mir/isc-dhcp
2
0
Fork 0
mirror of https://gitlab.isc.org/isc-projects/dhcp synced 2025-08-22 09:57:20 +00:00
Code Issues Releases Wiki Activity

[master] Add option to suppress the use of fsync when writing lease files

Browse Source 
The option is dont-use-async <flag> and it defaults to disabled.
This commit is contained in:
Shawn Routhier 2013-11-08 12:00:02 -08:00
parent 1534fff7c5
commit cde11a4cdb
6 changed files with 136 additions and 127 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
RELNOTES
View File

@ -89,6 +89,13 @@ work on other platforms. Please report any problems and suggested fixes to
key for security reasons.
[ISC-Bugs 30461]
- Add a configuration option to the server to suppress using fsync().
Enabling this option will mean that fsync() is never called. This
may provide better performance but there is also a risk that a lease
will not be properly written to the disk after it has been issued
to a client and before the server stops. Using this option is
not recommended.
Changes since 4.2.5
- Address static analysis warnings.

2
includes/dhcpd.h
View File

@ -732,6 +732,7 @@ struct lease_state {
#endif
#endif
#define SV_CACHE_THRESHOLD 78
#define SV_DONT_USE_FSYNC 79
#if !defined (DEFAULT_PING_TIMEOUT)
# define DEFAULT_PING_TIMEOUT 1
@ -1916,6 +1917,7 @@ extern struct timeval cur_tv;
#define cur_time cur_tv.tv_sec
extern int ddns_update_style;
extern int dont_use_fsync;
extern const char *path_dhcpd_conf;
extern const char *path_dhcpd_db;

13
server/db.c
View File

@ -1014,12 +1014,13 @@ int commit_leases ()
We need to do this even if we're rewriting the file below,
just in case the rewrite fails. */
if (fflush (db_file) == EOF) {
log_info ("commit_leases: unable to commit, fflush(): %m");
return 0;
log_info("commit_leases: unable to commit, fflush(): %m");
return (0);
}
if (fsync (fileno (db_file)) < 0) {
if ((dont_use_fsync == 0) &&
(fsync(fileno (db_file)) < 0)) {
log_info ("commit_leases: unable to commit, fsync(): %m");
return 0;
return (0);
}
/* send out all deferred ACKs now */
@ -1031,9 +1032,9 @@ int commit_leases ()
if (count && cur_time - write_time > LEASE_REWRITE_PERIOD) {
count = 0;
write_time = cur_time;
new_lease_file ();
new_lease_file();
}
return 1;
return (1);
}
/*

222
server/dhcpd.c
View File

@ -78,6 +78,7 @@ option server.ddns-rev-domainname = \"in-addr.arpa.\";";
#endif /* NSUPDATE */
int ddns_update_style;
int dont_use_fsync = 0; /* 0 = default, use fsync, 1 = don't use fsync */
const char *path_dhcpd_conf = _PATH_DHCPD_CONF;
const char *path_dhcpd_db = _PATH_DHCPD_DB;
@ -800,7 +801,7 @@ main(int argc, char **argv) {
void postconf_initialization (int quiet)
{
struct option_state *options = (struct option_state *)0;
struct option_state *options = NULL;
struct data_string db;
struct option_cache *oc;
char *s;
@ -808,39 +809,35 @@ void postconf_initialization (int quiet)
int tmp;
/* Now try to get the lease file name. */
option_state_allocate (&options, MDL);
option_state_allocate(&options, MDL);
execute_statements_in_scope(NULL, NULL, NULL, NULL, NULL,
options, &global_scope, root_group,
NULL, NULL);
memset (&db, 0, sizeof db);
oc = lookup_option (&server_universe, options, SV_LEASE_FILE_NAME);
memset(&db, 0, sizeof db);
oc = lookup_option(&server_universe, options, SV_LEASE_FILE_NAME);
if (oc &&
evaluate_option_cache (&db, (struct packet *)0,
(struct lease *)0, (struct client_state *)0,
options, (struct option_state *)0,
&global_scope, oc, MDL)) {
s = dmalloc (db.len + 1, MDL);
evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
s = dmalloc(db.len + 1, MDL);
if (!s)
log_fatal ("no memory for lease db filename.");
memcpy (s, db.data, db.len);
s [db.len] = 0;
data_string_forget (&db, MDL);
log_fatal("no memory for lease db filename.");
memcpy(s, db.data, db.len);
s[db.len] = 0;
data_string_forget(&db, MDL);
path_dhcpd_db = s;
}
oc = lookup_option (&server_universe, options, SV_PID_FILE_NAME);
oc = lookup_option(&server_universe, options, SV_PID_FILE_NAME);
if (oc &&
evaluate_option_cache (&db, (struct packet *)0,
(struct lease *)0, (struct client_state *)0,
options, (struct option_state *)0,
&global_scope, oc, MDL)) {
s = dmalloc (db.len + 1, MDL);
evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
s = dmalloc(db.len + 1, MDL);
if (!s)
log_fatal ("no memory for pid filename.");
memcpy (s, db.data, db.len);
s [db.len] = 0;
data_string_forget (&db, MDL);
log_fatal("no memory for pid filename.");
memcpy(s, db.data, db.len);
s[db.len] = 0;
data_string_forget(&db, MDL);
path_dhcpd_pid = s;
}
@ -853,137 +850,116 @@ void postconf_initialization (int quiet)
oc = lookup_option(&server_universe, options,
SV_DHCPV6_LEASE_FILE_NAME);
if (oc &&
evaluate_option_cache(&db, NULL, NULL, NULL,
options, NULL, &global_scope,
oc, MDL)) {
s = dmalloc (db.len + 1, MDL);
evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
s = dmalloc(db.len + 1, MDL);
if (!s)
log_fatal ("no memory for lease db filename.");
memcpy (s, db.data, db.len);
s [db.len] = 0;
data_string_forget (&db, MDL);
log_fatal("no memory for lease db filename.");
memcpy(s, db.data, db.len);
s[db.len] = 0;
data_string_forget(&db, MDL);
path_dhcpd_db = s;
}
oc = lookup_option(&server_universe, options,
SV_DHCPV6_PID_FILE_NAME);
if (oc &&
evaluate_option_cache(&db, NULL, NULL, NULL,
options, NULL, &global_scope,
oc, MDL)) {
s = dmalloc (db.len + 1, MDL);
evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
s = dmalloc(db.len + 1, MDL);
if (!s)
log_fatal ("no memory for pid filename.");
memcpy (s, db.data, db.len);
s [db.len] = 0;
data_string_forget (&db, MDL);
log_fatal("no memory for pid filename.");
memcpy(s, db.data, db.len);
s[db.len] = 0;
data_string_forget(&db, MDL);
path_dhcpd_pid = s;
}
}
#endif /* DHCPv6 */
omapi_port = -1;
oc = lookup_option (&server_universe, options, SV_OMAPI_PORT);
oc = lookup_option(&server_universe, options, SV_OMAPI_PORT);
if (oc &&
evaluate_option_cache (&db, (struct packet *)0,
(struct lease *)0, (struct client_state *)0,
options, (struct option_state *)0,
&global_scope, oc, MDL)) {
evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
if (db.len == 2) {
omapi_port = getUShort (db.data);
omapi_port = getUShort(db.data);
} else
log_fatal ("invalid omapi port data length");
data_string_forget (&db, MDL);
log_fatal("invalid omapi port data length");
data_string_forget(&db, MDL);
}
oc = lookup_option (&server_universe, options, SV_OMAPI_KEY);
oc = lookup_option(&server_universe, options, SV_OMAPI_KEY);
if (oc &&
evaluate_option_cache (&db, (struct packet *)0,
(struct lease *)0, (struct client_state *)0,
options,
(struct option_state *)0,
&global_scope, oc, MDL)) {
s = dmalloc (db.len + 1, MDL);
evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
s = dmalloc(db.len + 1, MDL);
if (!s)
log_fatal ("no memory for OMAPI key filename.");
memcpy (s, db.data, db.len);
s [db.len] = 0;
data_string_forget (&db, MDL);
result = omapi_auth_key_lookup_name (&omapi_key, s);
dfree (s, MDL);
log_fatal("no memory for OMAPI key filename.");
memcpy(s, db.data, db.len);
s[db.len] = 0;
data_string_forget(&db, MDL);
result = omapi_auth_key_lookup_name(&omapi_key, s);
dfree(s, MDL);
if (result != ISC_R_SUCCESS)
log_fatal ("OMAPI key %s: %s",
s, isc_result_totext (result));
log_fatal("OMAPI key %s: %s",
s, isc_result_totext (result));
}
oc = lookup_option (&server_universe, options, SV_LOCAL_PORT);
oc = lookup_option(&server_universe, options, SV_LOCAL_PORT);
if (oc &&
evaluate_option_cache (&db, (struct packet *)0,
(struct lease *)0, (struct client_state *)0,
options,
(struct option_state *)0,
&global_scope, oc, MDL)) {
evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
if (db.len == 2) {
