eCryptfs: fix dentry handling on create error, unlink, and inode destroy

This patch corrects some erroneous dentry handling in eCryptfs.

If there is a problem creating the lower file, then there is nothing that
the persistent lower file can do to really help us.  This patch makes a
vfs_create() failure in the lower filesystem always lead to an
unconditional do_create failure in eCryptfs.

Under certain sequences of operations, the eCryptfs dentry can remain in
the dcache after an unlink.  This patch calls d_drop() on the eCryptfs
dentry to correct this.

eCryptfs has no business calling d_delete() directly on a lower
filesystem's dentry.  This patch removes the call to d_delete() on the
lower persistent file's dentry in ecryptfs_destroy_inode().

(Thanks to David Kleikamp, Eric Sandeen, and Jeff Moyer for helping
identify and resolve this issue)
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ecryptfs/inode.c

@@ -120,22 +120,9 @@ ecryptfs_do_create(struct inode *directory_inode,
 	rc = ecryptfs_create_underlying_file(lower_dir_dentry->d_inode,
 					     ecryptfs_dentry, mode, nd);
 	if (rc) {
-		struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
-		struct ecryptfs_inode_info *inode_info =
-			ecryptfs_inode_to_private(ecryptfs_inode);
-
-		printk(KERN_WARNING "%s: Error creating underlying file; "
-		       "rc = [%d]; checking for existing\n", __FUNCTION__, rc);
-		if (inode_info) {
-			mutex_lock(&inode_info->lower_file_mutex);
-			if (!inode_info->lower_file) {
-				mutex_unlock(&inode_info->lower_file_mutex);
-				printk(KERN_ERR "%s: Failure to set underlying "
-				       "file; rc = [%d]\n", __FUNCTION__, rc);
-				goto out_lock;
-			}
-			mutex_unlock(&inode_info->lower_file_mutex);
-		}
+		printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
+		       "rc = [%d]\n", __FUNCTION__, rc);
+		goto out_lock;
 	}
 	rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
 				directory_inode->i_sb, 0);
@@ -451,6 +438,7 @@ static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
 	dentry->d_inode->i_nlink =
 		ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink;
 	dentry->d_inode->i_ctime = dir->i_ctime;
+	d_drop(dentry);
 out_unlock:
 	unlock_parent(lower_dentry);
 	return rc;

fs/ecryptfs/super.c

@@ -86,7 +86,6 @@ static void ecryptfs_destroy_inode(struct inode *inode)
 			fput(inode_info->lower_file);
 			inode_info->lower_file = NULL;
 			d_drop(lower_dentry);
-			d_delete(lower_dentry);
 		}
 	}
 	mutex_unlock(&inode_info->lower_file_mutex);