patches.pramfs/06-pramfs-inode-operations-for-dirs.patch

From ltsi-dev-bounces@lists.linuxfoundation.org Sat May 12 10:16:57 2012
From: Marco Stornelli <marco.stornelli@gmail.com>
Date: Sat, 12 May 2012 19:10:23 +0200
Subject: pramfs: inode operations for dirs
To: LTSI <ltsi-dev@lists.linuxfoundation.org>
Message-ID: <4FAE997F.6020507@gmail.com>


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

Inode operations for directories.

Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
---
 fs/pramfs/namei.c |  376 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 376 insertions(+)

--- /dev/null
+++ b/fs/pramfs/namei.c
@@ -0,0 +1,376 @@
+/*
+ * BRIEF DESCRIPTION
+ *
+ * Inode operations for directories.
+ *
+ * Copyright 2009-2011 Marco Stornelli <marco.stornelli@gmail.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.h"
+#include "acl.h"
+#include "xattr.h"
+#include "xip.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, NULL);
+}
+
+static inline void pram_dec_count(struct inode *inode)
+{
+	if (inode->i_nlink) {
+		inode->i_nlink--;
+		pram_write_inode(inode, NULL);
+	}
+}
+
+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);
+		unlock_new_inode(inode);
+		return 0;
+	}
+	pram_dec_count(inode);
+	unlock_new_inode(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 = be64_to_cpu(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 = be64_to_cpu(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) {
+		inode = pram_iget(dir->i_sb, ino);
+		if (inode == ERR_PTR(-ESTALE)) {
+			pram_err(dir->i_sb, __func__,
+				"deleted inode referenced: %lu",
+				(unsigned long) ino);
+			return ERR_PTR(-EIO);
+		}
+	}
+
+	return d_splice_alias(inode, dentry);
+}
+
+
+/*
+ * 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, &dentry->d_name);
+	int err = PTR_ERR(inode);
+	if (!IS_ERR(inode)) {
+		inode->i_op = &pram_file_inode_operations;
+		if (pram_use_xip(inode->i_sb)) {
+			inode->i_mapping->a_ops = &pram_aops_xip;
+			inode->i_fop = &pram_xip_file_operations;
+		} else {
+			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, &dentry->d_name);
+	int err = PTR_ERR(inode);
+	if (!IS_ERR(inode)) {
+		init_special_inode(inode, mode, rdev);
+		inode->i_op = &pram_special_inode_operations;
+		pram_write_inode(inode, NULL); /* 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, &dentry->d_name);
+	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, NULL);
+
+	err = pram_add_nondir(dir, dentry, inode);
+out:
+	return err;
+
+out_fail:
+	pram_dec_count(inode);
+	unlock_new_inode(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 -EOPNOTSUPP;
+}
+
+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;
+
+	if (dir->i_nlink >= PRAM_LINK_MAX)
+		goto out;
+
+	pram_inc_count(dir);
+
+	inode = pram_new_inode(dir, S_IFDIR | mode, &dentry->d_name);
+	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_memunlock_inode(dir->i_sb, pi);
+	pi->i_type.dir.head = pi->i_type.dir.tail = 0;
+	pram_memlock_inode(dir->i_sb, pi);
+
+	err = pram_add_link(dentry, inode);
+	if (err)
+		goto out_fail;
+
+	d_instantiate(dentry, inode);
+	unlock_new_inode(inode);
+out:
+	return err;
+
+out_fail:
+	pram_dec_count(inode);
+	pram_dec_count(inode);
+	unlock_new_inode(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, NULL);
+		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)
+				drop_nlink(new_inode);
+		}
+
+		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 dentry *pram_get_parent(struct dentry *child)
+{
+	struct inode *inode;
+	struct pram_inode *pi, *piparent;
+	ino_t ino;
+
+	pi = pram_get_inode(child->d_inode->i_sb, child->d_inode->i_ino);
+	if (!pi)
+		return ERR_PTR(-EACCES);
+
+	piparent = pram_get_inode(child->d_inode->i_sb,
+				  be64_to_cpu(pi->i_d.d_parent));
+	if (!pi)
+		return ERR_PTR(-ENOENT);
+
+	ino = pram_get_inodenr(child->d_inode->i_sb, piparent);
+	if (ino)
+		inode = pram_iget(child->d_inode->i_sb, ino);
+	else
+		return ERR_PTR(-ENOENT);
+
+	return d_obtain_alias(inode);
+}
+
+const 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,
+#ifdef CONFIG_PRAMFS_XATTR
+	.setxattr	= generic_setxattr,
+	.getxattr	= generic_getxattr,
+	.listxattr	= pram_listxattr,
+	.removexattr	= generic_removexattr,
+#endif
+	.setattr	= pram_notify_change,
+	.check_acl	= pram_check_acl,
+};
+
+const struct inode_operations pram_special_inode_operations = {
+#ifdef CONFIG_PRAMFS_XATTR
+	.setxattr	= generic_setxattr,
+	.getxattr	= generic_getxattr,
+	.listxattr	= pram_listxattr,
+	.removexattr	= generic_removexattr,
+#endif
+	.setattr	= pram_notify_change,
+	.check_acl	= pram_check_acl,
+};