leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity
79272b3562
linux/fs/gfs2/glock.c
Bob Peterson 79272b3562 GFS2: Only wait for demote when last holder is dequeued 
Function gfs2_glock_dq_wait is supposed to dequeue a glock and then
wait for the lock to be demoted. The problem is, if this is a shared
lock, its demote will depend on the other holders, which means you
might end up waiting forever because the other process is blocked.
This problem is especially apparent when dealing with nested flocks.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2014-07-18 11:12:14 +01:00

2139 lines
52 KiB
C
Raw Blame History

/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2008 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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/buffer_head.h>
#include <linux/delay.h>
#include <linux/sort.h>
#include <linux/jhash.h>
#include <linux/kallsyms.h>
#include <linux/gfs2_ondisk.h>
#include <linux/list.h>
#include <linux/wait.h>
#include <linux/module.h>
#include <asm/uaccess.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/workqueue.h>
#include <linux/jiffies.h>
#include <linux/rcupdate.h>
#include <linux/rculist_bl.h>
#include <linux/bit_spinlock.h>
#include <linux/percpu.h>
#include <linux/list_sort.h>
#include <linux/lockref.h>
#include "gfs2.h"
#include "incore.h"
#include "glock.h"
#include "glops.h"
#include "inode.h"
#include "lops.h"
#include "meta_io.h"
#include "quota.h"
#include "super.h"
#include "util.h"
#include "bmap.h"
#define CREATE_TRACE_POINTS
#include "trace_gfs2.h"
struct gfs2_glock_iter {
int hash; /* hash bucket index */
unsigned nhash; /* Index within current bucket */
struct gfs2_sbd *sdp; /* incore superblock */
struct gfs2_glock *gl; /* current glock struct */
loff_t last_pos; /* last position */
};
typedef void (*glock_examiner) (struct gfs2_glock * gl);
static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
static struct dentry *gfs2_root;
static struct workqueue_struct *glock_workqueue;
struct workqueue_struct *gfs2_delete_workqueue;
static LIST_HEAD(lru_list);
static atomic_t lru_count = ATOMIC_INIT(0);
static DEFINE_SPINLOCK(lru_lock);
#define GFS2_GL_HASH_SHIFT 15
#define GFS2_GL_HASH_SIZE (1 << GFS2_GL_HASH_SHIFT)
#define GFS2_GL_HASH_MASK (GFS2_GL_HASH_SIZE - 1)
static struct hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
static struct dentry *gfs2_root;
/**
* gl_hash() - Turn glock number into hash bucket number
* @lock: The glock number
*
* Returns: The number of the corresponding hash bucket
*/
static unsigned int gl_hash(const struct gfs2_sbd *sdp,
const struct lm_lockname *name)
{
unsigned int h;
h = jhash(&name->ln_number, sizeof(u64), 0);
h = jhash(&name->ln_type, sizeof(unsigned int), h);
h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
h &= GFS2_GL_HASH_MASK;
return h;
}
static inline void spin_lock_bucket(unsigned int hash)
{
hlist_bl_lock(&gl_hash_table[hash]);
}
static inline void spin_unlock_bucket(unsigned int hash)
{
hlist_bl_unlock(&gl_hash_table[hash]);
}
static void gfs2_glock_dealloc(struct rcu_head *rcu)
{
struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
if (gl->gl_ops->go_flags & GLOF_ASPACE) {
kmem_cache_free(gfs2_glock_aspace_cachep, gl);
} else {
kfree(gl->gl_lksb.sb_lvbptr);
kmem_cache_free(gfs2_glock_cachep, gl);
}
}
void gfs2_glock_free(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
if (atomic_dec_and_test(&sdp->sd_glock_disposal))
wake_up(&sdp->sd_glock_wait);
}
/**
* gfs2_glock_hold() - increment reference count on glock
* @gl: The glock to hold
*
*/
static void gfs2_glock_hold(struct gfs2_glock *gl)
{
GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
lockref_get(&gl->gl_lockref);
}
/**
* demote_ok - Check to see if it's ok to unlock a glock
* @gl: the glock
*
* Returns: 1 if it's ok
*/
static int demote_ok(const struct gfs2_glock *gl)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
if (gl->gl_state == LM_ST_UNLOCKED)
return 0;
if (!list_empty(&gl->gl_holders))
return 0;
if (glops->go_demote_ok)
return glops->go_demote_ok(gl);
return 1;
}
void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
{
spin_lock(&lru_lock);
if (!list_empty(&gl->gl_lru))
list_del_init(&gl->gl_lru);
else
atomic_inc(&lru_count);
list_add_tail(&gl->gl_lru, &lru_list);
set_bit(GLF_LRU, &gl->gl_flags);
spin_unlock(&lru_lock);
}
static void __gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
{
if (!list_empty(&gl->gl_lru)) {
list_del_init(&gl->gl_lru);
atomic_dec(&lru_count);
clear_bit(GLF_LRU, &gl->gl_flags);
}
}
static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
{
spin_lock(&lru_lock);
__gfs2_glock_remove_from_lru(gl);
spin_unlock(&lru_lock);
}
/**
* gfs2_glock_put() - Decrement reference count on glock
* @gl: The glock to put
*
*/
void gfs2_glock_put(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
struct address_space *mapping = gfs2_glock2aspace(gl);
if (lockref_put_or_lock(&gl->gl_lockref))
return;
lockref_mark_dead(&gl->gl_lockref);
spin_lock(&lru_lock);
__gfs2_glock_remove_from_lru(gl);
spin_unlock(&lru_lock);
spin_unlock(&gl->gl_lockref.lock);
spin_lock_bucket(gl->gl_hash);
hlist_bl_del_rcu(&gl->gl_list);
spin_unlock_bucket(gl->gl_hash);
GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
trace_gfs2_glock_put(gl);
sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
}
/**
* search_bucket() - Find struct gfs2_glock by lock number
* @bucket: the bucket to search
* @name: The lock name
*
* Returns: NULL, or the struct gfs2_glock with the requested number
*/
static struct gfs2_glock *search_bucket(unsigned int hash,
const struct gfs2_sbd *sdp,
const struct lm_lockname *name)
{
struct gfs2_glock *gl;
struct hlist_bl_node *h;
hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
if (!lm_name_equal(&gl->gl_name, name))
continue;
if (gl->gl_sbd != sdp)
continue;
if (lockref_get_not_dead(&gl->gl_lockref))
return gl;
}
return NULL;
}
/**
* may_grant - check if its ok to grant a new lock
* @gl: The glock
* @gh: The lock request which we wish to grant
*
* Returns: true if its ok to grant the lock
*/
static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
{
const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
if ((gh->gh_state == LM_ST_EXCLUSIVE ||
gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
return 0;
if (gl->gl_state == gh->gh_state)
return 1;
if (gh->gh_flags & GL_EXACT)
return 0;
if (gl->gl_state == LM_ST_EXCLUSIVE) {
if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
return 1;
if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
return 1;
}
if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
return 1;
return 0;
}
static void gfs2_holder_wake(struct gfs2_holder *gh)
{
clear_bit(HIF_WAIT, &gh->gh_iflags);
smp_mb__after_atomic();
wake_up_bit(&gh->gh_iflags, HIF_WAIT);
}
/**
* do_error - Something unexpected has happened during a lock request
*
*/
static inline void do_error(struct gfs2_glock *gl, const int ret)
{
struct gfs2_holder *gh, *tmp;
list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
if (test_bit(HIF_HOLDER, &gh->gh_iflags))
continue;
if (ret & LM_OUT_ERROR)
gh->gh_error = -EIO;
else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
gh->gh_error = GLR_TRYFAILED;
else
continue;
list_del_init(&gh->gh_list);
trace_gfs2_glock_queue(gh, 0);
gfs2_holder_wake(gh);
}
}
/**
* do_promote - promote as many requests as possible on the current queue
* @gl: The glock
*
* Returns: 1 if there is a blocked holder at the head of the list, or 2
* if a type specific operation is underway.
