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linux-stable/fs/gfs2/glock.c
Andreas Gruenbacher 7427f3bb49 gfs2: Fix glock_hash_walk bugs 
So far, glock_hash_walk took a reference on each glock it iterated over, and it
was the examiner's responsibility to drop those references.  Dropping the final
reference to a glock can sleep and the examiners are called in a RCU critical
section with spin locks held, so examiners that didn't need the extra reference
had to drop it asynchronously via gfs2_glock_queue_put or similar.  This wasn't
done correctly in thaw_glock which did call gfs2_glock_put, and not at all in
dump_glock_func.

Change glock_hash_walk to not take glock references at all.  That way, the
examiners that don't need them won't have to bother with slow asynchronous
puts, and the examiners that do need references can take them themselves.

Reported-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2021-10-25 08:42:20 +02:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/buffer_head.h>
#include <linux/delay.h>
#include <linux/sort.h>
#include <linux/hash.h>
#include <linux/jhash.h>
#include <linux/kallsyms.h>
#include <linux/gfs2_ondisk.h>
#include <linux/list.h>
#include <linux/wait.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/workqueue.h>
#include <linux/jiffies.h>
#include <linux/rcupdate.h>
#include <linux/rculist_bl.h>
#include <linux/bit_spinlock.h>
#include <linux/percpu.h>
#include <linux/list_sort.h>
#include <linux/lockref.h>
#include <linux/rhashtable.h>
#include "gfs2.h"
#include "incore.h"
#include "glock.h"
#include "glops.h"
#include "inode.h"
#include "lops.h"
#include "meta_io.h"
#include "quota.h"
#include "super.h"
#include "util.h"
#include "bmap.h"
#define CREATE_TRACE_POINTS
#include "trace_gfs2.h"
struct gfs2_glock_iter {
struct gfs2_sbd *sdp; /* incore superblock */
struct rhashtable_iter hti; /* rhashtable iterator */
struct gfs2_glock *gl; /* current glock struct */
loff_t last_pos; /* last position */
};
typedef void (*glock_examiner) (struct gfs2_glock * gl);
static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
static void __gfs2_glock_dq(struct gfs2_holder *gh);
static struct dentry *gfs2_root;
static struct workqueue_struct *glock_workqueue;
struct workqueue_struct *gfs2_delete_workqueue;
static LIST_HEAD(lru_list);
static atomic_t lru_count = ATOMIC_INIT(0);
static DEFINE_SPINLOCK(lru_lock);
#define GFS2_GL_HASH_SHIFT 15
#define GFS2_GL_HASH_SIZE BIT(GFS2_GL_HASH_SHIFT)
static const struct rhashtable_params ht_parms = {
.nelem_hint = GFS2_GL_HASH_SIZE * 3 / 4,
.key_len = offsetofend(struct lm_lockname, ln_type),
.key_offset = offsetof(struct gfs2_glock, gl_name),
.head_offset = offsetof(struct gfs2_glock, gl_node),
};
static struct rhashtable gl_hash_table;
#define GLOCK_WAIT_TABLE_BITS 12
#define GLOCK_WAIT_TABLE_SIZE (1 << GLOCK_WAIT_TABLE_BITS)
static wait_queue_head_t glock_wait_table[GLOCK_WAIT_TABLE_SIZE] __cacheline_aligned;
struct wait_glock_queue {
struct lm_lockname *name;
wait_queue_entry_t wait;
};
static int glock_wake_function(wait_queue_entry_t *wait, unsigned int mode,
int sync, void *key)
{
struct wait_glock_queue *wait_glock =
container_of(wait, struct wait_glock_queue, wait);
struct lm_lockname *wait_name = wait_glock->name;
struct lm_lockname *wake_name = key;
if (wake_name->ln_sbd != wait_name->ln_sbd ||
wake_name->ln_number != wait_name->ln_number ||
wake_name->ln_type != wait_name->ln_type)
return 0;
return autoremove_wake_function(wait, mode, sync, key);
}
static wait_queue_head_t *glock_waitqueue(struct lm_lockname *name)
{
u32 hash = jhash2((u32 *)name, ht_parms.key_len / 4, 0);
return glock_wait_table + hash_32(hash, GLOCK_WAIT_TABLE_BITS);
}
/**
* wake_up_glock - Wake up waiters on a glock
* @gl: the glock
*/
static void wake_up_glock(struct gfs2_glock *gl)
{
wait_queue_head_t *wq = glock_waitqueue(&gl->gl_name);
if (waitqueue_active(wq))
__wake_up(wq, TASK_NORMAL, 1, &gl->gl_name);
}
static void gfs2_glock_dealloc(struct rcu_head *rcu)
{
struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
kfree(gl->gl_lksb.sb_lvbptr);
if (gl->gl_ops->go_flags & GLOF_ASPACE)
kmem_cache_free(gfs2_glock_aspace_cachep, gl);
else
kmem_cache_free(gfs2_glock_cachep, gl);
}
/**
* glock_blocked_by_withdraw - determine if we can still use a glock
* @gl: the glock
*
* We need to allow some glocks to be enqueued, dequeued, promoted, and demoted
* when we're withdrawn. For example, to maintain metadata integrity, we should
* disallow the use of inode and rgrp glocks when withdrawn. Other glocks, like
* iopen or the transaction glocks may be safely used because none of their
* metadata goes through the journal. So in general, we should disallow all
* glocks that are journaled, and allow all the others. One exception is:
* we need to allow our active journal to be promoted and demoted so others
* may recover it and we can reacquire it when they're done.
*/
static bool glock_blocked_by_withdraw(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
if (likely(!gfs2_withdrawn(sdp)))
return false;
if (gl->gl_ops->go_flags & GLOF_NONDISK)
return false;
if (!sdp->sd_jdesc ||
gl->gl_name.ln_number == sdp->sd_jdesc->jd_no_addr)
return false;
return true;
}
void gfs2_glock_free(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
gfs2_glock_assert_withdraw(gl, atomic_read(&gl->gl_revokes) == 0);
rhashtable_remove_fast(&gl_hash_table, &gl->gl_node, ht_parms);
smp_mb();
wake_up_glock(gl);
call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
if (atomic_dec_and_test(&sdp->sd_glock_disposal))
wake_up(&sdp->sd_glock_wait);
}
/**
* gfs2_glock_hold() - increment reference count on glock
* @gl: The glock to hold
*
*/
void gfs2_glock_hold(struct gfs2_glock *gl)
{
GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
lockref_get(&gl->gl_lockref);
}
/**
* demote_ok - Check to see if it's ok to unlock a glock
* @gl: the glock
*
* Returns: 1 if it's ok
*/
static int demote_ok(const struct gfs2_glock *gl)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
if (gl->gl_state == LM_ST_UNLOCKED)
return 0;
/*
* Note that demote_ok is used for the lru process of disposing of
* glocks. For this purpose, we don't care if the glock's holders
* have the HIF_MAY_DEMOTE flag set or not. If someone is using
* them, don't demote.
*/
if (!list_empty(&gl->gl_holders))
return 0;
if (glops->go_demote_ok)
return glops->go_demote_ok(gl);
return 1;
}
void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
{
if (!(gl->gl_ops->go_flags & GLOF_LRU))
return;
spin_lock(&lru_lock);
list_move_tail(&gl->gl_lru, &lru_list);
if (!test_bit(GLF_LRU, &gl->gl_flags)) {
set_bit(GLF_LRU, &gl->gl_flags);
atomic_inc(&lru_count);
}
spin_unlock(&lru_lock);
}
static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
{
if (!(gl->gl_ops->go_flags & GLOF_LRU))
return;
spin_lock(&lru_lock);
if (test_bit(GLF_LRU, &gl->gl_flags)) {
list_del_init(&gl->gl_lru);
atomic_dec(&lru_count);
clear_bit(GLF_LRU, &gl->gl_flags);
}
spin_unlock(&lru_lock);
}
/*
* Enqueue the glock on the work queue. Passes one glock reference on to the
* work queue.
*/
static void __gfs2_glock_queue_work(struct gfs2_glock *gl, unsigned long delay) {
if (!queue_delayed_work(glock_workqueue, &gl->gl_work, delay)) {
/*
* We are holding the lockref spinlock, and the work was still
* queued above. The queued work (glock_work_func) takes that
* spinlock before dropping its glock reference(s), so it
* cannot have dropped them in the meantime.
*/
GLOCK_BUG_ON(gl, gl->gl_lockref.count < 2);
gl->gl_lockref.count--;
}
}
static void gfs2_glock_queue_work(struct gfs2_glock *gl, unsigned long delay) {
spin_lock(&gl->gl_lockref.lock);
__gfs2_glock_queue_work(gl, delay);
spin_unlock(&gl->gl_lockref.lock);
}
static void __gfs2_glock_put(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct address_space *mapping = gfs2_glock2aspace(gl);
lockref_mark_dead(&gl->gl_lockref);
gfs2_glock_remove_from_lru(gl);
spin_unlock(&gl->gl_lockref.lock);
GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
if (mapping) {
truncate_inode_pages_final(mapping);
if (!gfs2_withdrawn(sdp))
GLOCK_BUG_ON(gl, !mapping_empty(mapping));
}
trace_gfs2_glock_put(gl);
sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
}
/*
* Cause the glock to be put in work queue context.
