freebsd-dev/sys/fs/devfs/devfs_rule.c

833 lines
22 KiB
C

/*-
* Copyright (c) 2002 Dima Dorfman.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
/*
* DEVFS ruleset implementation.
*
* A note on terminology: To "run" a rule on a dirent is to take the
* prescribed action; to "apply" a rule is to check whether it matches
* a dirent and run if if it does.
*
* A note on locking: Only foreign entry points (non-static functions)
* should deal with locking. Everything else assumes we already hold
* the required kind of lock.
*
* A note on namespace: devfs_rules_* are the non-static functions for
* the entire "ruleset" subsystem, devfs_rule_* are the static
* functions that operate on rules, and devfs_ruleset_* are the static
* functions that operate on rulesets. The line between the last two
* isn't always clear, but the guideline is still useful.
*
* A note on "special" identifiers: Ruleset 0 is the NULL, or empty,
* ruleset; it cannot be deleted or changed in any way. This may be
* assumed inside the code; e.g., a ruleset of 0 may be interpeted to
* mean "no ruleset". The interpretation of rule 0 is
* command-dependent, but in no case is there a real rule with number
* 0.
*
* A note on errno codes: To make it easier for the userland to tell
* what went wrong, we sometimes use errno codes that are not entirely
* appropriate for the error but that would be less ambiguous than the
* appropriate "generic" code. For example, when we can't find a
* ruleset, we return ESRCH instead of ENOENT (except in
* DEVFSIO_{R,S}GETNEXT, where a nonexistent ruleset means "end of
* list", and the userland expects ENOENT to be this indicator); this
* way, when an operation fails, it's clear that what couldn't be
* found is a ruleset and not a rule (well, it's clear to those who
* know the convention).
*/
#include "opt_devfs.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/dirent.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/ioccom.h>
#include <fs/devfs/devfs.h>
/*
* Kernel version of devfs_rule.
*/
struct devfs_krule {
SLIST_ENTRY(devfs_krule) dk_list;
struct devfs_ruleset *dk_ruleset;
struct devfs_rule dk_rule;
};
/*
* Structure to describe a ruleset.
*/
struct devfs_ruleset {
SLIST_ENTRY(devfs_ruleset) ds_list;
devfs_rsnum ds_number;
SLIST_HEAD(, devfs_krule) ds_rules;
int ds_refcount;
int ds_flags;
#define DS_IMMUTABLE 0x001
int ds_running;
};
static devfs_rid devfs_rid_input(devfs_rid rid, struct devfs_mount *dm);
static void devfs_rule_applyde(struct devfs_krule *dk,struct devfs_dirent *de);
static void devfs_rule_applyde_recursive(struct devfs_krule *dk,
struct devfs_dirent *de);
static void devfs_rule_applydm(struct devfs_krule *dk, struct devfs_mount *dm);
static int devfs_rule_autonumber(struct devfs_ruleset *ds, devfs_rnum *rnp);
static struct devfs_krule *devfs_rule_byid(devfs_rid rid);
static int devfs_rule_delete(struct devfs_krule **dkp);
static struct cdev *devfs_rule_getdev(struct devfs_dirent *de);
static int devfs_rule_input(struct devfs_rule *dr, struct devfs_mount *dm);
static int devfs_rule_insert(struct devfs_rule *dr);
static int devfs_rule_match(struct devfs_krule *dk, struct devfs_dirent *de);
static int devfs_rule_matchpath(struct devfs_krule *dk,
struct devfs_dirent *de);
static void devfs_rule_run(struct devfs_krule *dk, struct devfs_dirent *de);
static void devfs_ruleset_applyde(struct devfs_ruleset *ds,
struct devfs_dirent *de);
static void devfs_ruleset_applydm(struct devfs_ruleset *ds,
struct devfs_mount *dm);
static struct devfs_ruleset *devfs_ruleset_bynum(devfs_rsnum rsnum);
static struct devfs_ruleset *devfs_ruleset_create(devfs_rsnum rsnum);
static void devfs_ruleset_destroy(struct devfs_ruleset **dsp);
static void devfs_ruleset_reap(struct devfs_ruleset **dsp);
static int devfs_ruleset_use(devfs_rsnum rsnum, struct devfs_mount *dm);
static SLIST_HEAD(, devfs_ruleset) devfs_rulesets;
/*
* Called to apply the proper rules for de before the latter can be
* exposed to the userland. This should be called with an exclusive
* lock on dm in case we need to run anything.
