fs/ocfs2/dcache.c - kernel/msm-5.4 - Gitiles

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* -*- mode: c; c-basic-offset: 8; -*-
  * vim: noexpandtab sw=8 ts=8 sts=0:
  *
  * dcache.c
  *
  * dentry cache handling code
  *
  * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
  */

 #include <linux/fs.h>
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/namei.h>

 #include <cluster/masklog.h>

 #include "ocfs2.h"

 #include "alloc.h"
 #include "dcache.h"
 #include "dlmglue.h"
 #include "file.h"
 #include "inode.h"
 #include "ocfs2_trace.h"

 void ocfs2_dentry_attach_gen(struct dentry *dentry)
 {
 	unsigned long gen =
 		OCFS2_I(d_inode(dentry->d_parent))->ip_dir_lock_gen;
 	BUG_ON(d_inode(dentry));
 	dentry->d_fsdata = (void *)gen;
 }


 static int ocfs2_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 {
 	struct inode *inode;
 	int ret = 0;    /* if all else fails, just return false */
 	struct ocfs2_super *osb;

 	if (flags & LOOKUP_RCU)
 		return -ECHILD;

 	inode = d_inode(dentry);
 	osb = OCFS2_SB(dentry->d_sb);

 	trace_ocfs2_dentry_revalidate(dentry, dentry->d_name.len,
 				      dentry->d_name.name);

 	/* For a negative dentry -
 	 * check the generation number of the parent and compare with the
 	 * one stored in the inode.
 	 */
 	if (inode == NULL) {
 		unsigned long gen = (unsigned long) dentry->d_fsdata;
 		unsigned long pgen;
 		spin_lock(&dentry->d_lock);
 		pgen = OCFS2_I(d_inode(dentry->d_parent))->ip_dir_lock_gen;
 		spin_unlock(&dentry->d_lock);
 		trace_ocfs2_dentry_revalidate_negative(dentry->d_name.len,
 						       dentry->d_name.name,
 						       pgen, gen);
 		if (gen != pgen)
 			goto bail;
 		goto valid;
 	}

 	BUG_ON(!osb);

 	if (inode == osb->root_inode || is_bad_inode(inode))
 		goto bail;

 	spin_lock(&OCFS2_I(inode)->ip_lock);
 	/* did we or someone else delete this inode? */
 	if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) {
 		spin_unlock(&OCFS2_I(inode)->ip_lock);
 		trace_ocfs2_dentry_revalidate_delete(
 				(unsigned long long)OCFS2_I(inode)->ip_blkno);
 		goto bail;
 	}
 	spin_unlock(&OCFS2_I(inode)->ip_lock);

 	/*
 	 * We don't need a cluster lock to test this because once an
 	 * inode nlink hits zero, it never goes back.
 	 */
 	if (inode->i_nlink == 0) {
 		trace_ocfs2_dentry_revalidate_orphaned(
 			(unsigned long long)OCFS2_I(inode)->ip_blkno,
 			S_ISDIR(inode->i_mode));
 		goto bail;
 	}

 	/*
 	 * If the last lookup failed to create dentry lock, let us
 	 * redo it.
 	 */
 	if (!dentry->d_fsdata) {
 		trace_ocfs2_dentry_revalidate_nofsdata(
 				(unsigned long long)OCFS2_I(inode)->ip_blkno);
 		goto bail;
 	}

 valid:
 	ret = 1;

 bail:
 	trace_ocfs2_dentry_revalidate_ret(ret);
 	return ret;
 }

 static int ocfs2_match_dentry(struct dentry *dentry,
 			      u64 parent_blkno,
 			      int skip_unhashed)
 {
 	struct inode *parent;

 	/*
 	 * ocfs2_lookup() does a d_splice_alias() _before_ attaching
 	 * to the lock data, so we skip those here, otherwise
 	 * ocfs2_dentry_attach_lock() will get its original dentry
 	 * back.
 	 */
 	if (!dentry->d_fsdata)
 		return 0;

 	if (!dentry->d_parent)
 		return 0;

 	if (skip_unhashed && d_unhashed(dentry))
 		return 0;

 	parent = d_inode(dentry->d_parent);
 	/* Negative parent dentry? */
 	if (!parent)
 		return 0;

