glock.c 49.9 KB
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/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
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 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
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 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
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 * of the GNU General Public License version 2.
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 */

#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/kref.h>
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#include <linux/kallsyms.h>
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#include <linux/gfs2_ondisk.h>
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#include <asm/uaccess.h>

#include "gfs2.h"
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#include "lm_interface.h"
#include "incore.h"
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#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"
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#include "util.h"
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/*  Must be kept in sync with the beginning of struct gfs2_glock  */
struct glock_plug {
	struct list_head gl_list;
	unsigned long gl_flags;
};

struct greedy {
	struct gfs2_holder gr_gh;
	struct work_struct gr_work;
};

typedef void (*glock_examiner) (struct gfs2_glock * gl);

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static int gfs2_dump_lockstate(struct gfs2_sbd *sdp);
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static int dump_glock(struct gfs2_glock *gl);
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static struct gfs2_gl_hash_bucket gl_hash_table[GFS2_GL_HASH_SIZE];

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/**
 * 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
 */

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static unsigned int gl_hash(const struct gfs2_sbd *sdp,
			    const struct lm_lockname *name)
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{
	unsigned int h;

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	h = jhash(&name->ln_number, sizeof(u64), 0);
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	h = jhash(&name->ln_type, sizeof(unsigned int), h);
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	h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
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	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)
{
	kref_get(&gl->gl_ref);
}

/* All work is done after the return from kref_put() so we
   can release the write_lock before the free. */

static void kill_glock(struct kref *kref)
{
	struct gfs2_glock *gl = container_of(kref, struct gfs2_glock, gl_ref);
	struct gfs2_sbd *sdp = gl->gl_sbd;

	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_waiters2));
	gfs2_assert(sdp, list_empty(&gl->gl_waiters3));
}

/**
 * gfs2_glock_put() - Decrement reference count on glock
 * @gl: The glock to put
 *
 */

int gfs2_glock_put(struct gfs2_glock *gl)
{
	struct gfs2_gl_hash_bucket *bucket = gl->gl_bucket;
	int rv = 0;

	write_lock(&bucket->hb_lock);
	if (kref_put(&gl->gl_ref, kill_glock)) {
		list_del_init(&gl->gl_list);
		write_unlock(&bucket->hb_lock);
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		BUG_ON(spin_is_locked(&gl->gl_spin));
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		glock_free(gl);
		rv = 1;
		goto out;
	}
	write_unlock(&bucket->hb_lock);
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out:
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	return rv;
}

/**
 * queue_empty - check to see if a glock's queue is empty
 * @gl: the glock
 * @head: the head of the queue to check
 *
 * This function protects the list in the event that a process already
 * has a holder on the list and is adding a second holder for itself.
 * The glmutex lock is what generally prevents processes from working
 * on the same glock at once, but the special case of adding a second
 * holder for yourself ("recursive" locking) doesn't involve locking
 * glmutex, making the spin lock necessary.
 *
 * Returns: 1 if the queue is empty
 */

static inline int queue_empty(struct gfs2_glock *gl, struct list_head *head)
{
	int empty;
	spin_lock(&gl->gl_spin);
	empty = list_empty(head);
	spin_unlock(&gl->gl_spin);
	return empty;
}

/**
 * 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(struct gfs2_gl_hash_bucket *bucket,
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					const struct gfs2_sbd *sdp,
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					const struct lm_lockname *name)
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{
	struct gfs2_glock *gl;

	list_for_each_entry(gl, &bucket->hb_list, gl_list) {
		if (test_bit(GLF_PLUG, &gl->gl_flags))
			continue;
		if (!lm_name_equal(&gl->gl_name, name))
			continue;
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		if (gl->gl_sbd != sdp)
			continue;
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		kref_get(&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
 */

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static struct gfs2_glock *gfs2_glock_find(const struct gfs2_sbd *sdp,
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					  const struct lm_lockname *name)
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{
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	struct gfs2_gl_hash_bucket *bucket = &gl_hash_table[gl_hash(sdp, name)];
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	struct gfs2_glock *gl;

	read_lock(&bucket->hb_lock);
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	gl = search_bucket(bucket, sdp, name);
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	read_unlock(&bucket->hb_lock);

	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
 */

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int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
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		   const struct gfs2_glock_operations *glops, int create,
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		   struct gfs2_glock **glp)
{
	struct lm_lockname name;
	struct gfs2_glock *gl, *tmp;
	struct gfs2_gl_hash_bucket *bucket;
	int error;

	name.ln_number = number;
	name.ln_type = glops->go_type;
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	bucket = &gl_hash_table[gl_hash(sdp, &name)];
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	read_lock(&bucket->hb_lock);
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	gl = search_bucket(bucket, sdp, &name);
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	read_unlock(&bucket->hb_lock);

	if (gl || !create) {
		*glp = gl;
		return 0;
	}

	gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
	if (!gl)
		return -ENOMEM;

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	gl->gl_flags = 0;
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	gl->gl_name = name;
	kref_init(&gl->gl_ref);
	gl->gl_state = LM_ST_UNLOCKED;
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	gl->gl_owner = NULL;
	gl->gl_ip = 0;
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	gl->gl_ops = glops;
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	gl->gl_req_gh = NULL;
	gl->gl_req_bh = NULL;
	gl->gl_vn = 0;
	gl->gl_stamp = jiffies;
	gl->gl_object = NULL;
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	gl->gl_bucket = bucket;
	gl->gl_sbd = sdp;
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	gl->gl_aspace = NULL;
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	lops_init_le(&gl->gl_le, &gfs2_glock_lops);

