eCryptfs: Lock lower directory inode mutex during lookup

This patch locks the lower directory inode's i_mutex before calling
lookup_one_len() to find the appropriate dentry in the lower filesystem.
This bug was found thanks to the warning set in commit 2f9092e1.

Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 5ed86e25b8a2d75c5dee47be964dc80ea4107c1f..d8325263ba6eb3a654441b573b455f5d0f5cdace 100644 (file)
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -379,9 +379,11 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
                goto out_d_drop;
        }
        lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
+       mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
        lower_dentry = lookup_one_len(ecryptfs_dentry->d_name.name,
                                      lower_dir_dentry,
                                      ecryptfs_dentry->d_name.len);
+       mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
        if (IS_ERR(lower_dentry)) {
                rc = PTR_ERR(lower_dentry);
                printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
@@ -406,9 +408,11 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
                       "filename; rc = [%d]\n", __func__, rc);
                goto out_d_drop;
        }
+       mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
        lower_dentry = lookup_one_len(encrypted_and_encoded_name,
                                      lower_dir_dentry,
                                      encrypted_and_encoded_name_size - 1);
+       mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
        if (IS_ERR(lower_dentry)) {
                rc = PTR_ERR(lower_dentry);
                printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "