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linux/fs/gfs2/glock.c
Bob Peterson 398bbe6832 [GFS2] Reorganize function gfs2_glmutex_lock 
This patch optimizes the function gfs2_glmutex_lock.
The basic theory is: Why bother initializing a holder, setting up
wait bits and then waiting on them, if you know the glock can be
yours.  So the holder stuff is placed inside the if checking if the
glock is locked.  This one needs careful scrutiny because changing
anything to do with locking should strike terror into one's heart.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25 08:13:52 +00:00

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/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2007 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/completion.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/lm_interface.h>
#include <linux/wait.h>
#include <linux/module.h>
#include <linux/rwsem.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 "lm.h"
#include "lops.h"
#include "meta_io.h"
#include "quota.h"
#include "super.h"
#include "util.h"
struct gfs2_gl_hash_bucket {
struct hlist_head hb_list;
};
struct glock_iter {
int hash; /* hash bucket index */
struct gfs2_sbd *sdp; /* incore superblock */
struct gfs2_glock *gl; /* current glock struct */
struct seq_file *seq; /* sequence file for debugfs */
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 glock_iter *gi, struct gfs2_glock *gl);
static void gfs2_glock_xmote_th(struct gfs2_glock *gl, struct gfs2_holder *gh);
static void gfs2_glock_drop_th(struct gfs2_glock *gl);
static void run_queue(struct gfs2_glock *gl);
static DECLARE_RWSEM(gfs2_umount_flush_sem);
static struct dentry *gfs2_root;
static struct task_struct *scand_process;
static unsigned int scand_secs = 5;
static struct workqueue_struct *glock_workqueue;
#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
/**
* relaxed_state_ok - is a requested lock compatible with the current lock mode?
* @actual: the current state of the lock
* @requested: the lock state that was requested by the caller
* @flags: the modifier flags passed in by the caller
*
* Returns: 1 if the locks are compatible, 0 otherwise
*/
static inline int relaxed_state_ok(unsigned int actual, unsigned requested,
int flags)
{
if (actual == requested)
return 1;
if (flags & GL_EXACT)
return 0;
if (actual == LM_ST_EXCLUSIVE && requested == LM_ST_SHARED)
return 1;
if (actual != LM_ST_UNLOCKED && (flags & LM_FLAG_ANY))
return 1;
return 0;
}
/**
* 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 inode *aspace = gl->gl_aspace;
gfs2_lm_put_lock(sdp, gl->gl_lock);
if (aspace)
gfs2_aspace_put(aspace);
kmem_cache_free(gfs2_glock_cachep, gl);
}
/**
* gfs2_glock_hold() - increment reference count on glock
* @gl: The glock to hold
*
*/
void gfs2_glock_hold(struct gfs2_glock *gl)
{
atomic_inc(&gl->gl_ref);
}
/**
* gfs2_glock_put() - Decrement reference count on glock
* @gl: The glock to put
*
*/
int gfs2_glock_put(struct gfs2_glock *gl)
{
int rv = 0;
struct gfs2_sbd *sdp = gl->gl_sbd;
write_lock(gl_lock_addr(gl->gl_hash));
if (atomic_dec_and_test(&gl->gl_ref)) {
hlist_del(&gl->gl_list);
write_unlock(gl_lock_addr(gl->gl_hash));
gfs2_assert(sdp, gl->gl_state == LM_ST_UNLOCKED);
gfs2_assert(sdp, list_empty(&gl->gl_reclaim));
gfs2_assert(sdp, list_empty(&gl->gl_holders));
gfs2_assert(sdp, list_empty(&gl->gl_waiters1));
gfs2_assert(sdp, list_empty(&gl->gl_waiters3));
glock_free(gl);
rv = 1;
goto out;
}
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;
}
/**
* gfs2_glock_find() - Find glock by lock number
* @sdp: The GFS2 superblock
* @name: The lock name
*
* Returns: NULL, or the struct gfs2_glock with the requested number
*/
static struct gfs2_glock *gfs2_glock_find(const struct gfs2_sbd *sdp,
const struct lm_lockname *name)
{
unsigned int hash = gl_hash(sdp, name);
struct gfs2_glock *gl;
read_lock(gl_lock_addr(hash));
gl = search_bucket(hash, sdp, name);
read_unlock(gl_lock_addr(hash));
return gl;
}
static void glock_work_func(struct work_struct *work)
{
struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
spin_lock(&gl->gl_spin);
if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags))
set_bit(GLF_DEMOTE, &gl->gl_flags);
run_queue(gl);
spin_unlock(&gl->gl_spin);
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 lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
struct gfs2_glock *gl, *tmp;
unsigned int hash = gl_hash(sdp, &name);
int error;
read_lock(gl_lock_addr(hash));
gl = search_bucket(hash, sdp, &name);
read_unlock(gl_lock_addr(hash));
if (gl || !create) {
*glp = gl;
return 0;
}
gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
if (!gl)
return -ENOMEM;
gl->gl_flags = 0;
gl->gl_name = name;
atomic_set(&gl->gl_ref, 1);
gl->gl_state = LM_ST_UNLOCKED;
gl->gl_demote_state = LM_ST_EXCLUSIVE;
gl->gl_hash = hash;
gl->gl_owner_pid = 0;
gl->gl_ip = 0;
gl->gl_ops = glops;
gl->gl_req_gh = NULL;
gl->gl_req_bh = NULL;
gl->gl_vn = 0;
gl->gl_stamp = jiffies;
gl->gl_tchange = jiffies;
gl->gl_object = NULL;
gl->gl_sbd = sdp;
gl->gl_aspace = NULL;
INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
/* If this glock protects actual on-disk data or metadata blocks,
create a VFS inode to manage the pages/buffers holding them. */
if (glops == &gfs2_inode_glops || glops == &gfs2_rgrp_glops) {
gl->gl_aspace = gfs2_aspace_get(sdp);
if (!gl->gl_aspace) {
error = -ENOMEM;
goto fail;
}
}
error = gfs2_lm_get_lock(sdp, &name, &gl->gl_lock);
if (error)
goto fail_aspace;
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;
fail_aspace:
if (gl->gl_aspace)
gfs2_aspace_put(gl->gl_aspace);
fail:
kmem_cache_free(gfs2_glock_cachep, gl);
return error;
}
/**
* 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 = current->pid;
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);
}
/**
* gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
* @gh: the holder structure
*
*/
void gfs2_holder_uninit(struct gfs2_holder *gh)
{
gfs2_glock_put(gh->gh_gl);
gh->gh_gl = NULL;
gh->gh_ip = 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);
}
static int just_schedule(void *word)
{
schedule();
return 0;
}
static void wait_on_holder(struct gfs2_holder *gh)
{
might_sleep();
wait_on_bit(&gh->gh_iflags, HIF_WAIT, just_schedule, TASK_UNINTERRUPTIBLE);
}
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);
}
static void wait_on_demote(struct gfs2_glock *gl)
{
might_sleep();
wait_on_bit(&gl->gl_flags, GLF_DEMOTE, just_schedule, TASK_UNINTERRUPTIBLE);
}
/**
* rq_mutex - process a mutex request in the queue
* @gh: the glock holder
*
* Returns: 1 if the queue is blocked
*/
static int rq_mutex(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
list_del_init(&gh->gh_list);
/* gh->gh_error never examined. */
set_bit(GLF_LOCK, &gl->gl_flags);
clear_bit(HIF_WAIT, &gh->gh_iflags);
smp_mb();
wake_up_bit(&gh->gh_iflags, HIF_WAIT);
return 1;
}
/**
* rq_promote - process a promote request in the queue
* @gh: the glock holder
*
* Acquire a new inter-node lock, or change a lock state to more restrictive.
*
* Returns: 1 if the queue is blocked
*/
static int rq_promote(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
if (!relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
if (list_empty(&gl->gl_holders)) {
gl->gl_req_gh = gh;
set_bit(GLF_LOCK, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
gfs2_glock_xmote_th(gh->gh_gl, gh);
spin_lock(&gl->gl_spin);
}
return 1;
}
if (list_empty(&gl->gl_holders)) {
set_bit(HIF_FIRST, &gh->gh_iflags);
set_bit(GLF_LOCK, &gl->gl_flags);
} else {
struct gfs2_holder *next_gh;
if (gh->gh_state == LM_ST_EXCLUSIVE)
return 1;
next_gh = list_entry(gl->gl_holders.next, struct gfs2_holder,
gh_list);
if (next_gh->gh_state == LM_ST_EXCLUSIVE)
return 1;
}
list_move_tail(&gh->gh_list, &gl->gl_holders);
gh->gh_error = 0;
set_bit(HIF_HOLDER, &gh->gh_iflags);
gfs2_holder_wake(gh);
return 0;
}
/**
* rq_demote - process a demote request in the queue
* @gh: the glock holder
*
* Returns: 1 if the queue is blocked
*/
static int rq_demote(struct gfs2_glock *gl)
{
if (!list_empty(&gl->gl_holders))
return 1;
if (gl->gl_state == gl->gl_demote_state ||
gl->gl_state == LM_ST_UNLOCKED) {
gfs2_demote_wake(gl);
return 0;
}
set_bit(GLF_LOCK, &gl->gl_flags);
set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
if (gl->gl_demote_state == LM_ST_UNLOCKED ||
gl->gl_state != LM_ST_EXCLUSIVE) {
spin_unlock(&gl->gl_spin);
gfs2_glock_drop_th(gl);
} else {
spin_unlock(&gl->gl_spin);
gfs2_glock_xmote_th(gl, NULL);
}
spin_lock(&gl->gl_spin);
clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
return 0;
}
/**
* run_queue - process holder structures on a glock
* @gl: the glock
*
*/
static void run_queue(struct gfs2_glock *gl)
{
struct gfs2_holder *gh;
int blocked = 1;
for (;;) {
if (test_bit(GLF_LOCK, &gl->gl_flags))
break;
if (!list_empty(&gl->gl_waiters1)) {
gh = list_entry(gl->gl_waiters1.next,
struct gfs2_holder, gh_list);
blocked = rq_mutex(gh);
} else if (test_bit(GLF_DEMOTE, &gl->gl_flags)) {
blocked = rq_demote(gl);
if (gl->gl_waiters2 && !blocked) {
set_bit(GLF_DEMOTE, &gl->gl_flags);
gl->gl_demote_state = LM_ST_UNLOCKED;
}
gl->gl_waiters2 = 0;
} else if (!list_empty(&gl->gl_waiters3)) {
gh = list_entry(gl->gl_waiters3.next,
struct gfs2_holder, gh_list);
blocked = rq_promote(gh);
} else
break;
if (blocked)
break;
}
}
/**
* gfs2_glmutex_lock - acquire a local lock on a glock
* @gl: the glock
*
* Gives caller exclusive access to manipulate a glock structure.
