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Message-ID: <5319A2DB.8040705@cn.fujitsu.com>
Date: Fri, 07 Mar 2014 18:43:39 +0800
From: Gu Zheng <guz.fnst@...fujitsu.com>
To: Kim <jaegeuk.kim@...sung.com>
CC: f2fs <linux-f2fs-devel@...ts.sourceforge.net>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH 5/5] f2fs: add a wait queue to avoid unnecessary, build_free_nid
Previously, when we try to alloc free nid while the build free nid
is going, the allocer will be run into the flow that waiting for
"nm_i->build_lock", see following:
/* We should not use stale free nids created by build_free_nids */
----> if (nm_i->fcnt && !on_build_free_nids(nm_i)) {
f2fs_bug_on(list_empty(&nm_i->free_nid_list));
list_for_each(this, &nm_i->free_nid_list) {
i = list_entry(this, struct free_nid, list);
if (i->state == NID_NEW)
break;
}
f2fs_bug_on(i->state != NID_NEW);
*nid = i->nid;
i->state = NID_ALLOC;
nm_i->fcnt--;
spin_unlock(&nm_i->free_nid_list_lock);
return true;
}
spin_unlock(&nm_i->free_nid_list_lock);
/* Let's scan nat pages and its caches to get free nids */
----> mutex_lock(&nm_i->build_lock);
build_free_nids(sbi);
mutex_unlock(&nm_i->build_lock);
and this will cause another unnecessary building free nid if the current
building free nid job is done.
So here we introduce a wait_queue to avoid this issue.
Signed-off-by: Gu Zheng <guz.fnst@...fujitsu.com>
---
fs/f2fs/f2fs.h | 1 +
fs/f2fs/node.c | 10 +++++++++-
2 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index f845e92..7ae193e 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -256,6 +256,7 @@ struct f2fs_nm_info {
spinlock_t free_nid_list_lock; /* protect free nid list */
unsigned int fcnt; /* the number of free node id */
struct mutex build_lock; /* lock for build free nids */
+ wait_queue_head_t build_wq; /* wait queue for build free nids */
/* for checkpoint */
char *nat_bitmap; /* NAT bitmap pointer */
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 4b7861d..ab44711 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1422,7 +1422,13 @@ retry:
spin_lock(&nm_i->free_nid_list_lock);
/* We should not use stale free nids created by build_free_nids */
- if (nm_i->fcnt && !on_build_free_nids(nm_i)) {
+ if (on_build_free_nids(nm_i)) {
+ spin_unlock(&nm_i->free_nid_list_lock);
+ wait_event(nm_i->build_wq, !on_build_free_nids(nm_i));
+ goto retry;
+ }
+
+ if (nm_i->fcnt) {
f2fs_bug_on(list_empty(&nm_i->free_nid_list));
list_for_each(this, &nm_i->free_nid_list) {
i = list_entry(this, struct free_nid, list);
@@ -1443,6 +1449,7 @@ retry:
mutex_lock(&nm_i->build_lock);
build_free_nids(sbi);
mutex_unlock(&nm_i->build_lock);
+ wake_up_all(&nm_i->build_wq);
goto retry;
}
@@ -1813,6 +1820,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
INIT_LIST_HEAD(&nm_i->dirty_nat_entries);
mutex_init(&nm_i->build_lock);
+ init_waitqueue_head(&nm_i->build_wq);
spin_lock_init(&nm_i->free_nid_list_lock);
rwlock_init(&nm_i->nat_tree_lock);
--
1.7.7
--
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