cifs: cache FILE_ALL_INFO for the shared root handle

When we open the shared root handle also ask for FILE_ALL_INFORMATION since
we can do this at zero cost as part of a compound.
Cache this information as long as the lease is held and return and serve any
future requests from cache.

This allows us to serve "stat /<mountpoint>" directly from cache and avoid
a network roundtrip.  Since clients often want to do this quite a lot
this improve performance slightly.

As an example: xfstest generic/533 performs 43 stat operations on the root
of the share while it is run. Which are eliminated with this patch.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

1 files changed, 10 insertions, 5 deletions

diff --git a/fs/cifs/smb2inode.c b/fs/cifs/smb2inode.c
index 01a76bccdb8d..b6e07e2eed10 100644
--- a/fs/cifs/smb2inode.c
+++ b/fs/cifs/smb2inode.c
@@ -309,12 +309,17 @@ smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
 		rc = open_shroot(xid, tcon, &fid);
 		if (rc)
 			goto out;
-		rc = SMB2_query_info(xid, tcon, fid.persistent_fid,
-				     fid.volatile_fid, smb2_data);
+
+		if (tcon->crfid.file_all_info_is_valid) {
+			move_smb2_info_to_cifs(data,
+					       &tcon->crfid.file_all_info);
+		} else {
+			rc = SMB2_query_info(xid, tcon, fid.persistent_fid,
+					     fid.volatile_fid, smb2_data);
+			if (!rc)
+				move_smb2_info_to_cifs(data, smb2_data);
+		}
 		close_shroot(&tcon->crfid);
-		if (rc)
-			goto out;
-		move_smb2_info_to_cifs(data, smb2_data);
 		goto out;
 	}