Remove vn_rename and vn_remove dependency

The only place vn_rename and vn_remove are used is when writing
out an updated pool configuration file.  By truncating the file
instead of renaming and removing it we can avoid having to implement
these interfaces entirely.  Functionally an empty cache file is
treated the same as a missing cache file.  This is particularly
advantageous because the Linux kernel has never provided a way
to reliably implement vn_rename and vn_remove.

The cachefile_004_pos.ksh test case was updated to understand
that an empty cache file is the same as a missing one.

The zfs-import-* systemd service files were not updated to use
ConditionFileNotEmpty in place of ConditionPathExists.  This
means that after exporting all pools and rebooting new pools
will not the scanned for on the next boot.  This small change
should not impact normal usage since pools are not exported
as part of a normal shutdown.

Documentation was updated accordingly.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Arkadiusz Bubała <arkadiusz.bubala@open-e.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes zfsonlinux/spl#648
Closes #6753
This commit is contained in:
Brian Behlendorf
2017-10-19 10:06:55 -07:00
committed by Tony Hutter
parent 6897ea475f
commit 5d62588032
3 changed files with 32 additions and 10 deletions
@@ -98,13 +98,13 @@ log_must zpool set cachefile=$CPATH2 $TESTPOOL1
log_must pool_in_cache $TESTPOOL1 $CPATH2
log_must zpool set cachefile=$CPATH2 $TESTPOOL2
log_must pool_in_cache $TESTPOOL2 $CPATH2
if [[ -f $CPATH1 ]]; then
if [[ -s $CPATH1 ]]; then
log_fail "Verify set when cachefile is set on pool."
fi
log_must zpool export $TESTPOOL1
log_must zpool export $TESTPOOL2
if [[ -f $CPATH2 ]]; then
if [[ -s $CPATH2 ]]; then
log_fail "Verify export when cachefile is set on pool."
fi
@@ -117,7 +117,7 @@ log_must pool_in_cache $TESTPOOL2 $CPATH2
log_must zpool destroy $TESTPOOL1
log_must zpool destroy $TESTPOOL2
if [[ -f $CPATH2 ]]; then
if [[ -s $CPATH2 ]]; then
log_fail "Verify destroy when cachefile is set on pool."
fi