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linux-next/fs/gfs2/sys.c
Steven Whitehouse 3942ae5319 GFS2: Fix race during filesystem mount
There is a potential race during filesystem mounting which has recently
been reported. It occurs when the userland gfs_controld is able to
process requests fast enough that it tries to use the sysfs interface
before the lock module is properly initialised. This is a pretty
unusual case as normally the lock module initialisation is very quick
compared with gfs_controld.

This patch adds an interruptible completion which is used to ensure that
userland will wait for the initialisation of the lock module to
complete.

There are other potential solutions to this problem, but this is the
quickest at this stage and has been tested both with and without
mount.gfs2 present in the system.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Reported-by: David Booher <dbooher@adams.net>
2011-07-12 09:15:46 +01:00

654 lines
16 KiB
C

/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License version 2.
*/
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/module.h>
#include <linux/kobject.h>
#include <asm/uaccess.h>
#include <linux/gfs2_ondisk.h>
#include <linux/genhd.h>
#include "gfs2.h"
#include "incore.h"
#include "sys.h"
#include "super.h"
#include "glock.h"
#include "quota.h"
#include "util.h"
#include "glops.h"
#include "recovery.h"
struct gfs2_attr {
struct attribute attr;
ssize_t (*show)(struct gfs2_sbd *, char *);
ssize_t (*store)(struct gfs2_sbd *, const char *, size_t);
};
static ssize_t gfs2_attr_show(struct kobject *kobj, struct attribute *attr,
char *buf)
{
struct gfs2_sbd *sdp = container_of(kobj, struct gfs2_sbd, sd_kobj);
struct gfs2_attr *a = container_of(attr, struct gfs2_attr, attr);
return a->show ? a->show(sdp, buf) : 0;
}
static ssize_t gfs2_attr_store(struct kobject *kobj, struct attribute *attr,
const char *buf, size_t len)
{
struct gfs2_sbd *sdp = container_of(kobj, struct gfs2_sbd, sd_kobj);
struct gfs2_attr *a = container_of(attr, struct gfs2_attr, attr);
return a->store ? a->store(sdp, buf, len) : len;
}
static const struct sysfs_ops gfs2_attr_ops = {
.show = gfs2_attr_show,
.store = gfs2_attr_store,
};
static struct kset *gfs2_kset;
static ssize_t id_show(struct gfs2_sbd *sdp, char *buf)
{
return snprintf(buf, PAGE_SIZE, "%u:%u\n",
MAJOR(sdp->sd_vfs->s_dev), MINOR(sdp->sd_vfs->s_dev));
}
static ssize_t fsname_show(struct gfs2_sbd *sdp, char *buf)
{
return snprintf(buf, PAGE_SIZE, "%s\n", sdp->sd_fsname);
}
static int gfs2_uuid_valid(const u8 *uuid)
{
int i;
for (i = 0; i < 16; i++) {
if (uuid[i])
return 1;
}
return 0;
}
static ssize_t uuid_show(struct gfs2_sbd *sdp, char *buf)
{
struct super_block *s = sdp->sd_vfs;
const u8 *uuid = s->s_uuid;
buf[0] = '\0';
if (!gfs2_uuid_valid(uuid))
return 0;
return snprintf(buf, PAGE_SIZE, "%pUB\n", uuid);
}
static ssize_t freeze_show(struct gfs2_sbd *sdp, char *buf)
{
unsigned int count;
mutex_lock(&sdp->sd_freeze_lock);
count = sdp->sd_freeze_count;
mutex_unlock(&sdp->sd_freeze_lock);
return snprintf(buf, PAGE_SIZE, "%u\n", count);
}
static ssize_t freeze_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
{
ssize_t ret = len;
