From be7ffc38a80a78e6b68d0f51fae8e8d57b55324c Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 6 Dec 2011 21:58:17 +0000 Subject: xfs: implement lazy removal for the dquot freelist Do not remove dquots from the freelist when we grab a reference to them in xfs_qm_dqlookup, but leave them on the freelist util scanning notices that they have a reference. This speeds up the lookup fastpath, and greatly simplifies the lock ordering constraints. Note that the same scheme is used by the VFS inode and dentry caches. Signed-off-by: Christoph Hellwig Reviewed-by: Dave Chinner Signed-off-by: Ben Myers --- fs/xfs/xfs_dquot.c | 67 +++++++++++++++--------------------------------------- 1 file changed, 18 insertions(+), 49 deletions(-) (limited to 'fs/xfs/xfs_dquot.c') diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c index 3f94f2428a35..35d2b8aad0f9 100644 --- a/fs/xfs/xfs_dquot.c +++ b/fs/xfs/xfs_dquot.c @@ -722,58 +722,25 @@ xfs_qm_dqlookup( * dqlock to look at the id field of the dquot, since the * id can't be modified without the hashlock anyway. */ - if (be32_to_cpu(dqp->q_core.d_id) == id && dqp->q_mount == mp) { - trace_xfs_dqlookup_found(dqp); + if (be32_to_cpu(dqp->q_core.d_id) != id || dqp->q_mount != mp) + continue; - /* - * All in core dquots must be on the dqlist of mp - */ - ASSERT(!list_empty(&dqp->q_mplist)); - - xfs_dqlock(dqp); - if (dqp->q_nrefs == 0) { - ASSERT(!list_empty(&dqp->q_freelist)); - if (!mutex_trylock(&xfs_Gqm->qm_dqfrlist_lock)) { - trace_xfs_dqlookup_want(dqp); - - /* - * We may have raced with dqreclaim_one() - * (and lost). So, flag that we don't - * want the dquot to be reclaimed. - */ - dqp->dq_flags |= XFS_DQ_WANT; - xfs_dqunlock(dqp); - mutex_lock(&xfs_Gqm->qm_dqfrlist_lock); - xfs_dqlock(dqp); - dqp->dq_flags &= ~(XFS_DQ_WANT); - } - - if (dqp->q_nrefs == 0) { - /* take it off the freelist */ - trace_xfs_dqlookup_freelist(dqp); - list_del_init(&dqp->q_freelist); - xfs_Gqm->qm_dqfrlist_cnt--; - } - XFS_DQHOLD(dqp); - mutex_unlock(&xfs_Gqm->qm_dqfrlist_lock); - } else { - XFS_DQHOLD(dqp); - } + trace_xfs_dqlookup_found(dqp); - /* - * move the dquot to the front of the hashchain - */ - ASSERT(mutex_is_locked(&qh->qh_lock)); - list_move(&dqp->q_hashlist, &qh->qh_list); - trace_xfs_dqlookup_done(dqp); - *O_dqpp = dqp; - return 0; - } + xfs_dqlock(dqp); + XFS_DQHOLD(dqp); + + /* + * move the dquot to the front of the hashchain + */ + list_move(&dqp->q_hashlist, &qh->qh_list); + trace_xfs_dqlookup_done(dqp); + *O_dqpp = dqp; + return 0; } *O_dqpp = NULL; - ASSERT(mutex_is_locked(&qh->qh_lock)); - return (1); + return 1; } /* @@ -1033,8 +1000,10 @@ xfs_qm_dqput( if (--dqp->q_nrefs == 0) { trace_xfs_dqput_free(dqp); - list_add_tail(&dqp->q_freelist, &xfs_Gqm->qm_dqfrlist); - xfs_Gqm->qm_dqfrlist_cnt++; + if (list_empty(&dqp->q_freelist)) { + list_add_tail(&dqp->q_freelist, &xfs_Gqm->qm_dqfrlist); + xfs_Gqm->qm_dqfrlist_cnt++; + } /* * If we just added a udquot to the freelist, then -- cgit v1.2.3-58-ga151