*/
void gfs2_glock_queue_put(struct gfs2_glock *gl)
{
gfs2_glock_queue_work(gl, 0);
}
/**
* gfs2_glock_put() - Decrement reference count on glock
* @gl: The glock to put
*
*/
void gfs2_glock_put(struct gfs2_glock *gl)
{
if (lockref_put_or_lock(&gl->gl_lockref))
return;
__gfs2_glock_put(gl);
}
/**
* may_grant - check if it's ok to grant a new lock
* @gl: The glock
* @current_gh: One of the current holders of @gl
* @gh: The lock request which we wish to grant
*
* With our current compatibility rules, if a glock has one or more active
* holders (HIF_HOLDER flag set), any of those holders can be passed in as
* @current_gh; they are all the same as far as compatibility with the new @gh
* goes.
*
* Returns true if it's ok to grant the lock.
*/
static inline bool may_grant(struct gfs2_glock *gl,
struct gfs2_holder *current_gh,
struct gfs2_holder *gh)
{
if (current_gh) {
GLOCK_BUG_ON(gl, !test_bit(HIF_HOLDER, &current_gh->gh_iflags));
switch(current_gh->gh_state) {
case LM_ST_EXCLUSIVE:
/*
* Here we make a special exception to grant holders
* who agree to share the EX lock with other holders
* who also have the bit set. If the original holder
* has the LM_FLAG_NODE_SCOPE bit set, we grant more
* holders with the bit set.
*/
return gh->gh_state == LM_ST_EXCLUSIVE &&
(current_gh->gh_flags & LM_FLAG_NODE_SCOPE) &&
(gh->gh_flags & LM_FLAG_NODE_SCOPE);
case LM_ST_SHARED:
case LM_ST_DEFERRED:
return gh->gh_state == current_gh->gh_state;
default:
return false;
}
}
if (gl->gl_state == gh->gh_state)
return true;
if (gh->gh_flags & GL_EXACT)
return false;
if (gl->gl_state == LM_ST_EXCLUSIVE) {
return gh->gh_state == LM_ST_SHARED ||
gh->gh_state == LM_ST_DEFERRED;
}
if (gh->gh_flags & LM_FLAG_ANY)
return gl->gl_state != LM_ST_UNLOCKED;
return false;
}
static void gfs2_holder_wake(struct gfs2_holder *gh)
{
clear_bit(HIF_WAIT, &gh->gh_iflags);
smp_mb__after_atomic();
wake_up_bit(&gh->gh_iflags, HIF_WAIT);
if (gh->gh_flags & GL_ASYNC) {
struct gfs2_sbd *sdp = gh->gh_gl->gl_name.ln_sbd;
wake_up(&sdp->sd_async_glock_wait);
}
}
/**
* do_error - Something unexpected has happened during a lock request
* @gl: The glock
* @ret: The status from the DLM
*/
static void do_error(struct gfs2_glock *gl, const int ret)
{
struct gfs2_holder *gh, *tmp;
list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
if (!test_bit(HIF_WAIT, &gh->gh_iflags))
continue;
if (ret & LM_OUT_ERROR)
gh->gh_error = -EIO;
else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
gh->gh_error = GLR_TRYFAILED;
else
continue;
list_del_init(&gh->gh_list);
trace_gfs2_glock_queue(gh, 0);
gfs2_holder_wake(gh);
}
}
/**
* demote_incompat_holders - demote incompatible demoteable holders
* @gl: the glock we want to promote
* @new_gh: the new holder to be promoted
*/
static void demote_incompat_holders(struct gfs2_glock *gl,
struct gfs2_holder *new_gh)
{
struct gfs2_holder *gh;
/*
* Demote incompatible holders before we make ourselves eligible.
* (This holder may or may not allow auto-demoting, but we don't want
* to demote the new holder before it's even granted.)
*/
list_for_each_entry(gh, &gl->gl_holders, gh_list) {
/*
* Since holders are at the front of the list, we stop when we
* find the first non-holder.
*/
if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
return;
if (test_bit(HIF_MAY_DEMOTE, &gh->gh_iflags) &&
!may_grant(gl, new_gh, gh)) {
/*
* We should not recurse into do_promote because
* __gfs2_glock_dq only calls handle_callback,
* gfs2_glock_add_to_lru and __gfs2_glock_queue_work.
*/
__gfs2_glock_dq(gh);
}
}
}
/**
* find_first_holder - find the first "holder" gh
* @gl: the glock
*/
static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
{
struct gfs2_holder *gh;
if (!list_empty(&gl->gl_holders)) {
gh = list_first_entry(&gl->gl_holders, struct gfs2_holder,
gh_list);
if (test_bit(HIF_HOLDER, &gh->gh_iflags))
return gh;
}
return NULL;
}
/**
* find_first_strong_holder - find the first non-demoteable holder
* @gl: the glock
*
* Find the first holder that doesn't have the HIF_MAY_DEMOTE flag set.
*/
static inline struct gfs2_holder *
find_first_strong_holder(struct gfs2_glock *gl)
{
struct gfs2_holder *gh;
list_for_each_entry(gh, &gl->gl_holders, gh_list) {
if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
return NULL;
if (!test_bit(HIF_MAY_DEMOTE, &gh->gh_iflags))
return gh;
}
return NULL;
}
/*
* gfs2_instantiate - Call the glops instantiate function
* @gl: The glock
*
* Returns: 0 if instantiate was successful, 2 if type specific operation is
* underway, or error.
*/
int gfs2_instantiate(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
const struct gfs2_glock_operations *glops = gl->gl_ops;
int ret;
again:
if (!test_bit(GLF_INSTANTIATE_NEEDED, &gl->gl_flags))
return 0;
/*
* Since we unlock the lockref lock, we set a flag to indicate
* instantiate is in progress.
*/
if (test_bit(GLF_INSTANTIATE_IN_PROG, &gl->gl_flags)) {
wait_on_bit(&gl->gl_flags, GLF_INSTANTIATE_IN_PROG,
TASK_UNINTERRUPTIBLE);
/*
* Here we just waited for a different instantiate to finish.
* But that may not have been successful, as when a process
* locks an inode glock _before_ it has an actual inode to
* instantiate into. So we check again. This process might
* have an inode to instantiate, so might be successful.
*/
goto again;
}
set_bit(GLF_INSTANTIATE_IN_PROG, &gl->gl_flags);
ret = glops->go_instantiate(gh);
if (!ret)
clear_bit(GLF_INSTANTIATE_NEEDED, &gl->gl_flags);
clear_bit(GLF_INSTANTIATE_IN_PROG, &gl->gl_flags);
smp_mb__after_atomic();
wake_up_bit(&gl->gl_flags, GLF_INSTANTIATE_IN_PROG);
return ret;
}
/**
* do_promote - promote as many requests as possible on the current queue
* @gl: The glock
*
* Returns: 1 if there is a blocked holder at the head of the list, or 2
* if a type specific operation is underway.
*/
static int do_promote(struct gfs2_glock *gl)
__releases(&gl->gl_lockref.lock)
__acquires(&gl->gl_lockref.lock)
{
struct gfs2_holder *gh, *tmp, *first_gh;
bool incompat_holders_demoted = false;
bool lock_released;
int ret;
restart:
first_gh = find_first_strong_holder(gl);
list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
lock_released = false;
if (test_bit(HIF_HOLDER, &gh->gh_iflags))
continue;
if (!may_grant(gl, first_gh, gh)) {
/*
* If we get here, it means we may not grant this holder for
* some reason. If this holder is the head of the list, it
* means we have a blocked holder at the head, so return 1.
*/
if (gh->gh_list.prev == &gl->gl_holders)
return 1;
do_error(gl, 0);
break;
}
if (!incompat_holders_demoted) {
demote_incompat_holders(gl, first_gh);
incompat_holders_demoted = true;
first_gh = gh;
}
if (test_bit(GLF_INSTANTIATE_NEEDED, &gl->gl_flags) &&
!(gh->gh_flags & GL_SKIP) && gl->gl_ops->go_instantiate) {
lock_released = true;
spin_unlock(&gl->gl_lockref.lock);
ret = gfs2_instantiate(gh);
spin_lock(&gl->gl_lockref.lock);
if (ret) {
if (ret == 1)
return 2;
gh->gh_error = ret;
list_del_init(&gh->gh_list);
trace_gfs2_glock_queue(gh, 0);
gfs2_holder_wake(gh);
goto restart;
}
}
set_bit(HIF_HOLDER, &gh->gh_iflags);
trace_gfs2_promote(gh);
gfs2_holder_wake(gh);
/*
* If we released the gl_lockref.lock the holders list may have
* changed. For that reason, we start again at the start of
* the holders queue.