local_port = htons (getUShort (db.data));
local_port = htons(getUShort (db.data));
} else
log_fatal ("invalid local port data length");
data_string_forget (&db, MDL);
log_fatal("invalid local port data length");
data_string_forget(&db, MDL);
}
oc = lookup_option (&server_universe, options, SV_REMOTE_PORT);
oc = lookup_option(&server_universe, options, SV_REMOTE_PORT);
if (oc &&
evaluate_option_cache (&db, (struct packet *)0,
(struct lease *)0, (struct client_state *)0,
options, (struct option_state *)0,
&global_scope, oc, MDL)) {
evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
if (db.len == 2) {
remote_port = htons (getUShort (db.data));
remote_port = htons(getUShort (db.data));
} else
log_fatal ("invalid remote port data length");
data_string_forget (&db, MDL);
log_fatal("invalid remote port data length");
data_string_forget(&db, MDL);
}
oc = lookup_option (&server_universe, options,
SV_LIMITED_BROADCAST_ADDRESS);
oc = lookup_option(&server_universe, options,
SV_LIMITED_BROADCAST_ADDRESS);
if (oc &&
evaluate_option_cache (&db, (struct packet *)0,
(struct lease *)0, (struct client_state *)0,
options, (struct option_state *)0,
&global_scope, oc, MDL)) {
evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
if (db.len == 4) {
memcpy (&limited_broadcast, db.data, 4);
memcpy(&limited_broadcast, db.data, 4);
} else
log_fatal ("invalid broadcast address data length");
data_string_forget (&db, MDL);
log_fatal("invalid broadcast address data length");
data_string_forget(&db, MDL);
}
oc = lookup_option (&server_universe, options,
SV_LOCAL_ADDRESS);
oc = lookup_option(&server_universe, options, SV_LOCAL_ADDRESS);
if (oc &&
evaluate_option_cache (&db, (struct packet *)0,
(struct lease *)0, (struct client_state *)0,
options, (struct option_state *)0,
&global_scope, oc, MDL)) {
evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
if (db.len == 4) {
memcpy (&local_address, db.data, 4);
memcpy(&local_address, db.data, 4);
} else
log_fatal ("invalid local address data length");
data_string_forget (&db, MDL);
log_fatal("invalid local address data length");
data_string_forget(&db, MDL);
}
oc = lookup_option (&server_universe, options, SV_DDNS_UPDATE_STYLE);
oc = lookup_option(&server_universe, options, SV_DDNS_UPDATE_STYLE);
if (oc) {
if (evaluate_option_cache (&db, (struct packet *)0,
(struct lease *)0,
(struct client_state *)0,
options,
(struct option_state *)0,
&global_scope, oc, MDL)) {
if (evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
if (db.len == 1) {
ddns_update_style = db.data [0];
ddns_update_style = db.data[0];
} else
log_fatal ("invalid dns update type");
data_string_forget (&db, MDL);
log_fatal("invalid dns update type");
data_string_forget(&db, MDL);
}
} else {
ddns_update_style = DDNS_UPDATE_STYLE_NONE;
@ -1000,17 +976,13 @@ void postconf_initialization (int quiet)
}
#endif
oc = lookup_option (&server_universe, options, SV_LOG_FACILITY);
oc = lookup_option(&server_universe, options, SV_LOG_FACILITY);
if (oc) {
if (evaluate_option_cache (&db, (struct packet *)0,
(struct lease *)0,
(struct client_state *)0,
options,
(struct option_state *)0,
&global_scope, oc, MDL)) {
if (evaluate_option_cache(&db, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
if (db.len == 1) {
closelog ();
openlog ("dhcpd", LOG_NDELAY, db.data[0]);
openlog("dhcpd", LOG_NDELAY, db.data[0]);
/* Log the startup banner into the new
log file. */
if (!quiet) {
@ -1019,14 +991,14 @@ void postconf_initialization (int quiet)
log_perror = 0;
log_info("%s %s",
message, PACKAGE_VERSION);
log_info (copyright);
log_info (arr);
log_info (url);
log_info(copyright);
log_info(arr);
log_info(url);
log_perror = tmp;
}
} else
log_fatal ("invalid log facility");
data_string_forget (&db, MDL);
log_fatal("invalid log facility");
data_string_forget(&db, MDL);
}
}
@ -1058,8 +1030,16 @@ void postconf_initialization (int quiet)
data_string_forget(&db, MDL);
}
oc = lookup_option(&server_universe, options, SV_DONT_USE_FSYNC);
if ((oc != NULL) &&
evaluate_boolean_option_cache(NULL, NULL, NULL, NULL, options, NULL,
&global_scope, oc, MDL)) {
dont_use_fsync = 1;
log_error("Not using fsync() to flush lease writes");
}
/* Don't need the options anymore. */
option_state_dereference (&options, MDL);
option_state_dereference(&options, MDL);
}
void postdb_startup (void)

18
server/dhcpd.conf.5
View File

@ -2110,6 +2110,24 @@ will still honor the setting of the \fBclient-updates\fR flag.
.RE
.PP
The
.I dont-use-async
statement
.RS 0.25i
.PP
.B dont-use-async \fIflag\fB;\fR
.PP
The \fIdont-use-async\fR statement instructs the DHCP server if
it should call fsync() when writing leases to the lease file. By
default and if the flag is set to false the server \fBwill\fR call
fsync(). Suppressing the call to fsync() may increase the performance
of the server but it also adds a risk that a lease will not be
properly written to the disk after it has been issued to a client
and before the server stops. This can lead to duplicate leases
being issued to different clients. Using this option is \fBnot
recommended\FR.
.RE
.PP
The
.I dynamic-bootp-lease-cutoff
statement
.RS 0.25i

1
server/stables.c
View File

@ -267,6 +267,7 @@ static struct option server_options[] = {
#endif /* LDAP_USE_SSL */
#endif /* LDAP_CONFIGURATION */
{ "dhcp-cache-threshold", "B", &server_universe, 78, 1 },
{ "dont-use-fsync", "f", &server_universe, 79, 1 },
{ NULL, NULL, NULL, 0, 0 }
};