1 files changed, 470 insertions, 0 deletions
diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c
new file mode 100644
index 000000000..04fc83440
--- /dev/null
+++ b/fs/ocfs2/dcache.c
@@ -0,0 +1,470 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * 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);
+	if (unlikely(dentry->d_fsdata && !alias)) {
+		/* d_fsdata is set by a racing thread which is doing
+		 * the same thing as this thread is doing. Leave the racing
+		 * thread going ahead and we return here.
+		 */
+		spin_unlock(&dentry_attach_lock);
+		iput(dl->dl_inode);
+		ocfs2_lock_res_free(&dl->dl_lockres);
+		kfree(dl);
+		return 0;
+	}
+
+	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,
+};