int error = 0;
int n = simple_strtol(buf, NULL, 0);
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
switch (n) {
case 0:
gfs2_unfreeze_fs(sdp);
break;
case 1:
error = gfs2_freeze_fs(sdp);
break;
default:
ret = -EINVAL;
}
if (error)
fs_warn(sdp, "freeze %d error %d", n, error);
return ret;
}
static ssize_t withdraw_show(struct gfs2_sbd *sdp, char *buf)
{
unsigned int b = test_bit(SDF_SHUTDOWN, &sdp->sd_flags);
return snprintf(buf, PAGE_SIZE, "%u\n", b);
}
static ssize_t withdraw_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
{
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
if (simple_strtol(buf, NULL, 0) != 1)
return -EINVAL;
gfs2_lm_withdraw(sdp,
"GFS2: fsid=%s: withdrawing from cluster at user's request\n",
sdp->sd_fsname);
return len;
}
static ssize_t statfs_sync_store(struct gfs2_sbd *sdp, const char *buf,
size_t len)
{
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
if (simple_strtol(buf, NULL, 0) != 1)
return -EINVAL;
gfs2_statfs_sync(sdp->sd_vfs, 0);
return len;
}
static ssize_t quota_sync_store(struct gfs2_sbd *sdp, const char *buf,
size_t len)
{
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
if (simple_strtol(buf, NULL, 0) != 1)
return -EINVAL;
gfs2_quota_sync(sdp->sd_vfs, 0, 1);
return len;
}
static ssize_t quota_refresh_user_store(struct gfs2_sbd *sdp, const char *buf,
size_t len)
{
int error;
u32 id;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
id = simple_strtoul(buf, NULL, 0);
error = gfs2_quota_refresh(sdp, 1, id);
return error ? error : len;
}
static ssize_t quota_refresh_group_store(struct gfs2_sbd *sdp, const char *buf,
size_t len)
{
int error;
u32 id;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
id = simple_strtoul(buf, NULL, 0);
error = gfs2_quota_refresh(sdp, 0, id);
return error ? error : len;
}
static ssize_t demote_rq_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
{
struct gfs2_glock *gl;
const struct gfs2_glock_operations *glops;
unsigned int glmode;
unsigned int gltype;
unsigned long long glnum;
char mode[16];
int rv;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
rv = sscanf(buf, "%u:%llu %15s", &gltype, &glnum,
mode);
if (rv != 3)
return -EINVAL;
if (strcmp(mode, "EX") == 0)
glmode = LM_ST_UNLOCKED;
else if ((strcmp(mode, "CW") == 0) || (strcmp(mode, "DF") == 0))
glmode = LM_ST_DEFERRED;
else if ((strcmp(mode, "PR") == 0) || (strcmp(mode, "SH") == 0))
glmode = LM_ST_SHARED;
else
return -EINVAL;
if (gltype > LM_TYPE_JOURNAL)
return -EINVAL;
if (gltype == LM_TYPE_NONDISK && glnum == GFS2_TRANS_LOCK)
glops = &gfs2_trans_glops;
else
glops = gfs2_glops_list[gltype];
if (glops == NULL)
return -EINVAL;
if (!test_and_set_bit(SDF_DEMOTE, &sdp->sd_flags))
fs_info(sdp, "demote interface used\n");
rv = gfs2_glock_get(sdp, glnum, glops, 0, &gl);
if (rv)
return rv;
gfs2_glock_cb(gl, glmode);
gfs2_glock_put(gl);
return len;
}
#define GFS2_ATTR(name, mode, show, store) \
static struct gfs2_attr gfs2_attr_##name = __ATTR(name, mode, show, store)
GFS2_ATTR(id, 0444, id_show, NULL);
GFS2_ATTR(fsname, 0444, fsname_show, NULL);
GFS2_ATTR(uuid, 0444, uuid_show, NULL);
GFS2_ATTR(freeze, 0644, freeze_show, freeze_store);
GFS2_ATTR(withdraw, 0644, withdraw_show, withdraw_store);