*/
void
devfs_rules_apply(struct devfs_mount *dm, struct devfs_dirent *de)
{
struct devfs_ruleset *ds;
ds = devfs_ruleset_bynum(dm->dm_ruleset);
KASSERT(ds != NULL, ("mount-point has NULL ruleset"));
devfs_ruleset_applyde(ds, de);
}
/*
* Rule subsystem SYSINIT hook.
*/
static void
devfs_rules_init(void *junk __unused)
{
struct devfs_ruleset *ds;
SLIST_INIT(&devfs_rulesets);
ds = devfs_ruleset_create(0);
ds->ds_flags |= DS_IMMUTABLE;
ds->ds_refcount = 1; /* Prevent reaping. */
}
SYSINIT(devfs_rules, SI_SUB_DEVFS, SI_ORDER_FIRST, devfs_rules_init, NULL);
/*
* Rule subsystem ioctl hook.
*/
int
devfs_rules_ioctl(struct mount *mp, u_long cmd, caddr_t data, struct thread *td)
{
struct devfs_mount *dm = VFSTODEVFS(mp);
struct devfs_ruleset *ds;
struct devfs_krule *dk;
struct devfs_rule *dr;
devfs_rsnum rsnum;
devfs_rnum rnum;
devfs_rid rid;
int error;
/*
* XXX: This returns an error regardless of whether we
* actually support the cmd or not.
*/
error = suser(td);
if (error != 0)
return (error);
lockmgr(&dm->dm_lock, LK_SHARED, 0, td);
switch (cmd) {
case DEVFSIO_RADD:
dr = (struct devfs_rule *)data;
error = devfs_rule_input(dr, dm);
if (error != 0)
goto out;
dk = devfs_rule_byid(dr->dr_id);
if (dk != NULL) {
error = EEXIST;
goto out;
}
lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
error = devfs_rule_insert(dr);
break;
case DEVFSIO_RAPPLY:
dr = (struct devfs_rule *)data;
error = devfs_rule_input(dr, dm);
if (error != 0)
goto out;
/*
* This is one of many possible hackish
* implementations. The primary contender is an
* implementation where the rule we read in is
* temporarily inserted into some ruleset, perhaps
* with a hypothetical DRO_NOAUTO flag so that it
* doesn't get used where it isn't intended, and
* applied in the normal way. This can be done in the
* userland (DEVFSIO_ADD, DEVFSIO_APPLYID,
* DEVFSIO_DEL) or in the kernel; either way it breaks
* some corner case assumptions in other parts of the
* code (not that this implementation doesn't do
* that).
*/
if (dr->dr_iacts & DRA_INCSET &&
devfs_ruleset_bynum(dr->dr_incset) == NULL) {
error = ESRCH;
goto out;
}
dk = malloc(sizeof(*dk), M_TEMP, M_WAITOK | M_ZERO);
memcpy(&dk->dk_rule, dr, sizeof(*dr));
lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
devfs_rule_applydm(dk, dm);
lockmgr(&dm->dm_lock, LK_DOWNGRADE, 0, td);
free(dk, M_TEMP);
error = 0;
break;
case DEVFSIO_RAPPLYID:
rid = *(devfs_rid *)data;
rid = devfs_rid_input(rid, dm);
dk = devfs_rule_byid(rid);
if (dk == NULL) {
error = ENOENT;
goto out;
}
lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
devfs_rule_applydm(dk, dm);
error = 0;
break;
case DEVFSIO_RDEL:
rid = *(devfs_rid *)data;
rid = devfs_rid_input(rid, dm);
dk = devfs_rule_byid(rid);
if (dk == NULL) {
error = ENOENT;
goto out;
}
ds = dk->dk_ruleset;
lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
error = devfs_rule_delete(&dk);
devfs_ruleset_reap(&ds);
break;
case DEVFSIO_RGETNEXT:
dr = (struct devfs_rule *)data;
error = devfs_rule_input(dr, dm);
if (error != 0)
goto out;
/*
* We can't use devfs_rule_byid() here since that
* requires the rule specified to exist, but we want
* getnext(N) to work whether there is a rule N or not
* (specifically, getnext(0) must work, but we should
* never have a rule 0 since the add command
* interprets 0 to mean "auto-number").
*/
ds = devfs_ruleset_bynum(rid2rsn(dr->dr_id));
if (ds == NULL) {
error = ENOENT;
goto out;
}
rnum = rid2rn(dr->dr_id);
SLIST_FOREACH(dk, &ds->ds_rules, dk_list) {
if (rid2rn(dk->dk_rule.dr_id) > rnum)
break;
}
if (dk == NULL) {
error = ENOENT;
goto out;
}
memcpy(dr, &dk->dk_rule, sizeof(*dr));
error = 0;
break;
case DEVFSIO_SUSE:
rsnum = *(devfs_rsnum *)data;
lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
error = devfs_ruleset_use(rsnum, dm);
break;
case DEVFSIO_SAPPLY:
rsnum = *(devfs_rsnum *)data;
rsnum = rid2rsn(devfs_rid_input(mkrid(rsnum, 0), dm));
ds = devfs_ruleset_bynum(rsnum);
if (ds == NULL) {
error = ESRCH;
goto out;
}
lockmgr(&dm->dm_lock, LK_UPGRADE, 0, td);
devfs_ruleset_applydm(ds, dm);
error = 0;
break;
case DEVFSIO_SGETNEXT:
rsnum = *(devfs_rsnum *)data;
SLIST_FOREACH(ds, &devfs_rulesets, ds_list) {
if (ds->ds_number > rsnum)
break;
}
if (ds == NULL)
error = ENOENT;
else {
*(devfs_rsnum *)data = ds->ds_number;
error = 0;
}
break;
default:
error = ENOIOCTL;
break;
}
out:
lockmgr(&dm->dm_lock, LK_RELEASE, 0, td);
return (error);
}
/*
* Called to initialize dm_ruleset when there is a new mount-point.
*/
void
devfs_rules_newmount(struct devfs_mount *dm, struct thread *td)
{
struct devfs_ruleset *ds;
lockmgr(&dm->dm_lock, LK_EXCLUSIVE, 0, td);
/*
* We can't use devfs_ruleset_use() since it will try to
* decrement the refcount for the old ruleset, and there is no
* old ruleset. Making some value of ds_ruleset "special" to
* mean "don't decrement refcount" is uglier than this.
*/
ds = devfs_ruleset_bynum(0);
KASSERT(ds != NULL, ("no ruleset 0"));
++ds->ds_refcount;
dm->dm_ruleset = 0;
lockmgr(&dm->dm_lock, LK_RELEASE, 0, td);
}
/*
* Adjust the rule identifier to use the ruleset of dm if one isn't
* explicitly specified.
*
* Note that after this operation, rid2rsn(rid) might still be 0, and
* that's okay; ruleset 0 is a valid ruleset, but when it's read in
* from the userland, it means "current ruleset for this mount-point".
*/
static devfs_rid
devfs_rid_input(devfs_rid rid, struct devfs_mount *dm)
{
if (rid2rsn(rid) == 0)
return (mkrid(dm->dm_ruleset, rid2rn(rid)));
else
return (rid);
}
/*
* Apply dk to de.
*/
static void
devfs_rule_applyde(struct devfs_krule *dk, struct devfs_dirent *de)
{
if (devfs_rule_match(dk, de))
devfs_rule_run(dk, de);
}
/*
* Apply dk to de and everything under de.
*
* XXX: This method needs a function call for every nested
* subdirectory in a devfs mount. If we plan to have many of these,
* we might eventually run out of kernel stack space.
*/
static void
devfs_rule_applyde_recursive(struct devfs_krule *dk, struct devfs_dirent *de)
{
struct devfs_dirent *de2;
/* XXX: Should we apply to ourselves first or last? Does it matter? */
TAILQ_FOREACH(de2, &de->de_dlist, de_list) {
devfs_rule_applyde_recursive(dk, de2);
}
devfs_rule_applyde(dk, de);
}
/*
* Apply dk to all entires in dm.
*/
static void
devfs_rule_applydm(struct devfs_krule *dk, struct devfs_mount *dm)
{
devfs_rule_applyde_recursive(dk, dm->dm_basedir);
}
/*
* Automatically select a number for a new rule in ds, and write the
* result into rnump.
*/
static int
devfs_rule_autonumber(struct devfs_ruleset *ds, devfs_rnum *rnump)
{
struct devfs_krule *dk;
/* Find the last rule. */
SLIST_FOREACH(dk, &ds->ds_rules, dk_list) {
if (SLIST_NEXT(dk, dk_list) == NULL)
break;
}
if (dk == NULL)
*rnump = 100;
else {
*rnump = rid2rn(dk->dk_rule.dr_id) + 100;
/* Detect overflow. */
if (*rnump < rid2rn(dk->dk_rule.dr_id))
return (ERANGE);
}
KASSERT(devfs_rule_byid(mkrid(ds->ds_number, *rnump)) == NULL,
("autonumbering resulted in an already existing rule"));
return (0);
}
/*
* Find a krule by id.
*/
static struct devfs_krule *
devfs_rule_byid(devfs_rid rid)
{
struct devfs_ruleset *ds;
struct devfs_krule *dk;
devfs_rnum rn;
rn = rid2rn(rid);
ds = devfs_ruleset_bynum(rid2rsn(rid));
if (ds == NULL)
return (NULL);
SLIST_FOREACH(dk, &ds->ds_rules, dk_list) {
if (rid2rn(dk->dk_rule.dr_id) == rn)
return (dk);
else if (rid2rn(dk->dk_rule.dr_id) > rn)
break;
}
return (NULL);
}
/*
* Remove dkp from any lists it may be on and remove memory associated
* with it.
*/
static int
devfs_rule_delete(struct devfs_krule **dkp)
{
struct devfs_krule *dk = *dkp;
struct devfs_ruleset *ds;
if (dk->dk_rule.dr_iacts & DRA_INCSET) {
ds = devfs_ruleset_bynum(dk->dk_rule.dr_incset);
KASSERT(ds != NULL, ("DRA_INCSET but bad dr_incset"));
--ds->ds_refcount;
devfs_ruleset_reap(&ds);
}
SLIST_REMOVE(&dk->dk_ruleset->ds_rules, dk, devfs_krule, dk_list);
free(dk, M_DEVFS);
*dkp = NULL;
return (0);
}
/*
* Get a struct cdev *corresponding to de so we can try to match rules based
* on it. If this routine returns NULL, there is no struct cdev *associated
* with the dirent (symlinks and directories don't have dev_ts), and
* the caller should assume that any critera dependent on a dev_t
* don't match.
*/
static struct cdev *
devfs_rule_getdev(struct devfs_dirent *de)
{
struct cdev **devp, *dev;
devp = devfs_itod(de->de_inode);
if (devp != NULL)
dev = *devp;
else
dev = NULL;
/* If we think this dirent should have a struct cdev *, alert the user. */
if (dev == NULL && de->de_dirent->d_type != DT_LNK &&
de->de_dirent->d_type != DT_DIR)
printf("Warning: no struct cdev *for %s\n", de->de_dirent->d_name);
return (dev);
}
/*
* Do what we need to do to a rule that we just loaded from the
* userland. In particular, we need to check the magic, and adjust
* the ruleset appropriate if desired.
*/
static int
devfs_rule_input(struct devfs_rule *dr, struct devfs_mount *dm)
{
if (dr->dr_magic != DEVFS_MAGIC)
return (ERPCMISMATCH);
dr->dr_id = devfs_rid_input(dr->dr_id, dm);
return (0);
}
/*
* Import dr into the appropriate place in the kernel (i.e., make a
* krule). The value of dr is copied, so the pointer may be destroyed
* after this call completes.
*/
static int
devfs_rule_insert(struct devfs_rule *dr)
{
struct devfs_ruleset *ds, *dsi;
struct devfs_krule *k1, *k2;
struct devfs_krule *dk;
devfs_rsnum rsnum;
devfs_rnum dkrn;
int error;
/*
* This stuff seems out of place here, but we want to do it as
* soon as possible so that if it fails, we don't have to roll
* back any changes we already made (e.g., ruleset creation).
