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linux/fs/gfs2/glock.c
Steven Whitehouse 47a25380e3 GFS2: Merge glock state fields into a bitfield 
We can only merge the fields into a bitfield if the locking
rules for them are the same. In this case gl_spin covers all
of the fields (write side) but a couple of them are used
with GLF_LOCK as the read side lock, which should be ok
since we know that the field in question won't be changing
at the time.

The gl_req setting has to be done earlier (in glock.c) in order
to place it under gl_spin. The gl_reply setting also has to be
brought under gl_spin in order to comply with the new rules.

This saves 4*sizeof(unsigned int) per glock.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Bob Peterson <rpeterso@redhat.com>
2010-11-30 15:49:31 +00:00

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/*
* 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.
*/
#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 "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_gl_hash_bucket {
struct hlist_head hb_list;
};
struct gfs2_glock_iter {
int hash; /* hash bucket index */
struct gfs2_sbd *sdp; /* incore superblock */
struct gfs2_glock *gl; /* current glock struct */
char string[512]; /* scratch space */
};
typedef void (*glock_examiner) (struct gfs2_glock * gl);
static int gfs2_dump_lockstate(struct gfs2_sbd *sdp);
static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl);
#define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { __dump_glock(NULL, gl); BUG(); } } while(0)
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 gfs2_gl_hash_bucket gl_hash_table[GFS2_GL_HASH_SIZE];
static struct dentry *gfs2_root;
/*
* Despite what you might think, the numbers below are not arbitrary :-)
* They are taken from the ipv4 routing hash code, which is well tested
* and thus should be nearly optimal. Later on we might tweek the numbers
* but for now this should be fine.
*
* The reason for putting the locks in a separate array from the list heads
* is that we can have fewer locks than list heads and save memory. We use
* the same hash function for both, but with a different hash mask.
*/
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
defined(CONFIG_PROVE_LOCKING)
#ifdef CONFIG_LOCKDEP
# define GL_HASH_LOCK_SZ 256
#else
# if NR_CPUS >= 32
# define GL_HASH_LOCK_SZ 4096
# elif NR_CPUS >= 16
# define GL_HASH_LOCK_SZ 2048
# elif NR_CPUS >= 8
# define GL_HASH_LOCK_SZ 1024
# elif NR_CPUS >= 4
# define GL_HASH_LOCK_SZ 512
# else
# define GL_HASH_LOCK_SZ 256
# endif
#endif
/* We never want more locks than chains */
#if GFS2_GL_HASH_SIZE < GL_HASH_LOCK_SZ
# undef GL_HASH_LOCK_SZ
# define GL_HASH_LOCK_SZ GFS2_GL_HASH_SIZE
#endif
static rwlock_t gl_hash_locks[GL_HASH_LOCK_SZ];
static inline rwlock_t *gl_lock_addr(unsigned int x)
{
return &gl_hash_locks[x & (GL_HASH_LOCK_SZ-1)];
}
#else /* not SMP, so no spinlocks required */
static inline rwlock_t *gl_lock_addr(unsigned int x)
{
return NULL;
}
#endif
/**
* 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;
}
/**
* glock_free() - Perform a few checks and then release struct gfs2_glock
* @gl: The glock to release
*
* Also calls lock module to release its internal structure for this glock.