GFS2_ATTR(statfs_sync, 0200, NULL, statfs_sync_store);
GFS2_ATTR(quota_sync, 0200, NULL, quota_sync_store);
GFS2_ATTR(quota_refresh_user, 0200, NULL, quota_refresh_user_store);
GFS2_ATTR(quota_refresh_group, 0200, NULL, quota_refresh_group_store);
GFS2_ATTR(demote_rq, 0200, NULL, demote_rq_store);
static struct attribute *gfs2_attrs[] = {
&gfs2_attr_id.attr,
&gfs2_attr_fsname.attr,
&gfs2_attr_uuid.attr,
&gfs2_attr_freeze.attr,
&gfs2_attr_withdraw.attr,
&gfs2_attr_statfs_sync.attr,
&gfs2_attr_quota_sync.attr,
&gfs2_attr_quota_refresh_user.attr,
&gfs2_attr_quota_refresh_group.attr,
&gfs2_attr_demote_rq.attr,
NULL,
};
static struct kobj_type gfs2_ktype = {
.default_attrs = gfs2_attrs,
.sysfs_ops = &gfs2_attr_ops,
};
/*
* lock_module. Originally from lock_dlm
*/
static ssize_t proto_name_show(struct gfs2_sbd *sdp, char *buf)
{
const struct lm_lockops *ops = sdp->sd_lockstruct.ls_ops;
return sprintf(buf, "%s\n", ops->lm_proto_name);
}
static ssize_t block_show(struct gfs2_sbd *sdp, char *buf)
{
struct lm_lockstruct *ls = &sdp->sd_lockstruct;
ssize_t ret;
int val = 0;
if (test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))
val = 1;
ret = sprintf(buf, "%d\n", val);
return ret;
}
static ssize_t block_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
{
struct lm_lockstruct *ls = &sdp->sd_lockstruct;
ssize_t ret = len;
int val;
val = simple_strtol(buf, NULL, 0);
if (val == 1)
set_bit(DFL_BLOCK_LOCKS, &ls->ls_flags);
else if (val == 0) {
clear_bit(DFL_BLOCK_LOCKS, &ls->ls_flags);
smp_mb__after_clear_bit();
gfs2_glock_thaw(sdp);
} else {
ret = -EINVAL;
}
return ret;
}
static ssize_t lkfirst_show(struct gfs2_sbd *sdp, char *buf)
{
struct lm_lockstruct *ls = &sdp->sd_lockstruct;
return sprintf(buf, "%d\n", ls->ls_first);
}
static ssize_t lkfirst_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
{
unsigned first;
int rv;
rv = sscanf(buf, "%u", &first);
if (rv != 1 || first > 1)
return -EINVAL;
rv = wait_for_completion_killable(&sdp->sd_locking_init);
if (rv)
return rv;
spin_lock(&sdp->sd_jindex_spin);
rv = -EBUSY;
if (test_bit(SDF_NOJOURNALID, &sdp->sd_flags) == 0)
goto out;
rv = -EINVAL;
if (sdp->sd_args.ar_spectator)
goto out;
if (sdp->sd_lockstruct.ls_ops->lm_mount == NULL)
goto out;
sdp->sd_lockstruct.ls_first = first;
rv = 0;
out:
spin_unlock(&sdp->sd_jindex_spin);
return rv ? rv : len;
}
static ssize_t first_done_show(struct gfs2_sbd *sdp, char *buf)
{
struct lm_lockstruct *ls = &sdp->sd_lockstruct;
return sprintf(buf, "%d\n", ls->ls_first_done);
}
static ssize_t recover_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
{
unsigned jid;
struct gfs2_jdesc *jd;
int rv;
rv = sscanf(buf, "%u", &jid);
if (rv != 1)
return -EINVAL;
rv = -ESHUTDOWN;
spin_lock(&sdp->sd_jindex_spin);
if (test_bit(SDF_NORECOVERY, &sdp->sd_flags))
goto out;
rv = -EBUSY;
if (sdp->sd_jdesc->jd_jid == jid)
goto out;
rv = -ENOENT;
list_for_each_entry(jd, &sdp->sd_jindex_list, jd_list) {
if (jd->jd_jid != jid)
continue;
rv = gfs2_recover_journal(jd, false);
break;
}
out:
spin_unlock(&sdp->sd_jindex_spin);
return rv ? rv : len;
}
static ssize_t recover_done_show(struct gfs2_sbd *sdp, char *buf)
{
struct lm_lockstruct *ls = &sdp->sd_lockstruct;