 	/* Name is in a different directory. */
 	if (OCFS2_I(parent)->ip_blkno != parent_blkno)
 		return 0;

 	return 1;
 }

 /*
  * Walk the inode alias list, and find a dentry which has a given
  * parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it
  * is looking for a dentry_lock reference. The downconvert thread is
  * looking to unhash aliases, so we allow it to skip any that already
  * have that property.
  */
 struct dentry *ocfs2_find_local_alias(struct inode *inode,
 				      u64 parent_blkno,
 				      int skip_unhashed)
 {
 	struct dentry *dentry;

 	spin_lock(&inode->i_lock);
 	hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
 		spin_lock(&dentry->d_lock);
 		if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) {
 			trace_ocfs2_find_local_alias(dentry->d_name.len,
 						     dentry->d_name.name);

 			dget_dlock(dentry);
 			spin_unlock(&dentry->d_lock);
 			spin_unlock(&inode->i_lock);
 			return dentry;
 		}
 		spin_unlock(&dentry->d_lock);
 	}
 	spin_unlock(&inode->i_lock);
 	return NULL;
 }

 DEFINE_SPINLOCK(dentry_attach_lock);

 /*
  * Attach this dentry to a cluster lock.
  *
  * Dentry locks cover all links in a given directory to a particular
  * inode. We do this so that ocfs2 can build a lock name which all
  * nodes in the cluster can agree on at all times. Shoving full names
  * in the cluster lock won't work due to size restrictions. Covering
  * links inside of a directory is a good compromise because it still
  * allows us to use the parent directory lock to synchronize
  * operations.
  *
  * Call this function with the parent dir semaphore and the parent dir
  * cluster lock held.
  *
  * The dir semaphore will protect us from having to worry about
  * concurrent processes on our node trying to attach a lock at the
  * same time.
  *
  * The dir cluster lock (held at either PR or EX mode) protects us
  * from unlink and rename on other nodes.
  *
  * A dput() can happen asynchronously due to pruning, so we cover
  * attaching and detaching the dentry lock with a
  * dentry_attach_lock.
  *
  * A node which has done lookup on a name retains a protected read
  * lock until final dput. If the user requests and unlink or rename,
  * the protected read is upgraded to an exclusive lock. Other nodes
  * who have seen the dentry will then be informed that they need to
  * downgrade their lock, which will involve d_delete on the
  * dentry. This happens in ocfs2_dentry_convert_worker().
  */
 int ocfs2_dentry_attach_lock(struct dentry *dentry,
 			     struct inode *inode,
 			     u64 parent_blkno)
 {
 	int ret;
 	struct dentry *alias;
 	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;

 	trace_ocfs2_dentry_attach_lock(dentry->d_name.len, dentry->d_name.name,
 				       (unsigned long long)parent_blkno, dl);

 	/*
 	 * Negative dentry. We ignore these for now.
 	 *
 	 * XXX: Could we can improve ocfs2_dentry_revalidate() by
 	 * tracking these?
 	 */
 	if (!inode)
 		return 0;

 	if (d_really_is_negative(dentry) && dentry->d_fsdata) {
 		/* Converting a negative dentry to positive
 		   Clear dentry->d_fsdata */
 		dentry->d_fsdata = dl = NULL;
 	}

 	if (dl) {
 		mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
 				" \"%pd\": old parent: %llu, new: %llu\n",
 				dentry,
 				(unsigned long long)parent_blkno,
 				(unsigned long long)dl->dl_parent_blkno);
 		return 0;
 	}

 	alias = ocfs2_find_local_alias(inode, parent_blkno, 0);
 	if (alias) {
 		/*
 		 * Great, an alias exists, which means we must have a
 		 * dentry lock already. We can just grab the lock off
 		 * the alias and add it to the list.
 		 *
 		 * We're depending here on the fact that this dentry
 		 * was found and exists in the dcache and so must have
 		 * a reference to the dentry_lock because we can't
 		 * race creates. Final dput() cannot happen on it
 		 * since we have it pinned, so our reference is safe.
 		 */
 		dl = alias->d_fsdata;
 		mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n",
 				(unsigned long long)parent_blkno,
 				(unsigned long long)OCFS2_I(inode)->ip_blkno);

