[PATCH 1/4] staging: lustre: libcfs: use a workqueue for rehash work.

NeilBrown
2017-12-18T01:27:22Z

lustre has a work-item queuing scheme that provides the
same functionality as linux work_queues.
To make the code easier for linux devs to follow, change
to use work_queues.

Signed-off-by: NeilBrown <neilb@suse.com>
---
.../staging/lustre/include/linux/libcfs/libcfs.h | 2
.../lustre/include/linux/libcfs/libcfs_hash.h | 6 +
drivers/staging/lustre/lnet/libcfs/hash.c | 82 +++++---------------
drivers/staging/lustre/lnet/libcfs/module.c | 16 ++--
4 files changed, 31 insertions(+), 75 deletions(-)

diff --git a/drivers/staging/lustre/include/linux/libcfs/libcfs.h b/drivers/staging/lustre/include/linux/libcfs/libcfs.h
index 6ad8867e5451..dcdc05dde6b8 100644
--- a/drivers/staging/lustre/include/linux/libcfs/libcfs.h
+++ b/drivers/staging/lustre/include/linux/libcfs/libcfs.h
@@ -126,7 +126,7 @@ extern struct miscdevice libcfs_dev;
*/
extern char lnet_debug_log_upcall[1024];

-extern struct cfs_wi_sched *cfs_sched_rehash;
+extern struct workqueue_struct *cfs_rehash_wq;

struct lnet_debugfs_symlink_def {
char *name;
diff --git a/drivers/staging/lustre/include/linux/libcfs/libcfs_hash.h b/drivers/staging/lustre/include/linux/libcfs/libcfs_hash.h
index 5a27220cc608..0506f1d45757 100644
--- a/drivers/staging/lustre/include/linux/libcfs/libcfs_hash.h
+++ b/drivers/staging/lustre/include/linux/libcfs/libcfs_hash.h
@@ -248,7 +248,7 @@ struct cfs_hash {
/** # of iterators (caller of cfs_hash_for_each_*) */
u32 hs_iterators;
/** rehash workitem */
- struct cfs_workitem hs_rehash_wi;
+ struct work_struct hs_rehash_work;
/** refcount on this hash table */
atomic_t hs_refcount;
/** rehash buckets-table */
@@ -265,7 +265,7 @@ struct cfs_hash {
/** bits when we found the max depth */
unsigned int hs_dep_bits;
/** workitem to output max depth */
- struct cfs_workitem hs_dep_wi;
+ struct work_struct hs_dep_work;
#endif
/** name of htable */
char hs_name[0];
@@ -738,7 +738,7 @@ u64 cfs_hash_size_get(struct cfs_hash *hs);
*/
void cfs_hash_rehash_cancel_locked(struct cfs_hash *hs);
void cfs_hash_rehash_cancel(struct cfs_hash *hs);
-int cfs_hash_rehash(struct cfs_hash *hs, int do_rehash);
+void cfs_hash_rehash(struct cfs_hash *hs, int do_rehash);
void cfs_hash_rehash_key(struct cfs_hash *hs, const void *old_key,
void *new_key, struct hlist_node *hnode);

diff --git a/drivers/staging/lustre/lnet/libcfs/hash.c b/drivers/staging/lustre/lnet/libcfs/hash.c
index aabe29eef85c..f7b3c9306456 100644
--- a/drivers/staging/lustre/lnet/libcfs/hash.c
+++ b/drivers/staging/lustre/lnet/libcfs/hash.c
@@ -114,7 +114,7 @@ module_param(warn_on_depth, uint, 0644);
MODULE_PARM_DESC(warn_on_depth, "warning when hash depth is high.");
#endif

-struct cfs_wi_sched *cfs_sched_rehash;
+struct workqueue_struct *cfs_rehash_wq;

static inline void
cfs_hash_nl_lock(union cfs_hash_lock *lock, int exclusive) {}
@@ -519,7 +519,7 @@ cfs_hash_bd_dep_record(struct cfs_hash *hs, struct cfs_hash_bd *bd, int dep_cur)
hs->hs_dep_bits = hs->hs_cur_bits;
spin_unlock(&hs->hs_dep_lock);

- cfs_wi_schedule(cfs_sched_rehash, &hs->hs_dep_wi);
+ queue_work(cfs_rehash_wq, &hs->hs_dep_work);
# endif
}

