linux-kernel - Re: [PATCH 1/2] locks: let the caller free file

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Date:	Wed, 3 Nov 2010 16:41:48 -0400
From:	"J. Bruce Fields" <bfields@...ldses.org>
To:	Christoph Hellwig <hch@...radead.org>
Cc:	Arnd Bergmann <arnd@...db.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Bryan Schumaker <bjschuma@...app.com>,
	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] locks: let the caller free file_lock on ->setlease
 failure

On Sun, Oct 31, 2010 at 08:35:10AM -0400, Christoph Hellwig wrote:
> The caller allocated it, the caller should free it.  The only issue so
> far is that we could change the flp pointer even on an error return if
> the fl_change callback failed.  But we can simply move the flp assignment
> after the fl_change invocation, as the callers don't care about the
> flp return value if the setlease call failed.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>
> 
> Index: linux-2.6/fs/cifs/cifsfs.c
> ===================================================================
> --- linux-2.6.orig/fs/cifs/cifsfs.c	2010-10-31 07:10:07.636004223 -0400
> +++ linux-2.6/fs/cifs/cifsfs.c	2010-10-31 07:10:10.922004154 -0400
> @@ -625,11 +625,8 @@ static int cifs_setlease(struct file *fi
>  		   knows that the file won't be changed on the server
>  		   by anyone else */
>  		return generic_setlease(file, arg, lease);
> -	else {
> -		if (arg != F_UNLCK)
> -			locks_free_lock(*lease);
> +	else
>  		return -EAGAIN;
> -	}
>  }
>  
>  struct file_system_type cifs_fs_type = {
> Index: linux-2.6/fs/gfs2/file.c
> ===================================================================
> --- linux-2.6.orig/fs/gfs2/file.c	2010-10-31 07:10:07.643004363 -0400
> +++ linux-2.6/fs/gfs2/file.c	2010-10-31 07:10:10.923003665 -0400
> @@ -629,8 +629,6 @@ static ssize_t gfs2_file_aio_write(struc
>  
>  static int gfs2_setlease(struct file *file, long arg, struct file_lock **fl)
>  {
> -	if (arg != F_UNLCK)
> -		locks_free_lock(*fl);
>  	return -EINVAL;
>  }
>  
> Index: linux-2.6/fs/locks.c
> ===================================================================
> --- linux-2.6.orig/fs/locks.c	2010-10-31 07:10:07.649004084 -0400
> +++ linux-2.6/fs/locks.c	2010-10-31 07:34:10.102255587 -0400
> @@ -1428,8 +1425,9 @@ int generic_setlease(struct file *filp,
>  		goto out;
>  
>  	if (my_before != NULL) {
> -		*flp = *my_before;
>  		error = lease->fl_lmops->fl_change(my_before, arg);
> +		if (!error)
> +			*flp = *my_before;

Argh, missed this: we're leaking the passed-in lease in this case.

--b.

>  		goto out;
>  	}
>  
> @@ -1444,8 +1442,6 @@ int generic_setlease(struct file *filp,
>  	return 0;
>  
>  out:
> -	if (arg != F_UNLCK)
> -		locks_free_lock(lease);
>  	return error;
>  }
>  EXPORT_SYMBOL(generic_setlease);
> @@ -1524,8 +1520,11 @@ static int do_fcntl_add_lease(unsigned i
>  	}
>  	lock_flocks();
>  	error = __vfs_setlease(filp, arg, &fl);
> -	if (error)
> -		goto out_unlock;
> +	if (error) {
> +		unlock_flocks();
> +		locks_free_lock(fl);
> +		goto out_free_fasync;
> +	}
>  
>  	/*
>  	 * fasync_insert_entry() returns the old entry if any.
> @@ -1541,12 +1540,12 @@ static int do_fcntl_add_lease(unsigned i
>  		fl->fl_type = F_UNLCK | F_INPROGRESS;
>  		fl->fl_break_time = jiffies - 10;
>  		time_out_leases(inode);
> -		goto out_unlock;
> +	} else {
> +		error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
>  	}
> -
> -	error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
> -out_unlock:
>  	unlock_flocks();
> +
> +out_free_fasync:
>  	if (new)
>  		fasync_free(new);
>  	return error;
> Index: linux-2.6/fs/nfs/file.c
> ===================================================================
> --- linux-2.6.orig/fs/nfs/file.c	2010-10-31 07:10:07.658003804 -0400
> +++ linux-2.6/fs/nfs/file.c	2010-10-31 07:10:10.936003734 -0400
> @@ -884,7 +884,5 @@ static int nfs_setlease(struct file *fil
>  	dprintk("NFS: setlease(%s/%s, arg=%ld)\n",
>  			file->f_path.dentry->d_parent->d_name.name,
>  			file->f_path.dentry->d_name.name, arg);
> -	if (arg != F_UNLCK)
> -		locks_free_lock(*fl);
>  	return -EINVAL;
>  }
> Index: linux-2.6/fs/nfsd/nfs4state.c
> ===================================================================
> --- linux-2.6.orig/fs/nfsd/nfs4state.c	2010-10-31 07:10:07.666004084 -0400
> +++ linux-2.6/fs/nfsd/nfs4state.c	2010-10-31 07:32:56.906254608 -0400
> @@ -2652,6 +2652,7 @@ nfs4_open_delegation(struct svc_fh *fh,
>  	if ((status = vfs_setlease(fl->fl_file, fl->fl_type, &fl))) {
>  		dprintk("NFSD: setlease failed [%d], no delegation\n", status);
>  		dp->dl_flock = NULL;
> +		locks_free_lock(fl);
>  		unhash_delegation(dp);
>  		flag = NFS4_OPEN_DELEGATE_NONE;
>  		goto out;
--
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