*
*/
static void glock_free(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
struct address_space *mapping = gfs2_glock2aspace(gl);
struct kmem_cache *cachep = gfs2_glock_cachep;
GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
trace_gfs2_glock_put(gl);
if (mapping)
cachep = gfs2_glock_aspace_cachep;
sdp->sd_lockstruct.ls_ops->lm_put_lock(cachep, gl);
}
/**
* gfs2_glock_hold() - increment reference count on glock
* @gl: The glock to hold
*
*/
void gfs2_glock_hold(struct gfs2_glock *gl)
{
GLOCK_BUG_ON(gl, atomic_read(&gl->gl_ref) == 0);
atomic_inc(&gl->gl_ref);
}
/**
* 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;
}
/**
* gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
* @gl: the glock
*
*/
static void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
{
int may_reclaim;
may_reclaim = (demote_ok(gl) &&
(atomic_read(&gl->gl_ref) == 1 ||
(gl->gl_name.ln_type == LM_TYPE_INODE &&
atomic_read(&gl->gl_ref) <= 2)));
spin_lock(&lru_lock);
if (list_empty(&gl->gl_lru) && may_reclaim) {
list_add_tail(&gl->gl_lru, &lru_list);
atomic_inc(&lru_count);
}
spin_unlock(&lru_lock);
}
/**
* gfs2_glock_put_nolock() - Decrement reference count on glock
* @gl: The glock to put
*
* This function should only be used if the caller has its own reference
* to the glock, in addition to the one it is dropping.
*/
void gfs2_glock_put_nolock(struct gfs2_glock *gl)
{
if (atomic_dec_and_test(&gl->gl_ref))
GLOCK_BUG_ON(gl, 1);
gfs2_glock_schedule_for_reclaim(gl);
}
/**
* gfs2_glock_put() - Decrement reference count on glock
* @gl: The glock to put
*
*/
int gfs2_glock_put(struct gfs2_glock *gl)
{
int rv = 0;
write_lock(gl_lock_addr(gl->gl_hash));
if (atomic_dec_and_lock(&gl->gl_ref, &lru_lock)) {
hlist_del(&gl->gl_list);
if (!list_empty(&gl->gl_lru)) {
list_del_init(&gl->gl_lru);
atomic_dec(&lru_count);
}
spin_unlock(&lru_lock);
write_unlock(gl_lock_addr(gl->gl_hash));
GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
glock_free(gl);
rv = 1;
goto out;
}
spin_lock(&gl->gl_spin);
gfs2_glock_schedule_for_reclaim(gl);
spin_unlock(&gl->gl_spin);
write_unlock(gl_lock_addr(gl->gl_hash));
out:
return rv;
}
/**
* 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_node *h;
hlist_for_each_entry(gl, h, &gl_hash_table[hash].hb_list, gl_list) {
if (!lm_name_equal(&gl->gl_name, name))
continue;
if (gl->gl_sbd != sdp)
continue;
atomic_inc(&gl->gl_ref);
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_clear_bit();
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) {
if (held2)
gfs2_glock_hold(gl);
else
gfs2_glock_put_nolock(gl);
}
if (held1 && held2 && list_empty(&gl->gl_holders))
clear_bit(GLF_QUEUED, &gl->gl_flags);
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_clear_bit();
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 */
printk(KERN_ERR "GFS2: 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;
spin_unlock(&gl->gl_spin);
if (glops->go_xmote_th)
glops->go_xmote_th(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 (target != LM_ST_UNLOCKED && (gl->gl_state == LM_ST_SHARED ||
gl->gl_state == LM_ST_DEFERRED) &&
!(lck_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
lck_flags |= LM_FLAG_TRY_1CB;
if (sdp->sd_lockstruct.ls_ops->lm_lock) {
/* lock_dlm */
ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
GLOCK_BUG_ON(gl, ret);
} 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_clear_bit();
gfs2_glock_hold(gl);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put_nolock(gl);
return;
out_unlock:
clear_bit(GLF_LOCK, &gl->gl_flags);
smp_mb__after_clear_bit();
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);
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_and_clear_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_ops->go_min_hold_time;
if (time_before(now, holdtime))
delay = holdtime - now;
set_bit(delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE, &gl->gl_flags);
}
run_queue(gl, 0);
spin_unlock(&gl->gl_spin);
if (!delay ||
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;
read_lock(gl_lock_addr(hash));
gl = search_bucket(hash, sdp, &name);
