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authorChao Yu <chao2.yu@samsung.com>2016-02-19 18:12:28 +0800
committerJaegeuk Kim <jaegeuk@kernel.org>2016-02-22 21:39:55 -0800
commit1515aef0130845c6a5c72a3710df362f79eb9fb1 (patch)
tree5c5959c4643df4505b1fd53069a06360feba533c /fs/f2fs
parentb7ad7512b84b26f1c0ec823647a387627c138d32 (diff)
downloadlinux-1515aef0130845c6a5c72a3710df362f79eb9fb1.tar.bz2
f2fs: reorder nat cache lock in cache_nat_entry
When lookuping nat entry in cache_nat_entry, if we fail to hit nat cache, we try to load nat entries a) from journal of current segment cache or b) from NAT pages for updating, during the process, write lock of nat_tree_lock will be held to avoid inconsistent condition in between nid cache and nat cache caused by racing among nat entry shrinker, checkpointer, nat entry updater. But this way may cause low efficient when updating nat cache, because it serializes accessing in journal cache or reading NAT pages. Here, we reorder lock and update flow as below to enhance accessing concurrency: - get_node_info - down_read(nat_tree_lock) - lookup nat cache --- hit -> unlock & return - lookup journal cache --- hit -> unlock & goto update - up_read(nat_tree_lock) update: - down_write(nat_tree_lock) - cache_nat_entry - lookup nat cache --- nohit -> update - up_write(nat_tree_lock) Signed-off-by: Chao Yu <chao2.yu@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs')
-rw-r--r--fs/f2fs/node.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 94b8016db04e..966176b4027a 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -257,15 +257,20 @@ static struct nat_entry *grab_nat_entry(struct f2fs_nm_info *nm_i, nid_t nid)
return new;
}
-static void cache_nat_entry(struct f2fs_nm_info *nm_i, nid_t nid,
+static void cache_nat_entry(struct f2fs_sb_info *sbi, nid_t nid,
struct f2fs_nat_entry *ne)
{
+ struct f2fs_nm_info *nm_i = NM_I(sbi);
struct nat_entry *e;
e = __lookup_nat_cache(nm_i, nid);
if (!e) {
e = grab_nat_entry(nm_i, nid);
node_info_from_raw_nat(&e->ni, ne);
+ } else {
+ f2fs_bug_on(sbi, nat_get_ino(e) != ne->ino ||
+ nat_get_blkaddr(e) != ne->block_addr ||
+ nat_get_version(e) != ne->version);
}
}
@@ -371,15 +376,12 @@ void get_node_info(struct f2fs_sb_info *sbi, nid_t nid, struct node_info *ni)
ni->ino = nat_get_ino(e);
ni->blk_addr = nat_get_blkaddr(e);
ni->version = nat_get_version(e);
- }
- up_read(&nm_i->nat_tree_lock);
- if (e)
+ up_read(&nm_i->nat_tree_lock);
return;
+ }
memset(&ne, 0, sizeof(struct f2fs_nat_entry));
- down_write(&nm_i->nat_tree_lock);
-
/* Check current segment summary */
down_read(&curseg->journal_rwsem);
i = lookup_journal_in_cursum(journal, NAT_JOURNAL, nid, 0);
@@ -398,8 +400,10 @@ void get_node_info(struct f2fs_sb_info *sbi, nid_t nid, struct node_info *ni)
node_info_from_raw_nat(ni, &ne);
f2fs_put_page(page, 1);
cache:
+ up_read(&nm_i->nat_tree_lock);
/* cache nat entry */
- cache_nat_entry(NM_I(sbi), nid, &ne);
+ down_write(&nm_i->nat_tree_lock);
+ cache_nat_entry(sbi, nid, &ne);
up_write(&nm_i->nat_tree_lock);
}