Hi Andrew,

Could you please queue the following patch in the -mm tree ?

I hope this will be sent to upstream at the next merge window through
your tree. (probably only this single change).

Thanks,
Ryusuke Konishi
--
From: Ryusuke Konishi <[email protected]>

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 <[email protected]>
---
 fs/nilfs2/file.c  |   24 ++++++++++++++----------
 fs/nilfs2/ioctl.c |    8 +++++++-
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/fs/nilfs2/file.c b/fs/nilfs2/file.c
index 2660152..62cebc8 100644
--- a/fs/nilfs2/file.c
+++ b/fs/nilfs2/file.c
@@ -37,6 +37,7 @@ int nilfs_sync_file(struct file *file, loff_t start, loff_t 
end, int datasync)
         * This function should be implemented when the writeback function
         * will be implemented.
         */
+       struct the_nilfs *nilfs;
        struct inode *inode = file->f_mapping->host;
        int err;
 
@@ -45,18 +46,21 @@ int nilfs_sync_file(struct file *file, loff_t start, loff_t 
end, int datasync)
                return err;
        mutex_lock(&inode->i_mutex);
 
-       if (!nilfs_inode_dirty(inode)) {
-               mutex_unlock(&inode->i_mutex);
-               return 0;
+       if (nilfs_inode_dirty(inode)) {
+               if (datasync)
+                       err = nilfs_construct_dsync_segment(inode->i_sb, inode,
+                                                           0, LLONG_MAX);
+               else
+                       err = nilfs_construct_segment(inode->i_sb);
        }
-
-       if (datasync)
-               err = nilfs_construct_dsync_segment(inode->i_sb, inode, 0,
-                                                   LLONG_MAX);
-       else
-               err = nilfs_construct_segment(inode->i_sb);
-
        mutex_unlock(&inode->i_mutex);
+
+       nilfs = inode->i_sb->s_fs_info;
+       if (!err && nilfs_test_opt(nilfs, BARRIER)) {
+               err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
+               if (err != -EIO)
+                       err = 0;
+       }
        return err;
 }
 
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 2a70fce..06658ca 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);
-- 
1.7.9.3

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