Revision 35991652baa12ff3d0e420c0d0cb2ad9f7076e5b authored by Mikulas Patocka on 02 June 2012, 23:29:58 UTC, committed by Alasdair G Kergon on 02 June 2012, 23:29:58 UTC
After the failure of a group of paths, any alternative paths that
need initialising do not become available until further I/O is sent to
the device.  Until this has happened, ioctls return -EAGAIN.

With this patch, new paths are made available in response to an ioctl
too.  The processing of the ioctl gets delayed until this has happened.

Instead of returning an error, we submit a work item to kmultipathd
(that will potentially activate the new path) and retry in ten
milliseconds.

Note that the patch doesn't retry an ioctl if the ioctl itself fails due
to a path failure.  Such retries should be handled intelligently by the
code that generated the ioctl in the first place, noting that some SCSI
commands should not be retried because they are not idempotent (XOR write
commands).  For commands that could be retried, there is a danger that
if the device rejected the SCSI command, the path could be errorneously
marked as failed, and the request would be retried on another path which
might fail too.  It can be determined if the failure happens on the
device or on the SCSI controller, but there is no guarantee that all
SCSI drivers set these flags correctly.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
1 parent f220fd4
Raw File
sysctl.c
/* SCTP kernel implementation
 * (C) Copyright IBM Corp. 2002, 2004
 * Copyright (c) 2002 Intel Corp.
 *
 * This file is part of the SCTP kernel implementation
 *
 * Sysctl related interfaces for SCTP.
 *
 * This SCTP implementation is free software;
 * you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This SCTP implementation is distributed in the hope that it
 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 *                 ************************
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU CC; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <lksctp-developers@lists.sourceforge.net>
 *
 * Or submit a bug report through the following website:
 *    http://www.sf.net/projects/lksctp
 *
 * Written or modified by:
 *    Mingqin Liu           <liuming@us.ibm.com>
 *    Jon Grimm             <jgrimm@us.ibm.com>
 *    Ardelle Fan           <ardelle.fan@intel.com>
 *    Ryan Layer            <rmlayer@us.ibm.com>
 *    Sridhar Samudrala     <sri@us.ibm.com>
 *
 * Any bugs reported given to us we will try to fix... any fixes shared will
 * be incorporated into the next SCTP release.
 */

#include <net/sctp/structs.h>
#include <net/sctp/sctp.h>
#include <linux/sysctl.h>

static int zero = 0;
static int one = 1;
static int timer_max = 86400000; /* ms in one day */
static int int_max = INT_MAX;
static int sack_timer_min = 1;
static int sack_timer_max = 500;
static int addr_scope_max = 3; /* check sctp_scope_policy_t in include/net/sctp/constants.h for max entries */
static int rwnd_scale_max = 16;
static unsigned long max_autoclose_min = 0;
static unsigned long max_autoclose_max =
	(MAX_SCHEDULE_TIMEOUT / HZ > UINT_MAX)
	? UINT_MAX : MAX_SCHEDULE_TIMEOUT / HZ;

extern long sysctl_sctp_mem[3];
extern int sysctl_sctp_rmem[3];
extern int sysctl_sctp_wmem[3];

static ctl_table sctp_table[] = {
	{
		.procname	= "rto_initial",
		.data		= &sctp_rto_initial,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1         = &one,
		.extra2         = &timer_max
	},
	{
		.procname	= "rto_min",
		.data		= &sctp_rto_min,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1         = &one,
		.extra2         = &timer_max
	},
	{
		.procname	= "rto_max",
		.data		= &sctp_rto_max,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1         = &one,
		.extra2         = &timer_max
	},
	{
		.procname	= "valid_cookie_life",
		.data		= &sctp_valid_cookie_life,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1         = &one,
		.extra2         = &timer_max
	},
	{
		.procname	= "max_burst",
		.data		= &sctp_max_burst,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &zero,
		.extra2		= &int_max
	},
	{
		.procname	= "association_max_retrans",
		.data		= &sctp_max_retrans_association,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &one,
		.extra2		= &int_max
	},
	{
		.procname	= "sndbuf_policy",
		.data		= &sctp_sndbuf_policy,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "rcvbuf_policy",
		.data		= &sctp_rcvbuf_policy,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "path_max_retrans",
		.data		= &sctp_max_retrans_path,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &one,
		.extra2		= &int_max
	},
	{
		.procname	= "max_init_retransmits",
		.data		= &sctp_max_retrans_init,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &one,
		.extra2		= &int_max
	},
	{
		.procname	= "hb_interval",
		.data		= &sctp_hb_interval,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1         = &one,
		.extra2         = &timer_max
	},
	{
		.procname	= "cookie_preserve_enable",
		.data		= &sctp_cookie_preserve_enable,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "rto_alpha_exp_divisor",
		.data		= &sctp_rto_alpha,
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "rto_beta_exp_divisor",
		.data		= &sctp_rto_beta,
		.maxlen		= sizeof(int),
		.mode		= 0444,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "addip_enable",
		.data		= &sctp_addip_enable,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "default_auto_asconf",
		.data		= &sctp_default_auto_asconf,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "prsctp_enable",
		.data		= &sctp_prsctp_enable,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "sack_timeout",
		.data		= &sctp_sack_timeout,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1         = &sack_timer_min,
		.extra2         = &sack_timer_max,
	},
	{
		.procname	= "sctp_mem",
		.data		= &sysctl_sctp_mem,
		.maxlen		= sizeof(sysctl_sctp_mem),
		.mode		= 0644,
		.proc_handler	= proc_doulongvec_minmax
	},
	{
		.procname	= "sctp_rmem",
		.data		= &sysctl_sctp_rmem,
		.maxlen		= sizeof(sysctl_sctp_rmem),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "sctp_wmem",
		.data		= &sysctl_sctp_wmem,
		.maxlen		= sizeof(sysctl_sctp_wmem),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "auth_enable",
		.data		= &sctp_auth_enable,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "addip_noauth_enable",
		.data		= &sctp_addip_noauth,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "addr_scope_policy",
		.data		= &sctp_scope_policy,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &zero,
		.extra2		= &addr_scope_max,
	},
	{
		.procname	= "rwnd_update_shift",
		.data		= &sctp_rwnd_upd_shift,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.extra1		= &one,
		.extra2		= &rwnd_scale_max,
	},
	{
		.procname	= "max_autoclose",
		.data		= &sctp_max_autoclose,
		.maxlen		= sizeof(unsigned long),
		.mode		= 0644,
		.proc_handler	= &proc_doulongvec_minmax,
		.extra1		= &max_autoclose_min,
		.extra2		= &max_autoclose_max,
	},

	{ /* sentinel */ }
};

static struct ctl_path sctp_path[] = {
	{ .procname = "net", },
	{ .procname = "sctp", },
	{ }
};

static struct ctl_table_header * sctp_sysctl_header;

/* Sysctl registration.  */
void sctp_sysctl_register(void)
{
	sctp_sysctl_header = register_sysctl_paths(sctp_path, sctp_table);
}

/* Sysctl deregistration.  */
void sctp_sysctl_unregister(void)
{
	unregister_sysctl_table(sctp_sysctl_header);
}
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