--- /dev/null
+/* -*- 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(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,
+};
Code Review / kvmfornfv.git / blobdiff