*/
if (dr->dr_iacts & DRA_INCSET) {
dsi = devfs_ruleset_bynum(dr->dr_incset);
if (dsi == NULL)
return (ESRCH);
} else
dsi = NULL;
rsnum = rid2rsn(dr->dr_id);
ds = devfs_ruleset_bynum(rsnum);
if (ds == NULL)
ds = devfs_ruleset_create(rsnum);
if (ds->ds_flags & DS_IMMUTABLE)
return (EIO);
dkrn = rid2rn(dr->dr_id);
if (dkrn == 0) {
error = devfs_rule_autonumber(ds, &dkrn);
if (error != 0)
return (error);
}
dk = malloc(sizeof(*dk), M_DEVFS, M_WAITOK);
dk->dk_ruleset = ds;
if (dsi != NULL)
++dsi->ds_refcount;
/* XXX: Inspect dr? */
memcpy(&dk->dk_rule, dr, sizeof(*dr));
dk->dk_rule.dr_id = mkrid(rid2rsn(dk->dk_rule.dr_id), dkrn);
k1 = SLIST_FIRST(&ds->ds_rules);
if (k1 == NULL || rid2rn(k1->dk_rule.dr_id) > dkrn)
SLIST_INSERT_HEAD(&ds->ds_rules, dk, dk_list);
else {
SLIST_FOREACH(k1, &ds->ds_rules, dk_list) {
k2 = SLIST_NEXT(k1, dk_list);
if (k2 == NULL || rid2rn(k2->dk_rule.dr_id) > dkrn) {
SLIST_INSERT_AFTER(k1, dk, dk_list);
break;
}
}
}
return (0);
}
/*
* Determine whether dk matches de. Returns 1 if dk should be run on
* de; 0, otherwise.
*/
static int
devfs_rule_match(struct devfs_krule *dk, struct devfs_dirent *de)
{
struct devfs_rule *dr = &dk->dk_rule;
struct cdev *dev;
dev = devfs_rule_getdev(de);
/*
* At this point, if dev is NULL, we should assume that any
* criteria that depend on it don't match. We should *not*
* just ignore them (i.e., act like they weren't specified),
* since that makes a rule that only has criteria dependent on
* the struct cdev *match all symlinks and directories.
*
* Note also that the following tests are somewhat reversed:
* They're actually testing to see whether the condition does
* *not* match, since the default is to assume the rule should
* be run (such as if there are no conditions).
*
* XXX: lacks threadref on dev
*/
if (dr->dr_icond & DRC_DSWFLAGS)
if (dev == NULL ||
(dev->si_devsw->d_flags & dr->dr_dswflags) == 0)
goto nomatch;
if (dr->dr_icond & DRC_PATHPTRN)
if (!devfs_rule_matchpath(dk, de))
goto nomatch;
return (1);
nomatch:
return (0);
}
/*
* Determine whether dk matches de on account of dr_pathptrn.
*/
static int
devfs_rule_matchpath(struct devfs_krule *dk, struct devfs_dirent *de)
{
struct devfs_rule *dr = &dk->dk_rule;
char *pname;
struct cdev *dev;
dev = devfs_rule_getdev(de);
if (dev != NULL)
pname = dev->si_name;
else if (de->de_dirent->d_type == DT_LNK ||
de->de_dirent->d_type == DT_DIR)
pname = de->de_dirent->d_name;
else
return (0);
KASSERT(pname != NULL, ("devfs_rule_matchpath: NULL pname"));
return (fnmatch(dr->dr_pathptrn, pname, 0) == 0);
}
/*
* Run dk on de.
*/
static void
devfs_rule_run(struct devfs_krule *dk, struct devfs_dirent *de)
{
struct devfs_rule *dr = &dk->dk_rule;
struct devfs_ruleset *ds;
if (dr->dr_iacts & DRA_BACTS) {
if (dr->dr_bacts & DRB_HIDE)
de->de_flags |= DE_WHITEOUT;
if (dr->dr_bacts & DRB_UNHIDE)
de->de_flags &= ~DE_WHITEOUT;
}
if (dr->dr_iacts & DRA_UID)
de->de_uid = dr->dr_uid;
if (dr->dr_iacts & DRA_GID)
de->de_gid = dr->dr_gid;
if (dr->dr_iacts & DRA_MODE)
de->de_mode = dr->dr_mode;
if (dr->dr_iacts & DRA_INCSET) {
ds = devfs_ruleset_bynum(dk->dk_rule.dr_incset);
KASSERT(ds != NULL, ("DRA_INCSET but bad dr_incset"));
if (ds->ds_running)
printf("Warning: avoiding loop through ruleset %d\n",
ds->ds_number);
else
devfs_ruleset_applyde(ds, de);
}
}
/*
* Apply all the rules in ds to de.