 		mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
 				" \"%pd\": old parent: %llu, new: %llu\n",
 				dentry,
 				(unsigned long long)parent_blkno,
 				(unsigned long long)dl->dl_parent_blkno);

 		trace_ocfs2_dentry_attach_lock_found(dl->dl_lockres.l_name,
 				(unsigned long long)parent_blkno,
 				(unsigned long long)OCFS2_I(inode)->ip_blkno);

 		goto out_attach;
 	}

 	/*
 	 * There are no other aliases
 	 */
 	dl = kmalloc(sizeof(*dl), GFP_NOFS);
 	if (!dl) {
 		ret = -ENOMEM;
 		mlog_errno(ret);
 		return ret;
 	}

 	dl->dl_count = 0;
 	/*
 	 * Does this have to happen below, for all attaches, in case
 	 * the struct inode gets blown away by the downconvert thread?
 	 */
 	dl->dl_inode = igrab(inode);
 	dl->dl_parent_blkno = parent_blkno;
 	ocfs2_dentry_lock_res_init(dl, parent_blkno, inode);

 out_attach:
 	spin_lock(&dentry_attach_lock);
 	dentry->d_fsdata = dl;
 	dl->dl_count++;
 	spin_unlock(&dentry_attach_lock);

 	/*
 	 * This actually gets us our PRMODE level lock. From now on,
 	 * we'll have a notification if one of these names is
 	 * destroyed on another node.
 	 */
 	ret = ocfs2_dentry_lock(dentry, 0);
 	if (!ret)
 		ocfs2_dentry_unlock(dentry, 0);
 	else
 		mlog_errno(ret);

 	/*
 	 * In case of error, manually free the allocation and do the iput().
 	 * We need to do this because error here means no d_instantiate(),
 	 * which means iput() will not be called during dput(dentry).
 	 */
 	if (ret < 0 && !alias) {
 		ocfs2_lock_res_free(&dl->dl_lockres);
 		BUG_ON(dl->dl_count != 1);
 		spin_lock(&dentry_attach_lock);
 		dentry->d_fsdata = NULL;
 		spin_unlock(&dentry_attach_lock);
 		kfree(dl);
 		iput(inode);
 	}

 	dput(alias);

 	return ret;
 }

 /*
  * ocfs2_dentry_iput() and friends.
  *
  * At this point, our particular dentry is detached from the inodes
  * alias list, so there's no way that the locking code can find it.
  *
  * The interesting stuff happens when we determine that our lock needs
  * to go away because this is the last subdir alias in the
  * system. This function needs to handle a couple things:
  *
  * 1) Synchronizing lock shutdown with the downconvert threads. This
  *    is already handled for us via the lockres release drop function
  *    called in ocfs2_release_dentry_lock()
  *
  * 2) A race may occur when we're doing our lock shutdown and
  *    another process wants to create a new dentry lock. Right now we
  *    let them race, which means that for a very short while, this
  *    node might have two locks on a lock resource. This should be a
  *    problem though because one of them is in the process of being
  *    thrown out.
  */
 static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb,
 				   struct ocfs2_dentry_lock *dl)
 {
 	iput(dl->dl_inode);
 	ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
 	ocfs2_lock_res_free(&dl->dl_lockres);
 	kfree(dl);
 }

 void ocfs2_dentry_lock_put(struct ocfs2_super *osb,
 			   struct ocfs2_dentry_lock *dl)
 {
 	int unlock = 0;

 	BUG_ON(dl->dl_count == 0);

 	spin_lock(&dentry_attach_lock);
 	dl->dl_count--;
 	unlock = !dl->dl_count;
 	spin_unlock(&dentry_attach_lock);

 	if (unlock)
 		ocfs2_drop_dentry_lock(osb, dl);
 }

 static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode)
 {
 	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;

 	if (!dl) {
 		/*
 		 * No dentry lock is ok if we're disconnected or
 		 * unhashed.
 		 */
 		if (!(dentry->d_flags & DCACHE_DISCONNECTED) &&
 		    !d_unhashed(dentry)) {
 			unsigned long long ino = 0ULL;
 			if (inode)
 				ino = (unsigned long long)OCFS2_I(inode)->ip_blkno;
 			mlog(ML_ERROR, "Dentry is missing cluster lock. "
 			     "inode: %llu, d_flags: 0x%x, d_name: %pd\n",
 			     ino, dentry->d_flags, dentry);
 		}

 		goto out;
 	}

 	mlog_bug_on_msg(dl->dl_count == 0, "dentry: %pd, count: %u\n",
 			dentry, dl->dl_count);

 	ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl);

 out:
 	iput(inode);
 }

 /*
  * d_move(), but keep the locks in sync.
  *
  * When we are done, "dentry" will have the parent dir and name of
  * "target", which will be thrown away.
  *
  * We manually update the lock of "dentry" if need be.
  *
  * "target" doesn't have it's dentry lock touched - we allow the later
  * dput() to handle this for us.
  *
  * This is called during ocfs2_rename(), while holding parent
  * directory locks. The dentries have already been deleted on other
  * nodes via ocfs2_remote_dentry_delete().
  *
  * Normally, the VFS handles the d_move() for the file system, after
  * the ->rename() callback. OCFS2 wants to handle this internally, so
  * the new lock can be created atomically with respect to the cluster.
  */
 void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target,
 		       struct inode *old_dir, struct inode *new_dir)
 {
 	int ret;
 	struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb);
 	struct inode *inode = d_inode(dentry);

 	/*
 	 * Move within the same directory, so the actual lock info won't
 	 * change.
 	 *
 	 * XXX: Is there any advantage to dropping the lock here?
 	 */
 	if (old_dir == new_dir)
 		goto out_move;

 	ocfs2_dentry_lock_put(osb, dentry->d_fsdata);

 	dentry->d_fsdata = NULL;
 	ret = ocfs2_dentry_attach_lock(dentry, inode, OCFS2_I(new_dir)->ip_blkno);
 	if (ret)
 		mlog_errno(ret);

 out_move:
 	d_move(dentry, target);
 }

 const struct dentry_operations ocfs2_dentry_ops = {
 	.d_revalidate		= ocfs2_dentry_revalidate,
 	.d_iput			= ocfs2_dentry_iput,
 };
	// SPDX-License-Identifier: GPL-2.0-or-later
	/* -- mode: c; c-basic-offset: 8; --
	* vim: noexpandtab sw=8 ts=8 sts=0:
	*
	* dcache.c
	*
	* dentry cache handling code
	*
	* Copyright (C) 2002, 2004 Oracle. All rights reserved.
	*/

	#include <linux/fs.h>
	#include <linux/types.h>
	#include <linux/slab.h>
	#include <linux/namei.h>

	#include <cluster/masklog.h>

	#include "ocfs2.h"

	#include "alloc.h"
	#include "dcache.h"
	#include "dlmglue.h"
	#include "file.h"
	#include "inode.h"
	#include "ocfs2_trace.h"

	void ocfs2_dentry_attach_gen(struct dentry *dentry)
	{
	unsigned long gen =
	OCFS2_I(d_inode(dentry->d_parent))->ip_dir_lock_gen;
	BUG_ON(d_inode(dentry));
	dentry->d_fsdata = (void *)gen;
	}


	static int ocfs2_dentry_revalidate(struct dentry *dentry, unsigned int flags)
	{
	struct inode *inode;
	int ret = 0; /* if all else fails, just return false */
	struct ocfs2_super *osb;

	if (flags & LOOKUP_RCU)
	return -ECHILD;

	inode = d_inode(dentry);
	osb = OCFS2_SB(dentry->d_sb);

	trace_ocfs2_dentry_revalidate(dentry, dentry->d_name.len,
	dentry->d_name.name);

	/* For a negative dentry -
	* check the generation number of the parent and compare with the
	* one stored in the inode.
	*/
	if (inode == NULL) {
	unsigned long gen = (unsigned long) dentry->d_fsdata;
	unsigned long pgen;
	spin_lock(&dentry->d_lock);
	pgen = OCFS2_I(d_inode(dentry->d_parent))->ip_dir_lock_gen;
	spin_unlock(&dentry->d_lock);
	trace_ocfs2_dentry_revalidate_negative(dentry->d_name.len,
	dentry->d_name.name,
	pgen, gen);
	if (gen != pgen)
	goto bail;
	goto valid;
	}

	BUG_ON(!osb);

	if (inode == osb->root_inode \|\| is_bad_inode(inode))
	goto bail;

	spin_lock(&OCFS2_I(inode)->ip_lock);
	/* did we or someone else delete this inode? */
	if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) {
	spin_unlock(&OCFS2_I(inode)->ip_lock);
	trace_ocfs2_dentry_revalidate_delete(
	(unsigned long long)OCFS2_I(inode)->ip_blkno);
	goto bail;
	}
	spin_unlock(&OCFS2_I(inode)->ip_lock);

	/*
	* We don't need a cluster lock to test this because once an
	* inode nlink hits zero, it never goes back.
	*/
	if (inode->i_nlink == 0) {
	trace_ocfs2_dentry_revalidate_orphaned(
	(unsigned long long)OCFS2_I(inode)->ip_blkno,
	S_ISDIR(inode->i_mode));
	goto bail;
	}

	/*
	* If the last lookup failed to create dentry lock, let us
	* redo it.
	*/
	if (!dentry->d_fsdata) {
	trace_ocfs2_dentry_revalidate_nofsdata(
	(unsigned long long)OCFS2_I(inode)->ip_blkno);
	goto bail;
	}

	valid:
	ret = 1;

	bail:
	trace_ocfs2_dentry_revalidate_ret(ret);
	return ret;
	}

	static int ocfs2_match_dentry(struct dentry *dentry,
	u64 parent_blkno,
	int skip_unhashed)
	{
	struct inode *parent;

	/*
	* ocfs2_lookup() does a d_splice_alias() _before_ attaching
	* to the lock data, so we skip those here, otherwise
	* ocfs2_dentry_attach_lock() will get its original dentry
	* back.
	*/
	if (!dentry->d_fsdata)
	return 0;

	if (!dentry->d_parent)
	return 0;

	if (skip_unhashed && d_unhashed(dentry))
	return 0;

	parent = d_inode(dentry->d_parent);
	/* Negative parent dentry? */
	if (!parent)
	return 0;

	/* Name is in a different directory. */
	if (OCFS2_I(parent)->ip_blkno != parent_blkno)
	return 0;

	return 1;
	}

	/*
	* Walk the inode alias list, and find a dentry which has a given
	* parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it
	* is looking for a dentry_lock reference. The downconvert thread is
	* looking to unhash aliases, so we allow it to skip any that already
	* have that property.
	*/
	struct dentry ocfs2_find_local_alias(struct inode inode,
	u64 parent_blkno,
	int skip_unhashed)
	{
	struct dentry *dentry;

	spin_lock(&inode->i_lock);
	hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
	spin_lock(&dentry->d_lock);
	if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) {
	trace_ocfs2_find_local_alias(dentry->d_name.len,
	dentry->d_name.name);

	dget_dlock(dentry);
	spin_unlock(&dentry->d_lock);
	spin_unlock(&inode->i_lock);
	return dentry;
	}
	spin_unlock(&dentry->d_lock);
	}
	spin_unlock(&inode->i_lock);
	return NULL;
	}

	DEFINE_SPINLOCK(dentry_attach_lock);