*/
static void gfs2_glmutex_lock(struct gfs2_glock *gl)
{
spin_lock(&gl->gl_spin);
if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
struct gfs2_holder gh;
gfs2_holder_init(gl, 0, 0, &gh);
set_bit(HIF_WAIT, &gh.gh_iflags);
list_add_tail(&gh.gh_list, &gl->gl_waiters1);
spin_unlock(&gl->gl_spin);
wait_on_holder(&gh);
gfs2_holder_uninit(&gh);
} else {
gl->gl_owner_pid = current->pid;
gl->gl_ip = (unsigned long)__builtin_return_address(0);
spin_unlock(&gl->gl_spin);
}
}
/**
* gfs2_glmutex_trylock - try to acquire a local lock on a glock
* @gl: the glock
*
* Returns: 1 if the glock is acquired
*/
static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
{
int acquired = 1;
spin_lock(&gl->gl_spin);
if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
acquired = 0;
} else {
gl->gl_owner_pid = current->pid;
gl->gl_ip = (unsigned long)__builtin_return_address(0);
}
spin_unlock(&gl->gl_spin);
return acquired;
}
/**
* gfs2_glmutex_unlock - release a local lock on a glock
* @gl: the glock
*
*/
static void gfs2_glmutex_unlock(struct gfs2_glock *gl)
{
spin_lock(&gl->gl_spin);
clear_bit(GLF_LOCK, &gl->gl_flags);
gl->gl_owner_pid = 0;
gl->gl_ip = 0;
run_queue(gl);
spin_unlock(&gl->gl_spin);
}
/**
* 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,
int remote, unsigned long delay)
{
int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
spin_lock(&gl->gl_spin);
set_bit(bit, &gl->gl_flags);
if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
gl->gl_demote_state = state;
gl->gl_demote_time = jiffies;
if (remote && gl->gl_ops->go_type == LM_TYPE_IOPEN &&
gl->gl_object) {
gfs2_glock_schedule_for_reclaim(gl);
spin_unlock(&gl->gl_spin);
return;
}
} else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
gl->gl_demote_state != state) {
if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
gl->gl_waiters2 = 1;
else
gl->gl_demote_state = LM_ST_UNLOCKED;
}
spin_unlock(&gl->gl_spin);
}
/**
* 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(gl);
}
gl->gl_state = new_state;
gl->gl_tchange = jiffies;
}
/**
* xmote_bh - Called after the lock module is done acquiring a lock
* @gl: The glock in question
* @ret: the int returned from the lock module
*
*/
static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
const struct gfs2_glock_operations *glops = gl->gl_ops;
struct gfs2_holder *gh = gl->gl_req_gh;
int prev_state = gl->gl_state;
int op_done = 1;
gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
gfs2_assert_warn(sdp, !(ret & LM_OUT_ASYNC));
state_change(gl, ret & LM_OUT_ST_MASK);
if (prev_state != LM_ST_UNLOCKED && !(ret & LM_OUT_CACHEABLE)) {
if (glops->go_inval)
glops->go_inval(gl, DIO_METADATA);
} else if (gl->gl_state == LM_ST_DEFERRED) {
/* We might not want to do this here.
Look at moving to the inode glops. */
if (glops->go_inval)
glops->go_inval(gl, 0);
}
/* Deal with each possible exit condition */
if (!gh) {
gl->gl_stamp = jiffies;
if (ret & LM_OUT_CANCELED) {
op_done = 0;
} else {
spin_lock(&gl->gl_spin);
if (gl->gl_state != gl->gl_demote_state) {
gl->gl_req_bh = NULL;
spin_unlock(&gl->gl_spin);
gfs2_glock_drop_th(gl);
gfs2_glock_put(gl);
return;
}
gfs2_demote_wake(gl);
spin_unlock(&gl->gl_spin);
}
} else {
spin_lock(&gl->gl_spin);
list_del_init(&gh->gh_list);
gh->gh_error = -EIO;
if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
goto out;
gh->gh_error = GLR_CANCELED;
if (ret & LM_OUT_CANCELED)
goto out;
if (relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
list_add_tail(&gh->gh_list, &gl->gl_holders);
gh->gh_error = 0;
set_bit(HIF_HOLDER, &gh->gh_iflags);
set_bit(HIF_FIRST, &gh->gh_iflags);
op_done = 0;
goto out;
}
gh->gh_error = GLR_TRYFAILED;
if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
goto out;
gh->gh_error = -EINVAL;
if (gfs2_assert_withdraw(sdp, 0) == -1)
fs_err(sdp, "ret = 0x%.8X\n", ret);
out:
spin_unlock(&gl->gl_spin);
}
if (glops->go_xmote_bh)
glops->go_xmote_bh(gl);
if (op_done) {
spin_lock(&gl->gl_spin);
gl->gl_req_gh = NULL;
gl->gl_req_bh = NULL;
clear_bit(GLF_LOCK, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
}
gfs2_glock_put(gl);
if (gh)
gfs2_holder_wake(gh);
}
/**
* gfs2_glock_xmote_th - Call into the lock module to acquire or change a glock
* @gl: The glock in question
* @state: the requested state
* @flags: modifier flags to the lock call
*
*/
static void gfs2_glock_xmote_th(struct gfs2_glock *gl, struct gfs2_holder *gh)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
int flags = gh ? gh->gh_flags : 0;
unsigned state = gh ? gh->gh_state : gl->gl_demote_state;
const struct gfs2_glock_operations *glops = gl->gl_ops;