*/
if (lock_released)
goto restart;
}
return 0;
}
/**
* find_first_waiter - find the first gh that's waiting for the glock
* @gl: the glock
*/
static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
{
struct gfs2_holder *gh;
list_for_each_entry(gh, &gl->gl_holders, gh_list) {
if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
return gh;
}
return NULL;
}
/**
* state_change - record that the glock is now in a different state
* @gl: the glock
* @new_state: the new state
*/
static void state_change(struct gfs2_glock *gl, unsigned int new_state)
{
int held1, held2;
held1 = (gl->gl_state != LM_ST_UNLOCKED);
held2 = (new_state != LM_ST_UNLOCKED);
if (held1 != held2) {
GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
if (held2)
gl->gl_lockref.count++;
else
gl->gl_lockref.count--;
}
if (new_state != gl->gl_target)
/* shorten our minimum hold time */
gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
GL_GLOCK_MIN_HOLD);
gl->gl_state = new_state;
gl->gl_tchange = jiffies;
}
static void gfs2_set_demote(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
set_bit(GLF_DEMOTE, &gl->gl_flags);
smp_mb();
wake_up(&sdp->sd_async_glock_wait);
}
static void gfs2_demote_wake(struct gfs2_glock *gl)
{
gl->gl_demote_state = LM_ST_EXCLUSIVE;
clear_bit(GLF_DEMOTE, &gl->gl_flags);
smp_mb__after_atomic();
wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
}
/**
* finish_xmote - The DLM has replied to one of our lock requests
* @gl: The glock
* @ret: The status from the DLM
*
*/
static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
struct gfs2_holder *gh;
unsigned state = ret & LM_OUT_ST_MASK;
int rv;
spin_lock(&gl->gl_lockref.lock);
trace_gfs2_glock_state_change(gl, state);
state_change(gl, state);
gh = find_first_waiter(gl);
/* Demote to UN request arrived during demote to SH or DF */
if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
gl->gl_target = LM_ST_UNLOCKED;
/* Check for state != intended state */
if (unlikely(state != gl->gl_target)) {
if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
/* move to back of queue and try next entry */
if (ret & LM_OUT_CANCELED) {
if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
list_move_tail(&gh->gh_list, &gl->gl_holders);
gh = find_first_waiter(gl);
gl->gl_target = gh->gh_state;
goto retry;
}
/* Some error or failed "try lock" - report it */
if ((ret & LM_OUT_ERROR) ||
(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
gl->gl_target = gl->gl_state;
do_error(gl, ret);
goto out;
}
}
switch(state) {
/* Unlocked due to conversion deadlock, try again */
case LM_ST_UNLOCKED:
retry:
do_xmote(gl, gh, gl->gl_target);
break;
/* Conversion fails, unlock and try again */
case LM_ST_SHARED:
case LM_ST_DEFERRED:
do_xmote(gl, gh, LM_ST_UNLOCKED);
break;
default: /* Everything else */
fs_err(gl->gl_name.ln_sbd, "wanted %u got %u\n",
gl->gl_target, state);
GLOCK_BUG_ON(gl, 1);
}
spin_unlock(&gl->gl_lockref.lock);
return;
}
/* Fast path - we got what we asked for */
if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
gfs2_demote_wake(gl);
if (state != LM_ST_UNLOCKED) {
if (glops->go_xmote_bh) {
spin_unlock(&gl->gl_lockref.lock);
rv = glops->go_xmote_bh(gl);
spin_lock(&gl->gl_lockref.lock);
if (rv) {
do_error(gl, rv);
goto out;
}
}
rv = do_promote(gl);
if (rv == 2)
goto out_locked;
}
out:
clear_bit(GLF_LOCK, &gl->gl_flags);
out_locked:
spin_unlock(&gl->gl_lockref.lock);
}
static bool is_system_glock(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
if (gl == m_ip->i_gl)
return true;
return false;
}
/**
* do_xmote - Calls the DLM to change the state of a lock
* @gl: The lock state
* @gh: The holder (only for promotes)
* @target: The target lock state
*
*/
static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
__releases(&gl->gl_lockref.lock)
__acquires(&gl->gl_lockref.lock)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
unsigned int lck_flags = (unsigned int)(gh ? gh->gh_flags : 0);
int ret;
if (target != LM_ST_UNLOCKED && glock_blocked_by_withdraw(gl) &&
gh && !(gh->gh_flags & LM_FLAG_NOEXP))
return;
lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
LM_FLAG_PRIORITY);
GLOCK_BUG_ON(gl, gl->gl_state == target);
GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
glops->go_inval) {
/*
* If another process is already doing the invalidate, let that
* finish first. The glock state machine will get back to this
* holder again later.
*/
if (test_and_set_bit(GLF_INVALIDATE_IN_PROGRESS,
&gl->gl_flags))
return;
do_error(gl, 0); /* Fail queued try locks */
}
gl->gl_req = target;
set_bit(GLF_BLOCKING, &gl->gl_flags);
if ((gl->gl_req == LM_ST_UNLOCKED) ||
(gl->gl_state == LM_ST_EXCLUSIVE) ||
(lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
clear_bit(GLF_BLOCKING, &gl->gl_flags);
spin_unlock(&gl->gl_lockref.lock);
if (glops->go_sync) {
ret = glops->go_sync(gl);
/* If we had a problem syncing (due to io errors or whatever,
* we should not invalidate the metadata or tell dlm to
* release the glock to other nodes.
*/
if (ret) {
if (cmpxchg(&sdp->sd_log_error, 0, ret)) {
fs_err(sdp, "Error %d syncing glock \n", ret);
gfs2_dump_glock(NULL, gl, true);
}
goto skip_inval;
}
}
if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags)) {
/*
* The call to go_sync should have cleared out the ail list.
* If there are still items, we have a problem. We ought to
* withdraw, but we can't because the withdraw code also uses
* glocks. Warn about the error, dump the glock, then fall
* through and wait for logd to do the withdraw for us.
*/
if ((atomic_read(&gl->gl_ail_count) != 0) &&
(!cmpxchg(&sdp->sd_log_error, 0, -EIO))) {
gfs2_glock_assert_warn(gl,
!atomic_read(&gl->gl_ail_count));
gfs2_dump_glock(NULL, gl, true);
}
glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
}
skip_inval:
gfs2_glock_hold(gl);
/*
* Check for an error encountered since we called go_sync and go_inval.
* If so, we can't withdraw from the glock code because the withdraw
* code itself uses glocks (see function signal_our_withdraw) to
* change the mount to read-only. Most importantly, we must not call
* dlm to unlock the glock until the journal is in a known good state
* (after journal replay) otherwise other nodes may use the object
* (rgrp or dinode) and then later, journal replay will corrupt the
* file system. The best we can do here is wait for the logd daemon
* to see sd_log_error and withdraw, and in the meantime, requeue the
* work for later.
*
* We make a special exception for some system glocks, such as the
* system statfs inode glock, which needs to be granted before the
* gfs2_quotad daemon can exit, and that exit needs to finish before
* we can unmount the withdrawn file system.
*
* However, if we're just unlocking the lock (say, for unmount, when
* gfs2_gl_hash_clear calls clear_glock) and recovery is complete
* then it's okay to tell dlm to unlock it.
*/
if (unlikely(sdp->sd_log_error && !gfs2_withdrawn(sdp)))
gfs2_withdraw_delayed(sdp);
if (glock_blocked_by_withdraw(gl) &&
(target != LM_ST_UNLOCKED ||
test_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags))) {
if (!is_system_glock(gl)) {
gfs2_glock_queue_work(gl, GL_GLOCK_DFT_HOLD);
goto out;
} else {
clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
}
}
if (sdp->sd_lockstruct.ls_ops->lm_lock) {
/* lock_dlm */
ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
if (ret == -EINVAL && gl->gl_target == LM_ST_UNLOCKED &&
target == LM_ST_UNLOCKED &&
test_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags)) {
finish_xmote(gl, target);
gfs2_glock_queue_work(gl, 0);
} else if (ret) {
fs_err(sdp, "lm_lock ret %d\n", ret);
GLOCK_BUG_ON(gl, !gfs2_withdrawn(sdp));
}
} else { /* lock_nolock */
finish_xmote(gl, target);
gfs2_glock_queue_work(gl, 0);
}
out:
spin_lock(&gl->gl_lockref.lock);
}
/**
* run_queue - do all outstanding tasks related to a glock
* @gl: The glock in question
* @nonblock: True if we must not block in run_queue
*
*/
static void run_queue(struct gfs2_glock *gl, const int nonblock)
__releases(&gl->gl_lockref.lock)
__acquires(&gl->gl_lockref.lock)
{
struct gfs2_holder *gh = NULL;
int ret;
if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
return;
GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
gl->gl_demote_state != gl->gl_state) {
if (find_first_holder(gl))
goto out_unlock;
if (nonblock)
goto out_sched;
set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
gl->gl_target = gl->gl_demote_state;
} else {
if (test_bit(GLF_DEMOTE, &gl->gl_flags))
gfs2_demote_wake(gl);
ret = do_promote(gl);
if (ret == 0)
goto out_unlock;
if (ret == 2)
goto out;
gh = find_first_waiter(gl);
gl->gl_target = gh->gh_state;
if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
do_error(gl, 0); /* Fail queued try locks */
}
do_xmote(gl, gh, gl->gl_target);
out:
return;
out_sched:
clear_bit(GLF_LOCK, &gl->gl_flags);
smp_mb__after_atomic();
gl->gl_lockref.count++;
__gfs2_glock_queue_work(gl, 0);
return;
out_unlock:
clear_bit(GLF_LOCK, &gl->gl_flags);
smp_mb__after_atomic();
return;
}
void gfs2_inode_remember_delete(struct gfs2_glock *gl, u64 generation)
{
struct gfs2_inode_lvb *ri = (void *)gl->gl_lksb.sb_lvbptr;
if (ri->ri_magic == 0)
ri->ri_magic = cpu_to_be32(GFS2_MAGIC);
if (ri->ri_magic == cpu_to_be32(GFS2_MAGIC))
ri->ri_generation_deleted = cpu_to_be64(generation);
}
bool gfs2_inode_already_deleted(struct gfs2_glock *gl, u64 generation)
{
struct gfs2_inode_lvb *ri = (void *)gl->gl_lksb.sb_lvbptr;
if (ri->ri_magic != cpu_to_be32(GFS2_MAGIC))
return false;
return generation <= be64_to_cpu(ri->ri_generation_deleted);
}
static void gfs2_glock_poke(struct gfs2_glock *gl)
{
int flags = LM_FLAG_TRY_1CB | LM_FLAG_ANY | GL_SKIP;
struct gfs2_holder gh;
int error;
__gfs2_holder_init(gl, LM_ST_SHARED, flags, &gh, _RET_IP_);
error = gfs2_glock_nq(&gh);
if (!error)
gfs2_glock_dq(&gh);
gfs2_holder_uninit(&gh);
}
static bool gfs2_try_evict(struct gfs2_glock *gl)
{
struct gfs2_inode *ip;
bool evicted = false;
/*
* If there is contention on the iopen glock and we have an inode, try
* to grab and release the inode so that it can be evicted. This will
* allow the remote node to go ahead and delete the inode without us
* having to do it, which will avoid rgrp glock thrashing.
