On Wed, 2011-03-23 at 17:14 +1100, Dave Chinner wrote: > From: Dave Chinner <dchinner@xxxxxxxxxx> > > There is an ABBA deadlock between synchronous inode flushing in > xfs_reclaim_inode and xfs_icluster_free. xfs_icluster_free locks the > buffer, then takes inode ilocks, whilst synchronous reclaim takes > the ilock followed by the buffer lock in xfs_iflush(). > > To avoid this deadlock, separate the inode cluster buffer locking > semantics from the synchronous inode flush semantics, allowing > callers to attempt to lock the buffer but still issue synchronous IO > if it can get the buffer. This requires xfs_iflush() calls that > currently use non-blocking semantics to pass SYNC_TRYLOCK rather > than 0 as the flags parameter. > > This allows xfs_reclaim_inode to avoid the deadlock on the buffer > lock and detect the failure so that it can drop the inode ilock and > restart the reclaim attempt on the inode. This allows > xfs_ifree_cluster to obtain the inode lock, mark the inode stale and > release it and hence defuse the deadlock situation. It also has the > pleasant side effect of avoiding IO in xfs_reclaim_inode when it > tries to next reclaim the inode as it is now marked stale. Looks good. Reviewed-by: Alex Elder <aelder@xxxxxxx> > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