int lck_flags = flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB |
LM_FLAG_NOEXP | LM_FLAG_ANY |
LM_FLAG_PRIORITY);
unsigned int lck_ret;
if (glops->go_xmote_th)
glops->go_xmote_th(gl);
gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
gfs2_assert_warn(sdp, state != LM_ST_UNLOCKED);
gfs2_assert_warn(sdp, state != gl->gl_state);
gfs2_glock_hold(gl);
gl->gl_req_bh = xmote_bh;
lck_ret = gfs2_lm_lock(sdp, gl->gl_lock, gl->gl_state, state, lck_flags);
if (gfs2_assert_withdraw(sdp, !(lck_ret & LM_OUT_ERROR)))
return;
if (lck_ret & LM_OUT_ASYNC)
gfs2_assert_warn(sdp, lck_ret == LM_OUT_ASYNC);
else
xmote_bh(gl, lck_ret);
}
/**
* drop_bh - Called after a lock module unlock completes
* @gl: the glock
* @ret: the return status
*
* Doesn't wake up the process waiting on the struct gfs2_holder (if any)
* Doesn't drop the reference on the glock the top half took out
*
*/
static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
const struct gfs2_glock_operations *glops = gl->gl_ops;
struct gfs2_holder *gh = gl->gl_req_gh;
gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
gfs2_assert_warn(sdp, !ret);
state_change(gl, LM_ST_UNLOCKED);
if (glops->go_inval)
glops->go_inval(gl, DIO_METADATA);
if (gh) {
spin_lock(&gl->gl_spin);
list_del_init(&gh->gh_list);
gh->gh_error = 0;
spin_unlock(&gl->gl_spin);
}
spin_lock(&gl->gl_spin);
gfs2_demote_wake(gl);
gl->gl_req_gh = NULL;
gl->gl_req_bh = NULL;
clear_bit(GLF_LOCK, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
gfs2_glock_put(gl);
if (gh)
gfs2_holder_wake(gh);
}
/**
* gfs2_glock_drop_th - call into the lock module to unlock a lock
* @gl: the glock
*
*/
static void gfs2_glock_drop_th(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
const struct gfs2_glock_operations *glops = gl->gl_ops;
unsigned int ret;
if (glops->go_xmote_th)
glops->go_xmote_th(gl);
gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
gfs2_assert_warn(sdp, gl->gl_state != LM_ST_UNLOCKED);
gfs2_glock_hold(gl);
gl->gl_req_bh = drop_bh;
ret = gfs2_lm_unlock(sdp, gl->gl_lock, gl->gl_state);
if (gfs2_assert_withdraw(sdp, !(ret & LM_OUT_ERROR)))
return;
if (!ret)
drop_bh(gl, ret);
else
gfs2_assert_warn(sdp, ret == LM_OUT_ASYNC);
}
/**
* do_cancels - cancel requests for locks stuck waiting on an expire flag
* @gh: the LM_FLAG_PRIORITY holder waiting to acquire the lock
*
* Don't cancel GL_NOCANCEL requests.
*/
static void do_cancels(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
spin_lock(&gl->gl_spin);
while (gl->gl_req_gh != gh &&
!test_bit(HIF_HOLDER, &gh->gh_iflags) &&
!list_empty(&gh->gh_list)) {
if (gl->gl_req_bh && !(gl->gl_req_gh &&
(gl->gl_req_gh->gh_flags & GL_NOCANCEL))) {
spin_unlock(&gl->gl_spin);
gfs2_lm_cancel(gl->gl_sbd, gl->gl_lock);
msleep(100);
spin_lock(&gl->gl_spin);
} else {
spin_unlock(&gl->gl_spin);
msleep(100);
spin_lock(&gl->gl_spin);
}
}
spin_unlock(&gl->gl_spin);
}
/**
* glock_wait_internal - wait on a glock acquisition
* @gh: the glock holder
*
* Returns: 0 on success
*/
static int glock_wait_internal(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_sbd *sdp = gl->gl_sbd;
const struct gfs2_glock_operations *glops = gl->gl_ops;
if (test_bit(HIF_ABORTED, &gh->gh_iflags))
return -EIO;
if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
spin_lock(&gl->gl_spin);
if (gl->gl_req_gh != gh &&
!test_bit(HIF_HOLDER, &gh->gh_iflags) &&
!list_empty(&gh->gh_list)) {
list_del_init(&gh->gh_list);
gh->gh_error = GLR_TRYFAILED;
run_queue(gl);
spin_unlock(&gl->gl_spin);
return gh->gh_error;
}
spin_unlock(&gl->gl_spin);
}
if (gh->gh_flags & LM_FLAG_PRIORITY)
do_cancels(gh);
wait_on_holder(gh);
if (gh->gh_error)
return gh->gh_error;
gfs2_assert_withdraw(sdp, test_bit(HIF_HOLDER, &gh->gh_iflags));
gfs2_assert_withdraw(sdp, relaxed_state_ok(gl->gl_state, gh->gh_state,
gh->gh_flags));
if (test_bit(HIF_FIRST, &gh->gh_iflags)) {
gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
if (glops->go_lock) {
gh->gh_error = glops->go_lock(gh);
if (gh->gh_error) {
spin_lock(&gl->gl_spin);
list_del_init(&gh->gh_list);
spin_unlock(&gl->gl_spin);
}
}
spin_lock(&gl->gl_spin);
gl->gl_req_gh = NULL;
gl->gl_req_bh = NULL;
clear_bit(GLF_LOCK, &gl->gl_flags);
run_queue(gl);
spin_unlock(&gl->gl_spin);
}
return gh->gh_error;
}
static inline struct gfs2_holder *
find_holder_by_owner(struct list_head *head, pid_t pid)
{
struct gfs2_holder *gh;
list_for_each_entry(gh, head, gh_list) {
if (gh->gh_owner_pid == pid)
return gh;
}
return NULL;
}
static void print_dbg(struct glock_iter *gi, const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
if (gi) {
vsprintf(gi->string, fmt, args);
seq_printf(gi->seq, gi->string);
}
else
vprintk(fmt, args);
va_end(args);
}
/**
* add_to_queue - Add a holder to the wait queue (but look for recursion)
* @gh: the holder structure to add
*
*/
static void add_to_queue(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_holder *existing;
BUG_ON(!gh->gh_owner_pid);
if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
BUG();
if (!(gh->gh_flags & GL_FLOCK)) {
existing = find_holder_by_owner(&gl->gl_holders,
gh->gh_owner_pid);
if (existing) {
print_symbol(KERN_WARNING "original: %s\n",
existing->gh_ip);
printk(KERN_INFO "pid : %d\n", existing->gh_owner_pid);
printk(KERN_INFO "lock type : %d lock state : %d\n",
existing->gh_gl->gl_name.ln_type,
existing->gh_gl->gl_state);
print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
printk(KERN_INFO "pid : %d\n", gh->gh_owner_pid);
printk(KERN_INFO "lock type : %d lock state : %d\n",
gl->gl_name.ln_type, gl->gl_state);
BUG();
}
existing = find_holder_by_owner(&gl->gl_waiters3,
gh->gh_owner_pid);
if (existing) {
print_symbol(KERN_WARNING "original: %s\n",
existing->gh_ip);
print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
BUG();
}
}
if (gh->gh_flags & LM_FLAG_PRIORITY)
list_add(&gh->gh_list, &gl->gl_waiters3);
else
list_add_tail(&gh->gh_list, &gl->gl_waiters3);
}
/**
* 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;
restart:
if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
set_bit(HIF_ABORTED, &gh->gh_iflags);
return -EIO;
}
spin_lock(&gl->gl_spin);
add_to_queue(gh);
run_queue(gl);
spin_unlock(&gl->gl_spin);
if (!(gh->gh_flags & GL_ASYNC)) {
error = glock_wait_internal(gh);
if (error == GLR_CANCELED) {
msleep(100);
goto restart;
}
}
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)
{
struct gfs2_glock *gl = gh->gh_gl;
int ready = 0;
spin_lock(&gl->gl_spin);
if (test_bit(HIF_HOLDER, &gh->gh_iflags))
ready = 1;
else if (list_empty(&gh->gh_list)) {
if (gh->gh_error == GLR_CANCELED) {
spin_unlock(&gl->gl_spin);
msleep(100);
if (gfs2_glock_nq(gh))
return 1;
return 0;
} else
ready = 1;
}
spin_unlock(&gl->gl_spin);
return ready;
}
/**
* gfs2_glock_wait - wait for a lock acquisition that ended in a GLR_ASYNC
* @gh: the holder structure
*
* Returns: 0, GLR_TRYFAILED, or errno on failure
*/
int gfs2_glock_wait(struct gfs2_holder *gh)
{
int error;
error = glock_wait_internal(gh);
if (error == GLR_CANCELED) {
msleep(100);
gh->gh_flags &= ~GL_ASYNC;
error = gfs2_glock_nq(gh);
}
return error;
}
/**
* 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;
if (gh->gh_flags & GL_NOCACHE)
handle_callback(gl, LM_ST_UNLOCKED, 0, 0);
gfs2_glmutex_lock(gl);
spin_lock(&gl->gl_spin);
list_del_init(&gh->gh_list);
if (list_empty(&gl->gl_holders)) {
if (glops->go_unlock) {
spin_unlock(&gl->gl_spin);
glops->go_unlock(gh);
spin_lock(&gl->gl_spin);
}
gl->gl_stamp = jiffies;
}
clear_bit(GLF_LOCK, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
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]);
}
/**
* gfs2_lvb_hold - attach a LVB from a glock
* @gl: The glock in question
*
*/
int gfs2_lvb_hold(struct gfs2_glock *gl)
{
int error;
gfs2_glmutex_lock(gl);
if (!atomic_read(&gl->gl_lvb_count)) {
error = gfs2_lm_hold_lvb(gl->gl_sbd, gl->gl_lock, &gl->gl_lvb);
if (error) {
gfs2_glmutex_unlock(gl);
return error;
}
gfs2_glock_hold(gl);
}
atomic_inc(&gl->gl_lvb_count);
gfs2_glmutex_unlock(gl);
return 0;
}
/**
* gfs2_lvb_unhold - detach a LVB from a glock
* @gl: The glock in question
*
*/
void gfs2_lvb_unhold(struct gfs2_glock *gl)
{
gfs2_glock_hold(gl);
gfs2_glmutex_lock(gl);
gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count) > 0);
if (atomic_dec_and_test(&gl->gl_lvb_count)) {
gfs2_lm_unhold_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
gl->gl_lvb = NULL;
gfs2_glock_put(gl);
}
gfs2_glmutex_unlock(gl);
gfs2_glock_put(gl);
}
static void blocking_cb(struct gfs2_sbd *sdp, struct lm_lockname *name,
unsigned int state)
{
struct gfs2_glock *gl;
unsigned long delay = 0;
unsigned long holdtime;
unsigned long now = jiffies;
gl = gfs2_glock_find(sdp, name);
if (!gl)
return;
holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
if (time_before(now, holdtime))
delay = holdtime - now;
handle_callback(gl, state, 1, delay);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
gfs2_glock_put(gl);
}
/**
* gfs2_glock_cb - Callback used by locking module
* @sdp: Pointer to the superblock
* @type: Type of callback
* @data: Type dependent data pointer
*
* Called by the locking module when it wants to tell us something.
* Either we need to drop a lock, one of our ASYNC requests completed, or
* a journal from another client needs to be recovered.
*/
void gfs2_glock_cb(void *cb_data, unsigned int type, void *data)
{
struct gfs2_sbd *sdp = cb_data;
switch (type) {
case LM_CB_NEED_E:
blocking_cb(sdp, data, LM_ST_UNLOCKED);
return;
case LM_CB_NEED_D:
blocking_cb(sdp, data, LM_ST_DEFERRED);
return;
case LM_CB_NEED_S:
blocking_cb(sdp, data, LM_ST_SHARED);
return;
case LM_CB_ASYNC: {
struct lm_async_cb *async = data;
struct gfs2_glock *gl;
down_read(&gfs2_umount_flush_sem);
gl = gfs2_glock_find(sdp, &async->lc_name);
if (gfs2_assert_warn(sdp, gl))
return;
if (!gfs2_assert_warn(sdp, gl->gl_req_bh))
gl->gl_req_bh(gl, async->lc_ret);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put(gl);
up_read(&gfs2_umount_flush_sem);
return;
}
case LM_CB_NEED_RECOVERY:
gfs2_jdesc_make_dirty(sdp, *(unsigned int *)data);
if (sdp->sd_recoverd_process)
wake_up_process(sdp->sd_recoverd_process);
return;
case LM_CB_DROPLOCKS:
gfs2_gl_hash_clear(sdp, NO_WAIT);
gfs2_quota_scan(sdp);
return;
default:
gfs2_assert_warn(sdp, 0);
return;
}
}
/**
* 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(struct gfs2_glock *gl)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
int demote = 1;
if (test_bit(GLF_STICKY, &gl->gl_flags))
demote = 0;
else if (glops->go_demote_ok)
demote = glops->go_demote_ok(gl);
return demote;
}
/**
* gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
* @gl: the glock
*
*/
void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
spin_lock(&sdp->sd_reclaim_lock);
if (list_empty(&gl->gl_reclaim)) {
gfs2_glock_hold(gl);
list_add(&gl->gl_reclaim, &sdp->sd_reclaim_list);
atomic_inc(&sdp->sd_reclaim_count);
}
spin_unlock(&sdp->sd_reclaim_lock);
wake_up(&sdp->sd_reclaim_wq);
}
/**
* gfs2_reclaim_glock - process the next glock on the filesystem's reclaim list
* @sdp: the filesystem
*
* Called from gfs2_glockd() glock reclaim daemon, or when promoting a
* different glock and we notice that there are a lot of glocks in the
* reclaim list.
*
*/
void gfs2_reclaim_glock(struct gfs2_sbd *sdp)
{
struct gfs2_glock *gl;
spin_lock(&sdp->sd_reclaim_lock);
if (list_empty(&sdp->sd_reclaim_list)) {
spin_unlock(&sdp->sd_reclaim_lock);
return;
}
gl = list_entry(sdp->sd_reclaim_list.next,
struct gfs2_glock, gl_reclaim);
list_del_init(&gl->gl_reclaim);
spin_unlock(&sdp->sd_reclaim_lock);
atomic_dec(&sdp->sd_reclaim_count);
atomic_inc(&sdp->sd_reclaimed);
if (gfs2_glmutex_trylock(gl)) {
if (list_empty(&gl->gl_holders) &&
gl->gl_state != LM_ST_UNLOCKED && demote_ok(gl))
handle_callback(gl, LM_ST_UNLOCKED, 0, 0);
gfs2_glmutex_unlock(gl);
}
gfs2_glock_put(gl);
}
/**
* 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;
}
/**
* scan_glock - look at a glock and see if we can reclaim it
* @gl: the glock to look at
*
*/
static void scan_glock(struct gfs2_glock *gl)
{
if (gl->gl_ops == &gfs2_inode_glops && gl->gl_object)
return;
if (gfs2_glmutex_trylock(gl)) {
if (list_empty(&gl->gl_holders) &&
gl->gl_state != LM_ST_UNLOCKED && demote_ok(gl))
goto out_schedule;
gfs2_glmutex_unlock(gl);
}
return;
out_schedule:
gfs2_glmutex_unlock(gl);
gfs2_glock_schedule_for_reclaim(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)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
int released;
spin_lock(&sdp->sd_reclaim_lock);
if (!list_empty(&gl->gl_reclaim)) {
list_del_init(&gl->gl_reclaim);
atomic_dec(&sdp->sd_reclaim_count);
spin_unlock(&sdp->sd_reclaim_lock);
released = gfs2_glock_put(gl);
gfs2_assert(sdp, !released);
} else {
spin_unlock(&sdp->sd_reclaim_lock);
}
if (gfs2_glmutex_trylock(gl)) {
if (list_empty(&gl->gl_holders) &&
gl->gl_state != LM_ST_UNLOCKED)
handle_callback(gl, LM_ST_UNLOCKED, 0, 0);
gfs2_glmutex_unlock(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, or when inter-node lock manager
* requests DROPLOCKS because it is running out of capacity.
