Btrfs: fix filemap_flush call in btrfs_file_release

We should only be flushing on close if the file was flagged as needing
it during truncate.  I broke this with my ordered data vs transaction
commit deadlock fix.

Thanks to Miao Xie for catching this.

Signed-off-by: Chris Mason <clm@fb.com>
Reported-by: Miao Xie <miaox@cn.fujitsu.com>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index f15c13f97018..36861b7a6757 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1840,7 +1840,15 @@ int btrfs_release_file(struct inode *inode, struct file *filp)
 {
         if (filp->private_data)
                 btrfs_ioctl_trans_end(filp);
-        filemap_flush(inode->i_mapping);
+        /*
+         * ordered_data_close is set by settattr when we are about to truncate
+         * a file from a non-zero size to a zero size.  This tries to
+         * flush down new bytes that may have been written if the
+         * application were using truncate to replace a file in place.
+         */
+        if (test_and_clear_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
+                               &BTRFS_I(inode)->runtime_flags))
+                        filemap_flush(inode->i_mapping);
         return 0;
 }