[Sheepdog] [PATCH] store: use O_DIRECT IO for backend store

[Liu Yuan]

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

Backend store don't need page cache, by this way we make room of memory for
object cache to maximize its performance.

Signed-off-by: Liu Yuan <tailai.ly at taobao.com>
---
 sheep/farm/farm.c    |    9 ++++++---
 sheep/simple_store.c |    6 +++---
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/sheep/farm/farm.c b/sheep/farm/farm.c
index fa008ea..7a9e9e5 100644
--- a/sheep/farm/farm.c
+++ b/sheep/farm/farm.c
@@ -20,7 +20,7 @@
 char farm_obj_dir[PATH_MAX];
 char farm_dir[PATH_MAX];
 
-static int def_open_flags = O_DSYNC | O_RDWR;
+static int def_open_flags = O_DIRECT | O_DSYNC | O_RDWR;
 extern char *obj_path;
 extern mode_t def_fmode;
 extern mode_t def_dmode;
@@ -153,8 +153,8 @@ static int farm_open(uint64_t oid, struct siocb *iocb, int create)
 	if (iocb->epoch < sys->epoch)
 		goto out;
 
-	if (sys->use_directio && is_data_obj(oid))
-		flags |= O_DIRECT;
+	if (is_vdi_obj(oid))
+		flags &= ~O_DIRECT;
 
 	if (create)
 		flags |= O_CREAT | O_TRUNC;
@@ -397,6 +397,9 @@ static int farm_atomic_put(uint64_t oid, struct siocb *iocb)
 	snprintf(path, sizeof(path), "%s%016" PRIx64, obj_path, oid);
 	snprintf(tmp_path, sizeof(tmp_path), "%s%016" PRIx64 ".tmp",
 		 obj_path, oid);
+
+	if (is_vdi_obj(oid))
+		flags &= ~O_DIRECT;
 	fd = open(tmp_path, flags, def_fmode);
 	if (fd < 0) {
 		eprintf("failed to open %s: %m\n", tmp_path);
diff --git a/sheep/simple_store.c b/sheep/simple_store.c
index dd3c62d..f1077f7 100644
--- a/sheep/simple_store.c
+++ b/sheep/simple_store.c
@@ -30,7 +30,7 @@ extern char *obj_path;
 
 extern mode_t def_fmode;
 
-static int def_store_flags = O_DSYNC | O_RDWR;
+static int def_store_flags = O_DIRECT | O_DSYNC | O_RDWR;
 
 static int simple_store_write(uint64_t oid, struct siocb *iocb);
 
@@ -108,8 +108,8 @@ static int simple_store_open(uint64_t oid, struct siocb *iocb, int create)
 	int ret;
 	int flags = def_store_flags;
 
-	if (sys->use_directio && is_data_obj(oid))
-		flags |= O_DIRECT;
+	if (is_vdi_obj(oid))
+		flags &= ~O_DIRECT;
 
 	if (create)
 		flags |= O_CREAT | O_TRUNC;
-- 
1.7.8.2