NFS: Writeback optimisation
Schedule writes using WB_SYNC_NONE first, then come back for a second pass
using WB_SYNC_ALL.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 75adb8e..b3c5f5d 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1325,21 +1325,14 @@
return ret;
}
-static int nfs_write_mapping(struct address_space *mapping, int how)
+static int __nfs_write_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
{
- struct writeback_control wbc = {
- .bdi = mapping->backing_dev_info,
- .sync_mode = WB_SYNC_ALL,
- .nr_to_write = LONG_MAX,
- .for_writepages = 1,
- .range_cyclic = 1,
- };
int ret;
- ret = nfs_writepages(mapping, &wbc);
+ ret = nfs_writepages(mapping, wbc);
if (ret < 0)
goto out;
- ret = nfs_sync_mapping_wait(mapping, &wbc, how);
+ ret = nfs_sync_mapping_wait(mapping, wbc, how);
if (ret < 0)
goto out;
return 0;
@@ -1348,6 +1341,25 @@
return ret;
}
+/* Two pass sync: first using WB_SYNC_NONE, then WB_SYNC_ALL */
+static int nfs_write_mapping(struct address_space *mapping, int how)
+{
+ struct writeback_control wbc = {
+ .bdi = mapping->backing_dev_info,
+ .sync_mode = WB_SYNC_NONE,
+ .nr_to_write = LONG_MAX,
+ .for_writepages = 1,
+ .range_cyclic = 1,
+ };
+ int ret;
+
+ ret = __nfs_write_mapping(mapping, &wbc, how);
+ if (ret < 0)
+ return ret;
+ wbc.sync_mode = WB_SYNC_ALL;
+ return __nfs_write_mapping(mapping, &wbc, how);
+}
+
/*
* flush the inode to disk.
*/
