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Merge pull request jimsalterjrs#920 from phreaker0/dataset-cache
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[sanoid] implemented dataset cache and fix race conditions
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@jimsalterjrs
jimsalterjrs authored Apr 26, 2024
2 parents b31ed6e + 9c0468e commit a7e6c2d
Showing 1 changed file with 125 additions and 27 deletions.
152 changes: 125 additions & 27 deletions sanoid
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Original file line number Diff line number Diff line change
Expand Up @@ -35,17 +35,6 @@ if (keys %args < 4) {
$args{'verbose'} = 1;
}


my $cacheTTL = 900; # 15 minutes

# Allow a much older snapshot cache file than default if _only_ "--monitor-*" action commands are given
# (ignore "--verbose", "--configdir" etc)
if (($args{'monitor-snapshots'} || $args{'monitor-health'} || $args{'monitor-capacity'}) && ! ($args{'cron'} || $args{'force-update'} || $args{'take-snapshots'} || $args{'prune-snapshots'} || $args{'force-prune'})) {
# The command combination above must not assert true for any command that takes or prunes snapshots
$cacheTTL = 18000; # 5 hours
if ($args{'debug'}) { print "DEBUG: command combo means that the cache file (provided it exists) will be allowed to be older than default.\n"; }
}

# for compatibility reasons, older versions used hardcoded command paths
$ENV{'PATH'} = $ENV{'PATH'} . ":/bin:/sbin";

Expand All @@ -57,25 +46,70 @@ my $zpool = 'zpool';
my $conf_file = "$args{'configdir'}/sanoid.conf";
my $default_conf_file = "$args{'configdir'}/sanoid.defaults.conf";

# parse config file
my %config = init($conf_file,$default_conf_file);

my $cache_dir = $args{'cache-dir'};
my $run_dir = $args{'run-dir'};

make_path($cache_dir);
make_path($run_dir);

# if we call getsnaps(%config,1) it will forcibly update the cache, TTL or no TTL
my $forcecacheupdate = 0;
my $cacheTTL = 1200; # 20 minutes

# Allow a much older snapshot cache file than default if _only_ "--monitor-*" action commands are given
# (ignore "--verbose", "--configdir" etc)
if (
(
$args{'monitor-snapshots'}
|| $args{'monitor-health'}
|| $args{'monitor-capacity'}
) && ! (
$args{'cron'}
|| $args{'force-update'}
|| $args{'take-snapshots'}
|| $args{'prune-snapshots'}
|| $args{'force-prune'}
)
) {
# The command combination above must not assert true for any command that takes or prunes snapshots
$cacheTTL = 18000; # 5 hours
if ($args{'debug'}) { print "DEBUG: command combo means that the cache file (provided it exists) will be allowed to be older than default.\n"; }
}

# snapshot cache
my $cache = "$cache_dir/snapshots.txt";
my %snaps = getsnaps( \%config, $cacheTTL, $forcecacheupdate );

# configured dataset cache
my $cachedatasetspath = "$cache_dir/datasets.txt";
my @cachedatasets;

# parse config file
my %config = init($conf_file,$default_conf_file);

my %pruned;
my %capacitycache;

my %snapsbytype = getsnapsbytype( \%config, \%snaps );
my %snaps;
my %snapsbytype;
my %snapsbypath;

# get snapshot list only if needed
if ($args{'monitor-snapshots'}
|| $args{'monitor-health'}
|| $args{'cron'}
|| $args{'take-snapshots'}
|| $args{'prune-snapshots'}
|| $args{'force-update'}
|| $args{'debug'}
) {
my $forcecacheupdate = 0;
if ($args{'force-update'}) {
$forcecacheupdate = 1;
}

my %snapsbypath = getsnapsbypath( \%config, \%snaps );
%snaps = getsnaps( \%config, $cacheTTL, $forcecacheupdate);

%snapsbytype = getsnapsbytype( \%config, \%snaps );
%snapsbypath = getsnapsbypath( \%config, \%snaps );
}

# let's make it a little easier to be consistent passing these hashes in the same order to each sub
my @params = ( \%config, \%snaps, \%snapsbytype, \%snapsbypath );
Expand All @@ -84,7 +118,6 @@ if ($args{'debug'}) { $args{'verbose'}=1; blabber (@params); }
if ($args{'monitor-snapshots'}) { monitor_snapshots(@params); }
if ($args{'monitor-health'}) { monitor_health(@params); }
if ($args{'monitor-capacity'}) { monitor_capacity(@params); }
if ($args{'force-update'}) { my $snaps = getsnaps( \%config, $cacheTTL, 1 ); }

if ($args{'cron'}) {
if ($args{'quiet'}) { $args{'verbose'} = 0; }
Expand Down Expand Up @@ -275,7 +308,6 @@ sub prune_snapshots {
my ($config, $snaps, $snapsbytype, $snapsbypath) = @_;

my %datestamp = get_date();
my $forcecacheupdate = 0;

foreach my $section (keys %config) {
if ($section =~ /^template/) { next; }
Expand Down Expand Up @@ -826,7 +858,7 @@ sub getsnaps {
if (checklock('sanoid_cacheupdate')) {
writelock('sanoid_cacheupdate');
if ($args{'verbose'}) {
if ($args{'force-update'}) {
if ($forcecacheupdate) {
print "INFO: cache forcibly expired - updating from zfs list.\n";
} else {
print "INFO: cache expired - updating from zfs list.\n";
Expand All @@ -836,9 +868,10 @@ sub getsnaps {
@rawsnaps = <FH>;
close FH;

