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linux/fs/gfs2/glock.c
Pavel Emelyanov eccba06891 gfs2: make gfs2_glock.gl_owner_pid be a struct pid * 
The gl_owner_pid field is used to get the lock owning task by its pid, so make
it in a proper manner, i.e.  by using the struct pid pointer and pid_task()
function.

The pid_task() becomes exported for the gfs2 module.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-07 08:42:06 -08:00

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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 = NULL;
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 = 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);
}
/**
* 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;
}
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 = get_pid(task_pid(current));
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 = get_pid(task_pid(current));
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)
{
struct pid *pid;
spin_lock(&gl->gl_spin);
clear_bit(GLF_LOCK, &gl->gl_flags);
pid = gl->gl_owner_pid;
gl->gl_owner_pid = NULL;
gl->gl_ip = 0;
run_queue(gl);
spin_unlock(&gl->gl_spin);
put_pid(pid);
}
/**
* 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, struct pid *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 == NULL);
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",
pid_nr(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",
pid_nr(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)pid_nr(gh->gh_owner_pid));
gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_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 = pid_task(gl->gl_owner_pid, PIDTYPE_PID);
if (gl_owner)
print_dbg(gi, " gl_owner = pid %d (%s)\n",
pid_nr(gl->gl_owner_pid), gl_owner->comm);
else
print_dbg(gi, " gl_owner = %d (ended)\n",
pid_nr(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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