cifs: flush before set-info if we have writeable handles

commit aa081859b10c5d8b19f5c525c78883a59d73c2b8 upstream.

Servers can defer destaging any data and updating the mtime until close().
This means that if we do a setinfo to modify the mtime while other handles
are open for write the server may overwrite our setinfo timestamps when
if flushes the file on close() of the writeable handle.

To solve this we add an explicit flush when the mtime is about to
be updated.

This fixes "cp -p" to preserve mtime when copying a file onto an SMB2 share.

CC: Stable <stable@vger.kernel.org>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 538fd7d807e476f9998820b2abc93ae7f6a7c127..9e71619ce7bc2584aed2227d386ab683ed52db71 100644 (file)
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -2371,6 +2371,8 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs)
        struct inode *inode = d_inode(direntry);
        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
        struct cifsInodeInfo *cifsInode = CIFS_I(inode);
+       struct cifsFileInfo *wfile;
+       struct cifs_tcon *tcon;
        char *full_path = NULL;
        int rc = -EACCES;
        __u32 dosattr = 0;
@@ -2417,6 +2419,20 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs)
        mapping_set_error(inode->i_mapping, rc);
        rc = 0;
 
+       if (attrs->ia_valid & ATTR_MTIME) {
+               rc = cifs_get_writable_file(cifsInode, false, &wfile);
+               if (!rc) {
+                       tcon = tlink_tcon(wfile->tlink);
+                       rc = tcon->ses->server->ops->flush(xid, tcon, &wfile->fid);
+                       cifsFileInfo_put(wfile);
+                       if (rc)
+                               return rc;
+               } else if (rc != -EBADF)
+                       return rc;
+               else
+                       rc = 0;
+       }
+
        if (attrs->ia_valid & ATTR_SIZE) {
                rc = cifs_set_file_size(inode, attrs, xid, full_path);
                if (rc != 0)