zpool reports 16E expandsize on disks with oddball number of sectors

The issue is caused by a small discrepancy in how userland creates the
partition layout and the kernel estimates available space:

 * zpool command: subtract 9M from the usable device size, then align
   to 1M boundary. 9M is the sum of 1M "start" partition alignment + 8M
   EFI "reserved" partition.

 * kernel module: subtract 10M from the device size. 10M is the sum of
   1M "start" partition alignment + 1m "end" partition alignment + 8M
   EFI "reserved" partition.

For devices where the number of sectors is not a multiple of the
alignment size the zpool command will create a partition layout which
reserves less than 1M after the 8M EFI "reserved" partition:

  Disk /dev/sda: 1024 MiB, 1073739776 bytes, 2097148 sectors
  Units: sectors of 1 * 512 = 512 bytes
  Sector size (logical/physical): 512 bytes / 512 bytes
  I/O size (minimum/optimal): 512 bytes / 512 bytes
  Disklabel type: gpt
  Disk identifier: 49811D40-16F4-4E41-84A9-387703950D7F

  Device       Start     End Sectors  Size Type
  /dev/sda1     2048 2078719 2076672 1014M Solaris /usr & Apple ZFS
  /dev/sda9  2078720 2095103   16384    8M Solaris reserved 1

When the kernel module vdev_open() the device its max_asize ends up
being slightly smaller than asize: this results in a huge number (16E)
reported by metaslab_class_expandable_space().

This change prevents bdev_max_capacity() from returing a size smaller
than bdev_capacity().

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Wilson <george.wilson@delphix.com>
Reviewed by: Sara Hartse <sara.hartse@delphix.com>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #1468 
Closes #8391
This commit is contained in:
loli10K
2019-02-23 00:36:34 +01:00
committed by Brian Behlendorf
parent 8d9e51c084
commit 0c637f3100
2 changed files with 22 additions and 4 deletions
+11
View File
@@ -1645,6 +1645,17 @@ vdev_open(vdev_t *vd)
error = vd->vdev_ops->vdev_op_open(vd, &osize, &max_osize, &ashift);
/*
* Physical volume size should never be larger than its max size, unless
* the disk has shrunk while we were reading it or the device is buggy
* or damaged: either way it's not safe for use, bail out of the open.
*/
if (osize > max_osize) {
vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
VDEV_AUX_OPEN_FAILED);
return (SET_ERROR(ENXIO));
}
/*
* Reset the vdev_reopening flag so that we actually close
* the vdev on error.