/* -*- 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>
#define MLOG_MASK_PREFIX ML_DCACHE
#include <cluster/masklog.h>
#include "ocfs2.h"
#include "alloc.h"
#include "dcache.h"
#include "dlmglue.h"
#include "file.h"
#include "inode.h"
static int ocfs2_dentry_revalidate(struct dentry *dentry,
struct nameidata *nd)
{
struct inode *inode = dentry->d_inode;
int ret = 0; /* if all else fails, just return false */
struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
mlog_entry("(0x%p, '%.*s')\n", dentry,
dentry->d_name.len, dentry->d_name.name);
/* Never trust a negative dentry - force a new lookup. */
if (inode == NULL) {
mlog(0, "negative dentry: %.*s\n", dentry->d_name.len,
dentry->d_name.name);
goto bail;
}
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);
mlog(0, "inode (%llu) deleted, returning false\n",
(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) {
mlog(0, "Inode %llu orphaned, returning false "
"dir = %d\n",
(unsigned long long)OCFS2_I(inode)->ip_blkno,
S_ISDIR(inode->i_mode));
goto bail;
}
ret = 1;
bail:
mlog_exit(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 vote 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 list_head *p;
struct dentry *dentry = NULL;
spin_lock(&dcache_lock);
list_for_each(p, &inode->i_dentry) {
dentry = list_entry(p, struct dentry, d_alias);
if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) {
mlog(0, "dentry found: %.*s\n",
dentry->d_name.len, dentry->d_name.name);
dget_locked(dentry);
break;
}
dentry = NULL;
}
spin_unlock(&dcache_lock);
return dentry;
}
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.
*
* The 'create' flag tells us whether we're doing this as a result of
* a file creation.
*
* 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 create)
{
int ret;
struct dentry *alias;
struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
mlog(0, "Attach \"%.*s\", parent %llu, create %d, fsdata: %p\n",
dentry->d_name.len, dentry->d_name.name,
(unsigned long long)parent_blkno, create, dl);
/*
* Negative dentry. We ignore these for now.
*
* XXX: Could we can improve ocfs2_dentry_revalidate() by
* tracking these?
*/
if (!inode)
return 0;
if (dl) {
mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
" \"%.*s\": old parent: %llu, new: %llu\n",
dentry->d_name.len, dentry->d_name.name,
(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, create %d\n",
(unsigned long long)parent_blkno,
(unsigned long long)OCFS2_I(inode)->ip_blkno,
create);
mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
" \"%.*s\": old parent: %llu, new: %llu\n",
dentry->d_name.len, dentry->d_name.name,
(unsigned long long)parent_blkno,
(unsigned long long)dl->dl_parent_blkno);
mlog(0, "Found: %s\n", dl->dl_lockres.l_name);
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 votes?
*/
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);
/*
* Creation of a new file means that nobody can possibly have
* this name in the system, which means that acquiry of those
* locks can easily be optimized.
*/
if (create) {
ret = ocfs2_create_new_lock(OCFS2_SB(inode->i_sb),
&dl->dl_lockres, 0);
if (ret)
mlog_errno(ret);
goto out;
}
/*
* 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) {
mlog_errno(ret);
goto out;
}
ocfs2_dentry_unlock(dentry, 0);
out:
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)
{
ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
ocfs2_lock_res_free(&dl->dl_lockres);
iput(dl->dl_inode);
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;
mlog_bug_on_msg(!dl && !(dentry->d_flags & DCACHE_DISCONNECTED),
"dentry: %.*s\n", dentry->d_name.len,
dentry->d_name.name);
if (!dl)
goto out;
mlog_bug_on_msg(dl->dl_count == 0, "dentry: %.*s, count: %u\n",
dentry->d_name.len, dentry->d_name.name,
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 sytem, 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 = dentry->d_inode;
/*
* 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, 0);
if (ret)
mlog_errno(ret);
out_move:
d_move(dentry, target);
}
struct dentry_operations ocfs2_dentry_ops = {
.d_revalidate = ocfs2_dentry_revalidate,
.d_iput = ocfs2_dentry_iput,
};
