diff mbox

[v2,1/8] libmultipath: load_config: skip setting unnecessary defaults

Message ID 20170620114614.26261-2-mwilck@suse.com (mailing list archive)
State Not Applicable, archived
Delegated to: Mike Snitzer
Headers show

Commit Message

Martin Wilck June 20, 2017, 11:46 a.m. UTC 
We have the logic for setting defaults for paths and maps
in propsel.c. By pre-setting conf values with defaults in
load_config(), we generate irritating log messages like
'features = "0" (setting: multipath.conf defaults/devices section)'
if multipath.conf doesn't contain a features setting at all.

For some config settings, we need to use declare_def_snprint_defint()
now to make sure "multipathd show config" prints all defaults correctly.
To avoid confusion, we don't do this for "max_sectors", because
multipathd leaves this untouched by default.

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 libmultipath/config.c  | 16 ----------------
 libmultipath/dict.c    | 11 +++++++----
 libmultipath/propsel.c |  5 +++++
 3 files changed, 12 insertions(+), 20 deletions(-)

Comments

Hannes Reinecke June 20, 2017, 2:36 p.m. UTC | #1 
On 06/20/2017 01:46 PM, Martin Wilck wrote:
> We have the logic for setting defaults for paths and maps
> in propsel.c. By pre-setting conf values with defaults in
> load_config(), we generate irritating log messages like
> 'features = "0" (setting: multipath.conf defaults/devices section)'
> if multipath.conf doesn't contain a features setting at all.
> 
> For some config settings, we need to use declare_def_snprint_defint()
> now to make sure "multipathd show config" prints all defaults correctly.
> To avoid confusion, we don't do this for "max_sectors", because
> multipathd leaves this untouched by default.
> 
> Signed-off-by: Martin Wilck <mwilck@suse.com>
> ---
>  libmultipath/config.c  | 16 ----------------
>  libmultipath/dict.c    | 11 +++++++----
>  libmultipath/propsel.c |  5 +++++
>  3 files changed, 12 insertions(+), 20 deletions(-)
> 
> diff --git a/libmultipath/config.c b/libmultipath/config.c
> index bb6619b3..61bbba91 100644
> --- a/libmultipath/config.c
> +++ b/libmultipath/config.c
> @@ -599,40 +599,24 @@ load_config (char * file)
>  	if (!conf->verbosity)
>  		conf->verbosity = DEFAULT_VERBOSITY;
>  
> -	conf->minio = DEFAULT_MINIO;
> -	conf->minio_rq = DEFAULT_MINIO_RQ;
>  	get_sys_max_fds(&conf->max_fds);
>  	conf->bindings_file = set_default(DEFAULT_BINDINGS_FILE);
>  	conf->wwids_file = set_default(DEFAULT_WWIDS_FILE);
>  	conf->multipath_dir = set_default(DEFAULT_MULTIPATHDIR);
> -	conf->features = set_default(DEFAULT_FEATURES);
> -	conf->flush_on_last_del = DEFAULT_FLUSH;
>  	conf->attribute_flags = 0;
>  	conf->reassign_maps = DEFAULT_REASSIGN_MAPS;
>  	conf->checkint = DEFAULT_CHECKINT;
>  	conf->max_checkint = 0;
> -	conf->pgfailback = DEFAULT_FAILBACK;
> -	conf->fast_io_fail = DEFAULT_FAST_IO_FAIL;
> -	conf->retain_hwhandler = DEFAULT_RETAIN_HWHANDLER;
> -	conf->detect_prio = DEFAULT_DETECT_PRIO;
> -	conf->detect_checker = DEFAULT_DETECT_CHECKER;
>  	conf->force_sync = DEFAULT_FORCE_SYNC;
>  	conf->partition_delim = DEFAULT_PARTITION_DELIM;
>  	conf->processed_main_config = 0;
>  	conf->find_multipaths = DEFAULT_FIND_MULTIPATHS;
>  	conf->uxsock_timeout = DEFAULT_REPLY_TIMEOUT;
> -	conf->uid_attribute = set_default(DEFAULT_UID_ATTRIBUTE);
>  	conf->retrigger_tries = DEFAULT_RETRIGGER_TRIES;
>  	conf->retrigger_delay = DEFAULT_RETRIGGER_DELAY;
>  	conf->uev_wait_timeout = DEFAULT_UEV_WAIT_TIMEOUT;
> -	conf->deferred_remove = DEFAULT_DEFERRED_REMOVE;
> -	conf->skip_kpartx = DEFAULT_SKIP_KPARTX;
>  	conf->disable_changed_wwids = DEFAULT_DISABLE_CHANGED_WWIDS;
>  	conf->remove_retries = 0;
> -	conf->max_sectors_kb = DEFAULT_MAX_SECTORS_KB;
> -	conf->san_path_err_threshold = DEFAULT_ERR_CHECKS;
> -	conf->san_path_err_forget_rate = DEFAULT_ERR_CHECKS;
> -	conf->san_path_err_recovery_time = DEFAULT_ERR_CHECKS;
>  
>  	/*
>  	 * preload default hwtable
> diff --git a/libmultipath/dict.c b/libmultipath/dict.c
> index 82066f67..9dc10904 100644
> --- a/libmultipath/dict.c
> +++ b/libmultipath/dict.c
> @@ -630,7 +630,7 @@ print_fast_io_fail(char * buff, int len, void *ptr)
>  }
>  
>  declare_def_handler(fast_io_fail, set_fast_io_fail)
> -declare_def_snprint(fast_io_fail, print_fast_io_fail)
> +declare_def_snprint_defint(fast_io_fail, print_fast_io_fail, DEFAULT_FAST_IO_FAIL)
>  declare_ovr_handler(fast_io_fail, set_fast_io_fail)
>  declare_ovr_snprint(fast_io_fail, print_fast_io_fail)
>  declare_hw_handler(fast_io_fail, set_fast_io_fail)
> @@ -1082,7 +1082,8 @@ declare_hw_snprint(delay_wait_checks, print_off_int_undef)
>  declare_mp_handler(delay_wait_checks, set_off_int_undef)
>  declare_mp_snprint(delay_wait_checks, print_off_int_undef)
>  declare_def_handler(san_path_err_threshold, set_off_int_undef)
> -declare_def_snprint(san_path_err_threshold, print_off_int_undef)
> +declare_def_snprint_defint(san_path_err_threshold, print_off_int_undef,
> +			   DEFAULT_ERR_CHECKS)
>  declare_ovr_handler(san_path_err_threshold, set_off_int_undef)
>  declare_ovr_snprint(san_path_err_threshold, print_off_int_undef)
>  declare_hw_handler(san_path_err_threshold, set_off_int_undef)
> @@ -1090,7 +1091,8 @@ declare_hw_snprint(san_path_err_threshold, print_off_int_undef)
>  declare_mp_handler(san_path_err_threshold, set_off_int_undef)
>  declare_mp_snprint(san_path_err_threshold, print_off_int_undef)
>  declare_def_handler(san_path_err_forget_rate, set_off_int_undef)
> -declare_def_snprint(san_path_err_forget_rate, print_off_int_undef)
> +declare_def_snprint_defint(san_path_err_forget_rate, print_off_int_undef,
> +			   DEFAULT_ERR_CHECKS)
>  declare_ovr_handler(san_path_err_forget_rate, set_off_int_undef)
>  declare_ovr_snprint(san_path_err_forget_rate, print_off_int_undef)
>  declare_hw_handler(san_path_err_forget_rate, set_off_int_undef)
> @@ -1098,7 +1100,8 @@ declare_hw_snprint(san_path_err_forget_rate, print_off_int_undef)
>  declare_mp_handler(san_path_err_forget_rate, set_off_int_undef)
>  declare_mp_snprint(san_path_err_forget_rate, print_off_int_undef)
>  declare_def_handler(san_path_err_recovery_time, set_off_int_undef)
> -declare_def_snprint(san_path_err_recovery_time, print_off_int_undef)
> +declare_def_snprint_defint(san_path_err_recovery_time, print_off_int_undef,
> +			   DEFAULT_ERR_CHECKS)
>  declare_ovr_handler(san_path_err_recovery_time, set_off_int_undef)
>  declare_ovr_snprint(san_path_err_recovery_time, print_off_int_undef)
>  declare_hw_handler(san_path_err_recovery_time, set_off_int_undef)
> diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c
> index 385063aa..68436433 100644
> --- a/libmultipath/propsel.c
> +++ b/libmultipath/propsel.c
> @@ -752,6 +752,11 @@ int select_max_sectors_kb(struct config *conf, struct multipath * mp)
>  	mp_set_ovr(max_sectors_kb);
>  	mp_set_hwe(max_sectors_kb);
>  	mp_set_conf(max_sectors_kb);
> +	mp_set_default(max_sectors_kb, DEFAULT_MAX_SECTORS_KB);
> +	/*
> +	 * In the default case, we will not modify max_sectors_kb.
> +	 * Don't print a log message to avoid user confusion.
> +	 */
>  	return 0;
>  out:
>  	condlog(3, "%s: max_sectors_kb = %i %s", mp->alias, mp->max_sectors_kb,
> 
Errm. You just set the default value, no?
Care to clarify this comment?

