Btrfs: use dget_parent where we can UPDATED

There are lots of places where we do dentry->d_parent->d_inode without holding
the dentry->d_lock.  This could cause problems with rename.  So instead we need
to use dget_parent() and hold the reference to the parent as long as we are
going to use it's inode and then dput it at the end.

Signed-off-by: Josef Bacik <josef@redhat.com>
Cc: raven@themaw.net
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index fc22f556aa24..c0faf47d0cd9 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4811,10 +4811,12 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
         if (err) {
                 drop_inode = 1;
         } else {
+                struct dentry *parent = dget_parent(dentry);
                 btrfs_update_inode_block_group(trans, dir);
                 err = btrfs_update_inode(trans, root, inode);
                 BUG_ON(err);
-                btrfs_log_new_name(trans, inode, NULL, dentry->d_parent);
+                btrfs_log_new_name(trans, inode, NULL, parent);
+                dput(parent);
         }
 
         nr = trans->blocks_used;
@@ -6768,8 +6770,9 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
         BUG_ON(ret);
 
         if (old_inode->i_ino != BTRFS_FIRST_FREE_OBJECTID) {
-                btrfs_log_new_name(trans, old_inode, old_dir,
-                                   new_dentry->d_parent);
+                struct dentry *parent = dget_parent(new_dentry);
+                btrfs_log_new_name(trans, old_inode, old_dir, parent);
+                dput(parent);
                 btrfs_end_log_trans(root);
         }
 out_fail: