From b870553cdecb26d5291af09602352b763e323df2 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Wed, 28 Nov 2012 13:01:02 +1100 Subject: [PATCH] xfs: fix stray dquot unlock when reclaiming dquots When we fail to get a dquot lock during reclaim, we jump to an error handler that unlocks the dquot. This is wrong as we didn't lock the dquot, and unlocking it means who-ever is holding the lock has had it silently taken away, and hence it results in a lock imbalance. Found by inspection while modifying the code for the numa-lru patchset. This fixes a random hang I've been seeing on xfstest 232 for the past several months. cc: Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers --- fs/xfs/xfs_qm.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c index e6a0af0ba007..60eff4763156 100644 --- a/fs/xfs/xfs_qm.c +++ b/fs/xfs/xfs_qm.c @@ -1456,7 +1456,7 @@ xfs_qm_dqreclaim_one( int error; if (!xfs_dqlock_nowait(dqp)) - goto out_busy; + goto out_move_tail; /* * This dquot has acquired a reference in the meantime remove it from @@ -1479,7 +1479,7 @@ xfs_qm_dqreclaim_one( * getting flushed to disk, we don't want to reclaim it. */ if (!xfs_dqflock_nowait(dqp)) - goto out_busy; + goto out_unlock_move_tail; if (XFS_DQ_IS_DIRTY(dqp)) { struct xfs_buf *bp = NULL; @@ -1490,7 +1490,7 @@ xfs_qm_dqreclaim_one( if (error) { xfs_warn(mp, "%s: dquot %p flush failed", __func__, dqp); - goto out_busy; + goto out_unlock_move_tail; } xfs_buf_delwri_queue(bp, buffer_list); @@ -1499,7 +1499,7 @@ xfs_qm_dqreclaim_one( * Give the dquot another try on the freelist, as the * flushing will take some time. */ - goto out_busy; + goto out_unlock_move_tail; } xfs_dqfunlock(dqp); @@ -1518,14 +1518,13 @@ xfs_qm_dqreclaim_one( XFS_STATS_INC(xs_qm_dqreclaims); return; -out_busy: - xfs_dqunlock(dqp); - /* * Move the dquot to the tail of the list so that we don't spin on it. */ +out_unlock_move_tail: + xfs_dqunlock(dqp); +out_move_tail: list_move_tail(&dqp->q_lru, &qi->qi_lru_list); - trace_xfs_dqreclaim_busy(dqp); XFS_STATS_INC(xs_qm_dqreclaim_misses); } -- GitLab