@@ -937,12 +937,12 @@ cfs_hash_buckets_realloc(struct cfs_hash *hs, struct cfs_hash_bucket **old_bkts,
* @flags - CFS_HASH_REHASH enable synamic hash resizing
* - CFS_HASH_SORT enable chained hash sort
*/
-static int cfs_hash_rehash_worker(struct cfs_workitem *wi);
+static void cfs_hash_rehash_worker(struct work_struct *work);

#if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
-static int cfs_hash_dep_print(struct cfs_workitem *wi)
+static void cfs_hash_dep_print(struct work_struct *work)
{
- struct cfs_hash *hs = container_of(wi, struct cfs_hash, hs_dep_wi);
+ struct cfs_hash *hs = container_of(work, struct cfs_hash, hs_dep_work);
int dep;
int bkt;
int off;
@@ -966,21 +966,12 @@ static int cfs_hash_dep_print(struct cfs_workitem *wi)
static void cfs_hash_depth_wi_init(struct cfs_hash *hs)
{
spin_lock_init(&hs->hs_dep_lock);
- cfs_wi_init(&hs->hs_dep_wi, hs, cfs_hash_dep_print);
+ INIT_WORK(&hs->hs_dep_work, cfs_hash_dep_print);
}

static void cfs_hash_depth_wi_cancel(struct cfs_hash *hs)
{
- if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_dep_wi))
- return;
-
- spin_lock(&hs->hs_dep_lock);
- while (hs->hs_dep_bits) {
- spin_unlock(&hs->hs_dep_lock);
- cond_resched();
- spin_lock(&hs->hs_dep_lock);
- }
- spin_unlock(&hs->hs_dep_lock);
+ cancel_work_sync(&hs->hs_dep_work);
}

#else /* CFS_HASH_DEBUG_LEVEL < CFS_HASH_DEBUG_1 */
@@ -1042,7 +1033,7 @@ cfs_hash_create(char *name, unsigned int cur_bits, unsigned int max_bits,
hs->hs_ops = ops;
hs->hs_extra_bytes = extra_bytes;
hs->hs_rehash_bits = 0;
- cfs_wi_init(&hs->hs_rehash_wi, hs, cfs_hash_rehash_worker);
+ INIT_WORK(&hs->hs_rehash_work, cfs_hash_rehash_worker);
cfs_hash_depth_wi_init(hs);

if (cfs_hash_with_rehash(hs))
@@ -1362,6 +1353,7 @@ cfs_hash_for_each_enter(struct cfs_hash *hs)

cfs_hash_lock(hs, 1);
hs->hs_iterators++;
+ cfs_hash_unlock(hs, 1);

/* NB: iteration is mostly called by service thread,
* we tend to cancel pending rehash-request, instead of
@@ -1369,8 +1361,7 @@ cfs_hash_for_each_enter(struct cfs_hash *hs)
* after iteration
*/
if (cfs_hash_is_rehashing(hs))
- cfs_hash_rehash_cancel_locked(hs);
- cfs_hash_unlock(hs, 1);
+ cfs_hash_rehash_cancel(hs);
}

static void
@@ -1771,43 +1762,14 @@ EXPORT_SYMBOL(cfs_hash_for_each_key);
* this approach assumes a reasonably uniform hashing function. The
* theta thresholds for @hs are tunable via cfs_hash_set_theta().
*/
-void
-cfs_hash_rehash_cancel_locked(struct cfs_hash *hs)
-{
- int i;
-
- /* need hold cfs_hash_lock(hs, 1) */
- LASSERT(cfs_hash_with_rehash(hs) &&
- !cfs_hash_with_no_lock(hs));
-
- if (!cfs_hash_is_rehashing(hs))
- return;
-
- if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_rehash_wi)) {
- hs->hs_rehash_bits = 0;
- return;
- }
-
- for (i = 2; cfs_hash_is_rehashing(hs); i++) {
- cfs_hash_unlock(hs, 1);
- /* raise console warning while waiting too long */
- CDEBUG(is_power_of_2(i >> 3) ? D_WARNING : D_INFO,
- "hash %s is still rehashing, rescheded %d\n",
- hs->hs_name, i - 1);
- cond_resched();
- cfs_hash_lock(hs, 1);
- }
-}
-
void
cfs_hash_rehash_cancel(struct cfs_hash *hs)
{
- cfs_hash_lock(hs, 1);
- cfs_hash_rehash_cancel_locked(hs);
- cfs_hash_unlock(hs, 1);
+ LASSERT(cfs_hash_with_rehash(hs));
+ cancel_work_sync(&hs->hs_rehash_work);
}