Cheers,

Hannes
Benjamin Marzinski June 20, 2017, 4:25 p.m. UTC | #2 
On Tue, Jun 20, 2017 at 04:36:47PM +0200, Hannes Reinecke wrote:
> On 06/20/2017 01:46 PM, Martin Wilck wrote:
> > We have the logic for setting defaults for paths and maps
> > in propsel.c. By pre-setting conf values with defaults in
> > load_config(), we generate irritating log messages like
> > 'features = "0" (setting: multipath.conf defaults/devices section)'
> > if multipath.conf doesn't contain a features setting at all.
> > 
> > For some config settings, we need to use declare_def_snprint_defint()
> > now to make sure "multipathd show config" prints all defaults correctly.
> > To avoid confusion, we don't do this for "max_sectors", because
> > multipathd leaves this untouched by default.
> > 
> > Signed-off-by: Martin Wilck <mwilck@suse.com>
> > ---
> >  libmultipath/config.c  | 16 ----------------
> >  libmultipath/dict.c    | 11 +++++++----
> >  libmultipath/propsel.c |  5 +++++
> >  3 files changed, 12 insertions(+), 20 deletions(-)
> > 
> > diff --git a/libmultipath/config.c b/libmultipath/config.c
> > index bb6619b3..61bbba91 100644
> > --- a/libmultipath/config.c
> > +++ b/libmultipath/config.c
> > @@ -599,40 +599,24 @@ load_config (char * file)
> >  	if (!conf->verbosity)
> >  		conf->verbosity = DEFAULT_VERBOSITY;
> >  
> > -	conf->minio = DEFAULT_MINIO;
> > -	conf->minio_rq = DEFAULT_MINIO_RQ;
> >  	get_sys_max_fds(&conf->max_fds);
> >  	conf->bindings_file = set_default(DEFAULT_BINDINGS_FILE);
> >  	conf->wwids_file = set_default(DEFAULT_WWIDS_FILE);
> >  	conf->multipath_dir = set_default(DEFAULT_MULTIPATHDIR);
> > -	conf->features = set_default(DEFAULT_FEATURES);
> > -	conf->flush_on_last_del = DEFAULT_FLUSH;
> >  	conf->attribute_flags = 0;
> >  	conf->reassign_maps = DEFAULT_REASSIGN_MAPS;
> >  	conf->checkint = DEFAULT_CHECKINT;
> >  	conf->max_checkint = 0;
> > -	conf->pgfailback = DEFAULT_FAILBACK;
> > -	conf->fast_io_fail = DEFAULT_FAST_IO_FAIL;
> > -	conf->retain_hwhandler = DEFAULT_RETAIN_HWHANDLER;
> > -	conf->detect_prio = DEFAULT_DETECT_PRIO;
> > -	conf->detect_checker = DEFAULT_DETECT_CHECKER;
> >  	conf->force_sync = DEFAULT_FORCE_SYNC;
> >  	conf->partition_delim = DEFAULT_PARTITION_DELIM;
> >  	conf->processed_main_config = 0;
> >  	conf->find_multipaths = DEFAULT_FIND_MULTIPATHS;
> >  	conf->uxsock_timeout = DEFAULT_REPLY_TIMEOUT;
> > -	conf->uid_attribute = set_default(DEFAULT_UID_ATTRIBUTE);
> >  	conf->retrigger_tries = DEFAULT_RETRIGGER_TRIES;
> >  	conf->retrigger_delay = DEFAULT_RETRIGGER_DELAY;
> >  	conf->uev_wait_timeout = DEFAULT_UEV_WAIT_TIMEOUT;
> > -	conf->deferred_remove = DEFAULT_DEFERRED_REMOVE;
> > -	conf->skip_kpartx = DEFAULT_SKIP_KPARTX;
> >  	conf->disable_changed_wwids = DEFAULT_DISABLE_CHANGED_WWIDS;
> >  	conf->remove_retries = 0;
> > -	conf->max_sectors_kb = DEFAULT_MAX_SECTORS_KB;
> > -	conf->san_path_err_threshold = DEFAULT_ERR_CHECKS;
> > -	conf->san_path_err_forget_rate = DEFAULT_ERR_CHECKS;
> > -	conf->san_path_err_recovery_time = DEFAULT_ERR_CHECKS;
> >  
> >  	/*
> >  	 * preload default hwtable
> > diff --git a/libmultipath/dict.c b/libmultipath/dict.c
> > index 82066f67..9dc10904 100644
> > --- a/libmultipath/dict.c
> > +++ b/libmultipath/dict.c