*/
static void
devfs_ruleset_applyde(struct devfs_ruleset *ds, struct devfs_dirent *de)
{
struct devfs_krule *dk;
KASSERT(!ds->ds_running,("ruleset %d already running", ds->ds_number));
ds->ds_running = 1;
SLIST_FOREACH(dk, &ds->ds_rules, dk_list) {
devfs_rule_applyde(dk, de);
}
ds->ds_running = 0;
}
/*
* Apply all the rules in ds to all the entires in dm.
*/
static void
devfs_ruleset_applydm(struct devfs_ruleset *ds, struct devfs_mount *dm)
{
struct devfs_krule *dk;
KASSERT(!ds->ds_running,("ruleset %d already running", ds->ds_number));
ds->ds_running = 1;
/*
* XXX: Does it matter whether we do
*
* foreach(dk in ds)
* foreach(de in dm)
* apply(dk to de)
*
* as opposed to
*
* foreach(de in dm)
* foreach(dk in ds)
* apply(dk to de)
*
* The end result is obviously the same, but does the order
* matter?
*/
SLIST_FOREACH(dk, &ds->ds_rules, dk_list) {
devfs_rule_applydm(dk, dm);
}
ds->ds_running = 0;
}
/*
* Find a ruleset by number.
*/
static struct devfs_ruleset *
devfs_ruleset_bynum(devfs_rsnum rsnum)
{
struct devfs_ruleset *ds;
SLIST_FOREACH(ds, &devfs_rulesets, ds_list) {
if (ds->ds_number == rsnum)
return (ds);
}
return (NULL);
}
/*
* Create a new ruleset.
*/
static struct devfs_ruleset *
devfs_ruleset_create(devfs_rsnum rsnum)
{
struct devfs_ruleset *s1, *s2;
struct devfs_ruleset *ds;
KASSERT(devfs_ruleset_bynum(rsnum) == NULL,
("creating already existent ruleset %d", rsnum));
ds = malloc(sizeof(*ds), M_DEVFS, M_WAITOK | M_ZERO);
ds->ds_number = rsnum;
ds->ds_refcount = ds->ds_flags = 0;
SLIST_INIT(&ds->ds_rules);
s1 = SLIST_FIRST(&devfs_rulesets);
if (s1 == NULL || s1->ds_number > rsnum)
SLIST_INSERT_HEAD(&devfs_rulesets, ds, ds_list);
else {
SLIST_FOREACH(s1, &devfs_rulesets, ds_list) {
s2 = SLIST_NEXT(s1, ds_list);
if (s2 == NULL || s2->ds_number > rsnum) {
SLIST_INSERT_AFTER(s1, ds, ds_list);
break;
}
}
}
return (ds);
}
/*
* Remove a ruleset form the system. The ruleset specified must be
* empty and not in use.
*/
static void
devfs_ruleset_destroy(struct devfs_ruleset **dsp)
{
struct devfs_ruleset *ds = *dsp;
KASSERT(SLIST_EMPTY(&ds->ds_rules), ("destroying non-empty ruleset"));
KASSERT(ds->ds_refcount == 0, ("destroying busy ruleset"));
KASSERT((ds->ds_flags & DS_IMMUTABLE) == 0,
("destroying immutable ruleset"));
SLIST_REMOVE(&devfs_rulesets, ds, devfs_ruleset, ds_list);
free(ds, M_DEVFS);
*dsp = NULL;
}
/*
* Remove a ruleset from the system if it's empty and not used
* anywhere. This should be called after every time a rule is deleted
* from this ruleset or the reference count is decremented.
*/
static void
devfs_ruleset_reap(struct devfs_ruleset **dsp)
{
struct devfs_ruleset *ds = *dsp;
if (SLIST_EMPTY(&ds->ds_rules) && ds->ds_refcount == 0) {
devfs_ruleset_destroy(&ds);
*dsp = ds;
}
}
/*
* Make rsnum the active ruleset for dm.
*/
static int
devfs_ruleset_use(devfs_rsnum rsnum, struct devfs_mount *dm)
{
struct devfs_ruleset *cds, *ds;
ds = devfs_ruleset_bynum(rsnum);
if (ds == NULL)
ds = devfs_ruleset_create(rsnum);
cds = devfs_ruleset_bynum(dm->dm_ruleset);
KASSERT(cds != NULL, ("mount-point has NULL ruleset"));
/* These should probably be made atomic somehow. */
--cds->ds_refcount;
++ds->ds_refcount;
dm->dm_ruleset = rsnum;
devfs_ruleset_reap(&cds);
return (0);
}