read_unlock(gl_lock_addr(hash));
*glp = gl;
if (gl)
return 0;
if (!create)
return -ENOENT;
if (glops->go_flags & GLOF_ASPACE)
gl = kmem_cache_alloc(gfs2_glock_aspace_cachep, GFP_KERNEL);
else
gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
if (!gl)
return -ENOMEM;
atomic_inc(&sdp->sd_glock_disposal);
gl->gl_flags = 0;
gl->gl_name = name;
atomic_set(&gl->gl_ref, 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;
snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
gl->gl_tchange = jiffies;
gl->gl_object = NULL;
gl->gl_sbd = sdp;
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->assoc_mapping = NULL;
mapping->backing_dev_info = s->s_bdi;
mapping->writeback_index = 0;
}
write_lock(gl_lock_addr(hash));
tmp = search_bucket(hash, sdp, &name);
if (tmp) {
write_unlock(gl_lock_addr(hash));
glock_free(gl);
gl = tmp;
} else {
hlist_add_head(&gl->gl_list, &gl_hash_table[hash].hb_list);
write_unlock(gl_lock_addr(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;
}
static void wait_on_holder(struct gfs2_holder *gh)
{
might_sleep();
wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
}
static void wait_on_demote(struct gfs2_glock *gl)
{
might_sleep();
wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
}
/**
* 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)
{
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);
trace_gfs2_demote_rq(gl);
}
/**
* gfs2_glock_wait - wait on a glock acquisition
* @gh: the glock holder
*
* Returns: 0 on success
*/
int gfs2_glock_wait(struct gfs2_holder *gh)
{
wait_on_holder(gh);
return gh->gh_error;
}
void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
{
struct va_format vaf;
va_list args;
va_start(args, fmt);
if (seq) {
struct gfs2_glock_iter *gi = seq->private;
vsprintf(gi->string, fmt, args);
seq_printf(seq, gi->string);
} else {
vaf.fmt = fmt;
vaf.va = &args;
printk(KERN_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_lock = 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_lock = 1;
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_lock &&
!(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
!may_grant(gl, gh)) {
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);
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;
}
trace_gfs2_glock_queue(gh, 1);
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:
print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
printk(KERN_ERR "lock type: %d req lock state : %d\n",
gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
printk(KERN_ERR "lock type: %d req lock state : %d\n",
gh->gh_gl->gl_name.ln_type, gh->gh_state);
__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;
spin_lock(&gl->gl_spin);
add_to_queue(gh);
if ((LM_FLAG_NOEXP & gh->gh_flags) &&
test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
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);
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;
}
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))
delay = gl->gl_ops->go_min_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);
wait_on_demote(gl);
}
/**
* 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 aquisition
* @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)
{
unsigned int x;
for (x = 0; x < num_gh; x++)
gfs2_glock_dq(&ghs[x]);
}
/**
* gfs2_glock_dq_uninit_m - release multiple glocks
* @num_gh: the number of structures
* @ghs: an array of struct gfs2_holder structures
*
*/
void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
{
unsigned int x;
for (x = 0; x < num_gh; x++)
gfs2_glock_dq_uninit(&ghs[x]);
}
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_ops->go_min_hold_time;
if (test_bit(GLF_QUEUED, &gl->gl_flags)) {
if (time_before(now, holdtime))
delay = holdtime - now;
if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
delay = gl->gl_ops->go_min_hold_time;
}
spin_lock(&gl->gl_spin);
handle_callback(gl, state, delay);
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_flags))) {
if (gfs2_should_freeze(gl)) {
set_bit(GLF_FROZEN, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
return;
}
}
spin_unlock(&gl->gl_spin);
set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
smp_wmb();
gfs2_glock_hold(gl);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put(gl);
}
static int gfs2_shrink_glock_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
{
struct gfs2_glock *gl;
int may_demote;
int nr_skipped = 0;
LIST_HEAD(skipped);
if (nr == 0)
goto out;
if (!(gfp_mask & __GFP_FS))
return -1;
spin_lock(&lru_lock);
while(nr && !list_empty(&lru_list)) {
gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
list_del_init(&gl->gl_lru);
atomic_dec(&lru_count);
/* Test for being demotable */
if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
gfs2_glock_hold(gl);
spin_unlock(&lru_lock);
spin_lock(&gl->gl_spin);
may_demote = demote_ok(gl);
if (may_demote) {
handle_callback(gl, LM_ST_UNLOCKED, 0);
nr--;
}
clear_bit(GLF_LOCK, &gl->gl_flags);
smp_mb__after_clear_bit();
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put_nolock(gl);
spin_unlock(&gl->gl_spin);
spin_lock(&lru_lock);
continue;
}
nr_skipped++;
list_add(&gl->gl_lru, &skipped);
}
list_splice(&skipped, &lru_list);
atomic_add(nr_skipped, &lru_count);
spin_unlock(&lru_lock);
out:
return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
}
static struct shrinker glock_shrinker = {
.shrink = gfs2_shrink_glock_memory,
.seeks = DEFAULT_SEEKS,
};
/**
* examine_bucket - Call a function for glock in a hash bucket
* @examiner: the function
* @sdp: the filesystem
* @bucket: the bucket
*
* Returns: 1 if the bucket has entries
*/
static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
unsigned int hash)
{
struct gfs2_glock *gl, *prev = NULL;
int has_entries = 0;
struct hlist_head *head = &gl_hash_table[hash].hb_list;
read_lock(gl_lock_addr(hash));
/* Can't use hlist_for_each_entry - don't want prefetch here */
if (hlist_empty(head))
goto out;
gl = list_entry(head->first, struct gfs2_glock, gl_list);
while(1) {
if (!sdp || gl->gl_sbd == sdp) {
gfs2_glock_hold(gl);
read_unlock(gl_lock_addr(hash));
if (prev)
gfs2_glock_put(prev);
prev = gl;
examiner(gl);
has_entries = 1;
read_lock(gl_lock_addr(hash));
}
if (gl->gl_list.next == NULL)
break;
gl = list_entry(gl->gl_list.next, struct gfs2_glock, gl_list);
}
out:
read_unlock(gl_lock_addr(hash));
if (prev)
gfs2_glock_put(prev);
cond_resched();
return has_entries;
}
/**
* thaw_glock - thaw out a glock which has an unprocessed reply waiting
* @gl: The glock to thaw
*
* N.B. When we freeze a glock, we leave a ref to the glock outstanding,
* so this has to result in the ref count being dropped by one.
*/
static void thaw_glock(struct gfs2_glock *gl)
{
if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
return;
set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
gfs2_glock_hold(gl);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
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)
{
spin_lock(&lru_lock);
if (!list_empty(&gl->gl_lru)) {
list_del_init(&gl->gl_lru);
atomic_dec(&lru_count);
}
spin_unlock(&lru_lock);
spin_lock(&gl->gl_spin);
if (gl->gl_state != LM_ST_UNLOCKED)
handle_callback(gl, LM_ST_UNLOCKED, 0);
spin_unlock(&gl->gl_spin);
gfs2_glock_hold(gl);
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)
{
unsigned x;
for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
examine_bucket(thaw_glock, sdp, x);
}
/**
* 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)
{
unsigned int x;
for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
examine_bucket(clear_glock, sdp, x);
flush_workqueue(glock_workqueue);
wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
gfs2_dump_lockstate(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
*
* Returns: 0 on success, -ENOBUFS when we run out of space
*/
static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
{
struct task_struct *gh_owner = NULL;
char flags_buf[32];
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);
return 0;
}
static const char *gflags2str(char *buf, const unsigned long *gflags)
{
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';
*p = 0;
return buf;
}
/**
* __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.