> > @@ -630,7 +630,7 @@ print_fast_io_fail(char * buff, int len, void *ptr)
> >  }
> >  
> >  declare_def_handler(fast_io_fail, set_fast_io_fail)
> > -declare_def_snprint(fast_io_fail, print_fast_io_fail)
> > +declare_def_snprint_defint(fast_io_fail, print_fast_io_fail, DEFAULT_FAST_IO_FAIL)
> >  declare_ovr_handler(fast_io_fail, set_fast_io_fail)
> >  declare_ovr_snprint(fast_io_fail, print_fast_io_fail)
> >  declare_hw_handler(fast_io_fail, set_fast_io_fail)
> > @@ -1082,7 +1082,8 @@ declare_hw_snprint(delay_wait_checks, print_off_int_undef)
> >  declare_mp_handler(delay_wait_checks, set_off_int_undef)
> >  declare_mp_snprint(delay_wait_checks, print_off_int_undef)
> >  declare_def_handler(san_path_err_threshold, set_off_int_undef)
> > -declare_def_snprint(san_path_err_threshold, print_off_int_undef)
> > +declare_def_snprint_defint(san_path_err_threshold, print_off_int_undef,
> > +			   DEFAULT_ERR_CHECKS)
> >  declare_ovr_handler(san_path_err_threshold, set_off_int_undef)
> >  declare_ovr_snprint(san_path_err_threshold, print_off_int_undef)
> >  declare_hw_handler(san_path_err_threshold, set_off_int_undef)
> > @@ -1090,7 +1091,8 @@ declare_hw_snprint(san_path_err_threshold, print_off_int_undef)
> >  declare_mp_handler(san_path_err_threshold, set_off_int_undef)
> >  declare_mp_snprint(san_path_err_threshold, print_off_int_undef)
> >  declare_def_handler(san_path_err_forget_rate, set_off_int_undef)
> > -declare_def_snprint(san_path_err_forget_rate, print_off_int_undef)
> > +declare_def_snprint_defint(san_path_err_forget_rate, print_off_int_undef,
> > +			   DEFAULT_ERR_CHECKS)
> >  declare_ovr_handler(san_path_err_forget_rate, set_off_int_undef)
> >  declare_ovr_snprint(san_path_err_forget_rate, print_off_int_undef)
> >  declare_hw_handler(san_path_err_forget_rate, set_off_int_undef)
> > @@ -1098,7 +1100,8 @@ declare_hw_snprint(san_path_err_forget_rate, print_off_int_undef)
> >  declare_mp_handler(san_path_err_forget_rate, set_off_int_undef)
> >  declare_mp_snprint(san_path_err_forget_rate, print_off_int_undef)
> >  declare_def_handler(san_path_err_recovery_time, set_off_int_undef)
> > -declare_def_snprint(san_path_err_recovery_time, print_off_int_undef)
> > +declare_def_snprint_defint(san_path_err_recovery_time, print_off_int_undef,
> > +			   DEFAULT_ERR_CHECKS)
> >  declare_ovr_handler(san_path_err_recovery_time, set_off_int_undef)
> >  declare_ovr_snprint(san_path_err_recovery_time, print_off_int_undef)
> >  declare_hw_handler(san_path_err_recovery_time, set_off_int_undef)
> > diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c
> > index 385063aa..68436433 100644
> > --- a/libmultipath/propsel.c
> > +++ b/libmultipath/propsel.c
> > @@ -752,6 +752,11 @@ int select_max_sectors_kb(struct config *conf, struct multipath * mp)
> >  	mp_set_ovr(max_sectors_kb);
> >  	mp_set_hwe(max_sectors_kb);
> >  	mp_set_conf(max_sectors_kb);
> > +	mp_set_default(max_sectors_kb, DEFAULT_MAX_SECTORS_KB);
> > +	/*
> > +	 * In the default case, we will not modify max_sectors_kb.
> > +	 * Don't print a log message to avoid user confusion.
> > +	 */
> >  	return 0;
> >  out:
> >  	condlog(3, "%s: max_sectors_kb = %i %s", mp->alias, mp->max_sectors_kb,
> > 
> Errm. You just set the default value, no?
> Care to clarify this comment?

