[sheepdog] [PATCH 3/6] object cache: fix object_cache_lookup()

[Liu Yuan]

From: Liu Yuan <tailai.ly at taobao.com>

one of object_cache_lookup() callers, object_is_cached() can be called in main
thread, then we shouldn't try to sleep at main thread, otherwise we'll meet a
deadlock between threads doing push and main thread.

Signed-off-by: Liu Yuan <tailai.ly at taobao.com>
---
 sheep/object_cache.c |   21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/sheep/object_cache.c b/sheep/object_cache.c
index e986bed..5e709c2 100644
--- a/sheep/object_cache.c
+++ b/sheep/object_cache.c
@@ -648,18 +648,23 @@ static int object_cache_lookup(struct object_cache *oc, uint32_t idx,
 	int fd, ret = SD_RES_SUCCESS, flags = def_open_flags;
 	unsigned data_length;
 
-	if (!create) {
-		pthread_rwlock_wrlock(&oc->lock);
-		if (!object_tree_search(&oc->object_tree, idx))
-			ret = SD_RES_NO_CACHE;
-		pthread_rwlock_unlock(&oc->lock);
-		return ret;
-	}
-
 	strbuf_init(&buf, PATH_MAX);
 	strbuf_addstr(&buf, cache_dir);
 	strbuf_addf(&buf, "/%06"PRIx32"/%08"PRIx32, oc->vid, idx);
 
+	if (!create) {
+		if (access(buf.buf, R_OK | W_OK) < 0) {
+			if (errno != ENOENT) {
+				dprintf("%m\n");
+				ret = SD_RES_EIO;
+			} else {
+				ret = SD_RES_NO_CACHE;
+			}
+			return ret;
+		}
+		return ret;
+	}
+
 	flags |= O_CREAT | O_TRUNC;
 
 	fd = open(buf.buf, flags, def_fmode);
-- 
1.7.10.2