-int
+void
cfs_hash_rehash(struct cfs_hash *hs, int do_rehash)
{
int rc;
@@ -1819,21 +1781,21 @@ cfs_hash_rehash(struct cfs_hash *hs, int do_rehash)
rc = cfs_hash_rehash_bits(hs);
if (rc <= 0) {
cfs_hash_unlock(hs, 1);
- return rc;
+ return;
}

hs->hs_rehash_bits = rc;
if (!do_rehash) {
/* launch and return */
- cfs_wi_schedule(cfs_sched_rehash, &hs->hs_rehash_wi);
+ queue_work(cfs_rehash_wq, &hs->hs_rehash_work);
cfs_hash_unlock(hs, 1);
- return 0;
+ return;
}

/* rehash right now */
cfs_hash_unlock(hs, 1);

- return cfs_hash_rehash_worker(&hs->hs_rehash_wi);
+ cfs_hash_rehash_worker(&hs->hs_rehash_work);
}

static int
@@ -1867,10 +1829,10 @@ cfs_hash_rehash_bd(struct cfs_hash *hs, struct cfs_hash_bd *old)
return c;
}

-static int
-cfs_hash_rehash_worker(struct cfs_workitem *wi)
+static void
+cfs_hash_rehash_worker(struct work_struct *work)
{
- struct cfs_hash *hs = container_of(wi, struct cfs_hash, hs_rehash_wi);
+ struct cfs_hash *hs = container_of(work, struct cfs_hash, hs_rehash_work);
struct cfs_hash_bucket **bkts;
struct cfs_hash_bd bd;
unsigned int old_size;
@@ -1954,8 +1916,6 @@ cfs_hash_rehash_worker(struct cfs_workitem *wi)
hs->hs_cur_bits = hs->hs_rehash_bits;
out:
hs->hs_rehash_bits = 0;
- if (rc == -ESRCH) /* never be scheduled again */
- cfs_wi_exit(cfs_sched_rehash, wi);
bsize = cfs_hash_bkt_size(hs);
cfs_hash_unlock(hs, 1);
/* can't refer to @hs anymore because it could be destroyed */
@@ -1963,8 +1923,6 @@ cfs_hash_rehash_worker(struct cfs_workitem *wi)
cfs_hash_buckets_free(bkts, bsize, new_size, old_size);
if (rc)
CDEBUG(D_INFO, "early quit of rehashing: %d\n", rc);
- /* return 1 only if cfs_wi_exit is called */
- return rc == -ESRCH;
}

/**
diff --git a/drivers/staging/lustre/lnet/libcfs/module.c b/drivers/staging/lustre/lnet/libcfs/module.c
index ff4b0cec1bbe..0254593b7f01 100644
--- a/drivers/staging/lustre/lnet/libcfs/module.c
+++ b/drivers/staging/lustre/lnet/libcfs/module.c
@@ -553,12 +553,10 @@ static int libcfs_init(void)
goto cleanup_deregister;
}

- /* max to 4 threads, should be enough for rehash */
- rc = min(cfs_cpt_weight(cfs_cpt_table, CFS_CPT_ANY), 4);
- rc = cfs_wi_sched_create("cfs_rh", cfs_cpt_table, CFS_CPT_ANY,
- rc, &cfs_sched_rehash);
- if (rc) {
- CERROR("Startup workitem scheduler: error: %d\n", rc);
+ cfs_rehash_wq = alloc_workqueue("cfs_rh", WQ_SYSFS, 4);
+ if (!cfs_rehash_wq) {
+ CERROR("Failed to start rehash workqueue.\n");
+ rc = -ENOMEM;
goto cleanup_deregister;
}

@@ -589,9 +587,9 @@ static void libcfs_exit(void)

lustre_remove_debugfs();

- if (cfs_sched_rehash) {
- cfs_wi_sched_destroy(cfs_sched_rehash);
- cfs_sched_rehash = NULL;
+ if (cfs_rehash_wq) {
+ destroy_workqueue(cfs_rehash_wq);
+ cfs_rehash_wq = NULL;
}

cfs_crypto_unregister();