The default value is "undefined". This isn't strictly necessary if all
the other code is correct, but in case mpp->max_sectors_kb was
previously set to something (or never zeroed out initially), this will
correctly set it back to undefined.

-Ben

> 
> Cheers,
> 
> Hannes
> -- 
> Dr. Hannes Reinecke		   Teamlead Storage & Networking
> hare@suse.de			               +49 911 74053 688
> SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
> GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
> HRB 21284 (AG Nürnberg)

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diff mbox

Patch

diff --git a/libmultipath/config.c b/libmultipath/config.c
index bb6619b3..61bbba91 100644
--- a/libmultipath/config.c
+++ b/libmultipath/config.c
@@ -599,40 +599,24 @@  load_config (char * file)
 	if (!conf->verbosity)
 		conf->verbosity = DEFAULT_VERBOSITY;
 
-	conf->minio = DEFAULT_MINIO;
-	conf->minio_rq = DEFAULT_MINIO_RQ;
 	get_sys_max_fds(&conf->max_fds);
 	conf->bindings_file = set_default(DEFAULT_BINDINGS_FILE);
 	conf->wwids_file = set_default(DEFAULT_WWIDS_FILE);
 	conf->multipath_dir = set_default(DEFAULT_MULTIPATHDIR);
-	conf->features = set_default(DEFAULT_FEATURES);
-	conf->flush_on_last_del = DEFAULT_FLUSH;
 	conf->attribute_flags = 0;
 	conf->reassign_maps = DEFAULT_REASSIGN_MAPS;
 	conf->checkint = DEFAULT_CHECKINT;
 	conf->max_checkint = 0;
-	conf->pgfailback = DEFAULT_FAILBACK;
-	conf->fast_io_fail = DEFAULT_FAST_IO_FAIL;
-	conf->retain_hwhandler = DEFAULT_RETAIN_HWHANDLER;
-	conf->detect_prio = DEFAULT_DETECT_PRIO;
-	conf->detect_checker = DEFAULT_DETECT_CHECKER;
 	conf->force_sync = DEFAULT_FORCE_SYNC;
 	conf->partition_delim = DEFAULT_PARTITION_DELIM;
 	conf->processed_main_config = 0;
 	conf->find_multipaths = DEFAULT_FIND_MULTIPATHS;
 	conf->uxsock_timeout = DEFAULT_REPLY_TIMEOUT;
-	conf->uid_attribute = set_default(DEFAULT_UID_ATTRIBUTE);
 	conf->retrigger_tries = DEFAULT_RETRIGGER_TRIES;
 	conf->retrigger_delay = DEFAULT_RETRIGGER_DELAY;
 	conf->uev_wait_timeout = DEFAULT_UEV_WAIT_TIMEOUT;
-	conf->deferred_remove = DEFAULT_DEFERRED_REMOVE;
-	conf->skip_kpartx = DEFAULT_SKIP_KPARTX;
 	conf->disable_changed_wwids = DEFAULT_DISABLE_CHANGED_WWIDS;
 	conf->remove_retries = 0;
-	conf->max_sectors_kb = DEFAULT_MAX_SECTORS_KB;
-	conf->san_path_err_threshold = DEFAULT_ERR_CHECKS;
-	conf->san_path_err_forget_rate = DEFAULT_ERR_CHECKS;
-	conf->san_path_err_recovery_time = DEFAULT_ERR_CHECKS;
 
 	/*
 	 * preload default hwtable
diff --git a/libmultipath/dict.c b/libmultipath/dict.c
index 82066f67..9dc10904 100644
--- a/libmultipath/dict.c
+++ b/libmultipath/dict.c
@@ -630,7 +630,7 @@  print_fast_io_fail(char * buff, int len, void *ptr)
 }
 
 declare_def_handler(fast_io_fail, set_fast_io_fail)
-declare_def_snprint(fast_io_fail, print_fast_io_fail)
+declare_def_snprint_defint(fast_io_fail, print_fast_io_fail, DEFAULT_FAST_IO_FAIL)
 declare_ovr_handler(fast_io_fail, set_fast_io_fail)
 declare_ovr_snprint(fast_io_fail, print_fast_io_fail)
 declare_hw_handler(fast_io_fail, set_fast_io_fail)
@@ -1082,7 +1082,8 @@  declare_hw_snprint(delay_wait_checks, print_off_int_undef)
 declare_mp_handler(delay_wait_checks, set_off_int_undef)
 declare_mp_snprint(delay_wait_checks, print_off_int_undef)
 declare_def_handler(san_path_err_threshold, set_off_int_undef)
-declare_def_snprint(san_path_err_threshold, print_off_int_undef)
+declare_def_snprint_defint(san_path_err_threshold, print_off_int_undef,
+			   DEFAULT_ERR_CHECKS)
 declare_ovr_handler(san_path_err_threshold, set_off_int_undef)
 declare_ovr_snprint(san_path_err_threshold, print_off_int_undef)
 declare_hw_handler(san_path_err_threshold, set_off_int_undef)
@@ -1090,7 +1091,8 @@  declare_hw_snprint(san_path_err_threshold, print_off_int_undef)
 declare_mp_handler(san_path_err_threshold, set_off_int_undef)
 declare_mp_snprint(san_path_err_threshold, print_off_int_undef)
 declare_def_handler(san_path_err_forget_rate, set_off_int_undef)
-declare_def_snprint(san_path_err_forget_rate, print_off_int_undef)
+declare_def_snprint_defint(san_path_err_forget_rate, print_off_int_undef,
+			   DEFAULT_ERR_CHECKS)
 declare_ovr_handler(san_path_err_forget_rate, set_off_int_undef)
 declare_ovr_snprint(san_path_err_forget_rate, print_off_int_undef)
 declare_hw_handler(san_path_err_forget_rate, set_off_int_undef)
@@ -1098,7 +1100,8 @@  declare_hw_snprint(san_path_err_forget_rate, print_off_int_undef)
 declare_mp_handler(san_path_err_forget_rate, set_off_int_undef)
 declare_mp_snprint(san_path_err_forget_rate, print_off_int_undef)
 declare_def_handler(san_path_err_recovery_time, set_off_int_undef)
-declare_def_snprint(san_path_err_recovery_time, print_off_int_undef)
+declare_def_snprint_defint(san_path_err_recovery_time, print_off_int_undef,
+			   DEFAULT_ERR_CHECKS)
 declare_ovr_handler(san_path_err_recovery_time, set_off_int_undef)
 declare_ovr_snprint(san_path_err_recovery_time, print_off_int_undef)
 declare_hw_handler(san_path_err_recovery_time, set_off_int_undef)
diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c
index 385063aa..68436433 100644
--- a/libmultipath/propsel.c
+++ b/libmultipath/propsel.c
@@ -752,6 +752,11 @@  int select_max_sectors_kb(struct config *conf, struct multipath * mp)
 	mp_set_ovr(max_sectors_kb);
 	mp_set_hwe(max_sectors_kb);
 	mp_set_conf(max_sectors_kb);
+	mp_set_default(max_sectors_kb, DEFAULT_MAX_SECTORS_KB);
+	/*
+	 * In the default case, we will not modify max_sectors_kb.
+	 * Don't print a log message to avoid user confusion.
+	 */
 	return 0;
 out:
 	condlog(3, "%s: max_sectors_kb = %i %s", mp->alias, mp->max_sectors_kb,