*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; If not, see
- * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
+ * http://www.gnu.org/licenses/gpl-2.0.html
*
* GPL HEADER END
*/
* Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
* Use is subject to license terms.
*
- * Copyright (c) 2011, 2013, Intel Corporation.
+ * Copyright (c) 2011, 2017, Intel Corporation.
*/
/*
* This file is part of Lustre, http://www.lustre.org/
*/
#define DEBUG_SUBSYSTEM S_OSC
+#include <lustre_osc.h>
-#include "osc_cl_internal.h"
+#include "osc_internal.h"
static void osc_lru_del(struct client_obd *cli, struct osc_page *opg);
static void osc_lru_use(struct client_obd *cli, struct osc_page *opg);
-static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
- struct osc_page *opg);
+static int osc_lru_alloc(const struct lu_env *env, struct client_obd *cli,
+ struct osc_page *opg);
/** \addtogroup osc
* @{
*/
/*
- * Comment out osc_page_protected because it may sleep inside the
- * the client_obd_list_lock.
- * client_obd_list_lock -> osc_ap_completion -> osc_completion ->
- * -> osc_page_protected -> osc_page_is_dlocked -> osc_match_base
- * -> ldlm_lock_match -> sptlrpc_import_check_ctx -> sleep.
- */
-#if 0
-static int osc_page_is_dlocked(const struct lu_env *env,
- const struct osc_page *opg,
- enum cl_lock_mode mode, int pending, int unref)
-{
- struct cl_page *page;
- struct osc_object *obj;
- struct osc_thread_info *info;
- struct ldlm_res_id *resname;
- struct lustre_handle *lockh;
- ldlm_policy_data_t *policy;
- ldlm_mode_t dlmmode;
- __u64 flags;
-
- might_sleep();
-
- info = osc_env_info(env);
- resname = &info->oti_resname;
- policy = &info->oti_policy;
- lockh = &info->oti_handle;
- page = opg->ops_cl.cpl_page;
- obj = cl2osc(opg->ops_cl.cpl_obj);
-
- flags = LDLM_FL_TEST_LOCK | LDLM_FL_BLOCK_GRANTED;
- if (pending)
- flags |= LDLM_FL_CBPENDING;
-
- dlmmode = osc_cl_lock2ldlm(mode) | LCK_PW;
- osc_lock_build_res(env, obj, resname);
- osc_index2policy(policy, page->cp_obj, osc_index(opg), osc_index(opg));
- return osc_match_base(osc_export(obj), resname, LDLM_EXTENT, policy,
- dlmmode, &flags, NULL, lockh, unref);
-}
-
-/**
- * Checks an invariant that a page in the cache is covered by a lock, as
- * needed.
- */
-static int osc_page_protected(const struct lu_env *env,
- const struct osc_page *opg,
- enum cl_lock_mode mode, int unref)
-{
- struct cl_object_header *hdr;
- struct cl_lock *scan;
- struct cl_page *page;
- struct cl_lock_descr *descr;
- int result;
-
- LINVRNT(!opg->ops_temp);
-
- page = opg->ops_cl.cpl_page;
- if (page->cp_owner != NULL &&
- cl_io_top(page->cp_owner)->ci_lockreq == CILR_NEVER)
- /*
- * If IO is done without locks (liblustre, or lloop), lock is
- * not required.
- */
- result = 1;
- else
- /* otherwise check for a DLM lock */
- result = osc_page_is_dlocked(env, opg, mode, 1, unref);
- if (result == 0) {
- /* maybe this page is a part of a lockless io? */
- hdr = cl_object_header(opg->ops_cl.cpl_obj);
- descr = &osc_env_info(env)->oti_descr;
- descr->cld_mode = mode;
- descr->cld_start = osc_index(opg);
- descr->cld_end = osc_index(opg);
- spin_lock(&hdr->coh_lock_guard);
- cfs_list_for_each_entry(scan, &hdr->coh_locks, cll_linkage) {
- /*
- * Lock-less sub-lock has to be either in HELD state
- * (when io is actively going on), or in CACHED state,
- * when top-lock is being unlocked:
- * cl_io_unlock()->cl_unuse()->...->lov_lock_unuse().
- */
- if ((scan->cll_state == CLS_HELD ||
- scan->cll_state == CLS_CACHED) &&
- cl_lock_ext_match(&scan->cll_descr, descr)) {
- struct osc_lock *olck;
-
- olck = osc_lock_at(scan);
- result = osc_lock_is_lockless(olck);
- break;
- }
- }
- spin_unlock(&hdr->coh_lock_guard);
- }
- return result;
-}
-#else
-static int osc_page_protected(const struct lu_env *env,
- const struct osc_page *opg,
- enum cl_lock_mode mode, int unref)
-{
- return 1;
-}
-#endif
-
-/*****************************************************************************
- *
* Page operations.
