[PATCH] autofs4: use libfs routines for readdir

Change readdir routines to use the cursor based routines in libfs.c.  This
removes reliance on old readdir code from 2.4 and should improve efficiency of
readdir in autofs4.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/autofs4/root.c

@@ -30,7 +30,6 @@ static int autofs4_dir_close(struct inode *inode, struct file *file);
 static int autofs4_dir_readdir(struct file * filp, void * dirent, filldir_t filldir);
 static int autofs4_root_readdir(struct file * filp, void * dirent, filldir_t filldir);
 static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
-static int autofs4_dcache_readdir(struct file *, void *, filldir_t);
 
 struct file_operations autofs4_root_operations = {
 	.open		= dcache_dir_open,
@@ -82,7 +81,7 @@ static int autofs4_root_readdir(struct file *file, void *dirent,
 
 	DPRINTK("needs_reghost = %d", sbi->needs_reghost);
 
-	return autofs4_dcache_readdir(file, dirent, filldir);
+	return dcache_readdir(file, dirent, filldir);
 }
 
 /* Update usage from here to top of tree, so that scan of
@@ -103,75 +102,21 @@ static void autofs4_update_usage(struct vfsmount *mnt, struct dentry *dentry)
 	spin_unlock(&dcache_lock);
 }
 
-/*
- * From 2.4 kernel readdir.c
- */
-static int autofs4_dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
-{
-	int i;
-	struct dentry *dentry = filp->f_dentry;
-
-	i = filp->f_pos;
-	switch (i) {
-		case 0:
-			if (filldir(dirent, ".", 1, i, dentry->d_inode->i_ino, DT_DIR) < 0)
-				break;
-			i++;
-			filp->f_pos++;
-			/* fallthrough */
-		case 1:
-			if (filldir(dirent, "..", 2, i, dentry->d_parent->d_inode->i_ino, DT_DIR) < 0)
-				break;
-			i++;
-			filp->f_pos++;
-			/* fallthrough */
-		default: {
-			struct list_head *list;
-			int j = i-2;
-
-			spin_lock(&dcache_lock);
-			list = dentry->d_subdirs.next;
-
-			for (;;) {
-				if (list == &dentry->d_subdirs) {
-					spin_unlock(&dcache_lock);
-					return 0;
-				}
-				if (!j)
-					break;
-				j--;
-				list = list->next;
-			}
-
-			while(1) {
-				struct dentry *de = list_entry(list,
-						struct dentry, d_u.d_child);
-
-				if (!d_unhashed(de) && de->d_inode) {
-					spin_unlock(&dcache_lock);
-					if (filldir(dirent, de->d_name.name, de->d_name.len, filp->f_pos, de->d_inode->i_ino, DT_UNKNOWN) < 0)
-						break;
-					spin_lock(&dcache_lock);
-				}
-				filp->f_pos++;
-				list = list->next;
-				if (list != &dentry->d_subdirs)
-					continue;
-				spin_unlock(&dcache_lock);
-				break;
-			}
-		}
-	}
-	return 0;
-}
-
 static int autofs4_dir_open(struct inode *inode, struct file *file)
 {
 	struct dentry *dentry = file->f_dentry;
 	struct vfsmount *mnt = file->f_vfsmnt;
 	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+	struct dentry *cursor;
 	int status;
 
+	status = dcache_dir_open(inode, file);
+	if (status)
+		goto out;
+
+	cursor = file->private_data;
+	cursor->d_fsdata = NULL;
+
 	DPRINTK("file=%p dentry=%p %.*s",
 		file, dentry, dentry->d_name.len, dentry->d_name.name);
 
@@ -180,12 +125,15 @@ static int autofs4_dir_open(struct inode *inode, struct file *file)
 
 	if (autofs4_ispending(dentry)) {
 		DPRINTK("dentry busy");
-		return -EBUSY;
+		dcache_dir_close(inode, file);
+		status = -EBUSY;
+		goto out;
 	}
 
+	status = -ENOENT;
 	if (!d_mountpoint(dentry) && dentry->d_op && dentry->d_op->d_revalidate) {
 		struct nameidata nd;
-		int empty;
+		int empty, ret;
 
 		/* In case there are stale directory dentrys from a failed mount */
 		spin_lock(&dcache_lock);
@@ -195,13 +143,13 @@ static int autofs4_dir_open(struct inode *inode, struct file *file)
 		if (!empty)
 			d_invalidate(dentry);
 
-		nd.dentry = dentry;
-		nd.mnt = mnt;
 		nd.flags = LOOKUP_DIRECTORY;
-		status = (dentry->d_op->d_revalidate)(dentry, &nd);
+		ret = (dentry->d_op->d_revalidate)(dentry, &nd);
 
-		if (!status)
-			return -ENOENT;
+		if (!ret) {
+			dcache_dir_close(inode, file);
+			goto out;
+		}
 	}
 
 	if (d_mountpoint(dentry)) {
@@ -212,25 +160,29 @@ static int autofs4_dir_open(struct inode *inode, struct file *file)
 		if (!autofs4_follow_mount(&fp_mnt, &fp_dentry)) {
 			dput(fp_dentry);
 			mntput(fp_mnt);
-			return -ENOENT;
+			dcache_dir_close(inode, file);
+			goto out;
 		}
 
 		fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
 		status = PTR_ERR(fp);
 		if (IS_ERR(fp)) {
-			file->private_data = NULL;
-			return status;
+			dcache_dir_close(inode, file);
+			goto out;
 		}
-		file->private_data = fp;
+		cursor->d_fsdata = fp;
 	}
-out:
 	return 0;
+out:
+	return status;
 }
 
 static int autofs4_dir_close(struct inode *inode, struct file *file)
 {
 	struct dentry *dentry = file->f_dentry;
 	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+	struct dentry *cursor = file->private_data;
+	int status = 0;
 
 	DPRINTK("file=%p dentry=%p %.*s",
 		file, dentry, dentry->d_name.len, dentry->d_name.name);
@@ -240,26 +192,28 @@ static int autofs4_dir_close(struct inode *inode, struct file *file)
 
 	if (autofs4_ispending(dentry)) {
 		DPRINTK("dentry busy");
-		return -EBUSY;
+		status = -EBUSY;
+		goto out;
 	}
 
 	if (d_mountpoint(dentry)) {
-		struct file *fp = file->private_data;
-
-		if (!fp)
-			return -ENOENT;
-
+		struct file *fp = cursor->d_fsdata;
+		if (!fp) {
+			status = -ENOENT;
+			goto out;
+		}
 		filp_close(fp, current->files);
-		file->private_data = NULL;
 	}
 out:
-	return 0;
+	dcache_dir_close(inode, file);
+	return status;
 }
 
 static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldir)
 {
 	struct dentry *dentry = file->f_dentry;
 	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+	struct dentry *cursor = file->private_data;
 	int status;
 
 	DPRINTK("file=%p dentry=%p %.*s",
@@ -274,7 +228,7 @@ static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldi
 	}
 
 	if (d_mountpoint(dentry)) {
-		struct file *fp = file->private_data;
+		struct file *fp = cursor->d_fsdata;
 
 		if (!fp)
 			return -ENOENT;
@@ -289,7 +243,7 @@ static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldi
 		return status;
 	}
 out:
-	return autofs4_dcache_readdir(file, dirent, filldir);
+	return dcache_readdir(file, dirent, filldir);
 }
 
 static int try_to_fill_dentry(struct vfsmount *mnt, struct dentry *dentry, int flags)