	/* If this glock protects actual on-disk data or metadata blocks,
	   create a VFS inode to manage the pages/buffers holding them. */
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	if (glops == &gfs2_inode_glops || glops == &gfs2_rgrp_glops) {
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		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(&bucket->hb_lock);
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	tmp = search_bucket(bucket, sdp, &name);
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	if (tmp) {
		write_unlock(&bucket->hb_lock);
		glock_free(gl);
		gl = tmp;
	} else {
		list_add_tail(&gl->gl_list, &bucket->hb_list);
		write_unlock(&bucket->hb_lock);
	}

	*glp = gl;

	return 0;

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fail_aspace:
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	if (gl->gl_aspace)
		gfs2_aspace_put(gl->gl_aspace);
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fail:
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	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
 *
 */

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void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
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		      struct gfs2_holder *gh)
{
	INIT_LIST_HEAD(&gh->gh_list);
	gh->gh_gl = gl;
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	gh->gh_ip = (unsigned long)__builtin_return_address(0);
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	gh->gh_owner = current;
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	gh->gh_state = state;
	gh->gh_flags = flags;
	gh->gh_error = 0;
	gh->gh_iflags = 0;
	init_completion(&gh->gh_wait);

	if (gh->gh_state == LM_ST_EXCLUSIVE)
		gh->gh_flags |= GL_LOCAL_EXCL;

	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.
 *
 */

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void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
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{
	gh->gh_state = state;
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	gh->gh_flags = flags;
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	if (gh->gh_state == LM_ST_EXCLUSIVE)
		gh->gh_flags |= GL_LOCAL_EXCL;

	gh->gh_iflags &= 1 << HIF_ALLOCED;
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	gh->gh_ip = (unsigned long)__builtin_return_address(0);
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}

/**
 * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 * @gh: the holder structure
 *
 */

void gfs2_holder_uninit(struct gfs2_holder *gh)
{
	gfs2_glock_put(gh->gh_gl);
	gh->gh_gl = NULL;
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	gh->gh_ip = 0;
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}

/**
 * gfs2_holder_get - get a struct gfs2_holder structure
 * @gl: the glock
 * @state: the state we're requesting
 * @flags: the modifier flags
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 * @gfp_flags:
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 *
 * Figure out how big an impact this function has.  Either:
 * 1) Replace it with a cache of structures hanging off the struct gfs2_sbd
 * 2) Leave it like it is
 *
 * Returns: the holder structure, NULL on ENOMEM
 */

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static struct gfs2_holder *gfs2_holder_get(struct gfs2_glock *gl,
					   unsigned int state,
					   int flags, gfp_t gfp_flags)
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{
	struct gfs2_holder *gh;

	gh = kmalloc(sizeof(struct gfs2_holder), gfp_flags);
	if (!gh)
		return NULL;

	gfs2_holder_init(gl, state, flags, gh);
	set_bit(HIF_ALLOCED, &gh->gh_iflags);
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	gh->gh_ip = (unsigned long)__builtin_return_address(0);
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	return gh;
}

/**
 * gfs2_holder_put - get rid of a struct gfs2_holder structure
 * @gh: the holder structure
 *
 */

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static void gfs2_holder_put(struct gfs2_holder *gh)
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{
	gfs2_holder_uninit(gh);
	kfree(gh);
}

/**
 * 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);
	complete(&gh->gh_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;
	struct gfs2_sbd *sdp = gl->gl_sbd;
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	const struct gfs2_glock_operations *glops = gl->gl_ops;
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	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);

			if (atomic_read(&sdp->sd_reclaim_count) >
			    gfs2_tune_get(sdp, gt_reclaim_limit) &&
			    !(gh->gh_flags & LM_FLAG_PRIORITY)) {
				gfs2_reclaim_glock(sdp);
				gfs2_reclaim_glock(sdp);
			}

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			glops->go_xmote_th(gl, gh->gh_state, gh->gh_flags);
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			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_flags & GL_LOCAL_EXCL)
			return 1;
		next_gh = list_entry(gl->gl_holders.next, struct gfs2_holder,
				     gh_list);
		if (next_gh->gh_flags & GL_LOCAL_EXCL)
			 return 1;
	}

	list_move_tail(&gh->gh_list, &gl->gl_holders);
	gh->gh_error = 0;
	set_bit(HIF_HOLDER, &gh->gh_iflags);

	complete(&gh->gh_wait);

	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_holder *gh)
{
	struct gfs2_glock *gl = gh->gh_gl;
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	const struct gfs2_glock_operations *glops = gl->gl_ops;
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	if (!list_empty(&gl->gl_holders))
		return 1;

	if (gl->gl_state == gh->gh_state || gl->gl_state == LM_ST_UNLOCKED) {
		list_del_init(&gh->gh_list);
		gh->gh_error = 0;
		spin_unlock(&gl->gl_spin);
		if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
			gfs2_holder_put(gh);
		else
			complete(&gh->gh_wait);
		spin_lock(&gl->gl_spin);
	} else {
		gl->gl_req_gh = gh;
		set_bit(GLF_LOCK, &gl->gl_flags);
		spin_unlock(&gl->gl_spin);

		if (gh->gh_state == LM_ST_UNLOCKED ||
		    gl->gl_state != LM_ST_EXCLUSIVE)
			glops->go_drop_th(gl);
		else
			glops->go_xmote_th(gl, gh->gh_state, gh->gh_flags);

		spin_lock(&gl->gl_spin);
	}

	return 0;
}

/**
 * rq_greedy - process a queued request to drop greedy status
 * @gh: the glock holder
 *
 * Returns: 1 if the queue is blocked
 */

static int rq_greedy(struct gfs2_holder *gh)
{
	struct gfs2_glock *gl = gh->gh_gl;

	list_del_init(&gh->gh_list);
	/*  gh->gh_error never examined.  */
	clear_bit(GLF_GREEDY, &gl->gl_flags);
	spin_unlock(&gl->gl_spin);

	gfs2_holder_uninit(gh);
	kfree(container_of(gh, struct greedy, gr_gh));

	spin_lock(&gl->gl_spin);		

	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);

			if (test_bit(HIF_MUTEX, &gh->gh_iflags))
				blocked = rq_mutex(gh);
			else
				gfs2_assert_warn(gl->gl_sbd, 0);

		} else if (!list_empty(&gl->gl_waiters2) &&
			   !test_bit(GLF_SKIP_WAITERS2, &gl->gl_flags)) {
			gh = list_entry(gl->gl_waiters2.next,
					struct gfs2_holder, gh_list);

			if (test_bit(HIF_DEMOTE, &gh->gh_iflags))
				blocked = rq_demote(gh);
			else if (test_bit(HIF_GREEDY, &gh->gh_iflags))
				blocked = rq_greedy(gh);
			else
				gfs2_assert_warn(gl->gl_sbd, 0);

		} else if (!list_empty(&gl->gl_waiters3)) {
			gh = list_entry(gl->gl_waiters3.next,
					struct gfs2_holder, gh_list);

			if (test_bit(HIF_PROMOTE, &gh->gh_iflags))
				blocked = rq_promote(gh);
			else
				gfs2_assert_warn(gl->gl_sbd, 0);

		} 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.
 */

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static void gfs2_glmutex_lock(struct gfs2_glock *gl)
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{
	struct gfs2_holder gh;

	gfs2_holder_init(gl, 0, 0, &gh);
	set_bit(HIF_MUTEX, &gh.gh_iflags);

	spin_lock(&gl->gl_spin);
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	if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
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		list_add_tail(&gh.gh_list, &gl->gl_waiters1);
655
	} else {
656 657
		gl->gl_owner = current;
		gl->gl_ip = (unsigned long)__builtin_return_address(0);
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		complete(&gh.gh_wait);
659
	}
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	spin_unlock(&gl->gl_spin);

	wait_for_completion(&gh.gh_wait);
	gfs2_holder_uninit(&gh);
}

/**
 * gfs2_glmutex_trylock - try to acquire a local lock on a glock
 * @gl: the glock
 *
 * Returns: 1 if the glock is acquired
 */

673
static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
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{
	int acquired = 1;

	spin_lock(&gl->gl_spin);
678
	if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
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		acquired = 0;
680
	} else {
681 682 683
		gl->gl_owner = current;
		gl->gl_ip = (unsigned long)__builtin_return_address(0);
	}
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	spin_unlock(&gl->gl_spin);

	return acquired;
}

/**
 * gfs2_glmutex_unlock - release a local lock on a glock
 * @gl: the glock
 *
 */

695
static void gfs2_glmutex_unlock(struct gfs2_glock *gl)
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{
	spin_lock(&gl->gl_spin);
	clear_bit(GLF_LOCK, &gl->gl_flags);
699 700
	gl->gl_owner = NULL;
	gl->gl_ip = 0;
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	run_queue(gl);
702
	BUG_ON(!spin_is_locked(&gl->gl_spin));
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	spin_unlock(&gl->gl_spin);
}

/**
 * handle_callback - add a demote request to a lock's queue
 * @gl: the glock
 * @state: the state the caller wants us to change to
 *
711
 * Note: This may fail sliently if we are out of memory.
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 */

static void handle_callback(struct gfs2_glock *gl, unsigned int state)
{
	struct gfs2_holder *gh, *new_gh = NULL;

718
restart:
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	spin_lock(&gl->gl_spin);

	list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
		if (test_bit(HIF_DEMOTE, &gh->gh_iflags) &&
		    gl->gl_req_gh != gh) {
			if (gh->gh_state != state)
				gh->gh_state = LM_ST_UNLOCKED;
			goto out;
		}
	}

	if (new_gh) {
		list_add_tail(&new_gh->gh_list, &gl->gl_waiters2);
		new_gh = NULL;
	} else {
		spin_unlock(&gl->gl_spin);

736 737 738
		new_gh = gfs2_holder_get(gl, state, LM_FLAG_TRY, GFP_KERNEL);
		if (!new_gh)
			return;
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		set_bit(HIF_DEMOTE, &new_gh->gh_iflags);
		set_bit(HIF_DEALLOC, &new_gh->gh_iflags);

		goto restart;
	}

745
out:
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	spin_unlock(&gl->gl_spin);

	if (new_gh)
		gfs2_holder_put(new_gh);
}

752 753 754 755 756 757 758 759 760 761 762
void gfs2_glock_inode_squish(struct inode *inode)
{
	struct gfs2_holder gh;
	struct gfs2_glock *gl = GFS2_I(inode)->i_gl;
	gfs2_holder_init(gl, LM_ST_UNLOCKED, 0, &gh);
	set_bit(HIF_DEMOTE, &gh.gh_iflags);
	spin_lock(&gl->gl_spin);
	gfs2_assert(inode->i_sb->s_fs_info, list_empty(&gl->gl_holders));
	list_add_tail(&gh.gh_list, &gl->gl_waiters2);
	run_queue(gl);
	spin_unlock(&gl->gl_spin);
763
	wait_for_completion(&gh.gh_wait);
764 765 766
	gfs2_holder_uninit(&gh);
}

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/**
 * 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) {
782
		if (held2)
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			gfs2_glock_hold(gl);
784
		else
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			gfs2_glock_put(gl);
	}

	gl->gl_state = new_state;
}

/**
 * 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;
801
	const struct gfs2_glock_operations *glops = gl->gl_ops;
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	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, queue_empty(gl, &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 | DIO_DATA);
	} 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, DIO_DATA);
	}

	/*  Deal with each possible exit condition  */

	if (!gh)
		gl->gl_stamp = jiffies;
	else if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
		spin_lock(&gl->gl_spin);
		list_del_init(&gh->gh_list);
		gh->gh_error = -EIO;
		spin_unlock(&gl->gl_spin);
	} else if (test_bit(HIF_DEMOTE, &gh->gh_iflags)) {
		spin_lock(&gl->gl_spin);
		list_del_init(&gh->gh_list);
		if (gl->gl_state == gh->gh_state ||
835
		    gl->gl_state == LM_ST_UNLOCKED) {
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			gh->gh_error = 0;
837
		} else {
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			if (gfs2_assert_warn(sdp, gh->gh_flags &
					(LM_FLAG_TRY | LM_FLAG_TRY_1CB)) == -1)
				fs_warn(sdp, "ret = 0x%.8X\n", ret);
			gh->gh_error = GLR_TRYFAILED;
		}
		spin_unlock(&gl->gl_spin);

		if (ret & LM_OUT_CANCELED)
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			handle_callback(gl, LM_ST_UNLOCKED);
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	} else if (ret & LM_OUT_CANCELED) {
		spin_lock(&gl->gl_spin);
		list_del_init(&gh->gh_list);
		gh->gh_error = GLR_CANCELED;
		spin_unlock(&gl->gl_spin);

	} else if (relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
		spin_lock(&gl->gl_spin);
		list_move_tail(&gh->gh_list, &gl->gl_holders);
		gh->gh_error = 0;
		set_bit(HIF_HOLDER, &gh->gh_iflags);
		spin_unlock(&gl->gl_spin);

		set_bit(HIF_FIRST, &gh->gh_iflags);

		op_done = 0;

	} else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
		spin_lock(&gl->gl_spin);
		list_del_init(&gh->gh_list);
		gh->gh_error = GLR_TRYFAILED;
		spin_unlock(&gl->gl_spin);

	} else {
		if (gfs2_assert_withdraw(sdp, 0) == -1)
			fs_err(sdp, "ret = 0x%.8X\n", ret);
	}

	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);
		run_queue(gl);
		spin_unlock(&gl->gl_spin);
	}

	gfs2_glock_put(gl);

	if (gh) {
		if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
			gfs2_holder_put(gh);
		else
			complete(&gh->gh_wait);
	}
}

/**
 * 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
 *
 */

void gfs2_glock_xmote_th(struct gfs2_glock *gl, unsigned int state, int flags)
{
	struct gfs2_sbd *sdp = gl->gl_sbd;
909
	const struct gfs2_glock_operations *glops = gl->gl_ops;
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	int lck_flags = flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB |
				 LM_FLAG_NOEXP | LM_FLAG_ANY |
				 LM_FLAG_PRIORITY);
	unsigned int lck_ret;

	gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
	gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
	gfs2_assert_warn(sdp, state != LM_ST_UNLOCKED);
	gfs2_assert_warn(sdp, state != gl->gl_state);

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	if (gl->gl_state == LM_ST_EXCLUSIVE && glops->go_sync)
		glops->go_sync(gl, DIO_METADATA | DIO_DATA | DIO_RELEASE);
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	gfs2_glock_hold(gl);
	gl->gl_req_bh = xmote_bh;

926
	lck_ret = gfs2_lm_lock(sdp, gl->gl_lock, gl->gl_state, state, lck_flags);
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	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;
950
	const struct gfs2_glock_operations *glops = gl->gl_ops;
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951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999
	struct gfs2_holder *gh = gl->gl_req_gh;

	clear_bit(GLF_PREFETCH, &gl->gl_flags);

	gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
	gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
	gfs2_assert_warn(sdp, !ret);

	state_change(gl, LM_ST_UNLOCKED);

	if (glops->go_inval)
		glops->go_inval(gl, DIO_METADATA | DIO_DATA);

	if (gh) {
		spin_lock(&gl->gl_spin);
		list_del_init(&gh->gh_list);
		gh->gh_error = 0;
		spin_unlock(&gl->gl_spin);
	}

	if (glops->go_drop_bh)
		glops->go_drop_bh(gl);

	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);

	gfs2_glock_put(gl);

	if (gh) {
		if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
			gfs2_holder_put(gh);
		else
			complete(&gh->gh_wait);
	}
}

/**
 * gfs2_glock_drop_th - call into the lock module to unlock a lock
 * @gl: the glock
 *
 */

void gfs2_glock_drop_th(struct gfs2_glock *gl)
{
	struct gfs2_sbd *sdp = gl->gl_sbd;
1000
	const struct gfs2_glock_operations *glops = gl->gl_ops;
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1001 1002 1003 1004 1005 1006
	unsigned int ret;

	gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
	gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
	gfs2_assert_warn(sdp, gl->gl_state != LM_ST_UNLOCKED);

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Steven Whitehouse 已提交
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	if (gl->gl_state == LM_ST_EXCLUSIVE && glops->go_sync)
		glops->go_sync(gl, DIO_METADATA | DIO_DATA | DIO_RELEASE);
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David Teigland 已提交
1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039

	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)) {
S
Steven Whitehouse 已提交
1040 1041
		if (gl->gl_req_bh && !(gl->gl_req_gh &&
				     (gl->gl_req_gh->gh_flags & GL_NOCANCEL))) {
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1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066
			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;
1067
	const struct gfs2_glock_operations *glops = gl->gl_ops;
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1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094

	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_for_completion(&gh->gh_wait);

	if (gh->gh_error)
		return gh->gh_error;

	gfs2_assert_withdraw(sdp, test_bit(HIF_HOLDER, &gh->gh_iflags));
1095
	gfs2_assert_withdraw(sdp, relaxed_state_ok(gl->gl_state, gh->gh_state,
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1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144
						   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 task_struct *owner)
{
	struct gfs2_holder *gh;

	list_for_each_entry(gh, head, gh_list) {
		if (gh->gh_owner == owner)
			return gh;
	}

	return NULL;
}

/**
 * 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;

1145 1146
	BUG_ON(!gh->gh_owner);

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David Teigland 已提交
1147 1148
	existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner);
	if (existing) {
1149
		print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
1150 1151 1152
		printk(KERN_INFO "pid : %d\n", existing->gh_owner->pid);
		printk(KERN_INFO "lock type : %d lock state : %d\n", 
				existing->gh_gl->gl_name.ln_type, existing->gh_gl->gl_state);
1153
		print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
1154 1155 1156
		printk(KERN_INFO "pid : %d\n", gh->gh_owner->pid);
		printk(KERN_INFO "lock type : %d lock state : %d\n", 
				gl->gl_name.ln_type, gl->gl_state);
1157
		BUG();
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1158 1159 1160 1161
	}

	existing = find_holder_by_owner(&gl->gl_waiters3, gh->gh_owner);
	if (existing) {
1162 1163 1164
		print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
		print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
		BUG();
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1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187
	}

	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;

1188
restart:
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	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
		set_bit(HIF_ABORTED, &gh->gh_iflags);
		return -EIO;
	}

	set_bit(HIF_PROMOTE, &gh->gh_iflags);

	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) {
1204
			msleep(100);
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			goto restart;
		}
	}

	clear_bit(GLF_PREFETCH, &gl->gl_flags);

1211 1212 1213
	if (error == GLR_TRYFAILED && (gh->gh_flags & GL_DUMP))
		dump_glock(gl);

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	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);
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			msleep(100);
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			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) {
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		msleep(100);
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		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;
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	const struct gfs2_glock_operations *glops = gl->gl_ops;
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	if (gh->gh_flags & GL_NOCACHE)
		handle_callback(gl, LM_ST_UNLOCKED);

	gfs2_glmutex_lock(gl);

	spin_lock(&gl->gl_spin);
	list_del_init(&gh->gh_list);

	if (list_empty(&gl->gl_holders)) {
		spin_unlock(&gl->gl_spin);

		if (glops->go_unlock)
			glops->go_unlock(gh);

		gl->gl_stamp = jiffies;

		spin_lock(&gl->gl_spin);
	}

	clear_bit(GLF_LOCK, &gl->gl_flags);
	run_queue(gl);
	spin_unlock(&gl->gl_spin);
}

/**
 * gfs2_glock_prefetch - Try to prefetch a glock
 * @gl: the glock
 * @state: the state to prefetch in
 * @flags: flags passed to go_xmote_th()
 *
 */

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static void gfs2_glock_prefetch(struct gfs2_glock *gl, unsigned int state,
				int flags)
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{
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	const struct gfs2_glock_operations *glops = gl->gl_ops;
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	spin_lock(&gl->gl_spin);

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	if (test_bit(GLF_LOCK, &gl->gl_flags) || !list_empty(&gl->gl_holders) ||
	    !list_empty(&gl->gl_waiters1) || !list_empty(&gl->gl_waiters2) ||
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	    !list_empty(&gl->gl_waiters3) ||
	    relaxed_state_ok(gl->gl_state, state, flags)) {
		spin_unlock(&gl->gl_spin);
		return;
	}

	set_bit(GLF_PREFETCH, &gl->gl_flags);
	set_bit(GLF_LOCK, &gl->gl_flags);
	spin_unlock(&gl->gl_spin);

	glops->go_xmote_th(gl, state, flags);
}

static void greedy_work(void *data)
{
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	struct greedy *gr = data;
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	struct gfs2_holder *gh = &gr->gr_gh;
	struct gfs2_glock *gl = gh->gh_gl;
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	const struct gfs2_glock_operations *glops = gl->gl_ops;
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	clear_bit(GLF_SKIP_WAITERS2, &gl->gl_flags);

	if (glops->go_greedy)
		glops->go_greedy(gl);

	spin_lock(&gl->gl_spin);

	if (list_empty(&gl->gl_waiters2)) {
		clear_bit(GLF_GREEDY, &gl->gl_flags);
		spin_unlock(&gl->gl_spin);
		gfs2_holder_uninit(gh);
		kfree(gr);
	} else {
		gfs2_glock_hold(gl);
		list_add_tail(&gh->gh_list, &gl->gl_waiters2);
		run_queue(gl);
		spin_unlock(&gl->gl_spin);
		gfs2_glock_put(gl);
	}
}

/**
 * gfs2_glock_be_greedy -
 * @gl:
 * @time:
 *
 * Returns: 0 if go_greedy will be called, 1 otherwise
 */

int gfs2_glock_be_greedy(struct gfs2_glock *gl, unsigned int time)
{
	struct greedy *gr;
	struct gfs2_holder *gh;