- *
*/
static void osc_page_transfer_get(struct osc_page *opg, const char *label)
{
{
struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
- /* ops_lru and ops_inflight share the same field, so take it from LRU
- * first and then use it as inflight. */
osc_lru_use(osc_cli(obj), opg);
-
- spin_lock(&obj->oo_seatbelt);
- cfs_list_add(&opg->ops_inflight, &obj->oo_inflight[crt]);
- opg->ops_submitter = current;
- spin_unlock(&obj->oo_seatbelt);
}
int osc_page_cache_add(const struct lu_env *env,
int result;
ENTRY;
- LINVRNT(osc_page_protected(env, opg, CLM_WRITE, 0));
-
osc_page_transfer_get(opg, "transfer\0cache");
result = osc_queue_async_io(env, io, opg);
if (result != 0)
RETURN(result);
}
-void osc_index2policy(ldlm_policy_data_t *policy, const struct cl_object *obj,
- pgoff_t start, pgoff_t end)
+void osc_index2policy(union ldlm_policy_data *policy,
+ const struct cl_object *obj, pgoff_t start, pgoff_t end)
{
- memset(policy, 0, sizeof *policy);
- policy->l_extent.start = cl_offset(obj, start);
- policy->l_extent.end = cl_offset(obj, end + 1) - 1;
+ memset(policy, 0, sizeof *policy);
+ policy->l_extent.start = cl_offset(obj, start);
+ policy->l_extent.end = cl_offset(obj, end + 1) - 1;
}
-static int osc_page_is_under_lock(const struct lu_env *env,
- const struct cl_page_slice *slice,
- struct cl_io *unused)
+static const char *osc_list(struct list_head *head)
{
- struct osc_page *opg = cl2osc_page(slice);
- struct cl_lock *lock;
- int result = -ENODATA;
-
- ENTRY;
- lock = cl_lock_at_pgoff(env, slice->cpl_obj, osc_index(opg),
- NULL, 1, 0);
- if (lock != NULL) {
- cl_lock_put(env, lock);
- result = -EBUSY;
- }
- RETURN(result);
-}
-
-static const char *osc_list(cfs_list_t *head)
-{
- return cfs_list_empty(head) ? "-" : "+";
+ return list_empty(head) ? "-" : "+";
}
-static inline cfs_time_t osc_submit_duration(struct osc_page *opg)
+static inline s64 osc_submit_duration(struct osc_page *opg)
{
- if (opg->ops_submit_time == 0)
- return 0;
+ if (ktime_to_ns(opg->ops_submit_time) == 0)
+ return 0;
- return (cfs_time_current() - opg->ops_submit_time);
+ return ktime_ms_delta(ktime_get(), opg->ops_submit_time);
}
static int osc_page_print(const struct lu_env *env,
return (*printer)(env, cookie, LUSTRE_OSC_NAME"-page@%p %lu: "
"1< %#x %d %u %s %s > "
- "2< "LPU64" %u %u %#x %#x | %p %p %p > "
- "3< %s %p %d %lu %d > "
+ "2< %lld %u %u %#x %#x | %p %p %p > "
+ "3< %d %lld %d > "
"4< %d %d %d %lu %s | %s %s %s %s > "
"5< %s %s %s %s | %d %s | %d %s %s>\n",
opg, osc_index(opg),
oap->oap_obj_off, oap->oap_page_off, oap->oap_count,
oap->oap_async_flags, oap->oap_brw_flags,
oap->oap_request, oap->oap_cli, obj,
- /* 3 */
- osc_list(&opg->ops_inflight),
- opg->ops_submitter, opg->ops_transfer_pinned,
- osc_submit_duration(opg), opg->ops_srvlock,
+ /* 3 */
+ opg->ops_transfer_pinned,
+ osc_submit_duration(opg), opg->ops_srvlock,
/* 4 */
cli->cl_r_in_flight, cli->cl_w_in_flight,
cli->cl_max_rpcs_in_flight,
}
static void osc_page_delete(const struct lu_env *env,
- const struct cl_page_slice *slice)
+ const struct cl_page_slice *slice)
{
struct osc_page *opg = cl2osc_page(slice);
struct osc_object *obj = cl2osc(opg->ops_cl.cpl_obj);
- int rc;
-
- LINVRNT(opg->ops_temp || osc_page_protected(env, opg, CLM_READ, 1));
+ int rc;
- ENTRY;
- CDEBUG(D_TRACE, "%p\n", opg);
- osc_page_transfer_put(env, opg);
+ ENTRY;
+ CDEBUG(D_TRACE, "%p\n", opg);
+ osc_page_transfer_put(env, opg);
rc = osc_teardown_async_page(env, obj, opg);
if (rc) {
CL_PAGE_DEBUG(D_ERROR, env, slice->cpl_page,
LASSERT(0);
}
- spin_lock(&obj->oo_seatbelt);
- if (opg->ops_submitter != NULL) {
- LASSERT(!cfs_list_empty(&opg->ops_inflight));
- cfs_list_del_init(&opg->ops_inflight);
- opg->ops_submitter = NULL;
- }
- spin_unlock(&obj->oo_seatbelt);
-
osc_lru_del(osc_cli(obj), opg);
if (slice->cpl_page->cp_type == CPT_CACHEABLE) {
- void *value;
+ void *value = NULL;
spin_lock(&obj->oo_tree_lock);
- value = radix_tree_delete(&obj->oo_tree, osc_index(opg));
- if (value != NULL)
- --obj->oo_npages;
+ if (opg->ops_intree) {
+ value = radix_tree_delete(&obj->oo_tree,
+ osc_index(opg));
+ if (value != NULL) {
+ --obj->oo_npages;
+ opg->ops_intree = 0;
+ }
+ }
spin_unlock(&obj->oo_tree_lock);
LASSERT(ergo(value != NULL, value == opg));
EXIT;
}
-void osc_page_clip(const struct lu_env *env, const struct cl_page_slice *slice,
- int from, int to)
+static void osc_page_clip(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ int from, int to)
{
- struct osc_page *opg = cl2osc_page(slice);
- struct osc_async_page *oap = &opg->ops_oap;
-
- LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
+ struct osc_page *opg = cl2osc_page(slice);
+ struct osc_async_page *oap = &opg->ops_oap;
- opg->ops_from = from;
- opg->ops_to = to;
+ opg->ops_from = from;
+ opg->ops_to = to;
spin_lock(&oap->oap_lock);
oap->oap_async_flags |= ASYNC_COUNT_STABLE;
spin_unlock(&oap->oap_lock);
}
static int osc_page_cancel(const struct lu_env *env,
- const struct cl_page_slice *slice)
+ const struct cl_page_slice *slice)
{
struct osc_page *opg = cl2osc_page(slice);
- int rc = 0;
-
- LINVRNT(osc_page_protected(env, opg, CLM_READ, 0));
+ int rc = 0;
- /* Check if the transferring against this page
- * is completed, or not even queued. */
- if (opg->ops_transfer_pinned)
- /* FIXME: may not be interrupted.. */
+ /* Check if the transferring against this page
+ * is completed, or not even queued. */
+ if (opg->ops_transfer_pinned)
+ /* FIXME: may not be interrupted.. */
rc = osc_cancel_async_page(env, opg);
- LASSERT(ergo(rc == 0, opg->ops_transfer_pinned == 0));
- return rc;
+ LASSERT(ergo(rc == 0, opg->ops_transfer_pinned == 0));
+ return rc;
}
static int osc_page_flush(const struct lu_env *env,
RETURN(rc);
}
+static void osc_page_touch(const struct lu_env *env,
+ const struct cl_page_slice *slice, size_t to)
+{
+ struct osc_page *opg = cl2osc_page(slice);
+ struct cl_object *obj = opg->ops_cl.cpl_obj;
+
+ osc_page_touch_at(env, obj, osc_index(opg), to);
+}
+
static const struct cl_page_operations osc_page_ops = {
.cpo_print = osc_page_print,
.cpo_delete = osc_page_delete,
- .cpo_is_under_lock = osc_page_is_under_lock,
.cpo_clip = osc_page_clip,
.cpo_cancel = osc_page_cancel,
- .cpo_flush = osc_page_flush
+ .cpo_flush = osc_page_flush,
+ .cpo_page_touch = osc_page_touch,
};
int osc_page_init(const struct lu_env *env, struct cl_object *obj,
{
struct osc_object *osc = cl2osc(obj);
struct osc_page *opg = cl_object_page_slice(obj, page);
+ struct osc_io *oio = osc_env_io(env);
int result;
opg->ops_from = 0;
- opg->ops_to = PAGE_CACHE_SIZE;
- opg->ops_cl.cpl_index = index;
+ opg->ops_to = PAGE_SIZE;
+
+ INIT_LIST_HEAD(&opg->ops_lru);
result = osc_prep_async_page(osc, opg, page->cp_vmpage,
cl_offset(obj, index));
- if (result == 0) {
- struct osc_io *oio = osc_env_io(env);
- opg->ops_srvlock = osc_io_srvlock(oio);
- cl_page_slice_add(page, &opg->ops_cl, obj,
- &osc_page_ops);
- }
- /*
- * Cannot assert osc_page_protected() here as read-ahead
- * creates temporary pages outside of a lock.
