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![David Howells](/assets/img/avatar_default.png)
that's the bulk of filesystem drivers dealing with inodes of their own Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
474 lines
13 KiB
C
474 lines
13 KiB
C
/* -*- mode: c; c-basic-offset: 8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* dcache.c
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*
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* dentry cache handling code
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*
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* Copyright (C) 2002, 2004 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/fs.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/namei.h>
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#include <cluster/masklog.h>
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#include "ocfs2.h"
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#include "alloc.h"
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#include "dcache.h"
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#include "dlmglue.h"
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#include "file.h"
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#include "inode.h"
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#include "ocfs2_trace.h"
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void ocfs2_dentry_attach_gen(struct dentry *dentry)
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{
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unsigned long gen =
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OCFS2_I(d_inode(dentry->d_parent))->ip_dir_lock_gen;
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BUG_ON(d_inode(dentry));
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dentry->d_fsdata = (void *)gen;
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}
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static int ocfs2_dentry_revalidate(struct dentry *dentry, unsigned int flags)
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{
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struct inode *inode;
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int ret = 0; /* if all else fails, just return false */
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struct ocfs2_super *osb;
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if (flags & LOOKUP_RCU)
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return -ECHILD;
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inode = d_inode(dentry);
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osb = OCFS2_SB(dentry->d_sb);
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trace_ocfs2_dentry_revalidate(dentry, dentry->d_name.len,
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dentry->d_name.name);
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/* For a negative dentry -
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* check the generation number of the parent and compare with the
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* one stored in the inode.
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*/
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if (inode == NULL) {
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unsigned long gen = (unsigned long) dentry->d_fsdata;
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unsigned long pgen;
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spin_lock(&dentry->d_lock);
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pgen = OCFS2_I(d_inode(dentry->d_parent))->ip_dir_lock_gen;
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spin_unlock(&dentry->d_lock);
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trace_ocfs2_dentry_revalidate_negative(dentry->d_name.len,
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dentry->d_name.name,
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pgen, gen);
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if (gen != pgen)
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goto bail;
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goto valid;
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}
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BUG_ON(!osb);
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if (inode == osb->root_inode || is_bad_inode(inode))
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goto bail;
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spin_lock(&OCFS2_I(inode)->ip_lock);
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/* did we or someone else delete this inode? */
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if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) {
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spin_unlock(&OCFS2_I(inode)->ip_lock);
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trace_ocfs2_dentry_revalidate_delete(
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(unsigned long long)OCFS2_I(inode)->ip_blkno);
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goto bail;
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}
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spin_unlock(&OCFS2_I(inode)->ip_lock);
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/*
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* We don't need a cluster lock to test this because once an
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* inode nlink hits zero, it never goes back.
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*/
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if (inode->i_nlink == 0) {
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trace_ocfs2_dentry_revalidate_orphaned(
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(unsigned long long)OCFS2_I(inode)->ip_blkno,
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S_ISDIR(inode->i_mode));
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goto bail;
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}
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/*
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* If the last lookup failed to create dentry lock, let us
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* redo it.
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*/
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if (!dentry->d_fsdata) {
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trace_ocfs2_dentry_revalidate_nofsdata(
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(unsigned long long)OCFS2_I(inode)->ip_blkno);
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goto bail;
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}
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valid:
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ret = 1;
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bail:
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trace_ocfs2_dentry_revalidate_ret(ret);
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return ret;
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}
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static int ocfs2_match_dentry(struct dentry *dentry,
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u64 parent_blkno,
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int skip_unhashed)
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{
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struct inode *parent;
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/*
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* ocfs2_lookup() does a d_splice_alias() _before_ attaching
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* to the lock data, so we skip those here, otherwise
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* ocfs2_dentry_attach_lock() will get its original dentry
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* back.
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*/
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if (!dentry->d_fsdata)
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return 0;
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if (!dentry->d_parent)
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return 0;
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if (skip_unhashed && d_unhashed(dentry))
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return 0;
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parent = d_inode(dentry->d_parent);
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/* Negative parent dentry? */
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if (!parent)
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return 0;
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/* Name is in a different directory. */
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if (OCFS2_I(parent)->ip_blkno != parent_blkno)
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return 0;
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return 1;
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}
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/*
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* Walk the inode alias list, and find a dentry which has a given
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* parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it
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* is looking for a dentry_lock reference. The downconvert thread is
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* looking to unhash aliases, so we allow it to skip any that already
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* have that property.
