cifs: Deferred close for files

When file is closed, SMB2 close request is not sent to server
immediately and is deferred for acregmax defined interval. When file is
reopened by same process for read or write, the file handle
is reused if an oplock is held.

When client receives a oplock/lease break, file is closed immediately
if reference count is zero, else oplock is downgraded.

Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index c15a90e422be..e63fbd4a6bfe 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -672,6 +672,68 @@ cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
 	spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 }
 
+bool
+cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
+{
+	struct cifs_deferred_close *dclose;
+
+	list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
+		if ((dclose->netfid == cfile->fid.netfid) &&
+			(dclose->persistent_fid == cfile->fid.persistent_fid) &&
+			(dclose->volatile_fid == cfile->fid.volatile_fid)) {
+			*pdclose = dclose;
+			return true;
+		}
+	}
+	return false;
+}
+
+void
+cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
+{
+	bool is_deferred = false;
+	struct cifs_deferred_close *pdclose;
+
+	is_deferred = cifs_is_deferred_close(cfile, &pdclose);
+	if (is_deferred) {
+		kfree(dclose);
+		return;
+	}
+
+	dclose->tlink = cfile->tlink;
+	dclose->netfid = cfile->fid.netfid;
+	dclose->persistent_fid = cfile->fid.persistent_fid;
+	dclose->volatile_fid = cfile->fid.volatile_fid;
+	list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
+}
+
+void
+cifs_del_deferred_close(struct cifsFileInfo *cfile)
+{
+	bool is_deferred = false;
+	struct cifs_deferred_close *dclose;
+
+	is_deferred = cifs_is_deferred_close(cfile, &dclose);
+	if (!is_deferred)
+		return;
+	list_del(&dclose->dlist);
+	kfree(dclose);
+}
+
+void
+cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
+{
+	struct cifsFileInfo *cfile = NULL;
+	struct cifs_deferred_close *dclose;
+
+	list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
+		spin_lock(&cifs_inode->deferred_lock);
+		if (cifs_is_deferred_close(cfile, &dclose))
+			mod_delayed_work(deferredclose_wq, &cfile->deferred, 0);
+		spin_unlock(&cifs_inode->deferred_lock);
+	}
+}
+
 /* parses DFS refferal V3 structure
  * caller is responsible for freeing target_nodes
  * returns: