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>

1 files changed, 4 insertions, 16 deletions

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 0b1ab016fa2e..5a719180983c 100644
--- a/fs/ecryptfs/inode.c
+++ b/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;