*/
void gfs2_gl_hash_clear(struct gfs2_sbd *sdp, int wait)
{
unsigned long t;
unsigned int x;
int cont;
t = jiffies;
for (;;) {
cont = 0;
for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
if (examine_bucket(clear_glock, sdp, x))
cont = 1;
}
if (!wait || !cont)
break;
if (time_after_eq(jiffies,
t + gfs2_tune_get(sdp, gt_stall_secs) * HZ)) {
fs_warn(sdp, "Unmount seems to be stalled. "
"Dumping lock state...\n");
gfs2_dump_lockstate(sdp);
t = jiffies;
}
down_write(&gfs2_umount_flush_sem);
invalidate_inodes(sdp->sd_vfs);
up_write(&gfs2_umount_flush_sem);
msleep(10);
}
}
/*
* Diagnostic routines to help debug distributed deadlock
*/
static void gfs2_print_symbol(struct glock_iter *gi, const char *fmt,
unsigned long address)
{
char buffer[KSYM_SYMBOL_LEN];
sprint_symbol(buffer, address);
print_dbg(gi, fmt, buffer);
}
/**
* dump_holder - print information about a glock holder
* @str: a string naming the type of holder
* @gh: the glock holder
*
* Returns: 0 on success, -ENOBUFS when we run out of space
*/
static int dump_holder(struct glock_iter *gi, char *str,
struct gfs2_holder *gh)
{
unsigned int x;
struct task_struct *gh_owner;
print_dbg(gi, " %s\n", str);
if (gh->gh_owner_pid) {
print_dbg(gi, " owner = %ld ", (long)gh->gh_owner_pid);
gh_owner = find_task_by_pid(gh->gh_owner_pid);
if (gh_owner)
print_dbg(gi, "(%s)\n", gh_owner->comm);
else
print_dbg(gi, "(ended)\n");
} else
print_dbg(gi, " owner = -1\n");
print_dbg(gi, " gh_state = %u\n", gh->gh_state);
print_dbg(gi, " gh_flags =");
for (x = 0; x < 32; x++)
if (gh->gh_flags & (1 << x))
print_dbg(gi, " %u", x);
print_dbg(gi, " \n");
print_dbg(gi, " error = %d\n", gh->gh_error);
print_dbg(gi, " gh_iflags =");
for (x = 0; x < 32; x++)
if (test_bit(x, &gh->gh_iflags))
print_dbg(gi, " %u", x);
print_dbg(gi, " \n");
gfs2_print_symbol(gi, " initialized at: %s\n", gh->gh_ip);
return 0;
}
/**
* dump_inode - print information about an inode
* @ip: the inode
*
* Returns: 0 on success, -ENOBUFS when we run out of space
*/
static int dump_inode(struct glock_iter *gi, struct gfs2_inode *ip)
{
unsigned int x;
print_dbg(gi, " Inode:\n");
print_dbg(gi, " num = %llu/%llu\n",
(unsigned long long)ip->i_no_formal_ino,
(unsigned long long)ip->i_no_addr);
print_dbg(gi, " type = %u\n", IF2DT(ip->i_inode.i_mode));
print_dbg(gi, " i_flags =");
for (x = 0; x < 32; x++)
if (test_bit(x, &ip->i_flags))
print_dbg(gi, " %u", x);
print_dbg(gi, " \n");
return 0;
}
/**
* dump_glock - print information about a glock
* @gl: the glock
* @count: where we are in the buffer
*
* Returns: 0 on success, -ENOBUFS when we run out of space
*/
static int dump_glock(struct glock_iter *gi, struct gfs2_glock *gl)
{
struct gfs2_holder *gh;
unsigned int x;
int error = -ENOBUFS;
struct task_struct *gl_owner;
spin_lock(&gl->gl_spin);
print_dbg(gi, "Glock 0x%p (%u, 0x%llx)\n", gl, gl->gl_name.ln_type,
(unsigned long long)gl->gl_name.ln_number);
print_dbg(gi, " gl_flags =");
for (x = 0; x < 32; x++) {
if (test_bit(x, &gl->gl_flags))
print_dbg(gi, " %u", x);
}
if (!test_bit(GLF_LOCK, &gl->gl_flags))
print_dbg(gi, " (unlocked)");
print_dbg(gi, " \n");
print_dbg(gi, " gl_ref = %d\n", atomic_read(&gl->gl_ref));
print_dbg(gi, " gl_state = %u\n", gl->gl_state);
if (gl->gl_owner_pid) {
gl_owner = find_task_by_pid(gl->gl_owner_pid);
if (gl_owner)
print_dbg(gi, " gl_owner = pid %d (%s)\n",
gl->gl_owner_pid, gl_owner->comm);
else
print_dbg(gi, " gl_owner = %d (ended)\n",
gl->gl_owner_pid);
} else
print_dbg(gi, " gl_owner = -1\n");
print_dbg(gi, " gl_ip = %lu\n", gl->gl_ip);
print_dbg(gi, " req_gh = %s\n", (gl->gl_req_gh) ? "yes" : "no");
print_dbg(gi, " req_bh = %s\n", (gl->gl_req_bh) ? "yes" : "no");
print_dbg(gi, " lvb_count = %d\n", atomic_read(&gl->gl_lvb_count));
print_dbg(gi, " object = %s\n", (gl->gl_object) ? "yes" : "no");
print_dbg(gi, " reclaim = %s\n",
(list_empty(&gl->gl_reclaim)) ? "no" : "yes");
if (gl->gl_aspace)
print_dbg(gi, " aspace = 0x%p nrpages = %lu\n", gl->gl_aspace,
gl->gl_aspace->i_mapping->nrpages);
else
print_dbg(gi, " aspace = no\n");
print_dbg(gi, " ail = %d\n", atomic_read(&gl->gl_ail_count));
if (gl->gl_req_gh) {
error = dump_holder(gi, "Request", gl->gl_req_gh);
if (error)
goto out;
}
list_for_each_entry(gh, &gl->gl_holders, gh_list) {
error = dump_holder(gi, "Holder", gh);
if (error)
goto out;
}
list_for_each_entry(gh, &gl->gl_waiters1, gh_list) {
error = dump_holder(gi, "Waiter1", gh);
if (error)
goto out;
}
list_for_each_entry(gh, &gl->gl_waiters3, gh_list) {
error = dump_holder(gi, "Waiter3", gh);
if (error)
goto out;
}
if (test_bit(GLF_DEMOTE, &gl->gl_flags)) {
print_dbg(gi, " Demotion req to state %u (%llu uS ago)\n",
gl->gl_demote_state, (unsigned long long)
(jiffies - gl->gl_demote_time)*(1000000/HZ));
}
if (gl->gl_ops == &gfs2_inode_glops && gl->gl_object) {
if (!test_bit(GLF_LOCK, &gl->gl_flags) &&
list_empty(&gl->gl_holders)) {
error = dump_inode(gi, gl->gl_object);
if (error)
goto out;
} else {
error = -ENOBUFS;
print_dbg(gi, " Inode: busy\n");
}
}
error = 0;
out:
spin_unlock(&gl->gl_spin);
return error;
}
/**
* 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;
}
/**
* gfs2_scand - Look for cached glocks and inodes to toss from memory
* @sdp: Pointer to GFS2 superblock
*
* One of these daemons runs, finding candidates to add to sd_reclaim_list.
* See gfs2_glockd()
*/
static int gfs2_scand(void *data)
{
unsigned x;
unsigned delay;
while (!kthread_should_stop()) {
for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
examine_bucket(scan_glock, NULL, x);
if (freezing(current))
refrigerator();
delay = scand_secs;
if (delay < 1)
delay = 1;
schedule_timeout_interruptible(delay * HZ);
}
return 0;
}
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
scand_process = kthread_run(gfs2_scand, NULL, "gfs2_scand");
if (IS_ERR(scand_process))
return PTR_ERR(scand_process);
glock_workqueue = create_workqueue("glock_workqueue");
if (IS_ERR(glock_workqueue)) {
kthread_stop(scand_process);
return PTR_ERR(glock_workqueue);
}
return 0;
}
void gfs2_glock_exit(void)
{
destroy_workqueue(glock_workqueue);
kthread_stop(scand_process);
}
module_param(scand_secs, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(scand_secs, "The number of seconds between scand runs");
static int gfs2_glock_iter_next(struct 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);
if (gi->gl)
gfs2_glock_hold(gi->gl);
}
read_unlock(gl_lock_addr(gi->hash));
if (gl)
gfs2_glock_put(gl);
if (gl && gi->gl == NULL)
gi->hash++;
while(gi->gl == NULL) {
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));
gi->hash++;
}
if (gi->sdp != gi->gl->gl_sbd)
goto restart;
return 0;
}
static void gfs2_glock_iter_free(struct glock_iter *gi)
{
if (gi->gl)
gfs2_glock_put(gi->gl);
kfree(gi);
}
static struct glock_iter *gfs2_glock_iter_init(struct gfs2_sbd *sdp)
{
struct glock_iter *gi;
gi = kmalloc(sizeof (*gi), GFP_KERNEL);
if (!gi)
return NULL;
gi->sdp = sdp;
gi->hash = 0;
gi->seq = NULL;
gi->gl = NULL;
memset(gi->string, 0, sizeof(gi->string));
if (gfs2_glock_iter_next(gi)) {
gfs2_glock_iter_free(gi);
return NULL;
}
return gi;
}
static void *gfs2_glock_seq_start(struct seq_file *file, loff_t *pos)
{
struct glock_iter *gi;
loff_t n = *pos;
gi = gfs2_glock_iter_init(file->private);
if (!gi)
return NULL;
while(n--) {
if (gfs2_glock_iter_next(gi)) {
gfs2_glock_iter_free(gi);
return NULL;
}
}
return gi;
}
static void *gfs2_glock_seq_next(struct seq_file *file, void *iter_ptr,
loff_t *pos)
{
struct glock_iter *gi = iter_ptr;
(*pos)++;
if (gfs2_glock_iter_next(gi)) {
gfs2_glock_iter_free(gi);
return NULL;
}
return gi;
}
static void gfs2_glock_seq_stop(struct seq_file *file, void *iter_ptr)
{
struct glock_iter *gi = iter_ptr;
if (gi)
gfs2_glock_iter_free(gi);
}
static int gfs2_glock_seq_show(struct seq_file *file, void *iter_ptr)
{
struct glock_iter *gi = iter_ptr;
gi->seq = file;
dump_glock(gi, gi->gl);
return 0;
}
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)
{
struct seq_file *seq;
int ret;
ret = seq_open(file, &gfs2_glock_seq_ops);
if (ret)
return ret;
seq = file->private_data;
seq->private = inode->i_private;
return 0;
}
static const struct file_operations gfs2_debug_fops = {
.owner = THIS_MODULE,
.open = gfs2_debugfs_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release
};
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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