lkml.org 
[lkml]   [2014]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
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@cn.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



\
 
 \ /
  Last update: 2014-03-07 13:01    [W:0.094 / U:0.288 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site