*
* The remote node is likely still holding the corresponding inode
* glock, so it will run before we get to verify that the delete has
* happened below.
*/
spin_lock(&gl->gl_lockref.lock);
ip = gl->gl_object;
if (ip && !igrab(&ip->i_inode))
ip = NULL;
spin_unlock(&gl->gl_lockref.lock);
if (ip) {
struct gfs2_glock *inode_gl = NULL;
gl->gl_no_formal_ino = ip->i_no_formal_ino;
set_bit(GIF_DEFERRED_DELETE, &ip->i_flags);
d_prune_aliases(&ip->i_inode);
iput(&ip->i_inode);
/* If the inode was evicted, gl->gl_object will now be NULL. */
spin_lock(&gl->gl_lockref.lock);
ip = gl->gl_object;
if (ip) {
inode_gl = ip->i_gl;
lockref_get(&inode_gl->gl_lockref);
clear_bit(GIF_DEFERRED_DELETE, &ip->i_flags);
}
spin_unlock(&gl->gl_lockref.lock);
if (inode_gl) {
gfs2_glock_poke(inode_gl);
gfs2_glock_put(inode_gl);
}
evicted = !ip;
}
return evicted;
}
static void delete_work_func(struct work_struct *work)
{
struct delayed_work *dwork = to_delayed_work(work);
struct gfs2_glock *gl = container_of(dwork, struct gfs2_glock, gl_delete);
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct inode *inode;
u64 no_addr = gl->gl_name.ln_number;
spin_lock(&gl->gl_lockref.lock);
clear_bit(GLF_PENDING_DELETE, &gl->gl_flags);
spin_unlock(&gl->gl_lockref.lock);
if (test_bit(GLF_DEMOTE, &gl->gl_flags)) {
/*
* If we can evict the inode, give the remote node trying to
* delete the inode some time before verifying that the delete
* has happened. Otherwise, if we cause contention on the inode glock
* immediately, the remote node will think that we still have
* the inode in use, and so it will give up waiting.
*
* If we can't evict the inode, signal to the remote node that
* the inode is still in use. We'll later try to delete the
* inode locally in gfs2_evict_inode.
*
* FIXME: We only need to verify that the remote node has
* deleted the inode because nodes before this remote delete
* rework won't cooperate. At a later time, when we no longer
* care about compatibility with such nodes, we can skip this
* step entirely.
*/
if (gfs2_try_evict(gl)) {
if (gfs2_queue_delete_work(gl, 5 * HZ))
return;
}
goto out;
}
inode = gfs2_lookup_by_inum(sdp, no_addr, gl->gl_no_formal_ino,
GFS2_BLKST_UNLINKED);
if (!IS_ERR_OR_NULL(inode)) {
d_prune_aliases(inode);
iput(inode);
}
out:
gfs2_glock_put(gl);
}
static void glock_work_func(struct work_struct *work)
{
unsigned long delay = 0;
struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
unsigned int drop_refs = 1;
if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
finish_xmote(gl, gl->gl_reply);
drop_refs++;
}
spin_lock(&gl->gl_lockref.lock);
if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
gl->gl_state != LM_ST_UNLOCKED &&
gl->gl_demote_state != LM_ST_EXCLUSIVE) {
unsigned long holdtime, now = jiffies;
holdtime = gl->gl_tchange + gl->gl_hold_time;
if (time_before(now, holdtime))
delay = holdtime - now;
if (!delay) {
clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
gfs2_set_demote(gl);
}
}
run_queue(gl, 0);
if (delay) {
/* Keep one glock reference for the work we requeue. */
drop_refs--;
if (gl->gl_name.ln_type != LM_TYPE_INODE)
delay = 0;
__gfs2_glock_queue_work(gl, delay);
}
/*
* Drop the remaining glock references manually here. (Mind that
* __gfs2_glock_queue_work depends on the lockref spinlock begin held
* here as well.)
*/
gl->gl_lockref.count -= drop_refs;
if (!gl->gl_lockref.count) {
__gfs2_glock_put(gl);
return;
}
spin_unlock(&gl->gl_lockref.lock);
}
static struct gfs2_glock *find_insert_glock(struct lm_lockname *name,
struct gfs2_glock *new)
{
struct wait_glock_queue wait;
wait_queue_head_t *wq = glock_waitqueue(name);
struct gfs2_glock *gl;
wait.name = name;
init_wait(&wait.wait);
wait.wait.func = glock_wake_function;
again:
prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
rcu_read_lock();
if (new) {
gl = rhashtable_lookup_get_insert_fast(&gl_hash_table,
&new->gl_node, ht_parms);
if (IS_ERR(gl))
goto out;
} else {
gl = rhashtable_lookup_fast(&gl_hash_table,
name, ht_parms);
}
if (gl && !lockref_get_not_dead(&gl->gl_lockref)) {
rcu_read_unlock();
schedule();
goto again;
}
out:
rcu_read_unlock();
finish_wait(wq, &wait.wait);
return gl;
}
/**
* gfs2_glock_get() - Get a glock, or create one if one doesn't exist
* @sdp: The GFS2 superblock
* @number: the lock number
* @glops: The glock_operations to use
* @create: If 0, don't create the glock if it doesn't exist
* @glp: the glock is returned here
*
* This does not lock a glock, just finds/creates structures for one.
*
* Returns: errno
*/
int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
const struct gfs2_glock_operations *glops, int create,
struct gfs2_glock **glp)
{
struct super_block *s = sdp->sd_vfs;
struct lm_lockname name = { .ln_number = number,
.ln_type = glops->go_type,
.ln_sbd = sdp };
struct gfs2_glock *gl, *tmp;
struct address_space *mapping;
struct kmem_cache *cachep;
int ret = 0;
gl = find_insert_glock(&name, NULL);
if (gl) {
*glp = gl;
return 0;
}
if (!create)
return -ENOENT;
if (glops->go_flags & GLOF_ASPACE)
cachep = gfs2_glock_aspace_cachep;
else
cachep = gfs2_glock_cachep;
gl = kmem_cache_alloc(cachep, GFP_NOFS);
if (!gl)
return -ENOMEM;
memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
if (glops->go_flags & GLOF_LVB) {
gl->gl_lksb.sb_lvbptr = kzalloc(GDLM_LVB_SIZE, GFP_NOFS);
if (!gl->gl_lksb.sb_lvbptr) {
kmem_cache_free(cachep, gl);
return -ENOMEM;
}
}
atomic_inc(&sdp->sd_glock_disposal);
gl->gl_node.next = NULL;
gl->gl_flags = glops->go_instantiate ? BIT(GLF_INSTANTIATE_NEEDED) : 0;
gl->gl_name = name;
lockdep_set_subclass(&gl->gl_lockref.lock, glops->go_subclass);
gl->gl_lockref.count = 1;
gl->gl_state = LM_ST_UNLOCKED;
gl->gl_target = LM_ST_UNLOCKED;
gl->gl_demote_state = LM_ST_EXCLUSIVE;
gl->gl_ops = glops;
gl->gl_dstamp = 0;
preempt_disable();
/* We use the global stats to estimate the initial per-glock stats */
gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
preempt_enable();
gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
gl->gl_tchange = jiffies;
gl->gl_object = NULL;
gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
if (gl->gl_name.ln_type == LM_TYPE_IOPEN)
INIT_DELAYED_WORK(&gl->gl_delete, delete_work_func);
mapping = gfs2_glock2aspace(gl);
if (mapping) {
mapping->a_ops = &gfs2_meta_aops;
mapping->host = s->s_bdev->bd_inode;
mapping->flags = 0;
mapping_set_gfp_mask(mapping, GFP_NOFS);
mapping->private_data = NULL;
mapping->writeback_index = 0;
}
tmp = find_insert_glock(&name, gl);
if (!tmp) {
*glp = gl;
goto out;
}
if (IS_ERR(tmp)) {
ret = PTR_ERR(tmp);
goto out_free;
}
*glp = tmp;
out_free:
kfree(gl->gl_lksb.sb_lvbptr);
kmem_cache_free(cachep, gl);
if (atomic_dec_and_test(&sdp->sd_glock_disposal))
wake_up(&sdp->sd_glock_wait);
out:
return ret;
}
/**
* 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, u16 flags,
struct gfs2_holder *gh, unsigned long ip)
{
INIT_LIST_HEAD(&gh->gh_list);
gh->gh_gl = gl;
gh->gh_ip = ip;
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, u16 flags, struct gfs2_holder *gh)
{
gh->gh_state = state;
gh->gh_flags = flags;
gh->gh_iflags = 0;
gh->gh_ip = _RET_IP_;
put_pid(gh->gh_owner_pid);
gh->gh_owner_pid = get_pid(task_pid(current));
}
/**
* gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
* @gh: the holder structure
*
*/
void gfs2_holder_uninit(struct gfs2_holder *gh)
{
put_pid(gh->gh_owner_pid);
gfs2_glock_put(gh->gh_gl);
gfs2_holder_mark_uninitialized(gh);
gh->gh_ip = 0;
}
static void gfs2_glock_update_hold_time(struct gfs2_glock *gl,
unsigned long start_time)
{
/* Have we waited longer that a second? */
if (time_after(jiffies, start_time + HZ)) {
/* Lengthen the minimum hold time. */
gl->gl_hold_time = min(gl->gl_hold_time + GL_GLOCK_HOLD_INCR,
GL_GLOCK_MAX_HOLD);
}
}
/**
* gfs2_glock_wait - wait on a glock acquisition
* @gh: the glock holder
*
* Returns: 0 on success
*/
int gfs2_glock_wait(struct gfs2_holder *gh)
{
unsigned long start_time = jiffies;
might_sleep();
wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE);
gfs2_glock_update_hold_time(gh->gh_gl, start_time);
return gh->gh_error;
}
static int glocks_pending(unsigned int num_gh, struct gfs2_holder *ghs)
{
int i;
for (i = 0; i < num_gh; i++)
if (test_bit(HIF_WAIT, &ghs[i].gh_iflags))
return 1;
return 0;
}
/**
* gfs2_glock_async_wait - wait on multiple asynchronous glock acquisitions
* @num_gh: the number of holders in the array
* @ghs: the glock holder array
*
* Returns: 0 on success, meaning all glocks have been granted and are held.
