linux-kernel - [PATCH] ecryptfs: some inode attrs, and a question

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Message-ID: <7471.1231827621@jrobl>
Date:	Tue, 13 Jan 2009 15:20:21 +0900
From:	hooanon05@...oo.co.jp
To:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Michael Halcrow <mhalcrow@...ibm.com>
Subject: [PATCH] ecryptfs: some inode attrs, and a question


Here are several fixes for linux-2.6.27/fs/ecryptfs.

- The ecryptfs inode holds a reference to the lower inode, but doesn't
  increment the reference counter. When a user sets inotify to the
  ecryptfs inode, it may live without the corresponding dentry. In this
  case the referecen to the lower inode may be broken.
  This patch maintains the reference of the lower inode.

- follow the VFS unlink sequence in ecryptfs_unlink() which is
  inrementing and decrementing the inode->i_count and the reference
  counter for the dentry.

- maintain the link count and ctime in ecryptfs_rmdir() because a user
  may issue fstat(2) later.

- remove the unnecessary d_drop()s in ecryptfs_link().

And I have experienced a strange behaviour. When ecryptfs gets -ENOSPC
from the lower fs, it converts and returns EINVAL to the userspace. Is
this an intended behaviour?


J. R. Okajima

Index: linux-2.6.27/fs/ecryptfs/inode.c
===================================================================
retrieving revision 1.1
retrieving revision 1.2
diff -u -p -r1.1 -r1.2
--- linux-2.6.27/fs/ecryptfs/inode.c	19 Dec 2008 03:05:27 -0000	1.1
+++ linux-2.6.27/fs/ecryptfs/inode.c	19 Dec 2008 19:52:26 -0000	1.2
@@ -430,9 +430,6 @@ out_lock:
 	unlock_dir(lower_dir_dentry);
 	dput(lower_new_dentry);
 	dput(lower_old_dentry);
-	d_drop(lower_old_dentry);
-	d_drop(new_dentry);
-	d_drop(old_dentry);
 	return rc;
 }
 
@@ -444,7 +441,10 @@ static int ecryptfs_unlink(struct inode 
 	struct dentry *lower_dir_dentry;
 
 	lower_dir_dentry = lock_parent(lower_dentry);
+	dget(lower_dentry);
+	atomic_inc_return(&lower_dentry->d_inode->i_count);
 	rc = vfs_unlink(lower_dir_inode, lower_dentry);
+	dput(lower_dentry);
 	if (rc) {
 		printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
 		goto out_unlock;
@@ -455,6 +455,7 @@ static int ecryptfs_unlink(struct inode 
 	dentry->d_inode->i_ctime = dir->i_ctime;
 	d_drop(dentry);
 out_unlock:
+	iput(lower_dentry->d_inode);
 	unlock_dir(lower_dir_dentry);
 	return rc;
 }
@@ -538,8 +539,12 @@ static int ecryptfs_rmdir(struct inode *
 	fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
 	dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
 	unlock_dir(lower_dir_dentry);
-	if (!rc)
+	if (!rc) {
+		struct inode *inode = dentry->d_inode;
+		inode->i_nlink = ecryptfs_inode_to_lower(inode)->i_nlink;
+		inode->i_ctime = dir->i_ctime;
 		d_drop(dentry);
+	}
 	dput(dentry);
 	return rc;
 }
Index: linux-2.6.27/fs/ecryptfs/super.c
===================================================================
retrieving revision 1.1
retrieving revision 1.2
diff -u -p -r1.1 -r1.2
--- linux-2.6.27/fs/ecryptfs/super.c	19 Dec 2008 04:37:43 -0000	1.1
+++ linux-2.6.27/fs/ecryptfs/super.c	19 Dec 2008 19:52:26 -0000	1.2
@@ -89,6 +89,7 @@ static void ecryptfs_destroy_inode(struc
 		}
 	}
 	mutex_unlock(&inode_info->lower_file_mutex);
+	iput(inode_info->wii_inode);
 	ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
 	kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
 }
@@ -101,6 +102,7 @@ static void ecryptfs_destroy_inode(struc
  */
 void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode)
 {
+	atomic_inc_return(&lower_inode->i_count);
 	ecryptfs_set_inode_lower(inode, lower_inode);
 	inode->i_ino = lower_inode->i_ino;
 	inode->i_version++;
--
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