ecryptfs: avoid multiple aliases for directories

ecryptfs_lookup_interpose should use d_splice_alias(), not d_add()
(and return struct dentry * rather than int).  Get rid of
redundant dir_inode argument, while we are touching it...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 121114e..91ebc8f 100644 (file)
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -324,9 +324,8 @@ static int ecryptfs_i_size_read(struct dentry *dentry, struct inode *inode)
 /**
  * ecryptfs_lookup_interpose - Dentry interposition for a lookup
  */
-static int ecryptfs_lookup_interpose(struct dentry *dentry,
-                                    struct dentry *lower_dentry,
-                                    struct inode *dir_inode)
+static struct dentry *ecryptfs_lookup_interpose(struct dentry *dentry,
+                                    struct dentry *lower_dentry)
 {
        struct inode *inode, *lower_inode = d_inode(lower_dentry);
        struct ecryptfs_dentry_info *dentry_info;
@@ -339,11 +338,12 @@ static int ecryptfs_lookup_interpose(struct dentry *dentry,
                       "to allocate ecryptfs_dentry_info struct\n",
                        __func__);
                dput(lower_dentry);
-               return -ENOMEM;
+               return ERR_PTR(-ENOMEM);
        }
 
        lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
-       fsstack_copy_attr_atime(dir_inode, d_inode(lower_dentry->d_parent));
+       fsstack_copy_attr_atime(d_inode(dentry->d_parent),
+                               d_inode(lower_dentry->d_parent));
        BUG_ON(!d_count(lower_dentry));
 
        ecryptfs_set_dentry_private(dentry, dentry_info);
@@ -353,27 +353,25 @@ static int ecryptfs_lookup_interpose(struct dentry *dentry,
        if (d_really_is_negative(lower_dentry)) {
                /* We want to add because we couldn't find in lower */
                d_add(dentry, NULL);
-               return 0;
+               return NULL;
        }
-       inode = __ecryptfs_get_inode(lower_inode, dir_inode->i_sb);
+       inode = __ecryptfs_get_inode(lower_inode, dentry->d_sb);
        if (IS_ERR(inode)) {
                printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",
                       __func__, PTR_ERR(inode));
-               return PTR_ERR(inode);
+               return ERR_CAST(inode);
        }
        if (S_ISREG(inode->i_mode)) {
                rc = ecryptfs_i_size_read(dentry, inode);
                if (rc) {
                        make_bad_inode(inode);
-                       return rc;
+                       return ERR_PTR(rc);
                }
        }
 
        if (inode->i_state & I_NEW)
                unlock_new_inode(inode);
-       d_add(dentry, inode);
-
-       return rc;
+       return d_splice_alias(inode, dentry);
 }
 
 /**
@@ -393,6 +391,7 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
        size_t encrypted_and_encoded_name_size;
        struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
        struct dentry *lower_dir_dentry, *lower_dentry;
+       struct dentry *res;
        int rc = 0;
 
        lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
@@ -400,10 +399,10 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
                                      lower_dir_dentry,
                                      ecryptfs_dentry->d_name.len);
        if (IS_ERR(lower_dentry)) {
-               rc = PTR_ERR(lower_dentry);
                ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
-                               "[%d] on lower_dentry = [%pd]\n", __func__, rc,
-                               ecryptfs_dentry);
+                               "[%ld] on lower_dentry = [%pd]\n", __func__,
+                               PTR_ERR(lower_dentry), ecryptfs_dentry);
+               res = ERR_CAST(lower_dentry);
                goto out;
        }
        if (d_really_is_positive(lower_dentry))
@@ -421,24 +420,25 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
        if (rc) {
                printk(KERN_ERR "%s: Error attempting to encrypt and encode "
                       "filename; rc = [%d]\n", __func__, rc);
+               res = ERR_PTR(rc);
                goto out;
        }
        lower_dentry = lookup_one_len_unlocked(encrypted_and_encoded_name,
                                      lower_dir_dentry,
                                      encrypted_and_encoded_name_size);
        if (IS_ERR(lower_dentry)) {
-               rc = PTR_ERR(lower_dentry);
                ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
-                               "[%d] on lower_dentry = [%s]\n", __func__, rc,
+                               "[%ld] on lower_dentry = [%s]\n", __func__,
+                               PTR_ERR(lower_dentry),
                                encrypted_and_encoded_name);
+               res = ERR_CAST(lower_dentry);
                goto out;
        }
 interpose:
-       rc = ecryptfs_lookup_interpose(ecryptfs_dentry, lower_dentry,
-                                      ecryptfs_dir_inode);
+       res = ecryptfs_lookup_interpose(ecryptfs_dentry, lower_dentry);
 out:
        kfree(encrypted_and_encoded_name);
-       return ERR_PTR(rc);
+       return res;
 }
 
 static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,