[lustre-devel] [PATCH 08/43] staging/lustre/obdclass: Add a preallocated percpu cl_env
green at linuxhacker.ru
green at linuxhacker.ru
Wed Mar 30 09:47:40 PDT 2016
From: Jinshan Xiong <jinshan.xiong at intel.com>
This change adds support for a single preallocated cl_env per CPU
which can be used in circumstances where reschedule is not possible.
Currently this interface is only used by the ll_releasepage function.
Signed-off-by: Jinshan Xiong <jinshan.xiong at intel.com>
Signed-off-by: Prakash Surya <surya1 at llnl.gov>
Reviewed-on: http://review.whamcloud.com/8174
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3321
Reviewed-by: Lai Siyao <lai.siyao at intel.com>
Reviewed-by: Bobi Jam <bobijam at gmail.com>
Signed-off-by: Oleg Drokin <green at linuxhacker.ru>
---
drivers/staging/lustre/lustre/include/cl_object.h | 12 +++
drivers/staging/lustre/lustre/llite/rw26.c | 54 +++++++----
drivers/staging/lustre/lustre/obdclass/cl_lock.c | 1 -
drivers/staging/lustre/lustre/obdclass/cl_object.c | 107 +++++++++++++++++++++
drivers/staging/lustre/lustre/obdclass/cl_page.c | 1 -
5 files changed, 152 insertions(+), 23 deletions(-)
diff --git a/drivers/staging/lustre/lustre/include/cl_object.h b/drivers/staging/lustre/lustre/include/cl_object.h
index 5daf688..e8455dc 100644
--- a/drivers/staging/lustre/lustre/include/cl_object.h
+++ b/drivers/staging/lustre/lustre/include/cl_object.h
@@ -2773,6 +2773,16 @@ static inline void *cl_object_page_slice(struct cl_object *clob,
return (void *)((char *)page + clob->co_slice_off);
}
+/**
+ * Return refcount of cl_object.
+ */
+static inline int cl_object_refc(struct cl_object *clob)
+{
+ struct lu_object_header *header = clob->co_lu.lo_header;
+
+ return atomic_read(&header->loh_ref);
+}
+
/** @} cl_object */
/** \defgroup cl_page cl_page
@@ -3226,6 +3236,8 @@ void cl_env_reexit(void *cookie);
void cl_env_implant(struct lu_env *env, int *refcheck);
void cl_env_unplant(struct lu_env *env, int *refcheck);
unsigned int cl_env_cache_purge(unsigned int nr);
+struct lu_env *cl_env_percpu_get(void);
+void cl_env_percpu_put(struct lu_env *env);
/** @} cl_env */
diff --git a/drivers/staging/lustre/lustre/llite/rw26.c b/drivers/staging/lustre/lustre/llite/rw26.c
index b5335de..cc49c21 100644
--- a/drivers/staging/lustre/lustre/llite/rw26.c
+++ b/drivers/staging/lustre/lustre/llite/rw26.c
@@ -107,12 +107,12 @@ static void ll_invalidatepage(struct page *vmpage, unsigned int offset,
static int ll_releasepage(struct page *vmpage, gfp_t gfp_mask)
{
- struct cl_env_nest nest;
struct lu_env *env;
+ void *cookie;
struct cl_object *obj;
struct cl_page *page;
struct address_space *mapping;
- int result;
+ int result = 0;
LASSERT(PageLocked(vmpage));
if (PageWriteback(vmpage) || PageDirty(vmpage))
@@ -126,30 +126,42 @@ static int ll_releasepage(struct page *vmpage, gfp_t gfp_mask)
if (!obj)
return 1;
- /* 1 for page allocator, 1 for cl_page and 1 for page cache */
+ /* 1 for caller, 1 for cl_page and 1 for page cache */
if (page_count(vmpage) > 3)
return 0;
- /* TODO: determine what gfp should be used by @gfp_mask. */
- env = cl_env_nested_get(&nest);
- if (IS_ERR(env))
- /* If we can't allocate an env we won't call cl_page_put()
- * later on which further means it's impossible to drop
- * page refcount by cl_page, so ask kernel to not free
- * this page.
- */
- return 0;
-
page = cl_vmpage_page(vmpage, obj);
- result = !page;
- if (page) {
- if (!cl_page_in_use(page)) {
- result = 1;
- cl_page_delete(env, page);
- }
- cl_page_put(env, page);
+ if (!page)
+ return 1;
+
+ cookie = cl_env_reenter();
+ env = cl_env_percpu_get();
+ LASSERT(!IS_ERR(env));
+
+ if (!cl_page_in_use(page)) {
+ result = 1;
+ cl_page_delete(env, page);
}
- cl_env_nested_put(&nest, env);
+
+ /* To use percpu env array, the call path can not be rescheduled;
+ * otherwise percpu array will be messed if ll_releaspage() called
+ * again on the same CPU.
+ *
+ * If this page holds the last refc of cl_object, the following
+ * call path may cause reschedule:
+ * cl_page_put -> cl_page_free -> cl_object_put ->
+ * lu_object_put -> lu_object_free -> lov_delete_raid0 ->
+ * cl_locks_prune.
+ *
+ * However, the kernel can't get rid of this inode until all pages have
+ * been cleaned up. Now that we hold page lock here, it's pretty safe
+ * that we won't get into object delete path.
+ */
+ LASSERT(cl_object_refc(obj) > 1);
+ cl_page_put(env, page);
+
+ cl_env_percpu_put(env);
+ cl_env_reexit(cookie);
return result;
}
diff --git a/drivers/staging/lustre/lustre/obdclass/cl_lock.c b/drivers/staging/lustre/lustre/obdclass/cl_lock.c
index 32ecc5a..fe8059a 100644
--- a/drivers/staging/lustre/lustre/obdclass/cl_lock.c
+++ b/drivers/staging/lustre/lustre/obdclass/cl_lock.c
@@ -255,7 +255,6 @@ static void cl_lock_free(const struct lu_env *env, struct cl_lock *lock)
LINVRNT(!cl_lock_is_mutexed(lock));
cl_lock_trace(D_DLMTRACE, env, "free lock", lock);
- might_sleep();
while (!list_empty(&lock->cll_layers)) {
struct cl_lock_slice *slice;
diff --git a/drivers/staging/lustre/lustre/obdclass/cl_object.c b/drivers/staging/lustre/lustre/obdclass/cl_object.c
index 65b6402..fa9b083 100644
--- a/drivers/staging/lustre/lustre/obdclass/cl_object.c
+++ b/drivers/staging/lustre/lustre/obdclass/cl_object.c
@@ -390,6 +390,8 @@ static int cache_stats_print(const struct cache_stats *cs,
return 0;
}
+static void cl_env_percpu_refill(void);
+
/**
* Initialize client site.
*
@@ -409,6 +411,7 @@ int cl_site_init(struct cl_site *s, struct cl_device *d)
atomic_set(&s->cs_pages_state[0], 0);
for (i = 0; i < ARRAY_SIZE(s->cs_locks_state); ++i)
atomic_set(&s->cs_locks_state[i], 0);
+ cl_env_percpu_refill();
}
return result;
}
@@ -1001,6 +1004,104 @@ void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb)
}
EXPORT_SYMBOL(cl_lvb2attr);
+static struct cl_env cl_env_percpu[NR_CPUS];
+
+static int cl_env_percpu_init(void)
+{
+ struct cl_env *cle;
+ int tags = LCT_REMEMBER | LCT_NOREF;
+ int i, j;
+ int rc = 0;
+
+ for_each_possible_cpu(i) {
+ struct lu_env *env;
+
+ cle = &cl_env_percpu[i];
+ env = &cle->ce_lu;
+
+ INIT_LIST_HEAD(&cle->ce_linkage);
+ cle->ce_magic = &cl_env_init0;
+ rc = lu_env_init(env, LCT_CL_THREAD | tags);
+ if (rc == 0) {
+ rc = lu_context_init(&cle->ce_ses, LCT_SESSION | tags);
+ if (rc == 0) {
+ lu_context_enter(&cle->ce_ses);
+ env->le_ses = &cle->ce_ses;
+ } else {
+ lu_env_fini(env);
+ }
+ }
+ if (rc != 0)
+ break;
+ }
+ if (rc != 0) {
+ /* Indices 0 to i (excluding i) were correctly initialized,
+ * thus we must uninitialize up to i, the rest are undefined.
+ */
+ for (j = 0; j < i; j++) {
+ cle = &cl_env_percpu[i];
+ lu_context_exit(&cle->ce_ses);
+ lu_context_fini(&cle->ce_ses);
+ lu_env_fini(&cle->ce_lu);
+ }
+ }
+
+ return rc;
+}
+
+static void cl_env_percpu_fini(void)
+{
+ int i;
+
+ for_each_possible_cpu(i) {
+ struct cl_env *cle = &cl_env_percpu[i];
+
+ lu_context_exit(&cle->ce_ses);
+ lu_context_fini(&cle->ce_ses);
+ lu_env_fini(&cle->ce_lu);
+ }
+}
+
+static void cl_env_percpu_refill(void)
+{
+ int i;
+
+ for_each_possible_cpu(i)
+ lu_env_refill(&cl_env_percpu[i].ce_lu);
+}
+
+void cl_env_percpu_put(struct lu_env *env)
+{
+ struct cl_env *cle;
+ int cpu;
+
+ cpu = smp_processor_id();
+ cle = cl_env_container(env);
+ LASSERT(cle == &cl_env_percpu[cpu]);
+
+ cle->ce_ref--;
+ LASSERT(cle->ce_ref == 0);
+
+ CL_ENV_DEC(busy);
+ cl_env_detach(cle);
+ cle->ce_debug = NULL;
+
+ put_cpu();
+}
+EXPORT_SYMBOL(cl_env_percpu_put);
+
+struct lu_env *cl_env_percpu_get()
+{
+ struct cl_env *cle;
+
+ cle = &cl_env_percpu[get_cpu()];
+ cl_env_init0(cle, __builtin_return_address(0));
+
+ cl_env_attach(cle);
+ return &cle->ce_lu;
+}
+EXPORT_SYMBOL(cl_env_percpu_get);
+
/*****************************************************************************
*
* Temporary prototype thing: mirror obd-devices into cl devices.
@@ -1154,6 +1255,11 @@ int cl_global_init(void)
if (result)
goto out_lock;
+ result = cl_env_percpu_init();
+ if (result)
+ /* no cl_env_percpu_fini on error */
+ goto out_lock;
+
return 0;
out_lock:
cl_lock_fini();
@@ -1171,6 +1277,7 @@ out_store:
*/
void cl_global_fini(void)
{
+ cl_env_percpu_fini();
cl_lock_fini();
cl_page_fini();
lu_context_key_degister(&cl_key);
diff --git a/drivers/staging/lustre/lustre/obdclass/cl_page.c b/drivers/staging/lustre/lustre/obdclass/cl_page.c
index 8169836..bab8a74 100644
--- a/drivers/staging/lustre/lustre/obdclass/cl_page.c
+++ b/drivers/staging/lustre/lustre/obdclass/cl_page.c
@@ -123,7 +123,6 @@ static void cl_page_free(const struct lu_env *env, struct cl_page *page)
PASSERT(env, page, !page->cp_parent);
PASSERT(env, page, page->cp_state == CPS_FREEING);
- might_sleep();
while (!list_empty(&page->cp_layers)) {
struct cl_page_slice *slice;
--
2.1.0
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