From d9b3dbdcfd6213731c3eb985a3a83537e3894e12 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Wed, 20 Apr 2016 17:30:32 -0400
Subject: [PATCH] fuse: switch to ->iterate_shared()

Switch dcache pre-seeding on readdir to d_alloc_parallel();
nothing else is needed.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/fuse/dir.c | 94 ++++++++++++++++++++++++---------------------------
 1 file changed, 45 insertions(+), 49 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index b618527c05c6..b9419058108f 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1162,7 +1162,6 @@ static int fuse_direntplus_link(struct file *file,
 				struct fuse_direntplus *direntplus,
 				u64 attr_version)
 {
-	int err;
 	struct fuse_entry_out *o = &direntplus->entry_out;
 	struct fuse_dirent *dirent = &direntplus->dirent;
 	struct dentry *parent = file->f_path.dentry;
@@ -1172,6 +1171,7 @@ static int fuse_direntplus_link(struct file *file,
 	struct inode *dir = d_inode(parent);
 	struct fuse_conn *fc;
 	struct inode *inode;
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
 
 	if (!o->nodeid) {
 		/*
@@ -1204,65 +1204,61 @@ static int fuse_direntplus_link(struct file *file,
 
 	name.hash = full_name_hash(name.name, name.len);
 	dentry = d_lookup(parent, &name);
-	if (dentry) {
+	if (!dentry) {
+retry:
+		dentry = d_alloc_parallel(parent, &name, &wq);
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
+	}
+	if (!d_in_lookup(dentry)) {
+		struct fuse_inode *fi;
 		inode = d_inode(dentry);
-		if (!inode) {
-			d_drop(dentry);
-		} else if (get_node_id(inode) != o->nodeid ||
-			   ((o->attr.mode ^ inode->i_mode) & S_IFMT)) {
+		if (!inode ||
+		    get_node_id(inode) != o->nodeid ||
+		    ((o->attr.mode ^ inode->i_mode) & S_IFMT)) {
 			d_invalidate(dentry);
-		} else if (is_bad_inode(inode)) {
-			err = -EIO;
-			goto out;
-		} else {
-			struct fuse_inode *fi;
-			fi = get_fuse_inode(inode);
-			spin_lock(&fc->lock);
-			fi->nlookup++;
-			spin_unlock(&fc->lock);
-
-			fuse_change_attributes(inode, &o->attr,
-					       entry_attr_timeout(o),
-					       attr_version);
-
-			/*
-			 * The other branch to 'found' comes via fuse_iget()
-			 * which bumps nlookup inside
-			 */
-			goto found;
+			dput(dentry);
+			goto retry;
+		}
+		if (is_bad_inode(inode)) {
+			dput(dentry);
+			return -EIO;
 		}
-		dput(dentry);
-	}
-
-	dentry = d_alloc(parent, &name);
-	err = -ENOMEM;
-	if (!dentry)
-		goto out;
 
-	inode = fuse_iget(dir->i_sb, o->nodeid, o->generation,
-			  &o->attr, entry_attr_timeout(o), attr_version);
-	if (!inode)
-		goto out;
+		fi = get_fuse_inode(inode);
+		spin_lock(&fc->lock);
+		fi->nlookup++;
+		spin_unlock(&fc->lock);
 
-	alias = d_splice_alias(inode, dentry);
-	err = PTR_ERR(alias);
-	if (IS_ERR(alias))
-		goto out;
+		fuse_change_attributes(inode, &o->attr,
+				       entry_attr_timeout(o),
+				       attr_version);
+		/*
+		 * The other branch comes via fuse_iget()
+		 * which bumps nlookup inside
+		 */
+	} else {
+		inode = fuse_iget(dir->i_sb, o->nodeid, o->generation,
+				  &o->attr, entry_attr_timeout(o),
+				  attr_version);
+		if (!inode)
+			inode = ERR_PTR(-ENOMEM);
 
-	if (alias) {
-		dput(dentry);
-		dentry = alias;
+		alias = d_splice_alias(inode, dentry);
+		d_lookup_done(dentry);
+		if (alias) {
+			dput(dentry);
+			dentry = alias;
+		}
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
 	}
-
-found:
 	if (fc->readdirplus_auto)
 		set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);
 	fuse_change_entry_timeout(dentry, o);
 
-	err = 0;
-out:
 	dput(dentry);
-	return err;
+	return 0;
 }
 
 static int parse_dirplusfile(char *buf, size_t nbytes, struct file *file,
@@ -1892,7 +1888,7 @@ static const struct inode_operations fuse_dir_inode_operations = {
 static const struct file_operations fuse_dir_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= generic_read_dir,
-	.iterate	= fuse_readdir,
+	.iterate_shared	= fuse_readdir,
 	.open		= fuse_dir_open,
 	.release	= fuse_dir_release,
 	.fsync		= fuse_dir_fsync,
-- 
2.20.1