	/*
	* Attach this dentry to a cluster lock.
	*
	* Dentry locks cover all links in a given directory to a particular
	* inode. We do this so that ocfs2 can build a lock name which all
	* nodes in the cluster can agree on at all times. Shoving full names
	* in the cluster lock won't work due to size restrictions. Covering
	* links inside of a directory is a good compromise because it still
	* allows us to use the parent directory lock to synchronize
	* operations.
	*
	* Call this function with the parent dir semaphore and the parent dir
	* cluster lock held.
	*
	* The dir semaphore will protect us from having to worry about
	* concurrent processes on our node trying to attach a lock at the
	* same time.
	*
	* The dir cluster lock (held at either PR or EX mode) protects us
	* from unlink and rename on other nodes.
	*
	* A dput() can happen asynchronously due to pruning, so we cover
	* attaching and detaching the dentry lock with a
	* dentry_attach_lock.
	*
	* A node which has done lookup on a name retains a protected read
	* lock until final dput. If the user requests and unlink or rename,
	* the protected read is upgraded to an exclusive lock. Other nodes
	* who have seen the dentry will then be informed that they need to
	* downgrade their lock, which will involve d_delete on the
	* dentry. This happens in ocfs2_dentry_convert_worker().
	*/
	int ocfs2_dentry_attach_lock(struct dentry *dentry,
	struct inode *inode,
	u64 parent_blkno)
	{
	int ret;
	struct dentry *alias;
	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;

	trace_ocfs2_dentry_attach_lock(dentry->d_name.len, dentry->d_name.name,
	(unsigned long long)parent_blkno, dl);

	/*
	* Negative dentry. We ignore these for now.
	*
	* XXX: Could we can improve ocfs2_dentry_revalidate() by
	* tracking these?
	*/
	if (!inode)
	return 0;

	if (d_really_is_negative(dentry) && dentry->d_fsdata) {
	/* Converting a negative dentry to positive
	Clear dentry->d_fsdata */
	dentry->d_fsdata = dl = NULL;
	}

	if (dl) {
	mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
	" \"%pd\": old parent: %llu, new: %llu\n",
	dentry,
	(unsigned long long)parent_blkno,
	(unsigned long long)dl->dl_parent_blkno);
	return 0;
	}

	alias = ocfs2_find_local_alias(inode, parent_blkno, 0);
	if (alias) {
	/*
	* Great, an alias exists, which means we must have a
	* dentry lock already. We can just grab the lock off
	* the alias and add it to the list.
	*
	* We're depending here on the fact that this dentry
	* was found and exists in the dcache and so must have
	* a reference to the dentry_lock because we can't
	* race creates. Final dput() cannot happen on it
	* since we have it pinned, so our reference is safe.
	*/
	dl = alias->d_fsdata;
	mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n",
	(unsigned long long)parent_blkno,
	(unsigned long long)OCFS2_I(inode)->ip_blkno);

	mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
	" \"%pd\": old parent: %llu, new: %llu\n",
	dentry,
	(unsigned long long)parent_blkno,
	(unsigned long long)dl->dl_parent_blkno);

	trace_ocfs2_dentry_attach_lock_found(dl->dl_lockres.l_name,
	(unsigned long long)parent_blkno,
	(unsigned long long)OCFS2_I(inode)->ip_blkno);

	goto out_attach;
	}

	/*
	* There are no other aliases
	*/
	dl = kmalloc(sizeof(*dl), GFP_NOFS);
	if (!dl) {
	ret = -ENOMEM;
	mlog_errno(ret);
	return ret;
	}

	dl->dl_count = 0;
	/*
	* Does this have to happen below, for all attaches, in case
	* the struct inode gets blown away by the downconvert thread?
	*/
	dl->dl_inode = igrab(inode);
	dl->dl_parent_blkno = parent_blkno;
	ocfs2_dentry_lock_res_init(dl, parent_blkno, inode);

	out_attach:
	spin_lock(&dentry_attach_lock);
	dentry->d_fsdata = dl;
	dl->dl_count++;
	spin_unlock(&dentry_attach_lock);

	/*
	* This actually gets us our PRMODE level lock. From now on,
	* we'll have a notification if one of these names is
	* destroyed on another node.
	*/
	ret = ocfs2_dentry_lock(dentry, 0);
	if (!ret)
	ocfs2_dentry_unlock(dentry, 0);
	else
	mlog_errno(ret);

	/*
	* In case of error, manually free the allocation and do the iput().
	* We need to do this because error here means no d_instantiate(),
	* which means iput() will not be called during dput(dentry).
	*/
	if (ret < 0 && !alias) {
	ocfs2_lock_res_free(&dl->dl_lockres);
	BUG_ON(dl->dl_count != 1);
	spin_lock(&dentry_attach_lock);
	dentry->d_fsdata = NULL;
	spin_unlock(&dentry_attach_lock);
	kfree(dl);
	iput(inode);
	}

	dput(alias);

	return ret;
	}

	/*
	* ocfs2_dentry_iput() and friends.
	*
	* At this point, our particular dentry is detached from the inodes
	* alias list, so there's no way that the locking code can find it.
	*
	* The interesting stuff happens when we determine that our lock needs
	* to go away because this is the last subdir alias in the
	* system. This function needs to handle a couple things:
	*
	* 1) Synchronizing lock shutdown with the downconvert threads. This
	* is already handled for us via the lockres release drop function
	* called in ocfs2_release_dentry_lock()
	*
	* 2) A race may occur when we're doing our lock shutdown and
	* another process wants to create a new dentry lock. Right now we
	* let them race, which means that for a very short while, this
	* node might have two locks on a lock resource. This should be a
	* problem though because one of them is in the process of being
	* thrown out.
	*/
	static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb,
	struct ocfs2_dentry_lock *dl)
	{
	iput(dl->dl_inode);
	ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
	ocfs2_lock_res_free(&dl->dl_lockres);
	kfree(dl);
	}

	void ocfs2_dentry_lock_put(struct ocfs2_super *osb,
	struct ocfs2_dentry_lock *dl)
	{
	int unlock = 0;

	BUG_ON(dl->dl_count == 0);

	spin_lock(&dentry_attach_lock);
	dl->dl_count--;
	unlock = !dl->dl_count;
	spin_unlock(&dentry_attach_lock);

	if (unlock)
	ocfs2_drop_dentry_lock(osb, dl);
	}

	static void ocfs2_dentry_iput(struct dentry dentry, struct inode inode)
	{
	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;

	if (!dl) {
	/*
	* No dentry lock is ok if we're disconnected or
	* unhashed.
	*/
	if (!(dentry->d_flags & DCACHE_DISCONNECTED) &&
	!d_unhashed(dentry)) {
	unsigned long long ino = 0ULL;
	if (inode)
	ino = (unsigned long long)OCFS2_I(inode)->ip_blkno;
	mlog(ML_ERROR, "Dentry is missing cluster lock. "
	"inode: %llu, d_flags: 0x%x, d_name: %pd\n",
	ino, dentry->d_flags, dentry);
	}

	goto out;
	}

	mlog_bug_on_msg(dl->dl_count == 0, "dentry: %pd, count: %u\n",
	dentry, dl->dl_count);

	ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl);

	out:
	iput(inode);
	}

	/*
	* d_move(), but keep the locks in sync.
	*
	* When we are done, "dentry" will have the parent dir and name of
	* "target", which will be thrown away.
	*
	* We manually update the lock of "dentry" if need be.
	*
	* "target" doesn't have it's dentry lock touched - we allow the later
	* dput() to handle this for us.
	*
	* This is called during ocfs2_rename(), while holding parent
	* directory locks. The dentries have already been deleted on other
	* nodes via ocfs2_remote_dentry_delete().
	*
	* Normally, the VFS handles the d_move() for the file system, after
	* the ->rename() callback. OCFS2 wants to handle this internally, so
	* the new lock can be created atomically with respect to the cluster.
	*/
	void ocfs2_dentry_move(struct dentry dentry, struct dentry target,
	struct inode old_dir, struct inode new_dir)
	{
	int ret;
	struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb);
	struct inode *inode = d_inode(dentry);

	/*
	* Move within the same directory, so the actual lock info won't
	* change.
	*
	* XXX: Is there any advantage to dropping the lock here?
	*/
	if (old_dir == new_dir)
	goto out_move;

	ocfs2_dentry_lock_put(osb, dentry->d_fsdata);

	dentry->d_fsdata = NULL;
	ret = ocfs2_dentry_attach_lock(dentry, inode, OCFS2_I(new_dir)->ip_blkno);
	if (ret)
	mlog_errno(ret);

	out_move:
	d_move(dentry, target);
	}

	const struct dentry_operations ocfs2_dentry_ops = {
	.d_revalidate = ocfs2_dentry_revalidate,
	.d_iput = ocfs2_dentry_iput,
	};