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, 17 insertions, 4 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index a29f19384a27..054744ac5719 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2869,6 +2869,7 @@ static noinline int check_parent_dirs_for_sync(struct btrfs_trans_handle *trans,
 {
         int ret = 0;
         struct btrfs_root *root;
+        struct dentry *old_parent = NULL;
 
         /*
          * for regular files, if its inode is already on disk, we don't
@@ -2910,10 +2911,13 @@ static noinline int check_parent_dirs_for_sync(struct btrfs_trans_handle *trans,
                 if (IS_ROOT(parent))
                         break;
 
-                parent = parent->d_parent;
+                parent = dget_parent(parent);
+                dput(old_parent);
+                old_parent = parent;
                 inode = parent->d_inode;
 
         }
+        dput(old_parent);
 out:
         return ret;
 }
@@ -2945,6 +2949,7 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 {
         int inode_only = exists_only ? LOG_INODE_EXISTS : LOG_INODE_ALL;
         struct super_block *sb;
+        struct dentry *old_parent = NULL;
         int ret = 0;
         u64 last_committed = root->fs_info->last_trans_committed;
 
@@ -3016,10 +3021,13 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
                 if (IS_ROOT(parent))
                         break;
 
-                parent = parent->d_parent;
+                parent = dget_parent(parent);
+                dput(old_parent);
+                old_parent = parent;
         }
         ret = 0;
 end_trans:
+        dput(old_parent);
         if (ret < 0) {
                 BUG_ON(ret != -ENOSPC);
                 root->fs_info->last_trans_log_full_commit = trans->transid;
@@ -3039,8 +3047,13 @@ end_no_trans:
 int btrfs_log_dentry_safe(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root, struct dentry *dentry)
 {
-        return btrfs_log_inode_parent(trans, root, dentry->d_inode,
-                                      dentry->d_parent, 0);
+        struct dentry *parent = dget_parent(dentry);
+        int ret;
+
+        ret = btrfs_log_inode_parent(trans, root, dentry->d_inode, parent, 0);
+        dput(parent);
+
+        return ret;
 }
 
 /*