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|
/* -*- 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.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#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(dentry->d_parent->d_inode)->ip_dir_lock_gen;
BUG_ON(dentry->d_inode);
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 = dentry->d_inode;
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(dentry->d_parent->d_inode)->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 = dentry->d_parent->d_inode;
/* 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 (!dentry->d_inode && 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,
|