*
* Returns: 0 on success, -ENOBUFS when we run out of space
*/
static int __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];
int error = 0;
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 r:%d\n",
state2str(gl->gl_state),
gl->gl_name.ln_type,
(unsigned long long)gl->gl_name.ln_number,
gflags2str(gflags_buf, &gl->gl_flags),
state2str(gl->gl_target),
state2str(gl->gl_demote_state), dtime,
atomic_read(&gl->gl_ail_count),
atomic_read(&gl->gl_ref));
list_for_each_entry(gh, &gl->gl_holders, gh_list) {
error = dump_holder(seq, gh);
if (error)
goto out;
}
if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
error = glops->go_dump(seq, gl);
out:
return error;
}
static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
{
int ret;
spin_lock(&gl->gl_spin);
ret = __dump_glock(seq, gl);
spin_unlock(&gl->gl_spin);
return ret;
}
/**
* gfs2_dump_lockstate - print out the current lockstate
* @sdp: the filesystem
* @ub: the buffer to copy the information into
*
* If @ub is NULL, dump the lockstate to the console.
*
*/
static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
{
struct gfs2_glock *gl;
struct hlist_node *h;
unsigned int x;
int error = 0;
for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
read_lock(gl_lock_addr(x));
hlist_for_each_entry(gl, h, &gl_hash_table[x].hb_list, gl_list) {
if (gl->gl_sbd != sdp)
continue;
error = dump_glock(NULL, gl);
if (error)
break;
}
read_unlock(gl_lock_addr(x));
if (error)
break;
}
return error;
}
int __init gfs2_glock_init(void)
{
unsigned i;
for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
INIT_HLIST_HEAD(&gl_hash_table[i].hb_list);
}
#ifdef GL_HASH_LOCK_SZ
for(i = 0; i < GL_HASH_LOCK_SZ; i++) {
rwlock_init(&gl_hash_locks[i]);
}
#endif
glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
WQ_HIGHPRI | WQ_FREEZEABLE, 0);
if (IS_ERR(glock_workqueue))
return PTR_ERR(glock_workqueue);
gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
WQ_MEM_RECLAIM | WQ_FREEZEABLE,
0);
if (IS_ERR(gfs2_delete_workqueue)) {
destroy_workqueue(glock_workqueue);
return PTR_ERR(gfs2_delete_workqueue);
}
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 int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
{
struct gfs2_glock *gl;
restart:
read_lock(gl_lock_addr(gi->hash));
gl = gi->gl;
if (gl) {
gi->gl = hlist_entry(gl->gl_list.next,
struct gfs2_glock, gl_list);
} else {
gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
struct gfs2_glock, gl_list);
}
if (gi->gl)
gfs2_glock_hold(gi->gl);
read_unlock(gl_lock_addr(gi->hash));
if (gl)
gfs2_glock_put(gl);
while (gi->gl == NULL) {
gi->hash++;
if (gi->hash >= GFS2_GL_HASH_SIZE)
return 1;
read_lock(gl_lock_addr(gi->hash));
gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
struct gfs2_glock, gl_list);
if (gi->gl)
gfs2_glock_hold(gi->gl);
read_unlock(gl_lock_addr(gi->hash));
}
if (gi->sdp != gi->gl->gl_sbd)
goto restart;
return 0;
}
static void gfs2_glock_iter_free(struct gfs2_glock_iter *gi)
{
if (gi->gl)
gfs2_glock_put(gi->gl);
gi->gl = NULL;
}
static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
{
struct gfs2_glock_iter *gi = seq->private;
loff_t n = *pos;
gi->hash = 0;
do {
if (gfs2_glock_iter_next(gi)) {
gfs2_glock_iter_free(gi);
return NULL;
}
} while (n--);
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)++;
if (gfs2_glock_iter_next(gi)) {
gfs2_glock_iter_free(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;
gfs2_glock_iter_free(gi);
}
static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
{
return dump_glock(seq, iter_ptr);
}
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 int gfs2_debugfs_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;
}
return ret;
}
static const struct file_operations gfs2_debug_fops = {
.owner = THIS_MODULE,
.open = gfs2_debugfs_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_debug_fops);
if (!sdp->debugfs_dentry_glocks)
return -ENOMEM;
return 0;
}
void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
{
if (sdp && sdp->debugfs_dir) {
if (sdp->debugfs_dentry_glocks) {
debugfs_remove(sdp->debugfs_dentry_glocks);
sdp->debugfs_dentry_glocks = 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;
}
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