mirror of
https://gitlab.isc.org/isc-projects/dhcp
synced 2025-08-29 05:17:57 +00:00
[master] Add option to suppress the use of fsync when writing lease files
The option is dont-use-async <flag> and it defaults to disabled.
This commit is contained in:
Shawn Routhier
parent
1534fff7c5
commit
cde11a4cdb
7
RELNOTES
7
RELNOTES
@ -89,6 +89,13 @@ work on other platforms. Please report any problems and suggested fixes to
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key for security reasons.
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[ISC-Bugs 30461]
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- Add a configuration option to the server to suppress using fsync().
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Enabling this option will mean that fsync() is never called. This
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may provide better performance but there is also a risk that a lease
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will not be properly written to the disk after it has been issued
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to a client and before the server stops. Using this option is
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not recommended.
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Changes since 4.2.5
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- Address static analysis warnings.
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@ -732,6 +732,7 @@ struct lease_state {
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#endif
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#endif
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#define SV_CACHE_THRESHOLD 78
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#define SV_DONT_USE_FSYNC 79
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#if !defined (DEFAULT_PING_TIMEOUT)
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# define DEFAULT_PING_TIMEOUT 1
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@ -1916,6 +1917,7 @@ extern struct timeval cur_tv;
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#define cur_time cur_tv.tv_sec
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extern int ddns_update_style;
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extern int dont_use_fsync;
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extern const char *path_dhcpd_conf;
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extern const char *path_dhcpd_db;
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@ -1015,11 +1015,12 @@ int commit_leases ()
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just in case the rewrite fails. */
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if (fflush (db_file) == EOF) {
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log_info("commit_leases: unable to commit, fflush(): %m");
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return 0;
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return (0);
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}
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if (fsync (fileno (db_file)) < 0) {
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if ((dont_use_fsync == 0) &&
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(fsync(fileno (db_file)) < 0)) {
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log_info ("commit_leases: unable to commit, fsync(): %m");
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return 0;
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return (0);
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}
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/* send out all deferred ACKs now */
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@ -1033,7 +1034,7 @@ int commit_leases ()
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write_time = cur_time;
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new_lease_file();
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}
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return 1;
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return (1);
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}
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/*
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@ -78,6 +78,7 @@ option server.ddns-rev-domainname = \"in-addr.arpa.\";";
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#endif /* NSUPDATE */
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int ddns_update_style;
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int dont_use_fsync = 0; /* 0 = default, use fsync, 1 = don't use fsync */
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const char *path_dhcpd_conf = _PATH_DHCPD_CONF;
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const char *path_dhcpd_db = _PATH_DHCPD_DB;
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@ -800,7 +801,7 @@ main(int argc, char **argv) {
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void postconf_initialization (int quiet)
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{
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struct option_state *options = (struct option_state *)0;
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struct option_state *options = NULL;
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struct data_string db;
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struct option_cache *oc;
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char *s;
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@ -816,9 +817,7 @@ void postconf_initialization (int quiet)
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memset(&db, 0, sizeof db);
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oc = lookup_option(&server_universe, options, SV_LEASE_FILE_NAME);
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if (oc &&
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evaluate_option_cache (&db, (struct packet *)0,
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(struct lease *)0, (struct client_state *)0,
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options, (struct option_state *)0,
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evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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s = dmalloc(db.len + 1, MDL);
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if (!s)
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@ -831,9 +830,7 @@ void postconf_initialization (int quiet)
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oc = lookup_option(&server_universe, options, SV_PID_FILE_NAME);
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if (oc &&
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evaluate_option_cache (&db, (struct packet *)0,
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(struct lease *)0, (struct client_state *)0,
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options, (struct option_state *)0,
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evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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s = dmalloc(db.len + 1, MDL);
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if (!s)
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@ -853,9 +850,8 @@ void postconf_initialization (int quiet)
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oc = lookup_option(&server_universe, options,
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SV_DHCPV6_LEASE_FILE_NAME);
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if (oc &&
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evaluate_option_cache(&db, NULL, NULL, NULL,
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options, NULL, &global_scope,
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oc, MDL)) {
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evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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s = dmalloc(db.len + 1, MDL);
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if (!s)
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log_fatal("no memory for lease db filename.");
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@ -868,9 +864,8 @@ void postconf_initialization (int quiet)
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oc = lookup_option(&server_universe, options,
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SV_DHCPV6_PID_FILE_NAME);
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if (oc &&
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evaluate_option_cache(&db, NULL, NULL, NULL,
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options, NULL, &global_scope,
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oc, MDL)) {
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evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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s = dmalloc(db.len + 1, MDL);
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if (!s)
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log_fatal("no memory for pid filename.");
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@ -885,9 +880,7 @@ void postconf_initialization (int quiet)
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omapi_port = -1;
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oc = lookup_option(&server_universe, options, SV_OMAPI_PORT);
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if (oc &&
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evaluate_option_cache (&db, (struct packet *)0,
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(struct lease *)0, (struct client_state *)0,
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options, (struct option_state *)0,
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evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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if (db.len == 2) {
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omapi_port = getUShort(db.data);
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@ -898,10 +891,7 @@ void postconf_initialization (int quiet)
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oc = lookup_option(&server_universe, options, SV_OMAPI_KEY);
