[RFC v2 64/83] File operation: open, fsync, flush.

Andiry Xu
2018-03-10T18:21:36Z

NOVA persists file metadata and data before returning to the user space.
Hence, fsync is a no-op if the file is not mmaped.

Signed-off-by: Andiry Xu <jix024@cs.ucsd.edu>
---
fs/nova/file.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)

diff --git a/fs/nova/file.c b/fs/nova/file.c
index ecaf20a..f60fdf3 100644
--- a/fs/nova/file.c
+++ b/fs/nova/file.c
@@ -66,9 +66,59 @@ static loff_t nova_llseek(struct file *file, loff_t offset, int origin)
return offset;
}

+/* This function is called by both msync() and fsync().
+ * TODO: Check if we can avoid calling nova_flush_buffer() for fsync. We use
+ * movnti to write data to files, so we may want to avoid doing unnecessary
+ * nova_flush_buffer() on fsync()
+ */
+static int nova_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+ struct address_space *mapping = file->f_mapping;
+ unsigned long start_pgoff, end_pgoff;
+ int ret = 0;
+ timing_t fsync_time;
+
+ NOVA_START_TIMING(fsync_t, fsync_time);
+
+ if (datasync)
+ NOVA_STATS_ADD(fdatasync, 1);
+
+ /* No need to flush if the file is not mmaped */
+ if (!mapping_mapped(mapping))
+ goto persist;
+
+ start_pgoff = start >> PAGE_SHIFT;
+ end_pgoff = (end + 1) >> PAGE_SHIFT;
+ nova_dbgv("%s: msync pgoff range %lu to %lu\n",
+ __func__, start_pgoff, end_pgoff);
+
+ ret = generic_file_fsync(file, start, end, datasync);
+
+persist:
+ PERSISTENT_BARRIER();
+ NOVA_END_TIMING(fsync_t, fsync_time);
+
+ return ret;
+}
+
+/* This callback is called when a file is closed */
+static int nova_flush(struct file *file, fl_owner_t id)
+{
+ PERSISTENT_BARRIER();
+ return 0;
+}
+
+static int nova_open(struct inode *inode, struct file *filp)
+{
+ return generic_file_open(inode, filp);
+}
+

const struct file_operations nova_dax_file_operations = {
.llseek = nova_llseek,
+ .open = nova_open,
+ .fsync = nova_fsync,
+ .flush = nova_flush,
};

const struct inode_operations nova_file_inode_operations = {
--
2.7.4