*/
static int do_promote(struct gfs2_glock *gl)
__releases(&gl->gl_spin)
__acquires(&gl->gl_spin)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
struct gfs2_holder *gh, *tmp;
int ret;
restart:
list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
if (test_bit(HIF_HOLDER, &gh->gh_iflags))
continue;
if (may_grant(gl, gh)) {
if (gh->gh_list.prev == &gl->gl_holders &&
glops->go_lock) {
spin_unlock(&gl->gl_spin);
/* FIXME: eliminate this eventually */
ret = glops->go_lock(gh);
spin_lock(&gl->gl_spin);
if (ret) {
if (ret == 1)
return 2;
gh->gh_error = ret;
list_del_init(&gh->gh_list);
trace_gfs2_glock_queue(gh, 0);
gfs2_holder_wake(gh);
goto restart;
}
set_bit(HIF_HOLDER, &gh->gh_iflags);
trace_gfs2_promote(gh, 1);
gfs2_holder_wake(gh);
goto restart;
}
set_bit(HIF_HOLDER, &gh->gh_iflags);
trace_gfs2_promote(gh, 0);
gfs2_holder_wake(gh);
continue;
}
if (gh->gh_list.prev == &gl->gl_holders)
return 1;
do_error(gl, 0);
break;
}
return 0;
}
/**
* find_first_waiter - find the first gh that's waiting for the glock
* @gl: the glock
*/
static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
{
struct gfs2_holder *gh;
list_for_each_entry(gh, &gl->gl_holders, gh_list) {
if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
return gh;
}
return NULL;
}
/**
* state_change - record that the glock is now in a different state
* @gl: the glock
* @new_state the new state
*
*/
static void state_change(struct gfs2_glock *gl, unsigned int new_state)
{
int held1, held2;
held1 = (gl->gl_state != LM_ST_UNLOCKED);
held2 = (new_state != LM_ST_UNLOCKED);
if (held1 != held2) {
GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
if (held2)
gl->gl_lockref.count++;
else
gl->gl_lockref.count--;
}
if (held1 && held2 && list_empty(&gl->gl_holders))
clear_bit(GLF_QUEUED, &gl->gl_flags);
if (new_state != gl->gl_target)
/* shorten our minimum hold time */
gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
GL_GLOCK_MIN_HOLD);
gl->gl_state = new_state;
gl->gl_tchange = jiffies;
}
static void gfs2_demote_wake(struct gfs2_glock *gl)
{
gl->gl_demote_state = LM_ST_EXCLUSIVE;
clear_bit(GLF_DEMOTE, &gl->gl_flags);
smp_mb__after_atomic();
wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
}
/**
* finish_xmote - The DLM has replied to one of our lock requests
* @gl: The glock
* @ret: The status from the DLM
*
*/
static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
struct gfs2_holder *gh;
unsigned state = ret & LM_OUT_ST_MASK;
int rv;
spin_lock(&gl->gl_spin);
trace_gfs2_glock_state_change(gl, state);
state_change(gl, state);
gh = find_first_waiter(gl);
/* Demote to UN request arrived during demote to SH or DF */
if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
gl->gl_target = LM_ST_UNLOCKED;
/* Check for state != intended state */
if (unlikely(state != gl->gl_target)) {
if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
/* move to back of queue and try next entry */
if (ret & LM_OUT_CANCELED) {
if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
list_move_tail(&gh->gh_list, &gl->gl_holders);
gh = find_first_waiter(gl);
gl->gl_target = gh->gh_state;
goto retry;
}
/* Some error or failed "try lock" - report it */
if ((ret & LM_OUT_ERROR) ||
(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
gl->gl_target = gl->gl_state;
do_error(gl, ret);
goto out;
}
}
switch(state) {
/* Unlocked due to conversion deadlock, try again */
case LM_ST_UNLOCKED:
retry:
do_xmote(gl, gh, gl->gl_target);
break;
/* Conversion fails, unlock and try again */
case LM_ST_SHARED:
case LM_ST_DEFERRED:
do_xmote(gl, gh, LM_ST_UNLOCKED);
break;
default: /* Everything else */
pr_err("wanted %u got %u\n", gl->gl_target, state);
GLOCK_BUG_ON(gl, 1);
}
spin_unlock(&gl->gl_spin);
return;
}
/* Fast path - we got what we asked for */
if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
gfs2_demote_wake(gl);
if (state != LM_ST_UNLOCKED) {
if (glops->go_xmote_bh) {
spin_unlock(&gl->gl_spin);
rv = glops->go_xmote_bh(gl, gh);
spin_lock(&gl->gl_spin);
if (rv) {
do_error(gl, rv);
goto out;
}
}
rv = do_promote(gl);
if (rv == 2)
goto out_locked;
}
out:
clear_bit(GLF_LOCK, &gl->gl_flags);
out_locked:
spin_unlock(&gl->gl_spin);
}
/**
* do_xmote - Calls the DLM to change the state of a lock
* @gl: The lock state
* @gh: The holder (only for promotes)
* @target: The target lock state
*
*/
static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
__releases(&gl->gl_spin)
__acquires(&gl->gl_spin)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
struct gfs2_sbd *sdp = gl->gl_sbd;
unsigned int lck_flags = gh ? gh->gh_flags : 0;
int ret;
lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
LM_FLAG_PRIORITY);
GLOCK_BUG_ON(gl, gl->gl_state == target);
GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
glops->go_inval) {
set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
do_error(gl, 0); /* Fail queued try locks */
}
gl->gl_req = target;
set_bit(GLF_BLOCKING, &gl->gl_flags);
if ((gl->gl_req == LM_ST_UNLOCKED) ||
(gl->gl_state == LM_ST_EXCLUSIVE) ||
(lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
clear_bit(GLF_BLOCKING, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
if (glops->go_sync)
glops->go_sync(gl);
if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
gfs2_glock_hold(gl);
if (sdp->sd_lockstruct.ls_ops->lm_lock) {
/* lock_dlm */
ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
if (ret) {
pr_err("lm_lock ret %d\n", ret);
GLOCK_BUG_ON(gl, 1);
}
} else { /* lock_nolock */
finish_xmote(gl, target);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put(gl);
}
spin_lock(&gl->gl_spin);
}
/**
* find_first_holder - find the first "holder" gh
* @gl: the glock
*/
static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
{
struct gfs2_holder *gh;
if (!list_empty(&gl->gl_holders)) {
gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
if (test_bit(HIF_HOLDER, &gh->gh_iflags))
return gh;
}
return NULL;
}
/**
