Re: [PATCH] xfs: fix double unlock in xfs_swap_extents()

[Felix Blyakher]

On May 7, 2009, at 9:57 PM, Eric Sandeen wrote:

> Felix Blyakher wrote:
> > Regreesion from commit ef8f7fc, which rearranged the code in
> > xfs_swap_extents() leading to double unlock of xfs inode iolock.
> > That resulted in xfs_fsr deadlocking itself on platforms, which
> > don't handle double unlock of rw_semaphore nicely. It caused the
> > count go negative, which represents the write holder, without
> > really having one. ia64 is one of the platforms where deadlock
> > was easily reproduced and the fix was tested.
> >
> > Signed-off-by: Felix Blyakher <felixb@xxxxxxx>
>
> Also-written-by: Eric Sandeen <sandeen@xxxxxxxxxxx>
> Independently-arrived-at-by: Eric Sandeen <sandeen@xxxxxxxxxxx>

That would make it: Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxxx> :)

> ;)
>
> But seriously ...

Seriously.

Felix

> Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxxx>
>
> > ---
> > fs/xfs/xfs_dfrag.c |    8 +++++---
> > 1 files changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/xfs/xfs_dfrag.c b/fs/xfs/xfs_dfrag.c
> > index e6d839b..7465f9e 100644
> > --- a/fs/xfs/xfs_dfrag.c
> > +++ b/fs/xfs/xfs_dfrag.c
> > @@ -347,13 +347,15 @@ xfs_swap_extents(
> >
> > 	error = xfs_trans_commit(tp, XFS_TRANS_SWAPEXT);
> >
> > -out_unlock:
> > -	xfs_iunlock(ip,  XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
> > -	xfs_iunlock(tip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
> > out:
> > 	kmem_free(tempifp);
> > 	return error;
> >
> > +out_unlock:
> > +	xfs_iunlock(ip,  XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
> > +	xfs_iunlock(tip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
> > +	goto out;
> > +
> > out_trans_cancel:
> > 	xfs_trans_cancel(tp, 0);
> > 	goto out_unlock;
>
> --
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