- */
-#ifdef CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK
- opg->ops_temp = !osc_page_protected(env, opg, CLM_READ, 1);
-#endif
- /* ops_inflight and ops_lru are the same field, but it doesn't
- * hurt to initialize it twice :-) */
- CFS_INIT_LIST_HEAD(&opg->ops_inflight);
- CFS_INIT_LIST_HEAD(&opg->ops_lru);
+ if (result != 0)
+ return result;
+
+ opg->ops_srvlock = osc_io_srvlock(oio);
+ cl_page_slice_add(page, &opg->ops_cl, obj, index,
+ &osc_page_ops);
+
/* reserve an LRU space for this page */
- if (page->cp_type == CPT_CACHEABLE && result == 0) {
- result = osc_lru_reserve(env, osc, opg);
+ if (page->cp_type == CPT_CACHEABLE) {
+ result = osc_lru_alloc(env, osc_cli(osc), opg);
if (result == 0) {
- spin_lock(&osc->oo_tree_lock);
- result = radix_tree_insert(&osc->oo_tree, index, opg);
- if (result == 0)
- ++osc->oo_npages;
- spin_unlock(&osc->oo_tree_lock);
- LASSERT(result == 0);
+ result = radix_tree_preload(GFP_NOFS);
+ if (result == 0) {
+ spin_lock(&osc->oo_tree_lock);
+ result = radix_tree_insert(&osc->oo_tree,
+ index, opg);
+ if (result == 0) {
+ ++osc->oo_npages;
+ opg->ops_intree = 1;
+ }
+ spin_unlock(&osc->oo_tree_lock);
+
+ radix_tree_preload_end();
+ }
}
}
return result;
}
-
-int osc_over_unstable_soft_limit(struct client_obd *cli)
-{
- long obd_upages, obd_dpages, osc_upages;
-
- /* Can't check cli->cl_unstable_count, therefore, no soft limit */
- if (cli == NULL)
- return 0;
-
- obd_upages = atomic_read(&obd_unstable_pages);
- obd_dpages = atomic_read(&obd_dirty_pages);
-
- osc_upages = atomic_read(&cli->cl_unstable_count);
-
- /* obd_max_dirty_pages is the max number of (dirty + unstable)
- * pages allowed at any given time. To simulate an unstable page
- * only limit, we subtract the current number of dirty pages
- * from this max. This difference is roughly the amount of pages
- * currently available for unstable pages. Thus, the soft limit
- * is half of that difference. Check osc_upages to ensure we don't
- * set SOFT_SYNC for OSCs without any outstanding unstable pages. */
- return osc_upages != 0 &&
- obd_upages >= (obd_max_dirty_pages - obd_dpages) / 2;
-}
+EXPORT_SYMBOL(osc_page_init);
/**
* Helper function called by osc_io_submit() for every page in an immediate
void osc_page_submit(const struct lu_env *env, struct osc_page *opg,
enum cl_req_type crt, int brw_flags)
{
+ struct osc_io *oio = osc_env_io(env);
struct osc_async_page *oap = &opg->ops_oap;
- struct osc_object *obj = oap->oap_obj;
-
- LINVRNT(osc_page_protected(env, opg,
- crt == CRT_WRITE ? CLM_WRITE : CLM_READ, 1));
LASSERTF(oap->oap_magic == OAP_MAGIC, "Bad oap magic: oap %p, "
"magic 0x%x\n", oap, oap->oap_magic);
oap->oap_count = opg->ops_to - opg->ops_from;
oap->oap_brw_flags = OBD_BRW_SYNC | brw_flags;
- if (osc_over_unstable_soft_limit(oap->oap_cli))
- oap->oap_brw_flags |= OBD_BRW_SOFT_SYNC;
-
- if (!client_is_remote(osc_export(obj)) &&
- cfs_capable(CFS_CAP_SYS_RESOURCE)) {
+ if (oio->oi_cap_sys_resource) {
oap->oap_brw_flags |= OBD_BRW_NOQUOTA;
oap->oap_cmd |= OBD_BRW_NOQUOTA;
}
- opg->ops_submit_time = cfs_time_current();
+ opg->ops_submit_time = ktime_get();
osc_page_transfer_get(opg, "transfer\0imm");
osc_page_transfer_add(env, opg, crt);
}
* at any time.
*/
-static CFS_DECL_WAITQ(osc_lru_waitq);
-/* LRU pages are freed in batch mode. OSC should at least free this
- * number of pages to avoid running out of LRU budget, and.. */
-static const int lru_shrink_min = 2 << (20 - PAGE_CACHE_SHIFT); /* 2M */
-/* free this number at most otherwise it will take too long time to finsih. */
-static const int lru_shrink_max = 8 << (20 - PAGE_CACHE_SHIFT); /* 8M */
+static DECLARE_WAIT_QUEUE_HEAD(osc_lru_waitq);
+
+/**
+ * LRU pages are freed in batch mode. OSC should at least free this
+ * number of pages to avoid running out of LRU slots.
+ */
+static inline int lru_shrink_min(struct client_obd *cli)
+{
+ return cli->cl_max_pages_per_rpc * 2;
+}
+
+/**
+ * free this number at most otherwise it will take too long time to finsih.