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	if (!time || gl->gl_sbd->sd_args.ar_localcaching ||
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	    test_and_set_bit(GLF_GREEDY, &gl->gl_flags))
		return 1;

	gr = kmalloc(sizeof(struct greedy), GFP_KERNEL);
	if (!gr) {
		clear_bit(GLF_GREEDY, &gl->gl_flags);
		return 1;
	}
	gh = &gr->gr_gh;

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	gfs2_holder_init(gl, 0, 0, gh);
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	set_bit(HIF_GREEDY, &gh->gh_iflags);
	INIT_WORK(&gr->gr_work, greedy_work, gr);

	set_bit(GLF_SKIP_WAITERS2, &gl->gl_flags);
	schedule_delayed_work(&gr->gr_work, time);

	return 0;
}

/**
 * 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
 */

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int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
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		      const struct gfs2_glock_operations *glops,
		      unsigned int state, int flags, struct gfs2_holder *gh)
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{
	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)
{
	struct gfs2_holder *gh_a = *(struct gfs2_holder **)arg_a;
	struct gfs2_holder *gh_b = *(struct gfs2_holder **)arg_b;
	struct lm_lockname *a = &gh_a->gh_gl->gl_name;
	struct lm_lockname *b = &gh_b->gh_gl->gl_name;
	int ret = 0;

	if (a->ln_number > b->ln_number)
		ret = 1;
	else if (a->ln_number < b->ln_number)
		ret = -1;
	else {
		if (gh_a->gh_state == LM_ST_SHARED &&
		    gh_b->gh_state == LM_ST_EXCLUSIVE)
			ret = 1;
		else if (!(gh_a->gh_flags & GL_LOCAL_EXCL) &&
			 (gh_b->gh_flags & GL_LOCAL_EXCL))
			ret = 1;
	}

	return ret;
}

/**
 * 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
 *
 * Figure out how big an impact this function has.  Either:
 * 1) Replace this code with code that calls gfs2_glock_prefetch()
 * 2) Forget async stuff and just call nq_m_sync()
 * 3) Leave it like it is
 *
 * 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)
{
	int *e;
	unsigned int x;
	int borked = 0, serious = 0;
	int error = 0;

	if (!num_gh)
		return 0;

	if (num_gh == 1) {
		ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
		return gfs2_glock_nq(ghs);
	}

	e = kcalloc(num_gh, sizeof(struct gfs2_holder *), GFP_KERNEL);
	if (!e)
		return -ENOMEM;

	for (x = 0; x < num_gh; x++) {
		ghs[x].gh_flags |= LM_FLAG_TRY | GL_ASYNC;
		error = gfs2_glock_nq(&ghs[x]);
		if (error) {
			borked = 1;
			serious = error;
			num_gh = x;
			break;
		}
	}

	for (x = 0; x < num_gh; x++) {
		error = e[x] = glock_wait_internal(&ghs[x]);
		if (error) {
			borked = 1;
			if (error != GLR_TRYFAILED && error != GLR_CANCELED)
				serious = error;
		}
	}

	if (!borked) {
		kfree(e);
		return 0;
	}

	for (x = 0; x < num_gh; x++)
		if (!e[x])
			gfs2_glock_dq(&ghs[x]);

	if (serious)
		error = serious;
	else {
		for (x = 0; x < num_gh; x++)
			gfs2_holder_reinit(ghs[x].gh_state, ghs[x].gh_flags,
					  &ghs[x]);
		error = nq_m_sync(num_gh, ghs, (struct gfs2_holder **)e);
	}

	kfree(e);

	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_glock_prefetch_num - prefetch 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
 *
 * Returns: errno
 */

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void gfs2_glock_prefetch_num(struct gfs2_sbd *sdp, u64 number,
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			     const struct gfs2_glock_operations *glops,
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			     unsigned int state, int flags)
{
	struct gfs2_glock *gl;
	int error;

	if (atomic_read(&sdp->sd_reclaim_count) <
	    gfs2_tune_get(sdp, gt_reclaim_limit)) {
		error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
		if (!error) {
			gfs2_glock_prefetch(gl, state, flags);
			gfs2_glock_put(gl);
		}
	}
}

/**
 * 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;

	gl = gfs2_glock_find(sdp, name);
	if (!gl)
		return;

	if (gl->gl_ops->go_callback)
		gl->gl_ops->go_callback(gl, state);
	handle_callback(gl, state);

	spin_lock(&gl->gl_spin);
	run_queue(gl);
	spin_unlock(&gl->gl_spin);

	gfs2_glock_put(gl);
}

/**
 * gfs2_glock_cb - Callback used by locking module
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 * @sdp: Pointer to the superblock
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 * @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.
 */

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void gfs2_glock_cb(void *cb_data, unsigned int type, void *data)
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{
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	struct gfs2_sbd *sdp = cb_data;
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	switch (type) {
	case LM_CB_NEED_E:
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		blocking_cb(sdp, data, LM_ST_UNLOCKED);
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		return;

	case LM_CB_NEED_D:
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		blocking_cb(sdp, data, LM_ST_DEFERRED);
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		return;

	case LM_CB_NEED_S:
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		blocking_cb(sdp, data, LM_ST_SHARED);
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		return;

	case LM_CB_ASYNC: {
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		struct lm_async_cb *async = data;
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		struct gfs2_glock *gl;

		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);
		gfs2_glock_put(gl);
		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;
	}
}

/**
 * gfs2_iopen_go_callback - Try to kick the inode/vnode associated with an
 *                          iopen glock from memory
 * @io_gl: the iopen glock
 * @state: the state into which the glock should be put
 *
 */

void gfs2_iopen_go_callback(struct gfs2_glock *io_gl, unsigned int state)
{

	if (state != LM_ST_UNLOCKED)
		return;
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	/* FIXME: remove this? */
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}

/**
 * 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)
{
	struct gfs2_sbd *sdp = gl->gl_sbd;
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	const struct gfs2_glock_operations *glops = gl->gl_ops;
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	int demote = 1;

	if (test_bit(GLF_STICKY, &gl->gl_flags))
		demote = 0;
	else if (test_bit(GLF_PREFETCH, &gl->gl_flags))
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		demote = time_after_eq(jiffies, gl->gl_stamp +
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				    gfs2_tune_get(sdp, gt_prefetch_secs) * HZ);
	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 (queue_empty(gl, &gl->gl_holders) &&
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1853
		    gl->gl_state != LM_ST_UNLOCKED && demote_ok(gl))
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			handle_callback(gl, LM_ST_UNLOCKED);
		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,
			  struct gfs2_gl_hash_bucket *bucket)
{
	struct glock_plug plug;
	struct list_head *tmp;
	struct gfs2_glock *gl;
	int entries;

	/* Add "plug" to end of bucket list, work back up list from there */
	memset(&plug.gl_flags, 0, sizeof(unsigned long));
	set_bit(GLF_PLUG, &plug.gl_flags);

	write_lock(&bucket->hb_lock);
	list_add(&plug.gl_list, &bucket->hb_list);
	write_unlock(&bucket->hb_lock);

	for (;;) {
		write_lock(&bucket->hb_lock);

		for (;;) {
			tmp = plug.gl_list.next;

			if (tmp == &bucket->hb_list) {
				list_del(&plug.gl_list);
				entries = !list_empty(&bucket->hb_list);
				write_unlock(&bucket->hb_lock);
				return entries;
			}
			gl = list_entry(tmp, struct gfs2_glock, gl_list);

			/* Move plug up list */
			list_move(&plug.gl_list, &gl->gl_list);

			if (test_bit(GLF_PLUG, &gl->gl_flags))
				continue;
1905 1906
			if (gl->gl_sbd != sdp)
				continue;
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			/* examiner() must glock_put() */
			gfs2_glock_hold(gl);

			break;
		}

		write_unlock(&bucket->hb_lock);

		examiner(gl);
	}
}

/**
 * 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)
{
1928 1929 1930
	if (gl->gl_ops == &gfs2_inode_glops)
		goto out;

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	if (gfs2_glmutex_trylock(gl)) {
		if (queue_empty(gl, &gl->gl_holders) &&
		    gl->gl_state != LM_ST_UNLOCKED &&
		    demote_ok(gl))
			goto out_schedule;
		gfs2_glmutex_unlock(gl);
	}
1938
out:
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1939 1940 1941
	gfs2_glock_put(gl);
	return;

1942
out_schedule:
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1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958
	gfs2_glmutex_unlock(gl);
	gfs2_glock_schedule_for_reclaim(gl);
	gfs2_glock_put(gl);
}

/**
 * gfs2_scand_internal - Look for glocks and inodes to toss from memory
 * @sdp: the filesystem
 *
 */

void gfs2_scand_internal(struct gfs2_sbd *sdp)
{
	unsigned int x;

	for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1959
		examine_bucket(scan_glock, sdp, &gl_hash_table[x]);
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		cond_resched();
	}
}

/**
 * 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);
1979
		spin_unlock(&sdp->sd_reclaim_lock);
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		released = gfs2_glock_put(gl);
		gfs2_assert(sdp, !released);
1982 1983
	} else {
		spin_unlock(&sdp->sd_reclaim_lock);
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1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
	}

	if (gfs2_glmutex_trylock(gl)) {
		if (queue_empty(gl, &gl->gl_holders) &&
		    gl->gl_state != LM_ST_UNLOCKED)
			handle_callback(gl, LM_ST_UNLOCKED);

		gfs2_glmutex_unlock(gl);
	}

	gfs2_glock_put(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++)
2018
			if (examine_bucket(clear_glock, sdp, &gl_hash_table[x]))
D
David Teigland 已提交
2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032
				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;
		}

		invalidate_inodes(sdp->sd_vfs);
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Steven Whitehouse 已提交
2033
		msleep(10);
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David Teigland 已提交
2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053
	}
}

/*
 *  Diagnostic routines to help debug distributed deadlock
 */

/**
 * 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(char *str, struct gfs2_holder *gh)
{
	unsigned int x;
	int error = -ENOBUFS;

2054 2055
	printk(KERN_INFO "  %s\n", str);
	printk(KERN_INFO "    owner = %ld\n",
D
David Teigland 已提交
2056
		   (gh->gh_owner) ? (long)gh->gh_owner->pid : -1);
2057 2058
	printk(KERN_INFO "    gh_state = %u\n", gh->gh_state);
	printk(KERN_INFO "    gh_flags =");
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David Teigland 已提交
2059 2060 2061 2062
	for (x = 0; x < 32; x++)
		if (gh->gh_flags & (1 << x))
			printk(" %u", x);
	printk(" \n");
2063 2064
	printk(KERN_INFO "    error = %d\n", gh->gh_error);
	printk(KERN_INFO "    gh_iflags =");
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2065 2066 2067 2068
	for (x = 0; x < 32; x++)
		if (test_bit(x, &gh->gh_iflags))
			printk(" %u", x);
	printk(" \n");
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Steven Whitehouse 已提交
2069
	print_symbol(KERN_INFO "    initialized at: %s\n", gh->gh_ip);
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2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087

	error = 0;

	return error;
}

/**
 * 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 gfs2_inode *ip)
{
	unsigned int x;
	int error = -ENOBUFS;

