cifs: take read lock on GlobalSMBSes_lock in is_valid_oplock_break

...rather than a write lock. It doesn't change the list so a read lock
should be sufficient.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index f2d508d..191e622 100644 (file)
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -562,14 +562,14 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv)
                                continue;
 
                        cifs_stats_inc(&tcon->num_oplock_brks);
-                       write_lock(&GlobalSMBSeslock);
+                       read_lock(&GlobalSMBSeslock);
                        list_for_each(tmp2, &tcon->openFileList) {
                                netfile = list_entry(tmp2, struct cifsFileInfo,
                                                     tlist);
                                if (pSMB->Fid != netfile->netfid)
                                        continue;
 
-                               write_unlock(&GlobalSMBSeslock);
+                               read_unlock(&GlobalSMBSeslock);
                                read_unlock(&cifs_tcp_ses_lock);
                                cFYI(1, ("file id match, oplock break"));
                                pCifsInode = CIFS_I(netfile->pInode);
@@ -584,7 +584,7 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv)
 
                                return true;
                        }
-                       write_unlock(&GlobalSMBSeslock);
+                       read_unlock(&GlobalSMBSeslock);
                        read_unlock(&cifs_tcp_ses_lock);
                        cFYI(1, ("No matching file for oplock break"));
                        return true;