+ */
+static inline int lru_shrink_max(struct client_obd *cli)
+{
+ return cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
+}
-/* Check if we can free LRU slots from this OSC. If there exists LRU waiters,
+/**
+ * Check if we can free LRU slots from this OSC. If there exists LRU waiters,
* we should free slots aggressively. In this way, slots are freed in a steady
* step to maintain fairness among OSCs.
*
- * Return how many LRU pages should be freed. */
+ * Return how many LRU pages should be freed.
+ */
static int osc_cache_too_much(struct client_obd *cli)
{
struct cl_client_cache *cache = cli->cl_cache;
- int pages = atomic_read(&cli->cl_lru_in_list);
+ long pages = atomic_long_read(&cli->cl_lru_in_list);
unsigned long budget;
- budget = cache->ccc_lru_max / atomic_read(&cache->ccc_users);
+ LASSERT(cache != NULL);
+ budget = cache->ccc_lru_max / (atomic_read(&cache->ccc_users) - 2);
/* if it's going to run out LRU slots, we should free some, but not
* too much to maintain faireness among OSCs. */
- if (atomic_read(cli->cl_lru_left) < cache->ccc_lru_max >> 4) {
+ if (atomic_long_read(cli->cl_lru_left) < cache->ccc_lru_max >> 2) {
if (pages >= budget)
- return lru_shrink_max;
+ return lru_shrink_max(cli);
else if (pages >= budget / 2)
- return lru_shrink_min;
- } else if (pages >= budget * 2)
- return lru_shrink_min;
+ return lru_shrink_min(cli);
+ } else {
+ time64_t duration = ktime_get_real_seconds();
+ long timediff;
+
+ /* knock out pages by duration of no IO activity */
+ duration -= cli->cl_lru_last_used;
+ /*
+ * The difference shouldn't be more than 70 years
+ * so we can safely case to a long. Round to
+ * approximately 1 minute.
+ */
+ timediff = (long)(duration >> 6);
+ if (timediff > 0 && pages >= budget / timediff)
+ return lru_shrink_min(cli);
+ }
return 0;
}
int lru_queue_work(const struct lu_env *env, void *data)
{
struct client_obd *cli = data;
+ int count;
- CDEBUG(D_CACHE, "Run LRU work for client obd %p.\n", cli);
+ CDEBUG(D_CACHE, "%s: run LRU work for client obd\n", cli_name(cli));
+ count = osc_cache_too_much(cli);
+ if (count > 0) {
+ int rc = osc_lru_shrink(env, cli, count, false);
- if (osc_cache_too_much(cli))
- osc_lru_shrink(env, cli, lru_shrink_max, true);
+ CDEBUG(D_CACHE, "%s: shrank %d/%d pages from client obd\n",
+ cli_name(cli), rc, count);
+ if (rc >= count) {
+ CDEBUG(D_CACHE, "%s: queue again\n", cli_name(cli));
+ ptlrpcd_queue_work(cli->cl_lru_work);
+ }
+ }
RETURN(0);
}
-void osc_lru_add_batch(struct client_obd *cli, cfs_list_t *plist)
+void osc_lru_add_batch(struct client_obd *cli, struct list_head *plist)
{
- CFS_LIST_HEAD(lru);
+ struct list_head lru = LIST_HEAD_INIT(lru);
struct osc_async_page *oap;
- int npages = 0;
+ long npages = 0;
- cfs_list_for_each_entry(oap, plist, oap_pending_item) {
+ list_for_each_entry(oap, plist, oap_pending_item) {
struct osc_page *opg = oap2osc_page(oap);
if (!opg->ops_in_lru)
continue;
++npages;
- LASSERT(cfs_list_empty(&opg->ops_lru));
- cfs_list_add(&opg->ops_lru, &lru);
+ LASSERT(list_empty(&opg->ops_lru));
+ list_add(&opg->ops_lru, &lru);
}
if (npages > 0) {
- client_obd_list_lock(&cli->cl_lru_list_lock);
- cfs_list_splice_tail(&lru, &cli->cl_lru_list);
- atomic_sub(npages, &cli->cl_lru_busy);
- atomic_add(npages, &cli->cl_lru_in_list);
- client_obd_list_unlock(&cli->cl_lru_list_lock);
-
- /* XXX: May set force to be true for better performance */
- if (osc_cache_too_much(cli))
+ spin_lock(&cli->cl_lru_list_lock);
+ list_splice_tail(&lru, &cli->cl_lru_list);
+ atomic_long_sub(npages, &cli->cl_lru_busy);
+ atomic_long_add(npages, &cli->cl_lru_in_list);
+ cli->cl_lru_last_used = ktime_get_real_seconds();
+ spin_unlock(&cli->cl_lru_list_lock);
+
+ if (waitqueue_active(&osc_lru_waitq))
(void)ptlrpcd_queue_work(cli->cl_lru_work);
}
}
static void __osc_lru_del(struct client_obd *cli, struct osc_page *opg)
{
- LASSERT(atomic_read(&cli->cl_lru_in_list) > 0);
- cfs_list_del_init(&opg->ops_lru);
- atomic_dec(&cli->cl_lru_in_list);
+ LASSERT(atomic_long_read(&cli->cl_lru_in_list) > 0);
+ list_del_init(&opg->ops_lru);
+ atomic_long_dec(&cli->cl_lru_in_list);
}
/**
static void osc_lru_del(struct client_obd *cli, struct osc_page *opg)
{
if (opg->ops_in_lru) {
- client_obd_list_lock(&cli->cl_lru_list_lock);
- if (!cfs_list_empty(&opg->ops_lru)) {
+ spin_lock(&cli->cl_lru_list_lock);
+ if (!list_empty(&opg->ops_lru)) {
__osc_lru_del(cli, opg);
} else {
- LASSERT(atomic_read(&cli->cl_lru_busy) > 0);
- atomic_dec(&cli->cl_lru_busy);
+ LASSERT(atomic_long_read(&cli->cl_lru_busy) > 0);
+ atomic_long_dec(&cli->cl_lru_busy);
}
- client_obd_list_unlock(&cli->cl_lru_list_lock);
+ spin_unlock(&cli->cl_lru_list_lock);
- atomic_inc(cli->cl_lru_left);
+ atomic_long_inc(cli->cl_lru_left);
/* this is a great place to release more LRU pages if
* this osc occupies too many LRU pages and kernel is
* stealing one of them. */
- if (!memory_pressure_get())
+ if (osc_cache_too_much(cli)) {
+ CDEBUG(D_CACHE, "%s: queue LRU work\n", cli_name(cli));
(void)ptlrpcd_queue_work(cli->cl_lru_work);
+ }
wake_up(&osc_lru_waitq);
} else {
- LASSERT(cfs_list_empty(&opg->ops_lru));
+ LASSERT(list_empty(&opg->ops_lru));
}
}
/**
- * Delete page from LRUlist for redirty.