2088 2089
	printk(KERN_INFO "  Inode:\n");
	printk(KERN_INFO "    num = %llu %llu\n",
2090 2091
		    (unsigned long long)ip->i_num.no_formal_ino,
		    (unsigned long long)ip->i_num.no_addr);
2092 2093
	printk(KERN_INFO "    type = %u\n", IF2DT(ip->i_di.di_mode));
	printk(KERN_INFO "    i_flags =");
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David Teigland 已提交
2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119
	for (x = 0; x < 32; x++)
		if (test_bit(x, &ip->i_flags))
			printk(" %u", x);
	printk(" \n");

	error = 0;

	return error;
}

/**
 * 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 gfs2_glock *gl)
{
	struct gfs2_holder *gh;
	unsigned int x;
	int error = -ENOBUFS;

	spin_lock(&gl->gl_spin);

2120
	printk(KERN_INFO "Glock 0x%p (%u, %llu)\n", gl, gl->gl_name.ln_type,
2121
	       (unsigned long long)gl->gl_name.ln_number);
2122
	printk(KERN_INFO "  gl_flags =");
2123
	for (x = 0; x < 32; x++) {
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David Teigland 已提交
2124 2125
		if (test_bit(x, &gl->gl_flags))
			printk(" %u", x);
2126
	}
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2127
	printk(" \n");
2128 2129
	printk(KERN_INFO "  gl_ref = %d\n", atomic_read(&gl->gl_ref.refcount));
	printk(KERN_INFO "  gl_state = %u\n", gl->gl_state);
2130 2131
	printk(KERN_INFO "  gl_owner = %s\n", gl->gl_owner->comm);
	print_symbol(KERN_INFO "  gl_ip = %s\n", gl->gl_ip);
2132 2133 2134 2135 2136
	printk(KERN_INFO "  req_gh = %s\n", (gl->gl_req_gh) ? "yes" : "no");
	printk(KERN_INFO "  req_bh = %s\n", (gl->gl_req_bh) ? "yes" : "no");
	printk(KERN_INFO "  lvb_count = %d\n", atomic_read(&gl->gl_lvb_count));
	printk(KERN_INFO "  object = %s\n", (gl->gl_object) ? "yes" : "no");
	printk(KERN_INFO "  le = %s\n",
D
David Teigland 已提交
2137
		   (list_empty(&gl->gl_le.le_list)) ? "no" : "yes");
2138
	printk(KERN_INFO "  reclaim = %s\n",
D
David Teigland 已提交
2139 2140
		    (list_empty(&gl->gl_reclaim)) ? "no" : "yes");
	if (gl->gl_aspace)
2141
		printk(KERN_INFO "  aspace = 0x%p nrpages = %lu\n", gl->gl_aspace,
2142
		       gl->gl_aspace->i_mapping->nrpages);
D
David Teigland 已提交
2143
	else
2144 2145
		printk(KERN_INFO "  aspace = no\n");
	printk(KERN_INFO "  ail = %d\n", atomic_read(&gl->gl_ail_count));
D
David Teigland 已提交
2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170
	if (gl->gl_req_gh) {
		error = dump_holder("Request", gl->gl_req_gh);
		if (error)
			goto out;
	}
	list_for_each_entry(gh, &gl->gl_holders, gh_list) {
		error = dump_holder("Holder", gh);
		if (error)
			goto out;
	}
	list_for_each_entry(gh, &gl->gl_waiters1, gh_list) {
		error = dump_holder("Waiter1", gh);
		if (error)
			goto out;
	}
	list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
		error = dump_holder("Waiter2", gh);
		if (error)
			goto out;
	}
	list_for_each_entry(gh, &gl->gl_waiters3, gh_list) {
		error = dump_holder("Waiter3", gh);
		if (error)
			goto out;
	}
2171
	if (gl->gl_ops == &gfs2_inode_glops && gl->gl_object) {
D
David Teigland 已提交
2172 2173
		if (!test_bit(GLF_LOCK, &gl->gl_flags) &&
		    list_empty(&gl->gl_holders)) {
2174
			error = dump_inode(gl->gl_object);
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David Teigland 已提交
2175 2176 2177 2178
			if (error)
				goto out;
		} else {
			error = -ENOBUFS;
2179
			printk(KERN_INFO "  Inode: busy\n");
D
David Teigland 已提交
2180 2181 2182 2183 2184
		}
	}

	error = 0;

2185
out:
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2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198
	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.
 *
 */

2199
static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
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David Teigland 已提交
2200 2201 2202 2203 2204 2205 2206
{
	struct gfs2_gl_hash_bucket *bucket;
	struct gfs2_glock *gl;
	unsigned int x;
	int error = 0;

	for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
2207
		bucket = &gl_hash_table[x];
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David Teigland 已提交
2208 2209 2210 2211 2212 2213

		read_lock(&bucket->hb_lock);

		list_for_each_entry(gl, &bucket->hb_list, gl_list) {
			if (test_bit(GLF_PLUG, &gl->gl_flags))
				continue;
2214 2215
			if (gl->gl_sbd != sdp)
				continue;
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David Teigland 已提交
2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231

			error = dump_glock(gl);
			if (error)
				break;
		}

		read_unlock(&bucket->hb_lock);

		if (error)
			break;
	}


	return error;
}

2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242
int __init gfs2_glock_init(void)
{
	unsigned i;
	for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
		struct gfs2_gl_hash_bucket *hb = &gl_hash_table[i];
		rwlock_init(&hb->hb_lock);
		INIT_LIST_HEAD(&hb->hb_list);
	}
	return 0;
}