebsd.org>
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gibbs 2010-09-20 23:39:00 UTC
FreeBSD src repository
Modified files: (Branch: RELENG_8)
sys/cam/ata ata_da.c
sys/cam/scsi scsi_da.c
sys/cddl/contrib/opensolaris/uts/common/fs/zfs vdev_geom.c
sys/geom geom_io.c
sys/geom/sched subr_disk.c
sys/kern subr_disk.c
sys/sys bio.h
Log:
SVN rev 212939 on 2010-09-20 23:39:00Z by gibbs
MFC 212160:
Correct bioq_disksort so that bioq_insert_tail() offers barrier semantic.
Add the BIO_ORDERED flag for struct bio and update bio clients to use it.
The barrier semantics of bioq_insert_tail() were broken in two ways:
o In bioq_disksort(), an added bio could be inserted at the head of
the queue, even when a barrier was present, if the sort key for
the new entry was less than that of the last queued barrier bio.
o The last_offset used to generate the sort key for newly queued bios
did not stay at the position of the barrier until either the
barrier was de-queued, or a new barrier (which updates last_offset)
was queued. When a barrier is in effect, we know that the disk
will pass through the barrier position just before the
"blocked bios" are released, so using the barrier's offset for
last_offset is the optimal choice.
sys/geom/sched/subr_disk.c:
sys/kern/subr_disk.c:
o Update last_offset in bioq_insert_tail().
o Only update last_offset in bioq_remove() if the removed bio is
at the head of the queue (typically due to a call via
bioq_takefirst()) and no barrier is active.
o In bioq_disksort(), if we have a barrier (insert_point is non-NULL),
set prev to the barrier and cur to it's next element. Now that
last_offset is kept at the barrier position, this change isn't
strictly necessary, but since we have to take a decision branch
anyway, it does avoid one, no-op, loop iteration in the while
loop that immediately follows.
o In bioq_disksort(), bypass the normal sort for bios with the
BIO_ORDERED attribute and instead insert them into the queue
with bioq_insert_tail(). bioq_insert_tail() not only gives
the desired command order during insertion, but also provides
barrier semantics so that commands disksorted in the future
cannot pass the just enqueued transaction.
sys/sys/bio.h:
Add BIO_ORDERED as bit 4 of the bio_flags field in struct bio.
sys/cam/ata/ata_da.c:
sys/cam/scsi/scsi_da.c
Use an ordered command for SCSI/ATA-NCQ commands issued in
response to bios with the BIO_ORDERED flag set.
sys/cam/scsi/scsi_da.c
Use an ordered tag when issuing a synchronize cache command.
Wrap some lines to 80 columns.
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
sys/geom/geom_io.c
Mark bios with the BIO_FLUSH command as BIO_ORDERED.
Sponsored by: Spectra Logic Corporation
------------------------------------------------------------------------
Revision Changes Path
1.2.2.17 +2 -1 src/sys/cam/ata/ata_da.c
1.236.2.10 +15 -6 src/sys/cam/scsi/scsi_da.c
1.8.2.7 +1 -0 src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
1.80.2.5 +1 -0 src/sys/geom/geom_io.c
1.1.2.3 +27 -10 src/sys/geom/sched/subr_disk.c
1.90.2.2 +27 -10 src/sys/kern/subr_disk.c
1.148.2.3 +1 -0 src/sys/sys/bio.h
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