* -ESTALE if the request timed out, meaning all glocks were released,
* and the caller should retry the operation.
*/
int gfs2_glock_async_wait(unsigned int num_gh, struct gfs2_holder *ghs)
{
struct gfs2_sbd *sdp = ghs[0].gh_gl->gl_name.ln_sbd;
int i, ret = 0, timeout = 0;
unsigned long start_time = jiffies;
bool keep_waiting;
might_sleep();
/*
* Total up the (minimum hold time * 2) of all glocks and use that to
* determine the max amount of time we should wait.
*/
for (i = 0; i < num_gh; i++)
timeout += ghs[i].gh_gl->gl_hold_time << 1;
wait_for_dlm:
if (!wait_event_timeout(sdp->sd_async_glock_wait,
!glocks_pending(num_gh, ghs), timeout))
ret = -ESTALE; /* request timed out. */
/*
* If dlm granted all our requests, we need to adjust the glock
* minimum hold time values according to how long we waited.
*
* If our request timed out, we need to repeatedly release any held
* glocks we acquired thus far to allow dlm to acquire the remaining
* glocks without deadlocking. We cannot currently cancel outstanding
* glock acquisitions.
*
* The HIF_WAIT bit tells us which requests still need a response from
* dlm.
*
* If dlm sent us any errors, we return the first error we find.
*/
keep_waiting = false;
for (i = 0; i < num_gh; i++) {
/* Skip holders we have already dequeued below. */
if (!gfs2_holder_queued(&ghs[i]))
continue;
/* Skip holders with a pending DLM response. */
if (test_bit(HIF_WAIT, &ghs[i].gh_iflags)) {
keep_waiting = true;
continue;
}
if (test_bit(HIF_HOLDER, &ghs[i].gh_iflags)) {
if (ret == -ESTALE)
gfs2_glock_dq(&ghs[i]);
else
gfs2_glock_update_hold_time(ghs[i].gh_gl,
start_time);
}
if (!ret)
ret = ghs[i].gh_error;
}
if (keep_waiting)
goto wait_for_dlm;
/*
* At this point, we've either acquired all locks or released them all.
*/
return ret;
}
/**
* handle_callback - process a demote request
* @gl: the glock
* @state: the state the caller wants us to change to
* @delay: zero to demote immediately; otherwise pending demote
* @remote: true if this came from a different cluster node
*
* There are only two requests that we are going to see in actual
* practise: LM_ST_SHARED and LM_ST_UNLOCKED
*/
static void handle_callback(struct gfs2_glock *gl, unsigned int state,
unsigned long delay, bool remote)
{
if (delay)
set_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
else
gfs2_set_demote(gl);
if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
gl->gl_demote_state = state;
gl->gl_demote_time = jiffies;
} else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
gl->gl_demote_state != state) {
gl->gl_demote_state = LM_ST_UNLOCKED;
}
if (gl->gl_ops->go_callback)
gl->gl_ops->go_callback(gl, remote);
trace_gfs2_demote_rq(gl, remote);
}
void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
{
struct va_format vaf;
va_list args;
va_start(args, fmt);
if (seq) {
seq_vprintf(seq, fmt, args);
} else {
vaf.fmt = fmt;
vaf.va = &args;
pr_err("%pV", &vaf);
}
va_end(args);
}
/**
* add_to_queue - Add a holder to the wait queue (but look for recursion)
* @gh: the holder structure to add
*
* Eventually we should move the recursive locking trap to a
* debugging option or something like that. This is the fast
* path and needs to have the minimum number of distractions.
*
*/
static inline void add_to_queue(struct gfs2_holder *gh)
__releases(&gl->gl_lockref.lock)
__acquires(&gl->gl_lockref.lock)
{
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct list_head *insert_pt = NULL;
struct gfs2_holder *gh2;
int try_futile = 0;
GLOCK_BUG_ON(gl, gh->gh_owner_pid == NULL);
if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
GLOCK_BUG_ON(gl, true);
if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
if (test_bit(GLF_LOCK, &gl->gl_flags)) {
struct gfs2_holder *first_gh;
first_gh = find_first_strong_holder(gl);
try_futile = !may_grant(gl, first_gh, gh);
}
if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
goto fail;
}
list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
(gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK) &&
!test_bit(HIF_MAY_DEMOTE, &gh2->gh_iflags)))
goto trap_recursive;
if (try_futile &&
!(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
fail:
gh->gh_error = GLR_TRYFAILED;
gfs2_holder_wake(gh);
return;
}
if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
continue;
if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
insert_pt = &gh2->gh_list;
}
trace_gfs2_glock_queue(gh, 1);
gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
if (likely(insert_pt == NULL)) {
list_add_tail(&gh->gh_list, &gl->gl_holders);
if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
goto do_cancel;
return;
}
list_add_tail(&gh->gh_list, insert_pt);
do_cancel:
gh = list_first_entry(&gl->gl_holders, struct gfs2_holder, gh_list);
if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
spin_unlock(&gl->gl_lockref.lock);
if (sdp->sd_lockstruct.ls_ops->lm_cancel)
sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
spin_lock(&gl->gl_lockref.lock);
}
return;
trap_recursive:
fs_err(sdp, "original: %pSR\n", (void *)gh2->gh_ip);
fs_err(sdp, "pid: %d\n", pid_nr(gh2->gh_owner_pid));
fs_err(sdp, "lock type: %d req lock state : %d\n",
gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
fs_err(sdp, "new: %pSR\n", (void *)gh->gh_ip);
fs_err(sdp, "pid: %d\n", pid_nr(gh->gh_owner_pid));
fs_err(sdp, "lock type: %d req lock state : %d\n",
gh->gh_gl->gl_name.ln_type, gh->gh_state);
gfs2_dump_glock(NULL, gl, true);
BUG();
}
/**
* gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
* @gh: the holder structure
*
* if (gh->gh_flags & GL_ASYNC), this never returns an error
*
* Returns: 0, GLR_TRYFAILED, or errno on failure
*/
int gfs2_glock_nq(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
int error = 0;
if (glock_blocked_by_withdraw(gl) && !(gh->gh_flags & LM_FLAG_NOEXP))
return -EIO;
if (test_bit(GLF_LRU, &gl->gl_flags))
gfs2_glock_remove_from_lru(gl);
spin_lock(&gl->gl_lockref.lock);
add_to_queue(gh);
if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) &&
test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) {
set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
gl->gl_lockref.count++;
__gfs2_glock_queue_work(gl, 0);
}
run_queue(gl, 1);
spin_unlock(&gl->gl_lockref.lock);
if (!(gh->gh_flags & GL_ASYNC))
error = gfs2_glock_wait(gh);
return error;
}
/**
* gfs2_glock_poll - poll to see if an async request has been completed
* @gh: the holder
*
* Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
*/
int gfs2_glock_poll(struct gfs2_holder *gh)
{
return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
}
static inline bool needs_demote(struct gfs2_glock *gl)
{
return (test_bit(GLF_DEMOTE, &gl->gl_flags) ||
test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags));
}
static void __gfs2_glock_dq(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
unsigned delay = 0;
int fast_path = 0;
/*
* This while loop is similar to function demote_incompat_holders:
* If the glock is due to be demoted (which may be from another node
* or even if this holder is GL_NOCACHE), the weak holders are
* demoted as well, allowing the glock to be demoted.
*/
while (gh) {
/*
* If we're in the process of file system withdraw, we cannot
* just dequeue any glocks until our journal is recovered, lest
* we introduce file system corruption. We need two exceptions
* to this rule: We need to allow unlocking of nondisk glocks
* and the glock for our own journal that needs recovery.
*/
if (test_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags) &&
glock_blocked_by_withdraw(gl) &&
gh->gh_gl != sdp->sd_jinode_gl) {
sdp->sd_glock_dqs_held++;
spin_unlock(&gl->gl_lockref.lock);
might_sleep();
wait_on_bit(&sdp->sd_flags, SDF_WITHDRAW_RECOVERY,
TASK_UNINTERRUPTIBLE);
spin_lock(&gl->gl_lockref.lock);
}
/*
* This holder should not be cached, so mark it for demote.
* Note: this should be done before the check for needs_demote
* below.
