On Sun, Apr 22, 2018 at 08:06:05AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Delegate the dquot cache handling (radix tree lookup and insertion) to
> separate helper functions so that we can continue to simplify the body
> of dqget.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> fs/xfs/xfs_dquot.c | 112 ++++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 78 insertions(+), 34 deletions(-)
>
>
> diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
> index 79a9df6..43b0b32 100644
> --- a/fs/xfs/xfs_dquot.c
> +++ b/fs/xfs/xfs_dquot.c
> @@ -679,6 +679,81 @@ xfs_dq_get_next_id(
> }
>
> /*
> + * Look up the dquot in the in-core cache. If found, the dquot is returned
> + * locked and ready to go.
> + */
> +static struct xfs_dquot *
> +xfs_qm_dqget_cache_lookup(
> + struct xfs_mount *mp,
> + struct xfs_quotainfo *qi,
> + struct radix_tree_root *tree,
> + xfs_dqid_t id)
> +{
> + struct xfs_dquot *dqp;
> +
> +restart:
> + mutex_lock(&qi->qi_tree_lock);
> + dqp = radix_tree_lookup(tree, id);
> + if (!dqp) {
> + mutex_unlock(&qi->qi_tree_lock);
> + XFS_STATS_INC(mp, xs_qm_dqcachemisses);
> + return NULL;
> + }
> +
> + xfs_dqlock(dqp);
> + if (dqp->dq_flags & XFS_DQ_FREEING) {
> + xfs_dqunlock(dqp);
> + mutex_unlock(&qi->qi_tree_lock);
> + trace_xfs_dqget_freeing(dqp);
> + delay(1);
> + goto restart;
> + }
> +
> + dqp->q_nrefs++;
> + mutex_unlock(&qi->qi_tree_lock);
> +
> + trace_xfs_dqget_hit(dqp);
> + XFS_STATS_INC(mp, xs_qm_dqcachehits);
> + return dqp;
> +}
> +
> +/*
> + * Try to insert a new dquot into the in-core cache. If an error occurs the
> + * caller should throw away the dquot and start over. Otherwise, the dquot
> + * is returned locked (and held by the cache) as if there had been a cache
> + * hit.
> + */
> +static int
> +xfs_qm_dqget_cache_insert(
> + struct xfs_mount *mp,
> + struct xfs_quotainfo *qi,
> + struct radix_tree_root *tree,
> + xfs_dqid_t id,
> + struct xfs_dquot *dqp)
> +{
> + int error;
> +
> + mutex_lock(&qi->qi_tree_lock);
> + error = radix_tree_insert(tree, id, dqp);
> + if (unlikely(error)) {
> + /* Duplicate found! Caller must try again. */
> + WARN_ON(error != -EEXIST);
> + mutex_unlock(&qi->qi_tree_lock);
> + trace_xfs_dqget_dup(dqp);
> + return error;
> + }
> +
> + /* Return a locked dquot to the caller, with a reference taken. */
> + xfs_dqlock(dqp);
> + dqp->q_nrefs = 1;
> +
> + qi->qi_dquots++;
> + mutex_unlock(&qi->qi_tree_lock);
> +
> + return 0;
> +}
> +
> +/*
> * Given the file system, inode OR id, and type (UDQUOT/GDQUOT), return a
> * a locked dquot, doing an allocation (if requested) as needed.
> * When both an inode and an id are given, the inode's id takes precedence.
> @@ -716,28 +791,11 @@ xfs_qm_dqget(
> }
>
> restart:
> - mutex_lock(&qi->qi_tree_lock);
> - dqp = radix_tree_lookup(tree, id);
> + dqp = xfs_qm_dqget_cache_lookup(mp, qi, tree, id);
> if (dqp) {
> - xfs_dqlock(dqp);
> - if (dqp->dq_flags & XFS_DQ_FREEING) {
> - xfs_dqunlock(dqp);
> - mutex_unlock(&qi->qi_tree_lock);
> - trace_xfs_dqget_freeing(dqp);
> - delay(1);
> - goto restart;
> - }
> -
> - dqp->q_nrefs++;
> - mutex_unlock(&qi->qi_tree_lock);
> -
> - trace_xfs_dqget_hit(dqp);
> - XFS_STATS_INC(mp, xs_qm_dqcachehits);
> *O_dqpp = dqp;
> return 0;
> }
> - mutex_unlock(&qi->qi_tree_lock);
> - XFS_STATS_INC(mp, xs_qm_dqcachemisses);
>
> /*
> * Dquot cache miss. We don't want to keep the inode lock across
> @@ -779,31 +837,17 @@ xfs_qm_dqget(
> }
> }
>
> - mutex_lock(&qi->qi_tree_lock);
> - error = radix_tree_insert(tree, id, dqp);
> - if (unlikely(error)) {
> - WARN_ON(error != -EEXIST);
> -
> + error = xfs_qm_dqget_cache_insert(mp, qi, tree, id, dqp);
> + if (error) {
> /*
> * Duplicate found. Just throw away the new dquot and start
> * over.
> */
> - mutex_unlock(&qi->qi_tree_lock);
> - trace_xfs_dqget_dup(dqp);
> xfs_qm_dqdestroy(dqp);
> XFS_STATS_INC(mp, xs_qm_dquot_dups);
> goto restart;
> }
>
> - /*
> - * We return a locked dquot to the caller, with a reference taken
> - */
> - xfs_dqlock(dqp);
> - dqp->q_nrefs = 1;
> -
> - qi->qi_dquots++;
> - mutex_unlock(&qi->qi_tree_lock);
> -
> dqret:
> ASSERT((ip == NULL) || xfs_isilocked(ip, XFS_ILOCK_EXCL));
> trace_xfs_dqget_miss(dqp);
>
> --
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