Message-ID: <4A33A80C.4080001@gmail.com>
Date:	Sat, 13 Jun 2009 15:22:20 +0200
From:	Marco <marco.stornelli@...il.com>
To:	Linux FS Devel <linux-fsdevel@...r.kernel.org>
CC:	Linux Embedded <linux-embedded@...r.kernel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Daniel Walker <dwalker@....ucsc.edu>
Subject: [PATCH 09/14] Pramfs: Inode operations for directories

From: Marco Stornelli <marco.stornelli@...il.com>

Inode operations for directories.

Signed-off-by: Marco Stornelli <marco.stornelli@...il.com>
---

diff -uprN linux-2.6.30-orig/fs/pramfs/namei.c linux-2.6.30/fs/pramfs/namei.c
--- linux-2.6.30-orig/fs/pramfs/namei.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.30/fs/pramfs/namei.c	2009-06-13 12:53:15.000000000 +0200
@@ -0,0 +1,328 @@
+/*
+ * FILE NAME fs/pramfs/namei.c
+ *
+ * BRIEF DESCRIPTION
+ *
+ * Inode operations for directories.
+ *
+ * Copyright 2009 Marco Stornelli <marco.stornelli@...il.com>
+ * Copyright 2003 Sony Corporation
+ * Copyright 2003 Matsushita Electric Industrial Co., Ltd.
+ * 2003-2004 (c) MontaVista Software, Inc. , Steve Longerbeam
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include "pram_fs.h"
+
+/*
+ * Couple of helper functions - make the code slightly cleaner.
+ */
+
+static inline void pram_inc_count(struct inode *inode)
+{
+	inode->i_nlink++;
+	pram_write_inode(inode, 0);
+}
+
+static inline void pram_dec_count(struct inode *inode)
+{
+	if (inode->i_nlink) {
+		inode->i_nlink--;
+		pram_write_inode(inode, 0);
+	}
+}
+
+static inline int pram_add_nondir(struct inode *dir,
+				   struct dentry *dentry,
+				   struct inode *inode)
+{
+	int err = pram_add_link(dentry, inode);
+	if (!err) {
+		d_instantiate(dentry, inode);
+		return 0;
+	}
+	pram_dec_count(inode);
+	iput(inode);
+	return err;
+}
+
+/*
+ * Methods themselves.
+ */
+
+static ino_t
+pram_inode_by_name(struct inode *dir,
+		   struct dentry *dentry)
+{
+	struct pram_inode *pi;
+	ino_t ino;
+	int namelen;
+
+	pi = pram_get_inode(dir->i_sb, dir->i_ino);
+	ino = pi->i_type.dir.head;
+
+	while (ino) {
+		pi = pram_get_inode(dir->i_sb, ino);
+
+		if (pi->i_links_count) {
+			namelen = strlen(pi->i_d.d_name);
+
+			if (namelen == dentry->d_name.len &&
+			    !memcmp(dentry->d_name.name,
+				    pi->i_d.d_name, namelen))
+				break;
+		}
+
+		ino = pi->i_d.d_next;
+	}
+
+	return ino;
+}
+
+static struct dentry *
+pram_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
+{
+	struct inode *inode = NULL;
+	ino_t ino;
+
+	if (dentry->d_name.len > PRAM_NAME_LEN)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	ino = pram_inode_by_name(dir, dentry);
+	if (ino) {
+		struct pram_inode *pi = pram_get_inode(dir->i_sb, ino);
+		inode = pram_fill_new_inode(dir->i_sb, pi);
+		if (!inode)
+			return ERR_PTR(-EACCES);
+	}
+
+	d_add(dentry, inode);
+	return NULL;
+}
+
+
+/*
+ * By the time this is called, we already have created
+ * the directory cache entry for the new file, but it
+ * is so far negative - it has no inode.
+ *
+ * If the create succeeds, we fill in the inode information
+ * with d_instantiate().
+ */
+static int pram_create(struct inode *dir, struct dentry *dentry,
+			int mode, struct nameidata *nd)
+{
+	struct inode *inode = pram_new_inode(dir, mode);
+	int err = PTR_ERR(inode);
+	if (!IS_ERR(inode)) {
+
+		inode->i_op = &pram_file_inode_operations;
+		inode->i_fop = &pram_file_operations;
+		inode->i_mapping->a_ops = &pram_aops;
+		err = pram_add_nondir(dir, dentry, inode);
+	}
+	return err;
+}
+
+static int pram_mknod(struct inode *dir, struct dentry *dentry, int mode,
+		       dev_t rdev)
+{
+	struct inode *inode = pram_new_inode(dir, mode);
+	int err = PTR_ERR(inode);
+	if (!IS_ERR(inode)) {
+		init_special_inode(inode, mode, rdev);
+		pram_write_inode(inode, 0); /* update rdev */
+		err = pram_add_nondir(dir, dentry, inode);
+	}
+	return err;
+}
+
+static int pram_symlink(struct inode *dir,
+			  struct dentry *dentry,
+			  const char *symname)
+{
+	struct super_block *sb = dir->i_sb;
+	int err = -ENAMETOOLONG;
+	unsigned len = strlen(symname);
+	struct inode *inode;
+
+	if (len+1 > sb->s_blocksize)
+		goto out;
+
+	inode = pram_new_inode(dir, S_IFLNK | S_IRWXUGO);
+	err = PTR_ERR(inode);
+	if (IS_ERR(inode))
+		goto out;
+
+	inode->i_op = &pram_symlink_inode_operations;
+	inode->i_mapping->a_ops = &pram_aops;
+
+	err = pram_block_symlink(inode, symname, len);
+	if (err)
+		goto out_fail;
+
+	inode->i_size = len;
+	pram_write_inode(inode, 0);
+
+	err = pram_add_nondir(dir, dentry, inode);
+out:
+	return err;
+
+out_fail:
+	pram_dec_count(inode);
+	iput(inode);
+	goto out;
+}
+
+static int pram_link(struct dentry *dest_dentry,
+		       struct inode *dir,
+		       struct dentry *dentry)
+{
+	pram_dbg("hard links not supported\n");
+	return -ENOSYS;
+}
+
+static int pram_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = dentry->d_inode;
+	inode->i_ctime = dir->i_ctime;
+	pram_dec_count(inode);
+
+	return 0;
+}
+
+static int pram_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+	struct inode *inode;
+	struct pram_inode *pi;
+	int err = -EMLINK;
+	unsigned long flags;
+
+	flags = 0;
+
+	if (dir->i_nlink >= PRAM_LINK_MAX)
+		goto out;
+
+	pram_inc_count(dir);
+
+	inode = pram_new_inode(dir, S_IFDIR | mode);
+	err = PTR_ERR(inode);
+	if (IS_ERR(inode))
+		goto out_dir;
+
+	inode->i_op = &pram_dir_inode_operations;
+	inode->i_fop = &pram_dir_operations;
+	inode->i_mapping->a_ops = &pram_aops;
+
+	pram_inc_count(inode);
+
+	/* make the new directory empty */
+	pi = pram_get_inode(dir->i_sb, inode->i_ino);
+	pram_lock_inode(pi, flags);
+	pi->i_type.dir.head = pi->i_type.dir.tail = 0;
+	pram_unlock_inode(pi, flags);
+
+	err = pram_add_link(dentry, inode);
+	if (err)
+		goto out_fail;
+
+	d_instantiate(dentry, inode);
+out:
+	return err;
+
+out_fail:
+	pram_dec_count(inode);
+	pram_dec_count(inode);
+	iput(inode);
+out_dir:
+	pram_dec_count(dir);
+	goto out;
+}
+
+static int pram_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = dentry->d_inode;
+	struct pram_inode *pi;
+	int err = -ENOTEMPTY;
+
+	if (!inode)
+		return -ENOENT;
+
+	pi = pram_get_inode(dir->i_sb, inode->i_ino);
+
+	/* directory to delete is empty? */
+	if (pi->i_type.dir.tail == 0) {
+		inode->i_ctime = dir->i_ctime;
+		inode->i_size = 0;
+		inode->i_nlink = 0;
+		pram_write_inode(inode, 0);
+		pram_dec_count(dir);
+		err = 0;
+	} else {
+		pram_dbg("dir not empty\n");
+	}
+
+	return err;
+}
+
+static int pram_rename(struct inode  *old_dir,
+			struct dentry *old_dentry,
+			struct inode  *new_dir,
+			struct dentry *new_dentry)
+{
+	struct inode *old_inode = old_dentry->d_inode;
+	struct inode *new_inode = new_dentry->d_inode;
+	struct pram_inode *pi_new;
+	int err = -ENOENT;
+
+	if (new_inode) {
+		err = -ENOTEMPTY;
+		pi_new = pram_get_inode(new_dir->i_sb, new_inode->i_ino);
+		if (S_ISDIR(old_inode->i_mode)) {
+			if (pi_new->i_type.dir.tail != 0)
+				goto out;
+			if (new_inode->i_nlink)
+				new_inode->i_nlink--;
+		}
+
+		new_inode->i_ctime = CURRENT_TIME;
+		pram_dec_count(new_inode);
+	} else {
+		if (S_ISDIR(old_inode->i_mode)) {
+			err = -EMLINK;
+			if (new_dir->i_nlink >= PRAM_LINK_MAX)
+				goto out;
+			pram_dec_count(old_dir);
+			pram_inc_count(new_dir);
+		}
+	}
+
+	/* unlink the inode from the old directory ... */
+	err = pram_remove_link(old_inode);
+	if (err)
+		goto out;
+
+	/* and link it into the new directory. */
+	err = pram_add_link(new_dentry, old_inode);
+	if (err)
+		goto out;
+
+	err = 0;
+ out:
+	return err;
+}
+
+struct inode_operations pram_dir_inode_operations = {
+	.create		= pram_create,
+	.lookup		= pram_lookup,
+	.link		= pram_link,
+	.unlink		= pram_unlink,
+	.symlink	= pram_symlink,
+	.mkdir		= pram_mkdir,
+	.rmdir		= pram_rmdir,
+	.mknod		= pram_mknod,
+	.rename		= pram_rename,
+};


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