Btrfs: fix error cases for ioctl transactions

Fix leak of vfsmount write reference and open_ioctl_trans reference on
ENOMEM.  Clean up the error paths while we're at it.

Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 22 insertions, 19 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 4de7ef6f8603..9a780c8d0ac8 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1232,15 +1232,15 @@ static long btrfs_ioctl_trans_start(struct file *file)
         struct inode *inode = fdentry(file)->d_inode;
         struct btrfs_root *root = BTRFS_I(inode)->root;
         struct btrfs_trans_handle *trans;
-        int ret = 0;
+        int ret;
 
+        ret = -EPERM;
         if (!capable(CAP_SYS_ADMIN))
-                return -EPERM;
+                goto out;
 
-        if (file->private_data) {
-                ret = -EINPROGRESS;
+        ret = -EINPROGRESS;
+        if (file->private_data)
                 goto out;
-        }
 
         ret = mnt_want_write(file->f_path.mnt);
         if (ret)
@@ -1250,12 +1250,19 @@ static long btrfs_ioctl_trans_start(struct file *file)
         root->fs_info->open_ioctl_trans++;
         mutex_unlock(&root->fs_info->trans_mutex);
 
+        ret = -ENOMEM;
         trans = btrfs_start_ioctl_transaction(root, 0);
-        if (trans)
-                file->private_data = trans;
-        else
-                ret = -ENOMEM;
-        /*printk(KERN_INFO "btrfs_ioctl_trans_start on %p\n", file);*/
+        if (!trans)
+                goto out_drop;
+
+        file->private_data = trans;
+        return 0;
+
+out_drop:
+        mutex_lock(&root->fs_info->trans_mutex);
+        root->fs_info->open_ioctl_trans--;
+        mutex_unlock(&root->fs_info->trans_mutex);
+        mnt_drop_write(file->f_path.mnt);
 out:
         return ret;
 }
@@ -1271,24 +1278,20 @@ long btrfs_ioctl_trans_end(struct file *file)
         struct inode *inode = fdentry(file)->d_inode;
         struct btrfs_root *root = BTRFS_I(inode)->root;
         struct btrfs_trans_handle *trans;
-        int ret = 0;
 
         trans = file->private_data;
-        if (!trans) {
-                ret = -EINVAL;
-                goto out;
-        }
-        btrfs_end_transaction(trans, root);
+        if (!trans)
+                return -EINVAL;
         file->private_data = NULL;
 
+        btrfs_end_transaction(trans, root);
+
         mutex_lock(&root->fs_info->trans_mutex);
         root->fs_info->open_ioctl_trans--;
         mutex_unlock(&root->fs_info->trans_mutex);
 
         mnt_drop_write(file->f_path.mnt);
-
-out:
-        return ret;
+        return 0;
 }
 
 long btrfs_ioctl(struct file *file, unsigned int