* run_queue - do all outstanding tasks related to a glock
* @gl: The glock in question
* @nonblock: True if we must not block in run_queue
*
*/
static void run_queue(struct gfs2_glock *gl, const int nonblock)
__releases(&gl->gl_spin)
__acquires(&gl->gl_spin)
{
struct gfs2_holder *gh = NULL;
int ret;
if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
return;
GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
gl->gl_demote_state != gl->gl_state) {
if (find_first_holder(gl))
goto out_unlock;
if (nonblock)
goto out_sched;
set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
gl->gl_target = gl->gl_demote_state;
} else {
if (test_bit(GLF_DEMOTE, &gl->gl_flags))
gfs2_demote_wake(gl);
ret = do_promote(gl);
if (ret == 0)
goto out_unlock;
if (ret == 2)
goto out;
gh = find_first_waiter(gl);
gl->gl_target = gh->gh_state;
if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
do_error(gl, 0); /* Fail queued try locks */
}
do_xmote(gl, gh, gl->gl_target);
out:
return;
out_sched:
clear_bit(GLF_LOCK, &gl->gl_flags);
smp_mb__after_atomic();
gl->gl_lockref.count++;
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gl->gl_lockref.count--;
return;
out_unlock:
clear_bit(GLF_LOCK, &gl->gl_flags);
smp_mb__after_atomic();
return;
}
static void delete_work_func(struct work_struct *work)
{
struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
struct gfs2_sbd *sdp = gl->gl_sbd;
struct gfs2_inode *ip;
struct inode *inode;
u64 no_addr = gl->gl_name.ln_number;
ip = gl->gl_object;
/* Note: Unsafe to dereference ip as we don't hold right refs/locks */
if (ip)
inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
else
inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
if (inode && !IS_ERR(inode)) {
d_prune_aliases(inode);
iput(inode);
}
gfs2_glock_put(gl);
}
static void glock_work_func(struct work_struct *work)
{
unsigned long delay = 0;
struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
int drop_ref = 0;
if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
finish_xmote(gl, gl->gl_reply);
drop_ref = 1;
}
spin_lock(&gl->gl_spin);
if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
gl->gl_state != LM_ST_UNLOCKED &&
gl->gl_demote_state != LM_ST_EXCLUSIVE) {
unsigned long holdtime, now = jiffies;
holdtime = gl->gl_tchange + gl->gl_hold_time;
if (time_before(now, holdtime))
delay = holdtime - now;
if (!delay) {
clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
set_bit(GLF_DEMOTE, &gl->gl_flags);
}
}
run_queue(gl, 0);
spin_unlock(&gl->gl_spin);
if (!delay)
gfs2_glock_put(gl);
else {
if (gl->gl_name.ln_type != LM_TYPE_INODE)
delay = 0;
if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
gfs2_glock_put(gl);
}
if (drop_ref)
gfs2_glock_put(gl);
}
/**
* gfs2_glock_get() - Get a glock, or create one if one doesn't exist
* @sdp: The GFS2 superblock
* @number: the lock number
* @glops: The glock_operations to use
* @create: If 0, don't create the glock if it doesn't exist
* @glp: the glock is returned here
*
* This does not lock a glock, just finds/creates structures for one.
*
* Returns: errno
*/
int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
const struct gfs2_glock_operations *glops, int create,
struct gfs2_glock **glp)
{
struct super_block *s = sdp->sd_vfs;
struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
struct gfs2_glock *gl, *tmp;
unsigned int hash = gl_hash(sdp, &name);
struct address_space *mapping;
struct kmem_cache *cachep;
rcu_read_lock();
gl = search_bucket(hash, sdp, &name);
rcu_read_unlock();
*glp = gl;
if (gl)
return 0;
if (!create)
return -ENOENT;
if (glops->go_flags & GLOF_ASPACE)
cachep = gfs2_glock_aspace_cachep;
else
cachep = gfs2_glock_cachep;
gl = kmem_cache_alloc(cachep, GFP_KERNEL);
if (!gl)
return -ENOMEM;
memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
if (glops->go_flags & GLOF_LVB) {
gl->gl_lksb.sb_lvbptr = kzalloc(GFS2_MIN_LVB_SIZE, GFP_KERNEL);
if (!gl->gl_lksb.sb_lvbptr) {
kmem_cache_free(cachep, gl);
return -ENOMEM;
}
}
atomic_inc(&sdp->sd_glock_disposal);
gl->gl_sbd = sdp;
gl->gl_flags = 0;
gl->gl_name = name;
gl->gl_lockref.count = 1;
gl->gl_state = LM_ST_UNLOCKED;
gl->gl_target = LM_ST_UNLOCKED;
gl->gl_demote_state = LM_ST_EXCLUSIVE;
gl->gl_hash = hash;
gl->gl_ops = glops;
gl->gl_dstamp = ktime_set(0, 0);
preempt_disable();
/* We use the global stats to estimate the initial per-glock stats */
gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
preempt_enable();
gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
gl->gl_tchange = jiffies;
gl->gl_object = NULL;
gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
INIT_WORK(&gl->gl_delete, delete_work_func);
mapping = gfs2_glock2aspace(gl);
if (mapping) {
mapping->a_ops = &gfs2_meta_aops;
mapping->host = s->s_bdev->bd_inode;
mapping->flags = 0;
mapping_set_gfp_mask(mapping, GFP_NOFS);
mapping->private_data = NULL;
mapping->backing_dev_info = s->s_bdi;
mapping->writeback_index = 0;
}
spin_lock_bucket(hash);
tmp = search_bucket(hash, sdp, &name);
if (tmp) {
spin_unlock_bucket(hash);
kfree(gl->gl_lksb.sb_lvbptr);
kmem_cache_free(cachep, gl);
atomic_dec(&sdp->sd_glock_disposal);
gl = tmp;
} else {
hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
spin_unlock_bucket(hash);
}
*glp = gl;
return 0;
}
/**
* gfs2_holder_init - initialize a struct gfs2_holder in the default way
* @gl: the glock
* @state: the state we're requesting
* @flags: the modifier flags
* @gh: the holder structure
*
*/
void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
struct gfs2_holder *gh)
{
INIT_LIST_HEAD(&gh->gh_list);
gh->gh_gl = gl;
gh->gh_ip = (unsigned long)__builtin_return_address(0);
gh->gh_owner_pid = get_pid(task_pid(current));
gh->gh_state = state;
gh->gh_flags = flags;
gh->gh_error = 0;
gh->gh_iflags = 0;
gfs2_glock_hold(gl);
}
/**
* gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
* @state: the state we're requesting
* @flags: the modifier flags
* @gh: the holder structure
*
* Don't mess with the glock.
*
*/
void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
{
gh->gh_state = state;
gh->gh_flags = flags;
gh->gh_iflags = 0;
gh->gh_ip = (unsigned long)__builtin_return_address(0);
if (gh->gh_owner_pid)
put_pid(gh->gh_owner_pid);
gh->gh_owner_pid = get_pid(task_pid(current));
}
/**
* gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
* @gh: the holder structure
*
*/
void gfs2_holder_uninit(struct gfs2_holder *gh)
{
put_pid(gh->gh_owner_pid);
gfs2_glock_put(gh->gh_gl);
gh->gh_gl = NULL;
gh->gh_ip = 0;
}
/**
* gfs2_glock_holder_wait
* @word: unused
*
* This function and gfs2_glock_demote_wait both show up in the WCHAN
* field. Thus I've separated these otherwise identical functions in
* order to be more informative to the user.
*/
static int gfs2_glock_holder_wait(void *word)
{
schedule();
return 0;
}
static int gfs2_glock_demote_wait(void *word)
{
schedule();
return 0;
}
/**
* gfs2_glock_wait - wait on a glock acquisition
* @gh: the glock holder
*
* Returns: 0 on success
*/
int gfs2_glock_wait(struct gfs2_holder *gh)
{
unsigned long time1 = jiffies;
might_sleep();
wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
/* Lengthen the minimum hold time. */
gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
GL_GLOCK_HOLD_INCR,
GL_GLOCK_MAX_HOLD);
return gh->gh_error;
}
/**
* handle_callback - process a demote request
* @gl: the glock
* @state: the state the caller wants us to change to
*
* There are only two requests that we are going to see in actual
* practise: LM_ST_SHARED and LM_ST_UNLOCKED
*/
static void handle_callback(struct gfs2_glock *gl, unsigned int state,
unsigned long delay, bool remote)
{
int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
set_bit(bit, &gl->gl_flags);
if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
gl->gl_demote_state = state;
gl->gl_demote_time = jiffies;
} else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
gl->gl_demote_state != state) {
gl->gl_demote_state = LM_ST_UNLOCKED;
}
if (gl->gl_ops->go_callback)
gl->gl_ops->go_callback(gl, remote);
trace_gfs2_demote_rq(gl, remote);
}
void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
{
struct va_format vaf;
va_list args;
va_start(args, fmt);
if (seq) {
seq_vprintf(seq, fmt, args);
} else {
vaf.fmt = fmt;
vaf.va = &args;
pr_err("%pV", &vaf);
}
va_end(args);
}
/**
* add_to_queue - Add a holder to the wait queue (but look for recursion)
* @gh: the holder structure to add
*
* Eventually we should move the recursive locking trap to a
* debugging option or something like that. This is the fast
* path and needs to have the minimum number of distractions.
*
*/
static inline void add_to_queue(struct gfs2_holder *gh)
__releases(&gl->gl_spin)
__acquires(&gl->gl_spin)
{
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_sbd *sdp = gl->gl_sbd;
struct list_head *insert_pt = NULL;
struct gfs2_holder *gh2;
int try_futile = 0;
BUG_ON(gh->gh_owner_pid == NULL);
if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
BUG();
if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
if (test_bit(GLF_LOCK, &gl->gl_flags))
try_futile = !may_grant(gl, gh);
if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
goto fail;
}
list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
(gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
goto trap_recursive;
if (try_futile &&
!(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
fail:
gh->gh_error = GLR_TRYFAILED;
gfs2_holder_wake(gh);
return;
}
if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
continue;
if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
insert_pt = &gh2->gh_list;
}
set_bit(GLF_QUEUED, &gl->gl_flags);
trace_gfs2_glock_queue(gh, 1);
gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
if (likely(insert_pt == NULL)) {
list_add_tail(&gh->gh_list, &gl->gl_holders);
if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
goto do_cancel;
return;
}
list_add_tail(&gh->gh_list, insert_pt);
do_cancel:
gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
spin_unlock(&gl->gl_spin);
if (sdp->sd_lockstruct.ls_ops->lm_cancel)
sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
spin_lock(&gl->gl_spin);
}
return;
trap_recursive:
pr_err("original: %pSR\n", (void *)gh2->gh_ip);
pr_err("pid: %d\n", pid_nr(gh2->gh_owner_pid));
pr_err("lock type: %d req lock state : %d\n",
gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
pr_err("new: %pSR\n", (void *)gh->gh_ip);
pr_err("pid: %d\n", pid_nr(gh->gh_owner_pid));
pr_err("lock type: %d req lock state : %d\n",
gh->gh_gl->gl_name.ln_type, gh->gh_state);
gfs2_dump_glock(NULL, gl);
BUG();
}
/**
* gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
* @gh: the holder structure
*
* if (gh->gh_flags & GL_ASYNC), this never returns an error
*
* Returns: 0, GLR_TRYFAILED, or errno on failure
*/
int gfs2_glock_nq(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_sbd *sdp = gl->gl_sbd;
int error = 0;
if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
return -EIO;
if (test_bit(GLF_LRU, &gl->gl_flags))
gfs2_glock_remove_from_lru(gl);
spin_lock(&gl->gl_spin);
add_to_queue(gh);
if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) &&
test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) {
set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
gl->gl_lockref.count++;
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gl->gl_lockref.count--;
}
run_queue(gl, 1);
spin_unlock(&gl->gl_spin);
if (!(gh->gh_flags & GL_ASYNC))
error = gfs2_glock_wait(gh);
return error;
}
/**
* gfs2_glock_poll - poll to see if an async request has been completed
* @gh: the holder
*
* Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
*/
int gfs2_glock_poll(struct gfs2_holder *gh)
{
return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
}
/**
* gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
