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>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 4de7ef6..9a780c8 100644 (file)
--- 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