return sprintf(buf, "%d\n", ls->ls_recover_jid_done);
}
static ssize_t recover_status_show(struct gfs2_sbd *sdp, char *buf)
{
struct lm_lockstruct *ls = &sdp->sd_lockstruct;
return sprintf(buf, "%d\n", ls->ls_recover_jid_status);
}
static ssize_t jid_show(struct gfs2_sbd *sdp, char *buf)
{
return sprintf(buf, "%d\n", sdp->sd_lockstruct.ls_jid);
}
static ssize_t jid_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
{
int jid;
int rv;
rv = sscanf(buf, "%d", &jid);
if (rv != 1)
return -EINVAL;
rv = wait_for_completion_killable(&sdp->sd_locking_init);
if (rv)
return rv;
spin_lock(&sdp->sd_jindex_spin);
rv = -EINVAL;
if (sdp->sd_lockstruct.ls_ops->lm_mount == NULL)
goto out;
rv = -EBUSY;
if (test_bit(SDF_NOJOURNALID, &sdp->sd_flags) == 0)
goto out;
rv = 0;
if (sdp->sd_args.ar_spectator && jid > 0)
rv = jid = -EINVAL;
sdp->sd_lockstruct.ls_jid = jid;
clear_bit(SDF_NOJOURNALID, &sdp->sd_flags);
smp_mb__after_clear_bit();
wake_up_bit(&sdp->sd_flags, SDF_NOJOURNALID);
out:
spin_unlock(&sdp->sd_jindex_spin);
return rv ? rv : len;
}
#define GDLM_ATTR(_name,_mode,_show,_store) \
static struct gfs2_attr gdlm_attr_##_name = __ATTR(_name,_mode,_show,_store)
GDLM_ATTR(proto_name, 0444, proto_name_show, NULL);
GDLM_ATTR(block, 0644, block_show, block_store);
GDLM_ATTR(withdraw, 0644, withdraw_show, withdraw_store);
GDLM_ATTR(jid, 0644, jid_show, jid_store);
GDLM_ATTR(first, 0644, lkfirst_show, lkfirst_store);
GDLM_ATTR(first_done, 0444, first_done_show, NULL);
GDLM_ATTR(recover, 0600, NULL, recover_store);
GDLM_ATTR(recover_done, 0444, recover_done_show, NULL);
GDLM_ATTR(recover_status, 0444, recover_status_show, NULL);
static struct attribute *lock_module_attrs[] = {
&gdlm_attr_proto_name.attr,
&gdlm_attr_block.attr,
&gdlm_attr_withdraw.attr,
&gdlm_attr_jid.attr,
&gdlm_attr_first.attr,
&gdlm_attr_first_done.attr,
&gdlm_attr_recover.attr,
&gdlm_attr_recover_done.attr,
&gdlm_attr_recover_status.attr,
NULL,
};
/*
* get and set struct gfs2_tune fields
*/
static ssize_t quota_scale_show(struct gfs2_sbd *sdp, char *buf)
{
return snprintf(buf, PAGE_SIZE, "%u %u\n",
sdp->sd_tune.gt_quota_scale_num,
sdp->sd_tune.gt_quota_scale_den);
}
static ssize_t quota_scale_store(struct gfs2_sbd *sdp, const char *buf,
size_t len)
{
struct gfs2_tune *gt = &sdp->sd_tune;
unsigned int x, y;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
if (sscanf(buf, "%u %u", &x, &y) != 2 || !y)
return -EINVAL;
spin_lock(&gt->gt_spin);
gt->gt_quota_scale_num = x;
gt->gt_quota_scale_den = y;
spin_unlock(&gt->gt_spin);
return len;
}
static ssize_t tune_set(struct gfs2_sbd *sdp, unsigned int *field,
int check_zero, const char *buf, size_t len)
{
struct gfs2_tune *gt = &sdp->sd_tune;
unsigned int x;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
x = simple_strtoul(buf, NULL, 0);
if (check_zero && !x)
return -EINVAL;
spin_lock(&gt->gt_spin);
*field = x;
spin_unlock(&gt->gt_spin);
return len;
}
#define TUNE_ATTR_3(name, show, store) \
static struct gfs2_attr tune_attr_##name = __ATTR(name, 0644, show, store)
#define TUNE_ATTR_2(name, store) \
static ssize_t name##_show(struct gfs2_sbd *sdp, char *buf) \
{ \
return snprintf(buf, PAGE_SIZE, "%u\n", sdp->sd_tune.gt_##name); \
} \
TUNE_ATTR_3(name, name##_show, store)
#define TUNE_ATTR(name, check_zero) \
static ssize_t name##_store(struct gfs2_sbd *sdp, const char *buf, size_t len)\
{ \
return tune_set(sdp, &sdp->sd_tune.gt_##name, check_zero, buf, len); \
} \
TUNE_ATTR_2(name, name##_store)
TUNE_ATTR(quota_warn_period, 0);
TUNE_ATTR(quota_quantum, 0);
TUNE_ATTR(max_readahead, 0);
TUNE_ATTR(complain_secs, 0);
TUNE_ATTR(statfs_slow, 0);
TUNE_ATTR(new_files_jdata, 0);
TUNE_ATTR(quota_simul_sync, 1);
TUNE_ATTR(statfs_quantum, 1);
TUNE_ATTR_3(quota_scale, quota_scale_show, quota_scale_store);
static struct attribute *tune_attrs[] = {
&tune_attr_quota_warn_period.attr,
&tune_attr_quota_quantum.attr,
&tune_attr_max_readahead.attr,
&tune_attr_complain_secs.attr,
&tune_attr_statfs_slow.attr,
&tune_attr_quota_simul_sync.attr,
&tune_attr_statfs_quantum.attr,
&tune_attr_quota_scale.attr,
&tune_attr_new_files_jdata.attr,
NULL,
};
static struct attribute_group tune_group = {
.name = "tune",
.attrs = tune_attrs,
};
static struct attribute_group lock_module_group = {
.name = "lock_module",
.attrs = lock_module_attrs,
};
int gfs2_sys_fs_add(struct gfs2_sbd *sdp)
{
struct super_block *sb = sdp->sd_vfs;
int error;
char ro[20];
char spectator[20];
char *envp[] = { ro, spectator, NULL };
sprintf(ro, "RDONLY=%d", (sb->s_flags & MS_RDONLY) ? 1 : 0);
sprintf(spectator, "SPECTATOR=%d", sdp->sd_args.ar_spectator ? 1 : 0);
sdp->sd_kobj.kset = gfs2_kset;
error = kobject_init_and_add(&sdp->sd_kobj, &gfs2_ktype, NULL,
"%s", sdp->sd_table_name);
if (error)
goto fail;
error = sysfs_create_group(&sdp->sd_kobj, &tune_group);
if (error)
goto fail_reg;
error = sysfs_create_group(&sdp->sd_kobj, &lock_module_group);
if (error)
goto fail_tune;
error = sysfs_create_link(&sdp->sd_kobj,
&disk_to_dev(sb->s_bdev->bd_disk)->kobj,
"device");
if (error)
goto fail_lock_module;
kobject_uevent_env(&sdp->sd_kobj, KOBJ_ADD, envp);
return 0;
fail_lock_module:
sysfs_remove_group(&sdp->sd_kobj, &lock_module_group);
fail_tune:
sysfs_remove_group(&sdp->sd_kobj, &tune_group);
fail_reg:
kobject_put(&sdp->sd_kobj);
fail:
fs_err(sdp, "error %d adding sysfs files", error);
return error;
}
void gfs2_sys_fs_del(struct gfs2_sbd *sdp)
{
sysfs_remove_link(&sdp->sd_kobj, "device");
sysfs_remove_group(&sdp->sd_kobj, &tune_group);
sysfs_remove_group(&sdp->sd_kobj, &lock_module_group);
kobject_put(&sdp->sd_kobj);
}
static int gfs2_uevent(struct kset *kset, struct kobject *kobj,
struct kobj_uevent_env *env)
{
struct gfs2_sbd *sdp = container_of(kobj, struct gfs2_sbd, sd_kobj);
struct super_block *s = sdp->sd_vfs;
const u8 *uuid = s->s_uuid;
add_uevent_var(env, "LOCKTABLE=%s", sdp->sd_table_name);
add_uevent_var(env, "LOCKPROTO=%s", sdp->sd_proto_name);
if (!test_bit(SDF_NOJOURNALID, &sdp->sd_flags))
add_uevent_var(env, "JOURNALID=%d", sdp->sd_lockstruct.ls_jid);
if (gfs2_uuid_valid(uuid))
add_uevent_var(env, "UUID=%pUB", uuid);
return 0;
}
static const struct kset_uevent_ops gfs2_uevent_ops = {
.uevent = gfs2_uevent,
};
int gfs2_sys_init(void)
{
gfs2_kset = kset_create_and_add("gfs2", &gfs2_uevent_ops, fs_kobj);
if (!gfs2_kset)
return -ENOMEM;
return 0;
}
void gfs2_sys_uninit(void)
{
kset_unregister(gfs2_kset);
}