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if (oc &&
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evaluate_option_cache (&db, (struct packet *)0,
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(struct lease *)0, (struct client_state *)0,
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options,
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(struct option_state *)0,
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evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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s = dmalloc(db.len + 1, MDL);
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if (!s)
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@ -918,10 +908,7 @@ void postconf_initialization (int quiet)
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oc = lookup_option(&server_universe, options, SV_LOCAL_PORT);
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if (oc &&
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evaluate_option_cache (&db, (struct packet *)0,
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(struct lease *)0, (struct client_state *)0,
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options,
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(struct option_state *)0,
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evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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if (db.len == 2) {
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local_port = htons(getUShort (db.data));
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@ -932,9 +919,7 @@ void postconf_initialization (int quiet)
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oc = lookup_option(&server_universe, options, SV_REMOTE_PORT);
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if (oc &&
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evaluate_option_cache (&db, (struct packet *)0,
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(struct lease *)0, (struct client_state *)0,
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options, (struct option_state *)0,
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evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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if (db.len == 2) {
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remote_port = htons(getUShort (db.data));
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@ -946,9 +931,7 @@ void postconf_initialization (int quiet)
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oc = lookup_option(&server_universe, options,
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SV_LIMITED_BROADCAST_ADDRESS);
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if (oc &&
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evaluate_option_cache (&db, (struct packet *)0,
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(struct lease *)0, (struct client_state *)0,
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options, (struct option_state *)0,
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evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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if (db.len == 4) {
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memcpy(&limited_broadcast, db.data, 4);
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@ -957,12 +940,9 @@ void postconf_initialization (int quiet)
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data_string_forget(&db, MDL);
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}
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oc = lookup_option (&server_universe, options,
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SV_LOCAL_ADDRESS);
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oc = lookup_option(&server_universe, options, SV_LOCAL_ADDRESS);
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if (oc &&
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evaluate_option_cache (&db, (struct packet *)0,
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(struct lease *)0, (struct client_state *)0,
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options, (struct option_state *)0,
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evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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if (db.len == 4) {
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memcpy(&local_address, db.data, 4);
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@ -973,11 +953,7 @@ void postconf_initialization (int quiet)
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oc = lookup_option(&server_universe, options, SV_DDNS_UPDATE_STYLE);
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if (oc) {
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if (evaluate_option_cache (&db, (struct packet *)0,
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(struct lease *)0,
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(struct client_state *)0,
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options,
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(struct option_state *)0,
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if (evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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if (db.len == 1) {
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ddns_update_style = db.data[0];
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@ -1002,11 +978,7 @@ void postconf_initialization (int quiet)
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oc = lookup_option(&server_universe, options, SV_LOG_FACILITY);
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if (oc) {
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if (evaluate_option_cache (&db, (struct packet *)0,
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(struct lease *)0,
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(struct client_state *)0,
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options,
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(struct option_state *)0,
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if (evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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if (db.len == 1) {
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closelog ();
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@ -1058,6 +1030,14 @@ void postconf_initialization (int quiet)
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data_string_forget(&db, MDL);
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}
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oc = lookup_option(&server_universe, options, SV_DONT_USE_FSYNC);
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if ((oc != NULL) &&
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evaluate_boolean_option_cache(NULL, NULL, NULL, NULL, options, NULL,
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&global_scope, oc, MDL)) {
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dont_use_fsync = 1;
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log_error("Not using fsync() to flush lease writes");
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}
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/* Don't need the options anymore. */
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option_state_dereference(&options, MDL);
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}
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@ -2110,6 +2110,24 @@ will still honor the setting of the \fBclient-updates\fR flag.
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.RE
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.PP
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The
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.I dont-use-async
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statement
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.RS 0.25i
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.PP
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.B dont-use-async \fIflag\fB;\fR
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.PP
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The \fIdont-use-async\fR statement instructs the DHCP server if
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it should call fsync() when writing leases to the lease file. By
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default and if the flag is set to false the server \fBwill\fR call
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fsync(). Suppressing the call to fsync() may increase the performance
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of the server but it also adds a risk that a lease will not be
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properly written to the disk after it has been issued to a client
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and before the server stops. This can lead to duplicate leases
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being issued to different clients. Using this option is \fBnot
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recommended\FR.
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.RE
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.PP
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The
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.I dynamic-bootp-lease-cutoff
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statement
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.RS 0.25i
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@ -267,6 +267,7 @@ static struct option server_options[] = {
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#endif /* LDAP_USE_SSL */
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#endif /* LDAP_CONFIGURATION */
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{ "dhcp-cache-threshold", "B", &server_universe, 78, 1 },
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{ "dont-use-fsync", "f", &server_universe, 79, 1 },
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{ NULL, NULL, NULL, 0, 0 }
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};
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