eCryptfs: do not try to open device files on mknod

When creating device nodes, eCryptfs needs to delay actually opening the lower
persistent file until an application tries to open.  Device handles may not be
backed by anything when they first come into existence.

[Valdis.Kletnieks@vt.edu: build fix]
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: <Valdis.Kletnieks@vt.edu}
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 10 deletions

diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 10475d93ff53..ee4f84b20410 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -117,7 +117,7 @@ void __ecryptfs_printk(const char *fmt, ...)
  *
  * Returns zero on success; non-zero otherwise
  */
-static int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
+int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
 {
         struct ecryptfs_inode_info *inode_info =
                 ecryptfs_inode_to_private(ecryptfs_dentry->d_inode);
@@ -149,14 +149,14 @@ static int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
  * @lower_dentry: Existing dentry in the lower filesystem
  * @dentry: ecryptfs' dentry
  * @sb: ecryptfs's super_block
- * @flag: If set to true, then d_add is called, else d_instantiate is called
+ * @flags: flags to govern behavior of interpose procedure
  *
  * Interposes upper and lower dentries.
  *
  * Returns zero on success; non-zero otherwise
  */
 int ecryptfs_interpose(struct dentry *lower_dentry, struct dentry *dentry,
-                       struct super_block *sb, int flag)
+                       struct super_block *sb, u32 flags)
 {
         struct inode *lower_inode;
         struct inode *inode;
@@ -193,7 +193,7 @@ int ecryptfs_interpose(struct dentry *lower_dentry, struct dentry *dentry,
                 init_special_inode(inode, lower_inode->i_mode,
                                    lower_inode->i_rdev);
         dentry->d_op = &ecryptfs_dops;
-        if (flag)
+        if (flags & ECRYPTFS_INTERPOSE_FLAG_D_ADD)
                 d_add(dentry, inode);
         else
                 d_instantiate(dentry, inode);
@@ -201,12 +201,21 @@ int ecryptfs_interpose(struct dentry *lower_dentry, struct dentry *dentry,
         /* This size will be overwritten for real files w/ headers and
          * other metadata */
         fsstack_copy_inode_size(inode, lower_inode);
-        rc = ecryptfs_init_persistent_file(dentry);
-        if (rc) {
-                printk(KERN_ERR "%s: Error attempting to initialize the "
-                       "persistent file for the dentry with name [%s]; "
-                       "rc = [%d]\n", __func__, dentry->d_name.name, rc);
-                goto out;
+        if (!(flags & ECRYPTFS_INTERPOSE_FLAG_DELAY_PERSISTENT_FILE)) {
+                rc = ecryptfs_init_persistent_file(dentry);
+                if (rc) {
+                        printk(KERN_ERR "%s: Error attempting to initialize "
+                               "the persistent file for the dentry with name "
+                               "[%s]; rc = [%d]\n", __func__,
+                               dentry->d_name.name, rc);
+                        goto out;
+                }
+        } else {
+                struct ecryptfs_inode_info *inode_info =
+                        ecryptfs_inode_to_private(dentry->d_inode);
+
+                inode_info->lower_file = NULL;
+                inode_info->crypt_stat.flags |= ECRYPTFS_DELAY_PERSISTENT;
         }
 out:
         return rc;