nilfs2: flush disk caches in syncing

There are two cases that the cache flush is needed to avoid data loss
against unexpected hang or power failure.  One is sync file function (i.e.
 nilfs_sync_file) and another is checkpointing ioctl.

This issues a cache flush request to device for such cases if barrier
mount option is enabled, and makes sure data really is on persistent
storage on their completion.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 2a70fce70c65..06658caa18bd 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -692,8 +692,14 @@ static int nilfs_ioctl_sync(struct inode *inode, struct file *filp,
         if (ret < 0)
                 return ret;
 
+        nilfs = inode->i_sb->s_fs_info;
+        if (nilfs_test_opt(nilfs, BARRIER)) {
+                ret = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
+                if (ret == -EIO)
+                        return ret;
+        }
+
         if (argp != NULL) {
-                nilfs = inode->i_sb->s_fs_info;
                 down_read(&nilfs->ns_segctor_sem);
                 cno = nilfs->ns_cno - 1;
                 up_read(&nilfs->ns_segctor_sem);