* @gh: the glock holder
*
*/
void gfs2_glock_dq(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
const struct gfs2_glock_operations *glops = gl->gl_ops;
unsigned delay = 0;
int fast_path = 0;
spin_lock(&gl->gl_spin);
if (gh->gh_flags & GL_NOCACHE)
handle_callback(gl, LM_ST_UNLOCKED, 0, false);
list_del_init(&gh->gh_list);
if (find_first_holder(gl) == NULL) {
if (glops->go_unlock) {
GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
spin_unlock(&gl->gl_spin);
glops->go_unlock(gh);
spin_lock(&gl->gl_spin);
clear_bit(GLF_LOCK, &gl->gl_flags);
}
if (list_empty(&gl->gl_holders) &&
!test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
!test_bit(GLF_DEMOTE, &gl->gl_flags))
fast_path = 1;
}
if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl))
gfs2_glock_add_to_lru(gl);
trace_gfs2_glock_queue(gh, 0);
spin_unlock(&gl->gl_spin);
if (likely(fast_path))
return;
gfs2_glock_hold(gl);
if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
!test_bit(GLF_DEMOTE, &gl->gl_flags) &&
gl->gl_name.ln_type == LM_TYPE_INODE)
delay = gl->gl_hold_time;
if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
gfs2_glock_put(gl);
}
void gfs2_glock_dq_wait(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
gfs2_glock_dq(gh);
might_sleep();
if (!find_first_holder(gl))
wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait,
TASK_UNINTERRUPTIBLE);
}
/**
* gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
* @gh: the holder structure
*
*/
void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
{
gfs2_glock_dq(gh);
gfs2_holder_uninit(gh);
}
/**
* gfs2_glock_nq_num - acquire a glock based on lock number
* @sdp: the filesystem
* @number: the lock number
* @glops: the glock operations for the type of glock
* @state: the state to acquire the glock in
* @flags: modifier flags for the acquisition
* @gh: the struct gfs2_holder
*
* Returns: errno
*/
int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
const struct gfs2_glock_operations *glops,
unsigned int state, int flags, struct gfs2_holder *gh)
{
struct gfs2_glock *gl;
int error;
error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
if (!error) {
error = gfs2_glock_nq_init(gl, state, flags, gh);
gfs2_glock_put(gl);
}
return error;
}
/**
* glock_compare - Compare two struct gfs2_glock structures for sorting
* @arg_a: the first structure
* @arg_b: the second structure
*
*/
static int glock_compare(const void *arg_a, const void *arg_b)
{
const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
if (a->ln_number > b->ln_number)
return 1;
if (a->ln_number < b->ln_number)
return -1;
BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
return 0;
}
/**
* nq_m_sync - synchonously acquire more than one glock in deadlock free order
* @num_gh: the number of structures
* @ghs: an array of struct gfs2_holder structures
*
* Returns: 0 on success (all glocks acquired),
* errno on failure (no glocks acquired)
*/
static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
struct gfs2_holder **p)
{
unsigned int x;
int error = 0;
for (x = 0; x < num_gh; x++)
p[x] = &ghs[x];
sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
for (x = 0; x < num_gh; x++) {
p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
error = gfs2_glock_nq(p[x]);
if (error) {
while (x--)
gfs2_glock_dq(p[x]);
break;
}
}
return error;
}
/**
* gfs2_glock_nq_m - acquire multiple glocks
* @num_gh: the number of structures
* @ghs: an array of struct gfs2_holder structures
*
*
* Returns: 0 on success (all glocks acquired),
* errno on failure (no glocks acquired)
*/
int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
{
struct gfs2_holder *tmp[4];
struct gfs2_holder **pph = tmp;
int error = 0;
switch(num_gh) {
case 0:
return 0;
case 1:
ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
return gfs2_glock_nq(ghs);
default:
if (num_gh <= 4)
break;
pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
if (!pph)
return -ENOMEM;
}
error = nq_m_sync(num_gh, ghs, pph);
if (pph != tmp)
kfree(pph);
return error;
}
/**
* gfs2_glock_dq_m - release multiple glocks
* @num_gh: the number of structures
* @ghs: an array of struct gfs2_holder structures
*
*/
void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
{
while (num_gh--)
gfs2_glock_dq(&ghs[num_gh]);
}
void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
{
unsigned long delay = 0;
unsigned long holdtime;
unsigned long now = jiffies;
gfs2_glock_hold(gl);
holdtime = gl->gl_tchange + gl->gl_hold_time;
if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
gl->gl_name.ln_type == LM_TYPE_INODE) {
if (time_before(now, holdtime))
delay = holdtime - now;
if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
delay = gl->gl_hold_time;
}
spin_lock(&gl->gl_spin);
handle_callback(gl, state, delay, true);
spin_unlock(&gl->gl_spin);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
gfs2_glock_put(gl);
}
/**
* gfs2_should_freeze - Figure out if glock should be frozen
* @gl: The glock in question
*
* Glocks are not frozen if (a) the result of the dlm operation is
* an error, (b) the locking operation was an unlock operation or
* (c) if there is a "noexp" flagged request anywhere in the queue
*
* Returns: 1 if freezing should occur, 0 otherwise
*/
static int gfs2_should_freeze(const struct gfs2_glock *gl)
{
const struct gfs2_holder *gh;
if (gl->gl_reply & ~LM_OUT_ST_MASK)
return 0;
if (gl->gl_target == LM_ST_UNLOCKED)
return 0;
list_for_each_entry(gh, &gl->gl_holders, gh_list) {
if (test_bit(HIF_HOLDER, &gh->gh_iflags))
continue;
if (LM_FLAG_NOEXP & gh->gh_flags)
return 0;
}
return 1;
}
/**
* gfs2_glock_complete - Callback used by locking
* @gl: Pointer to the glock
* @ret: The return value from the dlm
*
* The gl_reply field is under the gl_spin lock so that it is ok
* to use a bitfield shared with other glock state fields.
