fix memory leak in xfs_inactive()

(this is back from May 16 2007, resending since it doesn't look like the patch ever made it in anywhere)

The Coverity checker found a memory leak in xfs_inactive().

The offending code is this bit :

1671 tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);

At conditional (1): "truncate != 0" taking true path

1672 if (truncate) {
1673 /*

1674                     * Do the xfs_itruncate_start() call before
1675                     * reserving any log space because itruncate_start
1676                     * will call into the buffer cache and we can't
1677                     * do that within a transaction.
1678                     */

1679 xfs_ilock(ip, XFS_IOLOCK_EXCL);
1680
1681 error = xfs_itruncate_start(ip, XFS_ITRUNC_DEFINITE, 0);

At conditional (2): "error != 0" taking true path

1682 if (error) {
1683 xfs_iunlock(ip, XFS_IOLOCK_EXCL);

Event leaked_storage: Returned without freeing storage "tp" Also see events: [alloc_fn][var_assign]

1684 return VN_INACTIVE_CACHE;
1685 }

So, the code allocates a transaction, but in the case where 'truncate' is !=0 and xfs_itruncate_start(ip, XFS_ITRUNC_DEFINITE, 0); happens to return an error, we'll just return from the function without dealing with the memory allocated byxfs_trans_alloc() and assigned to 'tp', thus it'll be orphaned/leaked - not good.

The bug was introduced by this commit:
http://git2.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d3cf209476b72c83907a412b6708c5e498410aa7

The patch below is

From: Dave Chinner <[email protected]>

---
 fs/xfs/xfs_vnodeops.c |    1 +
 1 file changed, 1 insertion(+)

Index: 2.6.x-xfs-new/fs/xfs/xfs_vnodeops.c
===================================================================
@@ -1710,6 +1710,7 @@ xfs_inactive(
 
 		error = xfs_itruncate_start(ip, XFS_ITRUNC_DEFINITE, 0);
 		if (error) {
+			xfs_trans_cancel(tp, 0);
 			xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 			return VN_INACTIVE_CACHE;
 		}

http://oss.sgi.com/cgi-bin/cvsweb.cgi/linux-2.6-xfs/fs/xfs/xfs_vnodeops.c.diff?r1=1.698;r2=1.699;f=h

Will get merged in 2.6.23-rc1 window.

Cheers,

Dave.

Dave Chinner
Principal Engineer
SGI Australian Software Group

Ok, good to know, I thought it had been forgotten :-) Thanks for the feedback Dave.

Jesper Juhl <[email protected]>
Don't top-post  http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please      http://www.expita.com/nomime.html

Also, in our master branch of oss git tree (used by Andrew).. git pull git://oss.sgi.com:8090/xfs/xfs-2.6.git master

commit 1ccb0a872f9cb5056b534fc80c746a68154e08c0

Author: Jesper Juhl <[email protected]>
Date:   Thu Jun 28 16:43:14 2007 +1000

[XFS] Cancel transactions on xfs_itruncate_start error.

SGI-PV: 966502
SGI-Modid: xfs-linux-melb:xfs-kern:28943a

--Tim