+ * Delete page from LRU list for redirty.
*/
static void osc_lru_use(struct client_obd *cli, struct osc_page *opg)
{
- /* If page is being transfered for the first time,
+ /* If page is being transferred for the first time,
* ops_lru should be empty */
- if (opg->ops_in_lru && !cfs_list_empty(&opg->ops_lru)) {
- client_obd_list_lock(&cli->cl_lru_list_lock);
- __osc_lru_del(cli, opg);
- client_obd_list_unlock(&cli->cl_lru_list_lock);
- atomic_inc(&cli->cl_lru_busy);
+ if (opg->ops_in_lru) {
+ if (list_empty(&opg->ops_lru))
+ return;
+ spin_lock(&cli->cl_lru_list_lock);
+ if (!list_empty(&opg->ops_lru)) {
+ __osc_lru_del(cli, opg);
+ atomic_long_inc(&cli->cl_lru_busy);
+ }
+ spin_unlock(&cli->cl_lru_list_lock);
}
}
static void discard_pagevec(const struct lu_env *env, struct cl_io *io,
struct cl_page **pvec, int max_index)
{
- int i;
+ struct pagevec *pagevec = &osc_env_info(env)->oti_pagevec;
+ int i;
- for (i = 0; i < max_index; i++) {
- struct cl_page *page = pvec[i];
+ ll_pagevec_init(pagevec, 0);
+ for (i = 0; i < max_index; i++) {
+ struct cl_page *page = pvec[i];
LASSERT(cl_page_is_owned(page, io));
+ cl_page_delete(env, page);
cl_page_discard(env, io, page);
cl_page_disown(env, io, page);
- cl_page_put(env, page);
+ cl_pagevec_put(env, page, pagevec);
- pvec[i] = NULL;
- }
+ pvec[i] = NULL;
+ }
+ pagevec_release(pagevec);
+}
+
+/**
+ * Check if a cl_page can be released, i.e, it's not being used.
+ *
+ * If unstable account is turned on, bulk transfer may hold one refcount
+ * for recovery so we need to check vmpage refcount as well; otherwise,
+ * even we can destroy cl_page but the corresponding vmpage can't be reused.
+ */
+static inline bool lru_page_busy(struct client_obd *cli, struct cl_page *page)
+{
+ if (cl_page_in_use_noref(page))
+ return true;
+
+ if (cli->cl_cache->ccc_unstable_check) {
+ struct page *vmpage = cl_page_vmpage(page);
+
+ /* vmpage have two known users: cl_page and VM page cache */
+ if (page_count(vmpage) - page_mapcount(vmpage) > 2)
+ return true;
+ }
+ return false;
}
/**
* Drop @target of pages from LRU at most.
*/
-int osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
- int target, bool force)
+long osc_lru_shrink(const struct lu_env *env, struct client_obd *cli,
+ long target, bool force)
{
struct cl_io *io;
struct cl_object *clobj = NULL;
struct cl_page **pvec;
struct osc_page *opg;
+ long count = 0;
int maxscan = 0;
- int count = 0;
int index = 0;
int rc = 0;
ENTRY;
- LASSERT(atomic_read(&cli->cl_lru_in_list) >= 0);
- if (atomic_read(&cli->cl_lru_in_list) == 0 || target <= 0)
+ LASSERT(atomic_long_read(&cli->cl_lru_in_list) >= 0);
+ if (atomic_long_read(&cli->cl_lru_in_list) == 0 || target <= 0)
RETURN(0);
+ CDEBUG(D_CACHE, "%s: shrinkers: %d, force: %d\n",
+ cli_name(cli), atomic_read(&cli->cl_lru_shrinkers), force);
if (!force) {
if (atomic_read(&cli->cl_lru_shrinkers) > 0)
RETURN(-EBUSY);
}
pvec = (struct cl_page **)osc_env_info(env)->oti_pvec;
- io = &osc_env_info(env)->oti_io;
+ io = osc_env_thread_io(env);
- client_obd_list_lock(&cli->cl_lru_list_lock);
- maxscan = min(target << 1, atomic_read(&cli->cl_lru_in_list));
- while (!cfs_list_empty(&cli->cl_lru_list)) {
+ spin_lock(&cli->cl_lru_list_lock);
+ if (force)
+ cli->cl_lru_reclaim++;
+ maxscan = min(target << 1, atomic_long_read(&cli->cl_lru_in_list));
+ while (!list_empty(&cli->cl_lru_list)) {
struct cl_page *page;
bool will_free = false;
+ if (!force && atomic_read(&cli->cl_lru_shrinkers) > 1)
+ break;
+
if (--maxscan < 0)
break;
- opg = cfs_list_entry(cli->cl_lru_list.next, struct osc_page,
- ops_lru);
+ opg = list_entry(cli->cl_lru_list.next, struct osc_page,
+ ops_lru);
page = opg->ops_cl.cpl_page;
- if (cl_page_in_use_noref(page)) {
- cfs_list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
+ if (lru_page_busy(cli, page)) {
+ list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
continue;
}
struct cl_object *tmp = page->cp_obj;
cl_object_get(tmp);
- client_obd_list_unlock(&cli->cl_lru_list_lock);
+ spin_unlock(&cli->cl_lru_list_lock);
if (clobj != NULL) {
discard_pagevec(env, io, pvec, index);
io->ci_ignore_layout = 1;
rc = cl_io_init(env, io, CIT_MISC, clobj);
- client_obd_list_lock(&cli->cl_lru_list_lock);
+ spin_lock(&cli->cl_lru_list_lock);
if (rc != 0)
break;
}
if (cl_page_own_try(env, io, page) == 0) {
- if (!cl_page_in_use_noref(page)) {
+ if (!lru_page_busy(cli, page)) {
/* remove it from lru list earlier to avoid
* lock contention */
__osc_lru_del(cli, opg);
}
if (!will_free) {
- cfs_list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
+ list_move_tail(&opg->ops_lru, &cli->cl_lru_list);
continue;
}
/* Don't discard and free the page with cl_lru_list held */
pvec[index++] = page;
if (unlikely(index == OTI_PVEC_SIZE)) {
- client_obd_list_unlock(&cli->cl_lru_list_lock);
+ spin_unlock(&cli->cl_lru_list_lock);
discard_pagevec(env, io, pvec, index);
index = 0;
- client_obd_list_lock(&cli->cl_lru_list_lock);
+ spin_lock(&cli->cl_lru_list_lock);
}
if (++count >= target)
break;
}
- client_obd_list_unlock(&cli->cl_lru_list_lock);
+ spin_unlock(&cli->cl_lru_list_lock);
if (clobj != NULL) {
discard_pagevec(env, io, pvec, index);
atomic_dec(&cli->cl_lru_shrinkers);
if (count > 0) {
- atomic_add(count, cli->cl_lru_left);
+ atomic_long_add(count, cli->cl_lru_left);
wake_up_all(&osc_lru_waitq);
}
RETURN(count > 0 ? count : rc);
}
+EXPORT_SYMBOL(osc_lru_shrink);
-static inline int max_to_shrink(struct client_obd *cli)
-{
- return min(atomic_read(&cli->cl_lru_in_list) >> 1, lru_shrink_max);
-}
-
-int osc_lru_reclaim(struct client_obd *cli)
+/**
+ * Reclaim LRU pages by an IO thread. The caller wants to reclaim at least
+ * \@npages of LRU slots. For performance consideration, it's better to drop
+ * LRU pages in batch. Therefore, the actual number is adjusted at least
+ * max_pages_per_rpc.
