cifs: use a refcount to protect open/closing the cached file handle

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

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 8826bc0a9b15d03154d74ab11fc507c74c84b5c6..0e6fd5fa4eb66efc1cc3e073a6166d49140bd951 100644 (file)
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -907,6 +907,7 @@ cap_unix(struct cifs_ses *ses)
 
 struct cached_fid {
        bool is_valid:1;        /* Do we have a useable root fid */
+       struct kref refcount;
        struct cifs_fid *fid;
        struct mutex fid_mutex;
        struct cifs_tcon *tcon;

diff --git a/fs/cifs/smb2inode.c b/fs/cifs/smb2inode.c
index d01ad706d7fc9a4db4f60e1e7e60ad9c7ba757ce..f22cbc0d1869ee28db90c291498d4e257b743f48 100644 (file)
--- a/fs/cifs/smb2inode.c
+++ b/fs/cifs/smb2inode.c
@@ -120,7 +120,9 @@ smb2_open_op_close(const unsigned int xid, struct cifs_tcon *tcon,
                break;
        }
 
-       if (use_cached_root_handle == false)
+       if (use_cached_root_handle)
+               close_shroot(&tcon->crfid);
+       else
                rc = SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
        if (tmprc)
                rc = tmprc;

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 314556c083f320c5e1c0422e4c09bb3ed053ae30..8929426ddaa67fc43b8da2132217e1953181a73a 100644 (file)
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -470,21 +470,36 @@ SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon)
        return rc;
 }
 
-void
-smb2_cached_lease_break(struct work_struct *work)
+static void
+smb2_close_cached_fid(struct kref *ref)
 {
-       struct cached_fid *cfid = container_of(work,
-                               struct cached_fid, lease_break);
-       mutex_lock(&cfid->fid_mutex);
+       struct cached_fid *cfid = container_of(ref, struct cached_fid,
+                                              refcount);
+
        if (cfid->is_valid) {
                cifs_dbg(FYI, "clear cached root file handle\n");
                SMB2_close(0, cfid->tcon, cfid->fid->persistent_fid,
                           cfid->fid->volatile_fid);
                cfid->is_valid = false;
        }
+}
+
+void close_shroot(struct cached_fid *cfid)
+{
+       mutex_lock(&cfid->fid_mutex);
+       kref_put(&cfid->refcount, smb2_close_cached_fid);
        mutex_unlock(&cfid->fid_mutex);
 }
 
+void
+smb2_cached_lease_break(struct work_struct *work)
+{
+       struct cached_fid *cfid = container_of(work,
+                               struct cached_fid, lease_break);
+
+       close_shroot(cfid);
+}
+
 /*
  * Open the directory at the root of a share
  */
@@ -499,6 +514,7 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
        if (tcon->crfid.is_valid) {
                cifs_dbg(FYI, "found a cached root file handle\n");
                memcpy(pfid, tcon->crfid.fid, sizeof(struct cifs_fid));
+               kref_get(&tcon->crfid.refcount);
                mutex_unlock(&tcon->crfid.fid_mutex);
                return 0;
        }
@@ -515,6 +531,8 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
                memcpy(tcon->crfid.fid, pfid, sizeof(struct cifs_fid));
                tcon->crfid.tcon = tcon;
                tcon->crfid.is_valid = true;
+               kref_init(&tcon->crfid.refcount);
+               kref_get(&tcon->crfid.refcount);
        }
        mutex_unlock(&tcon->crfid.fid_mutex);
        return rc;
@@ -558,6 +576,9 @@ smb3_qfs_tcon(const unsigned int xid, struct cifs_tcon *tcon)
                        FS_SECTOR_SIZE_INFORMATION); /* SMB3 specific */
        if (no_cached_open)
                SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
+       else
+               close_shroot(&tcon->crfid);
+
        return;
 }
 

diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
index 98d9b30c16a67ed5ec9a12b71b8b92a4f4675510..19aa483395c7e5d152df8b163099c9adf9ac2cd6 100644 (file)
--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -68,6 +68,7 @@ extern int smb3_handle_read_data(struct TCP_Server_Info *server,
 
 extern int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
                        struct cifs_fid *pfid);
+extern void close_shroot(struct cached_fid *cfid);
 extern void move_smb2_info_to_cifs(FILE_ALL_INFO *dst,
                                   struct smb2_file_all_info *src);
 extern int smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,