*/
if (gh->gh_flags & GL_NOCACHE)
handle_callback(gl, LM_ST_UNLOCKED, 0, false);
list_del_init(&gh->gh_list);
clear_bit(HIF_HOLDER, &gh->gh_iflags);
trace_gfs2_glock_queue(gh, 0);
/*
* If there hasn't been a demote request we are done.
* (Let the remaining holders, if any, keep holding it.)
*/
if (!needs_demote(gl)) {
if (list_empty(&gl->gl_holders))
fast_path = 1;
break;
}
/*
* If we have another strong holder (we cannot auto-demote)
* we are done. It keeps holding it until it is done.
*/
if (find_first_strong_holder(gl))
break;
/*
* If we have a weak holder at the head of the list, it
* (and all others like it) must be auto-demoted. If there
* are no more weak holders, we exit the while loop.
*/
gh = find_first_holder(gl);
}
if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl))
gfs2_glock_add_to_lru(gl);
if (unlikely(!fast_path)) {
gl->gl_lockref.count++;
if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
!test_bit(GLF_DEMOTE, &gl->gl_flags) &&
gl->gl_name.ln_type == LM_TYPE_INODE)
delay = gl->gl_hold_time;
__gfs2_glock_queue_work(gl, delay);
}
}
/**
* 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;
spin_lock(&gl->gl_lockref.lock);
__gfs2_glock_dq(gh);
spin_unlock(&gl->gl_lockref.lock);
}
void gfs2_glock_dq_wait(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
gfs2_glock_dq(gh);
might_sleep();
wait_on_bit(&gl->gl_flags, GLF_DEMOTE, TASK_UNINTERRUPTIBLE);
}
/**
* gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
* @gh: the holder structure
*
*/
void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
{
gfs2_glock_dq(gh);
gfs2_holder_uninit(gh);
}
/**
* gfs2_glock_nq_num - acquire a glock based on lock number
* @sdp: the filesystem
* @number: the lock number
* @glops: the glock operations for the type of glock
* @state: the state to acquire the glock in
* @flags: modifier flags for the acquisition
* @gh: the struct gfs2_holder
*
* Returns: errno
*/
int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
const struct gfs2_glock_operations *glops,
unsigned int state, u16 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
* @p: placeholder for the holder structure to pass back
*
* 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_array(num_gh, sizeof(struct gfs2_holder *),
GFP_NOFS);
if (!pph)
return -ENOMEM;
}
error = nq_m_sync(num_gh, ghs, pph);
if (pph != tmp)
kfree(pph);
return error;
}
/**
* gfs2_glock_dq_m - release multiple glocks
* @num_gh: the number of structures
* @ghs: an array of struct gfs2_holder structures
*
*/
void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
{
while (num_gh--)
gfs2_glock_dq(&ghs[num_gh]);
}
void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
{
struct gfs2_holder mock_gh = { .gh_gl = gl, .gh_state = state, };
unsigned long delay = 0;
unsigned long holdtime;
unsigned long now = jiffies;
gfs2_glock_hold(gl);
spin_lock(&gl->gl_lockref.lock);
holdtime = gl->gl_tchange + gl->gl_hold_time;
if (!list_empty(&gl->gl_holders) &&
gl->gl_name.ln_type == LM_TYPE_INODE) {
if (time_before(now, holdtime))
delay = holdtime - now;
if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
delay = gl->gl_hold_time;
}
/*
* Note 1: We cannot call demote_incompat_holders from handle_callback
* or gfs2_set_demote due to recursion problems like: gfs2_glock_dq ->
* handle_callback -> demote_incompat_holders -> gfs2_glock_dq
* Plus, we only want to demote the holders if the request comes from
* a remote cluster node because local holder conflicts are resolved
* elsewhere.
*
* Note 2: if a remote node wants this glock in EX mode, lock_dlm will
* request that we set our state to UNLOCKED. Here we mock up a holder
* to make it look like someone wants the lock EX locally. Any SH
* and DF requests should be able to share the lock without demoting.
*
* Note 3: We only want to demote the demoteable holders when there
* are no more strong holders. The demoteable holders might as well
* keep the glock until the last strong holder is done with it.
*/
if (!find_first_strong_holder(gl)) {
if (state == LM_ST_UNLOCKED)
mock_gh.gh_state = LM_ST_EXCLUSIVE;
demote_incompat_holders(gl, &mock_gh);
}
handle_callback(gl, state, delay, true);
__gfs2_glock_queue_work(gl, delay);
spin_unlock(&gl->gl_lockref.lock);
}
/**
* gfs2_should_freeze - Figure out if glock should be frozen
* @gl: The glock in question
*
* Glocks are not frozen if (a) the result of the dlm operation is
* an error, (b) the locking operation was an unlock operation or
* (c) if there is a "noexp" flagged request anywhere in the queue
*
* Returns: 1 if freezing should occur, 0 otherwise
*/
static int gfs2_should_freeze(const struct gfs2_glock *gl)
{
const struct gfs2_holder *gh;
if (gl->gl_reply & ~LM_OUT_ST_MASK)
return 0;
if (gl->gl_target == LM_ST_UNLOCKED)
return 0;
list_for_each_entry(gh, &gl->gl_holders, gh_list) {
if (test_bit(HIF_HOLDER, &gh->gh_iflags))
continue;
if (LM_FLAG_NOEXP & gh->gh_flags)
return 0;
}
return 1;
}
/**
* gfs2_glock_complete - Callback used by locking
* @gl: Pointer to the glock
* @ret: The return value from the dlm
*
* The gl_reply field is under the gl_lockref.lock lock so that it is ok
* to use a bitfield shared with other glock state fields.
*/
void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
{
struct lm_lockstruct *ls = &gl->gl_name.ln_sbd->sd_lockstruct;
spin_lock(&gl->gl_lockref.lock);
gl->gl_reply = ret;
if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
if (gfs2_should_freeze(gl)) {
set_bit(GLF_FROZEN, &gl->gl_flags);
spin_unlock(&gl->gl_lockref.lock);
return;
}
}
gl->gl_lockref.count++;
set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
__gfs2_glock_queue_work(gl, 0);
spin_unlock(&gl->gl_lockref.lock);
}
static int glock_cmp(void *priv, const struct list_head *a,
const struct list_head *b)
{
struct gfs2_glock *gla, *glb;
gla = list_entry(a, struct gfs2_glock, gl_lru);
glb = list_entry(b, struct gfs2_glock, gl_lru);
if (gla->gl_name.ln_number > glb->gl_name.ln_number)
return 1;
if (gla->gl_name.ln_number < glb->gl_name.ln_number)
return -1;
return 0;
}
/**
* gfs2_dispose_glock_lru - Demote a list of glocks
* @list: The list to dispose of
*
* Disposing of glocks may involve disk accesses, so that here we sort
* the glocks by number (i.e. disk location of the inodes) so that if
* there are any such accesses, they'll be sent in order (mostly).
*
* Must be called under the lru_lock, but may drop and retake this
* lock. While the lru_lock is dropped, entries may vanish from the
* list, but no new entries will appear on the list (since it is
* private)
*/
static void gfs2_dispose_glock_lru(struct list_head *list)
__releases(&lru_lock)
__acquires(&lru_lock)
{
struct gfs2_glock *gl;
list_sort(NULL, list, glock_cmp);
while(!list_empty(list)) {
gl = list_first_entry(list, struct gfs2_glock, gl_lru);
list_del_init(&gl->gl_lru);
clear_bit(GLF_LRU, &gl->gl_flags);
if (!spin_trylock(&gl->gl_lockref.lock)) {
add_back_to_lru:
list_add(&gl->gl_lru, &lru_list);
set_bit(GLF_LRU, &gl->gl_flags);
atomic_inc(&lru_count);
continue;
}
if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
spin_unlock(&gl->gl_lockref.lock);
goto add_back_to_lru;
}
gl->gl_lockref.count++;
if (demote_ok(gl))
handle_callback(gl, LM_ST_UNLOCKED, 0, false);
WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags));
__gfs2_glock_queue_work(gl, 0);
spin_unlock(&gl->gl_lockref.lock);
cond_resched_lock(&lru_lock);
}
}
/**
* gfs2_scan_glock_lru - Scan the LRU looking for locks to demote
* @nr: The number of entries to scan
*
* This function selects the entries on the LRU which are able to
* be demoted, and then kicks off the process by calling
* gfs2_dispose_glock_lru() above.
*/
static long gfs2_scan_glock_lru(int nr)
{
struct gfs2_glock *gl;
LIST_HEAD(skipped);
LIST_HEAD(dispose);
long freed = 0;
spin_lock(&lru_lock);
while ((nr-- >= 0) && !list_empty(&lru_list)) {
gl = list_first_entry(&lru_list, struct gfs2_glock, gl_lru);
/* Test for being demotable */
if (!test_bit(GLF_LOCK, &gl->gl_flags)) {
list_move(&gl->gl_lru, &dispose);
atomic_dec(&lru_count);
freed++;
continue;
}
list_move(&gl->gl_lru, &skipped);
}
list_splice(&skipped, &lru_list);
if (!list_empty(&dispose))
gfs2_dispose_glock_lru(&dispose);
spin_unlock(&lru_lock);
return freed;
}
static unsigned long gfs2_glock_shrink_scan(struct shrinker *shrink,
struct shrink_control *sc)
{
if (!(sc->gfp_mask & __GFP_FS))
return SHRINK_STOP;
return gfs2_scan_glock_lru(sc->nr_to_scan);
}
static unsigned long gfs2_glock_shrink_count(struct shrinker *shrink,
struct shrink_control *sc)
{
return vfs_pressure_ratio(atomic_read(&lru_count));
}
static struct shrinker glock_shrinker = {
.seeks = DEFAULT_SEEKS,
.count_objects = gfs2_glock_shrink_count,
.scan_objects = gfs2_glock_shrink_scan,
};
/**
* glock_hash_walk - Call a function for glock in a hash bucket
* @examiner: the function
* @sdp: the filesystem
*
* Note that the function can be called multiple times on the same
* object. So the user must ensure that the function can cope with
* that.
*/
static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
{
struct gfs2_glock *gl;
struct rhashtable_iter iter;
rhashtable_walk_enter(&gl_hash_table, &iter);
do {
rhashtable_walk_start(&iter);
while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl)) {
if (gl->gl_name.ln_sbd == sdp)
examiner(gl);
}
rhashtable_walk_stop(&iter);
} while (cond_resched(), gl == ERR_PTR(-EAGAIN));
rhashtable_walk_exit(&iter);
}
bool gfs2_queue_delete_work(struct gfs2_glock *gl, unsigned long delay)
{
bool queued;
spin_lock(&gl->gl_lockref.lock);
queued = queue_delayed_work(gfs2_delete_workqueue,
&gl->gl_delete, delay);
if (queued)
set_bit(GLF_PENDING_DELETE, &gl->gl_flags);
spin_unlock(&gl->gl_lockref.lock);
return queued;
}
void gfs2_cancel_delete_work(struct gfs2_glock *gl)
{
if (cancel_delayed_work(&gl->gl_delete)) {
clear_bit(GLF_PENDING_DELETE, &gl->gl_flags);
gfs2_glock_put(gl);
}
}
bool gfs2_delete_work_queued(const struct gfs2_glock *gl)
{
return test_bit(GLF_PENDING_DELETE, &gl->gl_flags);
}
static void flush_delete_work(struct gfs2_glock *gl)
{
if (gl->gl_name.ln_type == LM_TYPE_IOPEN) {
if (cancel_delayed_work(&gl->gl_delete)) {
queue_delayed_work(gfs2_delete_workqueue,
&gl->gl_delete, 0);
}
}
}
void gfs2_flush_delete_work(struct gfs2_sbd *sdp)
{
glock_hash_walk(flush_delete_work, sdp);
flush_workqueue(gfs2_delete_workqueue);
}
/**
* thaw_glock - thaw out a glock which has an unprocessed reply waiting
* @gl: The glock to thaw
*
*/
static void thaw_glock(struct gfs2_glock *gl)
{
if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
return;
if (!lockref_get_not_dead(&gl->gl_lockref))
return;
set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
gfs2_glock_queue_work(gl, 0);
}
/**
* clear_glock - look at a glock and see if we can free it from glock cache
* @gl: the glock to look at
*
*/
static void clear_glock(struct gfs2_glock *gl)
{
gfs2_glock_remove_from_lru(gl);
spin_lock(&gl->gl_lockref.lock);
if (!__lockref_is_dead(&gl->gl_lockref)) {
gl->gl_lockref.count++;
if (gl->gl_state != LM_ST_UNLOCKED)
handle_callback(gl, LM_ST_UNLOCKED, 0, false);
__gfs2_glock_queue_work(gl, 0);
}
spin_unlock(&gl->gl_lockref.lock);
}
/**
* gfs2_glock_thaw - Thaw any frozen glocks
* @sdp: The super block
*
*/
void gfs2_glock_thaw(struct gfs2_sbd *sdp)
{
glock_hash_walk(thaw_glock, sdp);
}
static void dump_glock(struct seq_file *seq, struct gfs2_glock *gl, bool fsid)
{
spin_lock(&gl->gl_lockref.lock);
gfs2_dump_glock(seq, gl, fsid);
spin_unlock(&gl->gl_lockref.lock);
}
static void dump_glock_func(struct gfs2_glock *gl)
{
dump_glock(NULL, gl, true);
}
/**
* gfs2_gl_hash_clear - Empty out the glock hash table
* @sdp: the filesystem
*
* Called when unmounting the filesystem.
*/
void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
{
set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
flush_workqueue(glock_workqueue);
glock_hash_walk(clear_glock, sdp);
flush_workqueue(glock_workqueue);
wait_event_timeout(sdp->sd_glock_wait,
atomic_read(&sdp->sd_glock_disposal) == 0,
HZ * 600);
glock_hash_walk(dump_glock_func, sdp);
}
void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
{
struct gfs2_glock *gl = ip->i_gl;
int ret;
ret = gfs2_truncatei_resume(ip);
gfs2_glock_assert_withdraw(gl, ret == 0);
spin_lock(&gl->gl_lockref.lock);
clear_bit(GLF_LOCK, &gl->gl_flags);
run_queue(gl, 1);
spin_unlock(&gl->gl_lockref.lock);
}
static const char *state2str(unsigned state)
{
switch(state) {
case LM_ST_UNLOCKED:
return "UN";
case LM_ST_SHARED:
return "SH";
case LM_ST_DEFERRED:
return "DF";
case LM_ST_EXCLUSIVE:
return "EX";
}
return "??";
}
static const char *hflags2str(char *buf, u16 flags, unsigned long iflags)
{
char *p = buf;
if (flags & LM_FLAG_TRY)
*p++ = 't';
if (flags & LM_FLAG_TRY_1CB)
*p++ = 'T';
if (flags & LM_FLAG_NOEXP)
*p++ = 'e';
if (flags & LM_FLAG_ANY)
*p++ = 'A';
if (flags & LM_FLAG_PRIORITY)
*p++ = 'p';
if (flags & LM_FLAG_NODE_SCOPE)
*p++ = 'n';
if (flags & GL_ASYNC)
*p++ = 'a';
if (flags & GL_EXACT)
*p++ = 'E';
if (flags & GL_NOCACHE)
*p++ = 'c';
if (test_bit(HIF_HOLDER, &iflags))
*p++ = 'H';
if (test_bit(HIF_WAIT, &iflags))
*p++ = 'W';
if (test_bit(HIF_MAY_DEMOTE, &iflags))
*p++ = 'D';
if (flags & GL_SKIP)
*p++ = 's';
*p = 0;
return buf;
}
/**
* dump_holder - print information about a glock holder
* @seq: the seq_file struct
* @gh: the glock holder
* @fs_id_buf: pointer to file system id (if requested)
*
*/
static void dump_holder(struct seq_file *seq, const struct gfs2_holder *gh,
const char *fs_id_buf)
{
struct task_struct *gh_owner = NULL;
char flags_buf[32];
rcu_read_lock();
if (gh->gh_owner_pid)
gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
gfs2_print_dbg(seq, "%s H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
fs_id_buf, state2str(gh->gh_state),
hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
gh->gh_error,
gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
gh_owner ? gh_owner->comm : "(ended)",
(void *)gh->gh_ip);
rcu_read_unlock();
}
static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
{
const unsigned long *gflags = &gl->gl_flags;
char *p = buf;
if (test_bit(GLF_LOCK, gflags))
*p++ = 'l';
if (test_bit(GLF_DEMOTE, gflags))
*p++ = 'D';
if (test_bit(GLF_PENDING_DEMOTE, gflags))
*p++ = 'd';
if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
*p++ = 'p';
if (test_bit(GLF_DIRTY, gflags))
*p++ = 'y';
if (test_bit(GLF_LFLUSH, gflags))
*p++ = 'f';
if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
*p++ = 'i';
if (test_bit(GLF_REPLY_PENDING, gflags))
*p++ = 'r';
if (test_bit(GLF_INITIAL, gflags))
*p++ = 'I';
if (test_bit(GLF_FROZEN, gflags))
*p++ = 'F';
if (!list_empty(&gl->gl_holders))
*p++ = 'q';
if (test_bit(GLF_LRU, gflags))
*p++ = 'L';
if (gl->gl_object)
*p++ = 'o';
if (test_bit(GLF_BLOCKING, gflags))
*p++ = 'b';
if (test_bit(GLF_PENDING_DELETE, gflags))
*p++ = 'P';
if (test_bit(GLF_FREEING, gflags))
*p++ = 'x';
if (test_bit(GLF_INSTANTIATE_NEEDED, gflags))
*p++ = 'n';
if (test_bit(GLF_INSTANTIATE_IN_PROG, gflags))
*p++ = 'N';
*p = 0;
return buf;
}
/**
* gfs2_dump_glock - print information about a glock
* @seq: The seq_file struct
* @gl: the glock
* @fsid: If true, also dump the file system id
*
* The file format is as follows:
* One line per object, capital letters are used to indicate objects
* G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
* other objects are indented by a single space and follow the glock to
* which they are related. Fields are indicated by lower case letters
* followed by a colon and the field value, except for strings which are in
* [] so that its possible to see if they are composed of spaces for
* example. The field's are n = number (id of the object), f = flags,
* t = type, s = state, r = refcount, e = error, p = pid.