*/
void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
{
struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
spin_lock(&gl->gl_spin);
gl->gl_reply = ret;
if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
if (gfs2_should_freeze(gl)) {
set_bit(GLF_FROZEN, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
return;
}
}
gl->gl_lockref.count++;
set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put(gl);
}
static int glock_cmp(void *priv, struct list_head *a, struct list_head *b)
{
struct gfs2_glock *gla, *glb;
gla = list_entry(a, struct gfs2_glock, gl_lru);
glb = list_entry(b, struct gfs2_glock, gl_lru);
if (gla->gl_name.ln_number > glb->gl_name.ln_number)
return 1;
if (gla->gl_name.ln_number < glb->gl_name.ln_number)
return -1;
return 0;
}
/**
* gfs2_dispose_glock_lru - Demote a list of glocks
* @list: The list to dispose of
*
* Disposing of glocks may involve disk accesses, so that here we sort
* the glocks by number (i.e. disk location of the inodes) so that if
* there are any such accesses, they'll be sent in order (mostly).
*
* Must be called under the lru_lock, but may drop and retake this
* lock. While the lru_lock is dropped, entries may vanish from the
* list, but no new entries will appear on the list (since it is
* private)
*/
static void gfs2_dispose_glock_lru(struct list_head *list)
__releases(&lru_lock)
__acquires(&lru_lock)
{
struct gfs2_glock *gl;
list_sort(NULL, list, glock_cmp);
while(!list_empty(list)) {
gl = list_entry(list->next, struct gfs2_glock, gl_lru);
list_del_init(&gl->gl_lru);
if (!spin_trylock(&gl->gl_spin)) {
list_add(&gl->gl_lru, &lru_list);
atomic_inc(&lru_count);
continue;
}
clear_bit(GLF_LRU, &gl->gl_flags);
spin_unlock(&lru_lock);
gl->gl_lockref.count++;
if (demote_ok(gl))
handle_callback(gl, LM_ST_UNLOCKED, 0, false);
WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags));
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gl->gl_lockref.count--;
spin_unlock(&gl->gl_spin);
spin_lock(&lru_lock);
}
}
/**
* gfs2_scan_glock_lru - Scan the LRU looking for locks to demote
* @nr: The number of entries to scan
*
* This function selects the entries on the LRU which are able to
* be demoted, and then kicks off the process by calling
* gfs2_dispose_glock_lru() above.
*/
static long gfs2_scan_glock_lru(int nr)
{
struct gfs2_glock *gl;
LIST_HEAD(skipped);
LIST_HEAD(dispose);
long freed = 0;
spin_lock(&lru_lock);
while ((nr-- >= 0) && !list_empty(&lru_list)) {
gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
/* Test for being demotable */
if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
list_move(&gl->gl_lru, &dispose);
atomic_dec(&lru_count);
freed++;
continue;
}
list_move(&gl->gl_lru, &skipped);
}
list_splice(&skipped, &lru_list);
if (!list_empty(&dispose))
gfs2_dispose_glock_lru(&dispose);
spin_unlock(&lru_lock);
return freed;
}
static unsigned long gfs2_glock_shrink_scan(struct shrinker *shrink,
struct shrink_control *sc)
{
if (!(sc->gfp_mask & __GFP_FS))
return SHRINK_STOP;
return gfs2_scan_glock_lru(sc->nr_to_scan);
}
static unsigned long gfs2_glock_shrink_count(struct shrinker *shrink,
struct shrink_control *sc)
{
return vfs_pressure_ratio(atomic_read(&lru_count));
}
static struct shrinker glock_shrinker = {
.seeks = DEFAULT_SEEKS,
.count_objects = gfs2_glock_shrink_count,
.scan_objects = gfs2_glock_shrink_scan,
};
/**
* examine_bucket - Call a function for glock in a hash bucket
* @examiner: the function
* @sdp: the filesystem
* @bucket: the bucket
*
*/
static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
unsigned int hash)
{
struct gfs2_glock *gl;
struct hlist_bl_head *head = &gl_hash_table[hash];
struct hlist_bl_node *pos;
rcu_read_lock();
hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
if ((gl->gl_sbd == sdp) && lockref_get_not_dead(&gl->gl_lockref))
examiner(gl);
}
rcu_read_unlock();
cond_resched();
}
static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
{
unsigned x;
for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
examine_bucket(examiner, sdp, x);
}
/**
* thaw_glock - thaw out a glock which has an unprocessed reply waiting
* @gl: The glock to thaw
*
*/
static void thaw_glock(struct gfs2_glock *gl)
{
if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
goto out;
set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0) {
out:
gfs2_glock_put(gl);
}
}
/**
* clear_glock - look at a glock and see if we can free it from glock cache
* @gl: the glock to look at
*
*/
static void clear_glock(struct gfs2_glock *gl)
{
gfs2_glock_remove_from_lru(gl);
spin_lock(&gl->gl_spin);
if (gl->gl_state != LM_ST_UNLOCKED)
handle_callback(gl, LM_ST_UNLOCKED, 0, false);
spin_unlock(&gl->gl_spin);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put(gl);
}
/**
* gfs2_glock_thaw - Thaw any frozen glocks
* @sdp: The super block
*
*/
void gfs2_glock_thaw(struct gfs2_sbd *sdp)
{
glock_hash_walk(thaw_glock, sdp);
}
static void dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
{
spin_lock(&gl->gl_spin);
gfs2_dump_glock(seq, gl);
spin_unlock(&gl->gl_spin);
}
static void dump_glock_func(struct gfs2_glock *gl)
{
dump_glock(NULL, gl);
}
/**
* gfs2_gl_hash_clear - Empty out the glock hash table
* @sdp: the filesystem
* @wait: wait until it's all gone
*
* Called when unmounting the filesystem.