open FH, "> $cache" or die 'Could not write to $cache!\n';
open FH, "> $cache.tmp" or die 'Could not write to $cache.tmp!\n';
print FH @rawsnaps;
close FH;
rename("$cache.tmp", "$cache") or die 'Could not rename to $cache!\n';
removelock('sanoid_cacheupdate');
} else {
if ($args{'verbose'}) { print "INFO: deferring cache update - valid cache update lock held by another sanoid process.\n"; }
Expand Down Expand Up @@ -901,6 +934,20 @@ sub init {
die "FATAL: you're using sanoid.defaults.conf v$defaults_version, this version of sanoid requires a minimum sanoid.defaults.conf v$MINIMUM_DEFAULTS_VERSION";
}

my @updatedatasets;

# load dataset cache if valid
if (!$args{'force-update'} && -f $cachedatasetspath) {
my ($dev, $ino, $mode, $nlink, $uid, $gid, $rdev, $size, $atime, $mtime, $ctime, $blksize, $blocks) = stat($cachedatasetspath);

if ((time() - $mtime) <= $cacheTTL) {
if ($args{'debug'}) { print "DEBUG: dataset cache not expired (" . (time() - $mtime) . " seconds old with TTL of $cacheTTL): pulling dataset list from cache.\n"; }
open FH, "< $cachedatasetspath";
@cachedatasets = <FH>;
close FH;
}
}

foreach my $section (keys %ini) {

# first up - die with honor if unknown parameters are set in any modules or templates by the user.
Expand Down Expand Up @@ -990,6 +1037,10 @@ sub init {
$config{$section}{'path'} = $section;
}

if (! @cachedatasets) {
push (@updatedatasets, "$config{$section}{'path'}\n");
}

# how 'bout some recursion? =)
if ($config{$section}{'zfs_recursion'} && $config{$section}{'zfs_recursion'} == 1 && $config{$section}{'autosnap'} == 1) {
warn "ignored autosnap configuration for '$section' because it's part of a zfs recursion.\n";
Expand All @@ -1007,6 +1058,10 @@ sub init {

@datasets = getchilddatasets($config{$section}{'path'});
DATASETS: foreach my $dataset(@datasets) {
if (! @cachedatasets) {
push (@updatedatasets, $dataset);
}

chomp $dataset;

if ($zfsRecursive) {
Expand Down Expand Up @@ -1038,9 +1093,27 @@ sub init {
$config{$dataset}{'initialized'} = 1;
}
}
}



# update dataset cache if it was unused
if (! @cachedatasets) {
if (checklock('sanoid_cachedatasetupdate')) {
writelock('sanoid_cachedatasetupdate');
if ($args{'verbose'}) {
if ($args{'force-update'}) {
print "INFO: dataset cache forcibly expired - updating from zfs list.\n";
} else {
print "INFO: dataset cache expired - updating from zfs list.\n";
}
}
open FH, "> $cachedatasetspath.tmp" or die 'Could not write to $cachedatasetspath.tmp!\n';
print FH @updatedatasets;
close FH;
rename("$cachedatasetspath.tmp", "$cachedatasetspath") or die 'Could not rename to $cachedatasetspath!\n';
removelock('sanoid_cachedatasetupdate');
} else {
if ($args{'verbose'}) { print "INFO: deferring dataset cache update - valid cache update lock held by another sanoid process.\n"; }
}
}

return %config;
Expand Down Expand Up @@ -1590,6 +1663,30 @@ sub getchilddatasets {
my $fs = shift;
my $mysudocmd = '';
# use dataset cache if available
if (@cachedatasets) {
my $foundparent = 0;
my @cachechildren = ();
foreach my $dataset (@cachedatasets) {
chomp $dataset;
my $ret = rindex $dataset, "${fs}/", 0;
if ($ret == 0) {
push (@cachechildren, $dataset);
} else {
if ($dataset eq $fs) {
$foundparent = 1;
}
}
}
# sanity check
if ($foundparent) {
return @cachechildren;
}
# fallback if cache misses items for whatever reason
}
my $getchildrencmd = "$mysudocmd $zfs list -o name -t filesystem,volume -Hr $fs |";
if ($args{'debug'}) { print "DEBUG: getting list of child datasets on $fs using $getchildrencmd...\n"; }
open FH, $getchildrencmd;
Expand Down Expand Up @@ -1636,16 +1733,17 @@ sub removecachedsnapshots {
my @rawsnaps = <FH>;
close FH;
open FH, "> $cache" or die 'Could not write to $cache!\n';
open FH, "> $cache.tmp" or die 'Could not write to $cache.tmp!\n';
foreach my $snapline ( @rawsnaps ) {
my @columns = split("\t", $snapline);
my $snap = $columns[0];
print FH $snapline unless ( exists($pruned{$snap}) );
}
close FH;
rename("$cache.tmp", "$cache") or die 'Could not rename to $cache!\n';
removelock('sanoid_cacheupdate');
%snaps = getsnaps(\%config,$cacheTTL,$forcecacheupdate);
%snaps = getsnaps(\%config,$cacheTTL,0);
# clear hash
undef %pruned;
Expand Down

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