linux/drivers/block
Paul Durrant f4eef1b652 xen-blkback: support dynamic unbind/bind
By simply re-attaching to shared rings during connect_ring() rather than
assuming they are freshly allocated (i.e assuming the counters are zero)
it is possible for vbd instances to be unbound and re-bound from and to
(respectively) a running guest.

This has been tested by running:

while true;
  do fio --name=randwrite --ioengine=libaio --iodepth=16 \
  --rw=randwrite --bs=4k --direct=1 --size=1G --verify=crc32;
  done

in a PV guest whilst running:

while true;
  do echo vbd-$DOMID-$VBD >unbind;
  echo unbound;
  sleep 5;
  echo vbd-$DOMID-$VBD >bind;
  echo bound;
  sleep 3;
  done

in dom0 from /sys/bus/xen-backend/drivers/vbd to continuously unbind and
re-bind its system disk image.

This is a highly useful feature for a backend module as it allows it to be
unloaded and re-loaded (i.e. updated) without requiring domUs to be halted.
This was also tested by running:

while true;
  do echo vbd-$DOMID-$VBD >unbind;
  echo unbound;
  sleep 5;
  rmmod xen-blkback;
  echo unloaded;
  sleep 1;
  modprobe xen-blkback;
  echo bound;
  cd $(pwd);
  sleep 3;
  done

in dom0 whilst running the same loop as above in the (single) PV guest.

Some (less stressful) testing has also been done using a Windows HVM guest
with the latest 9.0 PV drivers installed.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
2019-12-20 13:44:45 +01:00
..
aoe block: aoe: Fix kernel crash due to atomic sleep when exiting 2019-08-08 07:29:02 -06:00
drbd Printk changes for 5.5 2019-11-25 19:40:40 -08:00
mtip32xx block: mtip32xx: Spelling s/configration/configuration/ 2019-10-25 14:31:07 -06:00
paride paride/pcd: need to check if cd->disk is null in pcd_detect 2019-09-04 07:04:37 -06:00
rsxx rsxx: add missed destroy_workqueue calls in remove 2019-11-14 13:59:49 -07:00
xen-blkback xen-blkback: support dynamic unbind/bind 2019-12-20 13:44:45 +01:00
zram zram: fix race between backing_dev_show and backing_dev_store 2019-10-19 06:32:32 -04:00
amiflop.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
ataflop.c ataflop: Mark expected switch fall-through 2019-07-29 15:24:58 -06:00
brd.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
cryptoloop.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 30 2019-05-24 17:27:10 +02:00
floppy.c floppy: fix usercopy direction 2019-08-09 07:41:36 -06:00
Kconfig docs: blockdev: add it to the admin-guide 2019-07-15 11:03:01 -03:00
loop.c block: remove (__)blkdev_reread_part as an exported API 2019-11-14 07:43:59 -07:00
loop.h block/loop: Use global lock for ioctl() operation. 2018-11-08 06:30:11 -07:00
Makefile drivers/block: Remove DAC960 driver 2018-10-17 09:42:30 -06:00
nbd.c for-5.5/drivers-post-20191122 2019-11-25 11:18:03 -08:00
null_blk_main.c null_blk: Add zone_nr_conv to features 2019-11-12 19:12:02 -07:00
null_blk_zoned.c for-5.5/drivers-20191121 2019-11-25 11:15:41 -08:00
null_blk.h block: rework zone reporting 2019-11-12 19:12:07 -07:00
pktcdvd.c pktcdvd: remove warning on attempting to register non-passthrough dev 2019-09-22 10:01:05 -06:00
ps3disk.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 164 2019-05-30 11:26:38 -07:00
ps3vram.c block/ps3vram: Use %llu to format sector_t after LBDAF removal 2019-06-13 03:17:50 -06:00
rbd_types.h rbd: support for object-map and fast-diff 2019-07-08 14:01:45 +02:00
rbd.c rbd: silence bogus uninitialized warning in rbd_object_map_update_finish() 2019-11-14 19:00:53 +01:00
skd_main.c Linux 5.2-rc6 2019-07-01 08:16:08 -06:00
skd_s1120.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497 2019-06-19 17:09:53 +02:00
sunvdc.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
swim3.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
swim_asm.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
swim.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sx8.c sx8: use a per-host tag_set 2018-11-09 08:14:14 -07:00
umem.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 349 2019-06-05 17:37:08 +02:00
umem.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 348 2019-06-05 17:37:08 +02:00
virtio_blk.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
xen-blkfront.c xen/blkfront: Adjust indentation in xlvbd_alloc_gendisk 2019-12-20 13:38:13 +01:00
xsysace.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
z2ram.c powerpc updates for 4.20 2018-10-26 14:36:21 -07:00