*/
void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
{
set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
flush_workqueue(glock_workqueue);
glock_hash_walk(clear_glock, sdp);
flush_workqueue(glock_workqueue);
wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
glock_hash_walk(dump_glock_func, sdp);
}
void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
{
struct gfs2_glock *gl = ip->i_gl;
int ret;
ret = gfs2_truncatei_resume(ip);
gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
spin_lock(&gl->gl_spin);
clear_bit(GLF_LOCK, &gl->gl_flags);
run_queue(gl, 1);
spin_unlock(&gl->gl_spin);
}
static const char *state2str(unsigned state)
{
switch(state) {
case LM_ST_UNLOCKED:
return "UN";
case LM_ST_SHARED:
return "SH";
case LM_ST_DEFERRED:
return "DF";
case LM_ST_EXCLUSIVE:
return "EX";
}
return "??";
}
static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
{
char *p = buf;
if (flags & LM_FLAG_TRY)
*p++ = 't';
if (flags & LM_FLAG_TRY_1CB)
*p++ = 'T';
if (flags & LM_FLAG_NOEXP)
*p++ = 'e';
if (flags & LM_FLAG_ANY)
*p++ = 'A';
if (flags & LM_FLAG_PRIORITY)
*p++ = 'p';
if (flags & GL_ASYNC)
*p++ = 'a';
if (flags & GL_EXACT)
*p++ = 'E';
if (flags & GL_NOCACHE)
*p++ = 'c';
if (test_bit(HIF_HOLDER, &iflags))
*p++ = 'H';
if (test_bit(HIF_WAIT, &iflags))
*p++ = 'W';
if (test_bit(HIF_FIRST, &iflags))
*p++ = 'F';
*p = 0;
return buf;
}
/**
* dump_holder - print information about a glock holder
* @seq: the seq_file struct
* @gh: the glock holder
*
*/
static void dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
{
struct task_struct *gh_owner = NULL;
char flags_buf[32];
rcu_read_lock();
if (gh->gh_owner_pid)
gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
state2str(gh->gh_state),
hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
gh->gh_error,
gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
gh_owner ? gh_owner->comm : "(ended)",
(void *)gh->gh_ip);
rcu_read_unlock();
}
static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
{
const unsigned long *gflags = &gl->gl_flags;
char *p = buf;
if (test_bit(GLF_LOCK, gflags))
*p++ = 'l';
if (test_bit(GLF_DEMOTE, gflags))
*p++ = 'D';
if (test_bit(GLF_PENDING_DEMOTE, gflags))
*p++ = 'd';
if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
*p++ = 'p';
if (test_bit(GLF_DIRTY, gflags))
*p++ = 'y';
if (test_bit(GLF_LFLUSH, gflags))
*p++ = 'f';
if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
*p++ = 'i';
if (test_bit(GLF_REPLY_PENDING, gflags))
*p++ = 'r';
if (test_bit(GLF_INITIAL, gflags))
*p++ = 'I';
if (test_bit(GLF_FROZEN, gflags))
*p++ = 'F';
if (test_bit(GLF_QUEUED, gflags))
*p++ = 'q';
if (test_bit(GLF_LRU, gflags))
*p++ = 'L';
if (gl->gl_object)
*p++ = 'o';
if (test_bit(GLF_BLOCKING, gflags))
*p++ = 'b';
*p = 0;
return buf;
}
/**
* gfs2_dump_glock - print information about a glock
* @seq: The seq_file struct
* @gl: the glock
*
* The file format is as follows:
* One line per object, capital letters are used to indicate objects
* G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
* other objects are indented by a single space and follow the glock to
* which they are related. Fields are indicated by lower case letters
* followed by a colon and the field value, except for strings which are in
* [] so that its possible to see if they are composed of spaces for
* example. The field's are n = number (id of the object), f = flags,
* t = type, s = state, r = refcount, e = error, p = pid.
*
*/
void gfs2_dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
unsigned long long dtime;
const struct gfs2_holder *gh;
char gflags_buf[32];
dtime = jiffies - gl->gl_demote_time;
dtime *= 1000000/HZ; /* demote time in uSec */
if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
dtime = 0;
gfs2_print_dbg(seq, "G: s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d m:%ld\n",
state2str(gl->gl_state),
gl->gl_name.ln_type,
(unsigned long long)gl->gl_name.ln_number,
gflags2str(gflags_buf, gl),
state2str(gl->gl_target),
state2str(gl->gl_demote_state), dtime,
atomic_read(&gl->gl_ail_count),
atomic_read(&gl->gl_revokes),
(int)gl->gl_lockref.count, gl->gl_hold_time);
list_for_each_entry(gh, &gl->gl_holders, gh_list)
dump_holder(seq, gh);
if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
glops->go_dump(seq, gl);
}
static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
{
struct gfs2_glock *gl = iter_ptr;
seq_printf(seq, "G: n:%u/%llx rtt:%lld/%lld rttb:%lld/%lld irt:%lld/%lld dcnt: %lld qcnt: %lld\n",
gl->gl_name.ln_type,
(unsigned long long)gl->gl_name.ln_number,
(long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
(long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
(long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
(long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
(long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
(long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
(long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
(long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
return 0;
}
static const char *gfs2_gltype[] = {
"type",
"reserved",
"nondisk",
"inode",
"rgrp",
"meta",
"iopen",
"flock",
"plock",
"quota",
"journal",
};
static const char *gfs2_stype[] = {
[GFS2_LKS_SRTT] = "srtt",
[GFS2_LKS_SRTTVAR] = "srttvar",
[GFS2_LKS_SRTTB] = "srttb",
[GFS2_LKS_SRTTVARB] = "srttvarb",
[GFS2_LKS_SIRT] = "sirt",
[GFS2_LKS_SIRTVAR] = "sirtvar",
[GFS2_LKS_DCOUNT] = "dlm",
[GFS2_LKS_QCOUNT] = "queue",
};
#define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
{
struct gfs2_glock_iter *gi = seq->private;
struct gfs2_sbd *sdp = gi->sdp;
unsigned index = gi->hash >> 3;
unsigned subindex = gi->hash & 0x07;
s64 value;
int i;
if (index == 0 && subindex != 0)
return 0;
seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
(index == 0) ? "cpu": gfs2_stype[subindex]);
for_each_possible_cpu(i) {
const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
if (index == 0) {
value = i;
} else {
value = lkstats->lkstats[index - 1].stats[subindex];
}
seq_printf(seq, " %15lld", (long long)value);
}
seq_putc(seq, '\n');
return 0;
}
int __init gfs2_glock_init(void)
{
unsigned i;
for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
}
glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
WQ_HIGHPRI | WQ_FREEZABLE, 0);
if (!glock_workqueue)
return -ENOMEM;
gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
WQ_MEM_RECLAIM | WQ_FREEZABLE,
0);
if (!gfs2_delete_workqueue) {
destroy_workqueue(glock_workqueue);
return -ENOMEM;
}
register_shrinker(&glock_shrinker);
return 0;
}
void gfs2_glock_exit(void)
{
unregister_shrinker(&glock_shrinker);
destroy_workqueue(glock_workqueue);
destroy_workqueue(gfs2_delete_workqueue);
}
static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
{
return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
struct gfs2_glock, gl_list);
}
static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
{
return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
struct gfs2_glock, gl_list);
}
static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
{
struct gfs2_glock *gl;
do {
gl = gi->gl;
if (gl) {
gi->gl = glock_hash_next(gl);
gi->nhash++;
} else {
if (gi->hash >= GFS2_GL_HASH_SIZE) {
rcu_read_unlock();
return 1;
}
gi->gl = glock_hash_chain(gi->hash);
gi->nhash = 0;
}
while (gi->gl == NULL) {
gi->hash++;
if (gi->hash >= GFS2_GL_HASH_SIZE) {
rcu_read_unlock();
return 1;
}
gi->gl = glock_hash_chain(gi->hash);
gi->nhash = 0;
}
/* Skip entries for other sb and dead entries */
} while (gi->sdp != gi->gl->gl_sbd ||
__lockref_is_dead(&gi->gl->gl_lockref));
return 0;
}
static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
{
struct gfs2_glock_iter *gi = seq->private;
loff_t n = *pos;
if (gi->last_pos <= *pos)
n = gi->nhash + (*pos - gi->last_pos);
else
gi->hash = 0;
gi->nhash = 0;
rcu_read_lock();
do {
if (gfs2_glock_iter_next(gi))
return NULL;
} while (n--);
gi->last_pos = *pos;
return gi->gl;
}
static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
loff_t *pos)
{
struct gfs2_glock_iter *gi = seq->private;
(*pos)++;
gi->last_pos = *pos;
if (gfs2_glock_iter_next(gi))
return NULL;
return gi->gl;
}
static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
{
struct gfs2_glock_iter *gi = seq->private;
if (gi->gl)
rcu_read_unlock();
gi->gl = NULL;
}
static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
{
dump_glock(seq, iter_ptr);
return 0;
}
static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
{
struct gfs2_glock_iter *gi = seq->private;
gi->hash = *pos;
if (*pos >= GFS2_NR_SBSTATS)
return NULL;
preempt_disable();
return SEQ_START_TOKEN;
}
static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
loff_t *pos)
{
struct gfs2_glock_iter *gi = seq->private;
(*pos)++;
gi->hash++;
if (gi->hash >= GFS2_NR_SBSTATS) {
preempt_enable();
return NULL;
}
return SEQ_START_TOKEN;
}
static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
{
preempt_enable();
}
static const struct seq_operations gfs2_glock_seq_ops = {
.start = gfs2_glock_seq_start,
.next = gfs2_glock_seq_next,
.stop = gfs2_glock_seq_stop,
.show = gfs2_glock_seq_show,
};
static const struct seq_operations gfs2_glstats_seq_ops = {
.start = gfs2_glock_seq_start,
.next = gfs2_glock_seq_next,
.stop = gfs2_glock_seq_stop,
.show = gfs2_glstats_seq_show,
};
static const struct seq_operations gfs2_sbstats_seq_ops = {
.start = gfs2_sbstats_seq_start,
.next = gfs2_sbstats_seq_next,
.stop = gfs2_sbstats_seq_stop,
.show = gfs2_sbstats_seq_show,
};
#define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
static int gfs2_glocks_open(struct inode *inode, struct file *file)
{
int ret = seq_open_private(file, &gfs2_glock_seq_ops,
sizeof(struct gfs2_glock_iter));
if (ret == 0) {
struct seq_file *seq = file->private_data;
struct gfs2_glock_iter *gi = seq->private;
gi->sdp = inode->i_private;
seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
if (seq->buf)
seq->size = GFS2_SEQ_GOODSIZE;
}
return ret;
}
static int gfs2_glstats_open(struct inode *inode, struct file *file)
{
int ret = seq_open_private(file, &gfs2_glstats_seq_ops,
sizeof(struct gfs2_glock_iter));
if (ret == 0) {
struct seq_file *seq = file->private_data;
struct gfs2_glock_iter *gi = seq->private;
gi->sdp = inode->i_private;
seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
if (seq->buf)
seq->size = GFS2_SEQ_GOODSIZE;
}
return ret;
}
static int gfs2_sbstats_open(struct inode *inode, struct file *file)
{
int ret = seq_open_private(file, &gfs2_sbstats_seq_ops,
sizeof(struct gfs2_glock_iter));
if (ret == 0) {
struct seq_file *seq = file->private_data;
struct gfs2_glock_iter *gi = seq->private;
gi->sdp = inode->i_private;
}
return ret;
}
static const struct file_operations gfs2_glocks_fops = {
.owner = THIS_MODULE,
.open = gfs2_glocks_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release_private,
};
static const struct file_operations gfs2_glstats_fops = {
.owner = THIS_MODULE,
.open = gfs2_glstats_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release_private,
};
static const struct file_operations gfs2_sbstats_fops = {
.owner = THIS_MODULE,
.open = gfs2_sbstats_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release_private,
};
int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
{
sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
if (!sdp->debugfs_dir)
return -ENOMEM;
sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
S_IFREG | S_IRUGO,
sdp->debugfs_dir, sdp,
&gfs2_glocks_fops);
if (!sdp->debugfs_dentry_glocks)
goto fail;
sdp->debugfs_dentry_glstats = debugfs_create_file("glstats",
S_IFREG | S_IRUGO,
sdp->debugfs_dir, sdp,
&gfs2_glstats_fops);
if (!sdp->debugfs_dentry_glstats)
goto fail;
sdp->debugfs_dentry_sbstats = debugfs_create_file("sbstats",
S_IFREG | S_IRUGO,
sdp->debugfs_dir, sdp,
&gfs2_sbstats_fops);
if (!sdp->debugfs_dentry_sbstats)
goto fail;
return 0;
fail:
gfs2_delete_debugfs_file(sdp);
return -ENOMEM;
}
void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
{
if (sdp->debugfs_dir) {
if (sdp->debugfs_dentry_glocks) {
debugfs_remove(sdp->debugfs_dentry_glocks);
sdp->debugfs_dentry_glocks = NULL;
}
if (sdp->debugfs_dentry_glstats) {
debugfs_remove(sdp->debugfs_dentry_glstats);
sdp->debugfs_dentry_glstats = NULL;
}
if (sdp->debugfs_dentry_sbstats) {
debugfs_remove(sdp->debugfs_dentry_sbstats);
sdp->debugfs_dentry_sbstats = NULL;
}
debugfs_remove(sdp->debugfs_dir);
sdp->debugfs_dir = NULL;
}
}
int gfs2_register_debugfs(void)
{
gfs2_root = debugfs_create_dir("gfs2", NULL);
return gfs2_root ? 0 : -ENOMEM;
}
void gfs2_unregister_debugfs(void)
{
debugfs_remove(gfs2_root);
gfs2_root = NULL;
}
Reference in New Issue View Git Blame Copy Permalink