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*/
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struct dentry *ocfs2_find_local_alias(struct inode *inode,
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u64 parent_blkno,
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int skip_unhashed)
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{
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struct dentry *dentry;
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spin_lock(&inode->i_lock);
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hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
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spin_lock(&dentry->d_lock);
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if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) {
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trace_ocfs2_find_local_alias(dentry->d_name.len,
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dentry->d_name.name);
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dget_dlock(dentry);
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spin_unlock(&dentry->d_lock);
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spin_unlock(&inode->i_lock);
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return dentry;
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}
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spin_unlock(&dentry->d_lock);
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}
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spin_unlock(&inode->i_lock);
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return NULL;
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}
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DEFINE_SPINLOCK(dentry_attach_lock);
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/*
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* Attach this dentry to a cluster lock.
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*
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* Dentry locks cover all links in a given directory to a particular
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* inode. We do this so that ocfs2 can build a lock name which all
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* nodes in the cluster can agree on at all times. Shoving full names
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* in the cluster lock won't work due to size restrictions. Covering
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* links inside of a directory is a good compromise because it still
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* allows us to use the parent directory lock to synchronize
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* operations.
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*
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* Call this function with the parent dir semaphore and the parent dir
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* cluster lock held.
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*
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* The dir semaphore will protect us from having to worry about
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* concurrent processes on our node trying to attach a lock at the
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* same time.
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*
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* The dir cluster lock (held at either PR or EX mode) protects us
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* from unlink and rename on other nodes.
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*
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* A dput() can happen asynchronously due to pruning, so we cover
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* attaching and detaching the dentry lock with a
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* dentry_attach_lock.
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*
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* A node which has done lookup on a name retains a protected read
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* lock until final dput. If the user requests and unlink or rename,
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* the protected read is upgraded to an exclusive lock. Other nodes
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* who have seen the dentry will then be informed that they need to
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* downgrade their lock, which will involve d_delete on the
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* dentry. This happens in ocfs2_dentry_convert_worker().
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*/
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int ocfs2_dentry_attach_lock(struct dentry *dentry,
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struct inode *inode,
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u64 parent_blkno)
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{
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int ret;
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struct dentry *alias;
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struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
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trace_ocfs2_dentry_attach_lock(dentry->d_name.len, dentry->d_name.name,
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(unsigned long long)parent_blkno, dl);
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/*
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* Negative dentry. We ignore these for now.
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*
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* XXX: Could we can improve ocfs2_dentry_revalidate() by
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* tracking these?
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*/
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if (!inode)
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return 0;
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if (d_really_is_negative(dentry) && dentry->d_fsdata) {
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/* Converting a negative dentry to positive
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Clear dentry->d_fsdata */
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dentry->d_fsdata = dl = NULL;
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}
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if (dl) {
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mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
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" \"%pd\": old parent: %llu, new: %llu\n",
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dentry,
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(unsigned long long)parent_blkno,
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(unsigned long long)dl->dl_parent_blkno);
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return 0;
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}
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alias = ocfs2_find_local_alias(inode, parent_blkno, 0);
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if (alias) {
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/*
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* Great, an alias exists, which means we must have a
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* dentry lock already. We can just grab the lock off
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* the alias and add it to the list.
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*
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* We're depending here on the fact that this dentry
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* was found and exists in the dcache and so must have
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* a reference to the dentry_lock because we can't
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* race creates. Final dput() cannot happen on it
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* since we have it pinned, so our reference is safe.
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*/
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dl = alias->d_fsdata;
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mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n",
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(unsigned long long)parent_blkno,
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(unsigned long long)OCFS2_I(inode)->ip_blkno);
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mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
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" \"%pd\": old parent: %llu, new: %llu\n",
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dentry,
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(unsigned long long)parent_blkno,
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(unsigned long long)dl->dl_parent_blkno);
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trace_ocfs2_dentry_attach_lock_found(dl->dl_lockres.l_name,
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(unsigned long long)parent_blkno,
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(unsigned long long)OCFS2_I(inode)->ip_blkno);
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goto out_attach;
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}
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/*
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* There are no other aliases
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*/
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dl = kmalloc(sizeof(*dl), GFP_NOFS);
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if (!dl) {
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ret = -ENOMEM;
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mlog_errno(ret);
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return ret;
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}
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dl->dl_count = 0;
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/*
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* Does this have to happen below, for all attaches, in case
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* the struct inode gets blown away by the downconvert thread?
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*/
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dl->dl_inode = igrab(inode);
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dl->dl_parent_blkno = parent_blkno;
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ocfs2_dentry_lock_res_init(dl, parent_blkno, inode);
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out_attach:
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spin_lock(&dentry_attach_lock);
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dentry->d_fsdata = dl;
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dl->dl_count++;
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spin_unlock(&dentry_attach_lock);
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/*
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* This actually gets us our PRMODE level lock. From now on,
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* we'll have a notification if one of these names is
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* destroyed on another node.