*
*/
void gfs2_dump_glock(struct seq_file *seq, struct gfs2_glock *gl, bool fsid)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
unsigned long long dtime;
const struct gfs2_holder *gh;
char gflags_buf[32];
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
char fs_id_buf[sizeof(sdp->sd_fsname) + 7];
unsigned long nrpages = 0;
if (gl->gl_ops->go_flags & GLOF_ASPACE) {
struct address_space *mapping = gfs2_glock2aspace(gl);
nrpages = mapping->nrpages;
}
memset(fs_id_buf, 0, sizeof(fs_id_buf));
if (fsid && sdp) /* safety precaution */
sprintf(fs_id_buf, "fsid=%s: ", sdp->sd_fsname);
dtime = jiffies - gl->gl_demote_time;
dtime *= 1000000/HZ; /* demote time in uSec */
if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
dtime = 0;
gfs2_print_dbg(seq, "%sG: s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d "
"v:%d r:%d m:%ld p:%lu\n",
fs_id_buf, state2str(gl->gl_state),
gl->gl_name.ln_type,
(unsigned long long)gl->gl_name.ln_number,
gflags2str(gflags_buf, gl),
state2str(gl->gl_target),
state2str(gl->gl_demote_state), dtime,
atomic_read(&gl->gl_ail_count),
atomic_read(&gl->gl_revokes),
(int)gl->gl_lockref.count, gl->gl_hold_time, nrpages);
list_for_each_entry(gh, &gl->gl_holders, gh_list)
dump_holder(seq, gh, fs_id_buf);
if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
glops->go_dump(seq, gl, fs_id_buf);
}
static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
{
struct gfs2_glock *gl = iter_ptr;
seq_printf(seq, "G: n:%u/%llx rtt:%llu/%llu rttb:%llu/%llu irt:%llu/%llu dcnt: %llu qcnt: %llu\n",
gl->gl_name.ln_type,
(unsigned long long)gl->gl_name.ln_number,
(unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
(unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
(unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
(unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
(unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
(unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
(unsigned long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
(unsigned long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
return 0;
}
static const char *gfs2_gltype[] = {
"type",
"reserved",
"nondisk",
"inode",
"rgrp",
"meta",
"iopen",
"flock",
"plock",
"quota",
"journal",
};
static const char *gfs2_stype[] = {
[GFS2_LKS_SRTT] = "srtt",
[GFS2_LKS_SRTTVAR] = "srttvar",
[GFS2_LKS_SRTTB] = "srttb",
[GFS2_LKS_SRTTVARB] = "srttvarb",
[GFS2_LKS_SIRT] = "sirt",
[GFS2_LKS_SIRTVAR] = "sirtvar",
[GFS2_LKS_DCOUNT] = "dlm",
[GFS2_LKS_QCOUNT] = "queue",
};
#define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
{
struct gfs2_sbd *sdp = seq->private;
loff_t pos = *(loff_t *)iter_ptr;
unsigned index = pos >> 3;
unsigned subindex = pos & 0x07;
int i;
if (index == 0 && subindex != 0)
return 0;
seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
(index == 0) ? "cpu": gfs2_stype[subindex]);
for_each_possible_cpu(i) {
const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
if (index == 0)
seq_printf(seq, " %15u", i);
else
seq_printf(seq, " %15llu", (unsigned long long)lkstats->
lkstats[index - 1].stats[subindex]);
}
seq_putc(seq, '\n');
return 0;
}
int __init gfs2_glock_init(void)
{
int i, ret;
ret = rhashtable_init(&gl_hash_table, &ht_parms);
if (ret < 0)
return ret;
glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
WQ_HIGHPRI | WQ_FREEZABLE, 0);
if (!glock_workqueue) {
rhashtable_destroy(&gl_hash_table);
return -ENOMEM;
}
gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
WQ_MEM_RECLAIM | WQ_FREEZABLE,
0);
if (!gfs2_delete_workqueue) {
destroy_workqueue(glock_workqueue);
rhashtable_destroy(&gl_hash_table);
return -ENOMEM;
}
ret = register_shrinker(&glock_shrinker);
if (ret) {
destroy_workqueue(gfs2_delete_workqueue);
destroy_workqueue(glock_workqueue);
rhashtable_destroy(&gl_hash_table);
return ret;
}
for (i = 0; i < GLOCK_WAIT_TABLE_SIZE; i++)
init_waitqueue_head(glock_wait_table + i);
return 0;
}
void gfs2_glock_exit(void)
{
unregister_shrinker(&glock_shrinker);
rhashtable_destroy(&gl_hash_table);
destroy_workqueue(glock_workqueue);
destroy_workqueue(gfs2_delete_workqueue);
}
static void gfs2_glock_iter_next(struct gfs2_glock_iter *gi, loff_t n)
{
struct gfs2_glock *gl = gi->gl;
if (gl) {
if (n == 0)
return;
if (!lockref_put_not_zero(&gl->gl_lockref))
gfs2_glock_queue_put(gl);
}
for (;;) {
gl = rhashtable_walk_next(&gi->hti);
if (IS_ERR_OR_NULL(gl)) {
if (gl == ERR_PTR(-EAGAIN)) {
n = 1;
continue;
}
gl = NULL;
break;
}
if (gl->gl_name.ln_sbd != gi->sdp)
continue;
if (n <= 1) {
if (!lockref_get_not_dead(&gl->gl_lockref))
continue;
break;
} else {
if (__lockref_is_dead(&gl->gl_lockref))
continue;
n--;
}
}
gi->gl = gl;
}
static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
__acquires(RCU)
{
struct gfs2_glock_iter *gi = seq->private;
loff_t n;
/*
* We can either stay where we are, skip to the next hash table
* entry, or start from the beginning.
*/
if (*pos < gi->last_pos) {
rhashtable_walk_exit(&gi->hti);
rhashtable_walk_enter(&gl_hash_table, &gi->hti);
n = *pos + 1;
} else {
n = *pos - gi->last_pos;
}
rhashtable_walk_start(&gi->hti);
gfs2_glock_iter_next(gi, n);
gi->last_pos = *pos;
return gi->gl;
}
static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
loff_t *pos)
{
struct gfs2_glock_iter *gi = seq->private;
(*pos)++;
gi->last_pos = *pos;
gfs2_glock_iter_next(gi, 1);
return gi->gl;
}
static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
__releases(RCU)
{
struct gfs2_glock_iter *gi = seq->private;
rhashtable_walk_stop(&gi->hti);
}
static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
{
dump_glock(seq, iter_ptr, false);
return 0;
}
static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
{
preempt_disable();
if (*pos >= GFS2_NR_SBSTATS)
return NULL;
return pos;
}
static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
loff_t *pos)
{
(*pos)++;
if (*pos >= GFS2_NR_SBSTATS)
return NULL;
return pos;
}
static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
{
preempt_enable();
}
static const struct seq_operations gfs2_glock_seq_ops = {
.start = gfs2_glock_seq_start,
.next = gfs2_glock_seq_next,
.stop = gfs2_glock_seq_stop,
.show = gfs2_glock_seq_show,
};
static const struct seq_operations gfs2_glstats_seq_ops = {
.start = gfs2_glock_seq_start,
.next = gfs2_glock_seq_next,
.stop = gfs2_glock_seq_stop,
.show = gfs2_glstats_seq_show,
};
static const struct seq_operations gfs2_sbstats_sops = {
.start = gfs2_sbstats_seq_start,
.next = gfs2_sbstats_seq_next,
.stop = gfs2_sbstats_seq_stop,
.show = gfs2_sbstats_seq_show,
};
#define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
static int __gfs2_glocks_open(struct inode *inode, struct file *file,
const struct seq_operations *ops)
{
int ret = seq_open_private(file, ops, sizeof(struct gfs2_glock_iter));
if (ret == 0) {
struct seq_file *seq = file->private_data;
struct gfs2_glock_iter *gi = seq->private;
gi->sdp = inode->i_private;
seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
if (seq->buf)
seq->size = GFS2_SEQ_GOODSIZE;
/*
* Initially, we are "before" the first hash table entry; the
* first call to rhashtable_walk_next gets us the first entry.
*/
gi->last_pos = -1;
gi->gl = NULL;
rhashtable_walk_enter(&gl_hash_table, &gi->hti);
}
return ret;
}
static int gfs2_glocks_open(struct inode *inode, struct file *file)
{
return __gfs2_glocks_open(inode, file, &gfs2_glock_seq_ops);
}
static int gfs2_glocks_release(struct inode *inode, struct file *file)
{
struct seq_file *seq = file->private_data;
struct gfs2_glock_iter *gi = seq->private;
if (gi->gl)
gfs2_glock_put(gi->gl);
rhashtable_walk_exit(&gi->hti);
return seq_release_private(inode, file);
}
static int gfs2_glstats_open(struct inode *inode, struct file *file)
{
return __gfs2_glocks_open(inode, file, &gfs2_glstats_seq_ops);
}
static const struct file_operations gfs2_glocks_fops = {
.owner = THIS_MODULE,
.open = gfs2_glocks_open,
.read = seq_read,
.llseek = seq_lseek,
.release = gfs2_glocks_release,
};
static const struct file_operations gfs2_glstats_fops = {
.owner = THIS_MODULE,
.open = gfs2_glstats_open,
.read = seq_read,
.llseek = seq_lseek,
.release = gfs2_glocks_release,
};
DEFINE_SEQ_ATTRIBUTE(gfs2_sbstats);
void gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
{
sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
debugfs_create_file("glocks", S_IFREG | S_IRUGO, sdp->debugfs_dir, sdp,
&gfs2_glocks_fops);
debugfs_create_file("glstats", S_IFREG | S_IRUGO, sdp->debugfs_dir, sdp,
&gfs2_glstats_fops);
debugfs_create_file("sbstats", S_IFREG | S_IRUGO, sdp->debugfs_dir, sdp,
&gfs2_sbstats_fops);
}
void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
{
debugfs_remove_recursive(sdp->debugfs_dir);
sdp->debugfs_dir = NULL;
}
void gfs2_register_debugfs(void)
{
gfs2_root = debugfs_create_dir("gfs2", NULL);
}
void gfs2_unregister_debugfs(void)
{
debugfs_remove(gfs2_root);
gfs2_root = NULL;
}
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