+ */
+static long osc_lru_reclaim(struct client_obd *cli, unsigned long npages)
{
- struct cl_env_nest nest;
struct lu_env *env;
struct cl_client_cache *cache = cli->cl_cache;
int max_scans;
- int rc = 0;
+ __u16 refcheck;
+ long rc = 0;
ENTRY;
LASSERT(cache != NULL);
- LASSERT(!cfs_list_empty(&cache->ccc_lru));
- env = cl_env_nested_get(&nest);
+ env = cl_env_get(&refcheck);
if (IS_ERR(env))
RETURN(rc);
- rc = osc_lru_shrink(env, cli, osc_cache_too_much(cli), false);
- if (rc != 0) {
- if (rc == -EBUSY)
- rc = 0;
-
- CDEBUG(D_CACHE, "%s: Free %d pages from own LRU: %p.\n",
- cli->cl_import->imp_obd->obd_name, rc, cli);
+ npages = max_t(int, npages, cli->cl_max_pages_per_rpc);
+ CDEBUG(D_CACHE, "%s: start to reclaim %ld pages from LRU\n",
+ cli_name(cli), npages);
+ rc = osc_lru_shrink(env, cli, npages, true);
+ if (rc >= npages) {
+ CDEBUG(D_CACHE, "%s: reclaimed %ld/%ld pages from LRU\n",
+ cli_name(cli), rc, npages);
+ if (osc_cache_too_much(cli) > 0)
+ ptlrpcd_queue_work(cli->cl_lru_work);
GOTO(out, rc);
+ } else if (rc > 0) {
+ npages -= rc;
}
- CDEBUG(D_CACHE, "%s: cli %p no free slots, pages: %d, busy: %d.\n",
- cli->cl_import->imp_obd->obd_name, cli,
- atomic_read(&cli->cl_lru_in_list),
- atomic_read(&cli->cl_lru_busy));
+ CDEBUG(D_CACHE, "%s: cli %p no free slots, pages: %ld/%ld, want: %ld\n",
+ cli_name(cli), cli, atomic_long_read(&cli->cl_lru_in_list),
+ atomic_long_read(&cli->cl_lru_busy), npages);
/* Reclaim LRU slots from other client_obd as it can't free enough
* from its own. This should rarely happen. */
spin_lock(&cache->ccc_lru_lock);
+ LASSERT(!list_empty(&cache->ccc_lru));
+
cache->ccc_lru_shrinkers++;
- cfs_list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
+ list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
- max_scans = atomic_read(&cache->ccc_users);
- while (--max_scans > 0 && !cfs_list_empty(&cache->ccc_lru)) {
- cli = cfs_list_entry(cache->ccc_lru.next, struct client_obd,
- cl_lru_osc);
+ max_scans = atomic_read(&cache->ccc_users) - 2;
+ while (--max_scans > 0 && !list_empty(&cache->ccc_lru)) {
+ cli = list_entry(cache->ccc_lru.next, struct client_obd,
+ cl_lru_osc);
- CDEBUG(D_CACHE, "%s: cli %p LRU pages: %d, busy: %d.\n",
- cli->cl_import->imp_obd->obd_name, cli,
- atomic_read(&cli->cl_lru_in_list),
- atomic_read(&cli->cl_lru_busy));
+ CDEBUG(D_CACHE, "%s: cli %p LRU pages: %ld, busy: %ld.\n",
+ cli_name(cli), cli,
+ atomic_long_read(&cli->cl_lru_in_list),
+ atomic_long_read(&cli->cl_lru_busy));
- cfs_list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
+ list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
if (osc_cache_too_much(cli) > 0) {
spin_unlock(&cache->ccc_lru_lock);
- rc = osc_lru_shrink(env, cli, osc_cache_too_much(cli),
- true);
+ rc = osc_lru_shrink(env, cli, npages, true);
spin_lock(&cache->ccc_lru_lock);
- if (rc != 0)
+ if (rc >= npages)
break;
+ if (rc > 0)
+ npages -= rc;
}
}
spin_unlock(&cache->ccc_lru_lock);
out:
- cl_env_nested_put(&nest, env);
- CDEBUG(D_CACHE, "%s: cli %p freed %d pages.\n",
- cli->cl_import->imp_obd->obd_name, cli, rc);
+ cl_env_put(env, &refcheck);
+ CDEBUG(D_CACHE, "%s: cli %p freed %ld pages.\n",
+ cli_name(cli), cli, rc);
return rc;
}
-static int osc_lru_reserve(const struct lu_env *env, struct osc_object *obj,
- struct osc_page *opg)
+/**
+ * osc_lru_alloc() is called to allocate an LRU slot for a cl_page.
+ *
+ * Usually the LRU slots are reserved in osc_io_iter_rw_init().
+ * Only in the case that the LRU slots are in extreme shortage, it should
+ * have reserved enough slots for an IO.
+ */
+static int osc_lru_alloc(const struct lu_env *env, struct client_obd *cli,
+ struct osc_page *opg)
{
struct l_wait_info lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
struct osc_io *oio = osc_env_io(env);
- struct client_obd *cli = osc_cli(obj);
int rc = 0;
+
ENTRY;
if (cli->cl_cache == NULL) /* shall not be in LRU */
goto out;
}
- LASSERT(atomic_read(cli->cl_lru_left) >= 0);
- while (!atomic_add_unless(cli->cl_lru_left, -1, 0)) {
-
+ LASSERT(atomic_long_read(cli->cl_lru_left) >= 0);
+ while (!atomic_long_add_unless(cli->cl_lru_left, -1, 0)) {
/* run out of LRU spaces, try to drop some by itself */
- rc = osc_lru_reclaim(cli);
+ rc = osc_lru_reclaim(cli, 1);
if (rc < 0)
break;
if (rc > 0)
cond_resched();
rc = l_wait_event(osc_lru_waitq,
- atomic_read(cli->cl_lru_left) > 0,
+ atomic_long_read(cli->cl_lru_left) > 0,
&lwi);
if (rc < 0)
break;
out:
if (rc >= 0) {
- atomic_inc(&cli->cl_lru_busy);
+ atomic_long_inc(&cli->cl_lru_busy);
opg->ops_in_lru = 1;
rc = 0;
}
RETURN(rc);
}
+/**
+ * osc_lru_reserve() is called to reserve enough LRU slots for I/O.
+ *
+ * The benefit of doing this is to reduce contention against atomic counter
+ * cl_lru_left by changing it from per-page access to per-IO access.
+ */
+unsigned long osc_lru_reserve(struct client_obd *cli, unsigned long npages)
+{
+ unsigned long reserved = 0;
+ unsigned long max_pages;
+ unsigned long c;
+
+ /* reserve a full RPC window at most to avoid that a thread accidentally
+ * consumes too many LRU slots */
+ max_pages = cli->cl_max_pages_per_rpc * cli->cl_max_rpcs_in_flight;
+ if (npages > max_pages)
+ npages = max_pages;
+
+ c = atomic_long_read(cli->cl_lru_left);
+ if (c < npages && osc_lru_reclaim(cli, npages) > 0)
+ c = atomic_long_read(cli->cl_lru_left);
+ while (c >= npages) {
+ if (c == atomic_long_cmpxchg(cli->cl_lru_left, c, c - npages)) {
+ reserved = npages;
+ break;
+ }
+ c = atomic_long_read(cli->cl_lru_left);
+ }
+ if (atomic_long_read(cli->cl_lru_left) < max_pages) {
+ /* If there aren't enough pages in the per-OSC LRU then
+ * wake up the LRU thread to try and clear out space, so
+ * we don't block if pages are being dirtied quickly. */
+ CDEBUG(D_CACHE, "%s: queue LRU, left: %lu/%ld.\n",
+ cli_name(cli), atomic_long_read(cli->cl_lru_left),
+ max_pages);
+ (void)ptlrpcd_queue_work(cli->cl_lru_work);
+ }
+
+ return reserved;
+}
+
+/**
+ * osc_lru_unreserve() is called to unreserve LRU slots.
+ *
+ * LRU slots reserved by osc_lru_reserve() may have entries left due to several
+ * reasons such as page already existing or I/O error. Those reserved slots
+ * should be freed by calling this function.
+ */
+void osc_lru_unreserve(struct client_obd *cli, unsigned long npages)
+{
+ atomic_long_add(npages, cli->cl_lru_left);
+ wake_up_all(&osc_lru_waitq);
+}
+
+/**
+ * Atomic operations are expensive. We accumulate the accounting for the
+ * same page zone to get better performance.
+ * In practice this can work pretty good because the pages in the same RPC
+ * are likely from the same page zone.
+ */
+static inline void unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
+ struct osc_brw_async_args *aa,
+ int factor)
+{
+ int page_count;
+ void *zone = NULL;
+ int count = 0;
+ int i;
+
+ if (desc != NULL) {
+ LASSERT(ptlrpc_is_bulk_desc_kiov(desc->bd_type));
+ page_count = desc->bd_iov_count;
+ } else {
+ page_count = aa->aa_page_count;
+ }
+
+ for (i = 0; i < page_count; i++) {
+ void *pz;
+ if (desc)
+ pz = page_zone(BD_GET_KIOV(desc, i).kiov_page);
+ else
+ pz = page_zone(aa->aa_ppga[i]->pg);
+
+ if (likely(pz == zone)) {
+ ++count;
+ continue;
+ }
+
+ if (count > 0) {
+ mod_zone_page_state(zone, NR_UNSTABLE_NFS,
+ factor * count);
+ count = 0;
+ }
+ zone = pz;
+ ++count;
+ }
+ if (count > 0)
+ mod_zone_page_state(zone, NR_UNSTABLE_NFS, factor * count);
+}
+
+static inline void add_unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
+ struct osc_brw_async_args *aa)
+{
+ unstable_page_accounting(desc, aa, 1);
+}
+
+static inline void dec_unstable_page_accounting(struct ptlrpc_bulk_desc *desc,
+ struct osc_brw_async_args *aa)
+{
+ unstable_page_accounting(desc, aa, -1);
+}
+
+/**
+ * Performs "unstable" page accounting. This function balances the
+ * increment operations performed in osc_inc_unstable_pages. It is
+ * registered as the RPC request callback, and is executed when the
+ * bulk RPC is committed on the server. Thus at this point, the pages
+ * involved in the bulk transfer are no longer considered unstable.
+ *
+ * If this function is called, the request should have been committed
+ * or req:rq_unstable must have been set; it implies that the unstable
+ * statistic have been added.
+ */
+void osc_dec_unstable_pages(struct ptlrpc_request *req)
+{
+ struct ptlrpc_bulk_desc *desc = req->rq_bulk;
+ struct osc_brw_async_args *aa = (void *)&req->rq_async_args;
+ struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
+ int page_count;
+ long unstable_count;
+
+ if (desc)
+ page_count = desc->bd_iov_count;
+ else
+ page_count = aa->aa_page_count;
+
+ LASSERT(page_count >= 0);
+
+ dec_unstable_page_accounting(desc, aa);
+
+ unstable_count = atomic_long_sub_return(page_count,
+ &cli->cl_unstable_count);
+ LASSERT(unstable_count >= 0);
+
+ unstable_count = atomic_long_sub_return(page_count,
+ &cli->cl_cache->ccc_unstable_nr);
+ LASSERT(unstable_count >= 0);
+ if (unstable_count == 0)
+ wake_up_all(&cli->cl_cache->ccc_unstable_waitq);
+
+ if (waitqueue_active(&osc_lru_waitq))
+ (void)ptlrpcd_queue_work(cli->cl_lru_work);
+}
+
+/**
+ * "unstable" page accounting. See: osc_dec_unstable_pages.
+ */
+void osc_inc_unstable_pages(struct ptlrpc_request *req)
+{
+ struct ptlrpc_bulk_desc *desc = req->rq_bulk;
+ struct osc_brw_async_args *aa = (void *)&req->rq_async_args;
+ struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
+ long page_count;
+
+ /* No unstable page tracking */
+ if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
+ return;
+
+ if (desc)
+ page_count = desc->bd_iov_count;
+ else
+ page_count = aa->aa_page_count;
+
+ add_unstable_page_accounting(desc, aa);
+ atomic_long_add(page_count, &cli->cl_unstable_count);
+ atomic_long_add(page_count, &cli->cl_cache->ccc_unstable_nr);
+
+ /* If the request has already been committed (i.e. brw_commit
+ * called via rq_commit_cb), we need to undo the unstable page
+ * increments we just performed because rq_commit_cb wont be
+ * called again. */
+ spin_lock(&req->rq_lock);
+ if (unlikely(req->rq_committed)) {
+ spin_unlock(&req->rq_lock);
+
+ osc_dec_unstable_pages(req);
+ } else {
+ req->rq_unstable = 1;
+ spin_unlock(&req->rq_lock);
+ }
+}
+
+/**
+ * Check if it piggybacks SOFT_SYNC flag to OST from this OSC.
+ * This function will be called by every BRW RPC so it's critical
+ * to make this function fast.
+ */
+bool osc_over_unstable_soft_limit(struct client_obd *cli)
+{
+ long unstable_nr, osc_unstable_count;
+
+ /* Can't check cli->cl_unstable_count, therefore, no soft limit */
+ if (cli->cl_cache == NULL || !cli->cl_cache->ccc_unstable_check)
+ return false;
+
+ osc_unstable_count = atomic_long_read(&cli->cl_unstable_count);
+ unstable_nr = atomic_long_read(&cli->cl_cache->ccc_unstable_nr);
+
+ CDEBUG(D_CACHE,
+ "%s: cli: %p unstable pages: %lu, osc unstable pages: %lu\n",
+ cli_name(cli), cli, unstable_nr, osc_unstable_count);
+
+ /* If the LRU slots are in shortage - 25% remaining AND this OSC
+ * has one full RPC window of unstable pages, it's a good chance
+ * to piggyback a SOFT_SYNC flag.
+ * Please notice that the OST won't take immediate response for the
+ * SOFT_SYNC request so active OSCs will have more chance to carry
+ * the flag, this is reasonable. */
+ return unstable_nr > cli->cl_cache->ccc_lru_max >> 2 &&
+ osc_unstable_count > cli->cl_max_pages_per_rpc *
+ cli->cl_max_rpcs_in_flight;
+}
+
+/**
+ * Return how many LRU pages in the cache of all OSC devices
+ *
+ * \retval return # of cached LRU pages times reclaimation tendency
+ * \retval SHRINK_STOP if it cannot do any scanning in this time
+ */
+unsigned long osc_cache_shrink_count(struct shrinker *sk,
+ struct shrink_control *sc)
+{
+ struct client_obd *cli;
+ unsigned long cached = 0;
+
+ spin_lock(&osc_shrink_lock);
+ list_for_each_entry(cli, &osc_shrink_list, cl_shrink_list)
+ cached += atomic_long_read(&cli->cl_lru_in_list);
+ spin_unlock(&osc_shrink_lock);
+
+ return (cached * sysctl_vfs_cache_pressure) / 100;
+}
+
+/**
+ * Scan and try to reclaim sc->nr_to_scan cached LRU pages
+ *
+ * \retval number of cached LRU pages reclaimed
+ * \retval SHRINK_STOP if it cannot do any scanning in this time
+ *
+ * Linux kernel will loop calling this shrinker scan routine with
+ * sc->nr_to_scan = SHRINK_BATCH(128 for now) until kernel got enough memory.
+ *
+ * If sc->nr_to_scan is 0, the VM is querying the cache size, we don't need
+ * to scan and try to reclaim LRU pages, just return 0 and
+ * osc_cache_shrink_count() will report the LRU page number.
+ */
+unsigned long osc_cache_shrink_scan(struct shrinker *sk,
+ struct shrink_control *sc)
+{
+ struct client_obd *cli;
+ struct client_obd *stop_anchor = NULL;
+ struct lu_env *env;
+ long shrank = 0;
+ int rc;
+ __u16 refcheck;
+
+ if (sc->nr_to_scan == 0)
+ return 0;
+
+ if (!(sc->gfp_mask & __GFP_FS))
+ return SHRINK_STOP;
+
+ env = cl_env_get(&refcheck);
+ if (IS_ERR(env))
+ return SHRINK_STOP;
+
+ spin_lock(&osc_shrink_lock);
+ while (!list_empty(&osc_shrink_list)) {
+ cli = list_entry(osc_shrink_list.next, struct client_obd,
+ cl_shrink_list);
+
+ if (stop_anchor == NULL)
+ stop_anchor = cli;
+ else if (cli == stop_anchor)
+ break;
+
+ list_move_tail(&cli->cl_shrink_list, &osc_shrink_list);
+ spin_unlock(&osc_shrink_lock);
+
+ /* shrink no more than max_pages_per_rpc for an OSC */
+ rc = osc_lru_shrink(env, cli, (sc->nr_to_scan - shrank) >
+ cli->cl_max_pages_per_rpc ?
+ cli->cl_max_pages_per_rpc :
+ sc->nr_to_scan - shrank, true);
+ if (rc > 0)
+ shrank += rc;
+
+ if (shrank >= sc->nr_to_scan)
+ goto out;
+
+ spin_lock(&osc_shrink_lock);
+ }
+ spin_unlock(&osc_shrink_lock);
+
+out:
+ cl_env_put(env, &refcheck);
+
+ return shrank;
+}
+
/** @} osc */