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*/
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ret = ocfs2_dentry_lock(dentry, 0);
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if (!ret)
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ocfs2_dentry_unlock(dentry, 0);
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else
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mlog_errno(ret);
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/*
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* In case of error, manually free the allocation and do the iput().
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* We need to do this because error here means no d_instantiate(),
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* which means iput() will not be called during dput(dentry).
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*/
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if (ret < 0 && !alias) {
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ocfs2_lock_res_free(&dl->dl_lockres);
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BUG_ON(dl->dl_count != 1);
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spin_lock(&dentry_attach_lock);
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dentry->d_fsdata = NULL;
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spin_unlock(&dentry_attach_lock);
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kfree(dl);
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iput(inode);
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}
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dput(alias);
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return ret;
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}
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/*
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* ocfs2_dentry_iput() and friends.
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*
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* At this point, our particular dentry is detached from the inodes
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* alias list, so there's no way that the locking code can find it.
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*
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* The interesting stuff happens when we determine that our lock needs
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* to go away because this is the last subdir alias in the
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* system. This function needs to handle a couple things:
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*
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* 1) Synchronizing lock shutdown with the downconvert threads. This
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* is already handled for us via the lockres release drop function
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* called in ocfs2_release_dentry_lock()
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*
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* 2) A race may occur when we're doing our lock shutdown and
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* another process wants to create a new dentry lock. Right now we
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* let them race, which means that for a very short while, this
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* node might have two locks on a lock resource. This should be a
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* problem though because one of them is in the process of being
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* thrown out.
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*/
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static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb,
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struct ocfs2_dentry_lock *dl)
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{
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iput(dl->dl_inode);
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ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
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ocfs2_lock_res_free(&dl->dl_lockres);
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kfree(dl);
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}
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void ocfs2_dentry_lock_put(struct ocfs2_super *osb,
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struct ocfs2_dentry_lock *dl)
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{
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int unlock = 0;
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BUG_ON(dl->dl_count == 0);
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spin_lock(&dentry_attach_lock);
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dl->dl_count--;
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unlock = !dl->dl_count;
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spin_unlock(&dentry_attach_lock);
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if (unlock)
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ocfs2_drop_dentry_lock(osb, dl);
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}
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static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode)
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{
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struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
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if (!dl) {
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/*
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* No dentry lock is ok if we're disconnected or
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* unhashed.
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*/
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if (!(dentry->d_flags & DCACHE_DISCONNECTED) &&
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!d_unhashed(dentry)) {
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unsigned long long ino = 0ULL;
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if (inode)
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ino = (unsigned long long)OCFS2_I(inode)->ip_blkno;
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mlog(ML_ERROR, "Dentry is missing cluster lock. "
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"inode: %llu, d_flags: 0x%x, d_name: %pd\n",
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ino, dentry->d_flags, dentry);
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}
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goto out;
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}
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mlog_bug_on_msg(dl->dl_count == 0, "dentry: %pd, count: %u\n",
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dentry, dl->dl_count);
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ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl);
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out:
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iput(inode);
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}
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/*
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* d_move(), but keep the locks in sync.
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*
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* When we are done, "dentry" will have the parent dir and name of
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* "target", which will be thrown away.
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*
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* We manually update the lock of "dentry" if need be.
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*
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* "target" doesn't have it's dentry lock touched - we allow the later
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* dput() to handle this for us.
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*
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* This is called during ocfs2_rename(), while holding parent
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* directory locks. The dentries have already been deleted on other
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* nodes via ocfs2_remote_dentry_delete().
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*
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* Normally, the VFS handles the d_move() for the file system, after
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* the ->rename() callback. OCFS2 wants to handle this internally, so
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* the new lock can be created atomically with respect to the cluster.
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*/
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void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target,
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struct inode *old_dir, struct inode *new_dir)
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{
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int ret;
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struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb);
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struct inode *inode = d_inode(dentry);
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/*
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* Move within the same directory, so the actual lock info won't
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* change.
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*
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* XXX: Is there any advantage to dropping the lock here?
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*/
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if (old_dir == new_dir)
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goto out_move;
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ocfs2_dentry_lock_put(osb, dentry->d_fsdata);
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dentry->d_fsdata = NULL;
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ret = ocfs2_dentry_attach_lock(dentry, inode, OCFS2_I(new_dir)->ip_blkno);
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if (ret)
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mlog_errno(ret);
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out_move:
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d_move(dentry, target);
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}
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const struct dentry_operations ocfs2_dentry_ops = {
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.d_revalidate = ocfs2_dentry_revalidate,
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.d_iput = ocfs2_dentry_iput,
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};
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