[CIFS] Readdir fixes to allow search to start at arbitrary position in directory

Also includes first part of fix to compensate for servers which forget
to return . and .. as well as updates to changelog and cifs readme.

Signed-off-by: Steve French <[e-mail]>

fs/cifs/CHANGES

···
 Version 1.42
 ------------
 Fix slow oplock break when mounted to different servers at the same time and
-the tids match and we try to find matching fid on wrong server.
+the tids match and we try to find matching fid on wrong server. Fix read
+looping when signing required by server (2.6.16 kernel only). Fix readdir
+vs. rename race which could cause each to hang. Return . and .. even
+if server does not.  Allow searches to skip first three entries and
+begin at any location. Fix oops in find_writeable_file.
 
 Version 1.41
 ------------

fs/cifs/README

···
 			support and want to map the uid and gid fields 
 			to values supplied at mount (rather than the 
 			actual values, then set this to zero. (default 1)
+Experimental            When set to 1 used to enable certain experimental
+			features (currently enables multipage writes
+			when signing is enabled, the multipage write
+			performance enhancement was disabled when
+			signing turned on in case buffer was modified
+			just before it was sent, also this flag will
+			be used to use the new experimental sessionsetup
+			code).
 
 These experimental features and tracing can be enabled by changing flags in 
 /proc/fs/cifs (after the cifs module has been installed or built into the 

fs/cifs/cifssmb.c

···
 				psrch_inf->endOfSearch = FALSE;
 
 			psrch_inf->entries_in_buffer  = le16_to_cpu(parms->SearchCount);
-			psrch_inf->index_of_last_entry = 
+			psrch_inf->index_of_last_entry = 2 /* skip . and .. */ +
 				psrch_inf->entries_in_buffer;
 			*pnetfid = parms->SearchHandle;
 		} else {

fs/cifs/connect.c

···
 			pSesInfo->server->secMode,
 			pSesInfo->server->capabilities,
 			pSesInfo->server->timeZone));
-		if (extended_security
+		if(experimEnabled > 1)
+			rc = CIFS_SessSetup(xid, pSesInfo, CIFS_NTLM /* type */,
+					    &ntlmv2_flag, nls_info);	
+		else if (extended_security
 				&& (pSesInfo->capabilities & CAP_EXTENDED_SECURITY)
 				&& (pSesInfo->server->secType == NTLMSSP)) {
 			cFYI(1, ("New style sesssetup"));

fs/cifs/file.c

···
 				if (rc != 0)
 					break;
 			}
-			/* BB FIXME We can not sign across two buffers yet */
-			if((pTcon->ses->server->secMode & 
+			if(experimEnabled || (pTcon->ses->server->secMode & 
 			 (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) == 0) {
 				struct kvec iov[2];
 				unsigned int len;
···
 						*poffset, &bytes_written,
 						iov, 1, long_op);
 			} else
-			/* BB FIXME fixup indentation of line below */
-			rc = CIFSSMBWrite(xid, pTcon,
-				 open_file->netfid,
-				 min_t(const int, cifs_sb->wsize, 
-				       write_size - total_written),
-				 *poffset, &bytes_written,
-				 write_data + total_written, NULL, long_op);
+				rc = CIFSSMBWrite(xid, pTcon,
+					 open_file->netfid,
+					 min_t(const int, cifs_sb->wsize,
+					       write_size - total_written),
+					 *poffset, &bytes_written,
+					 write_data + total_written,
+					 NULL, long_op);
 		}
 		if (rc || (bytes_written == 0)) {
 			if (total_written)
···
 {
 	struct cifsFileInfo *open_file;
 	int rc;
+
+	/* Having a null inode here (because mapping->host was set to zero by
+	the VFS or MM) should not happen but we had reports of on oops (due to
+	it being zero) during stress testcases so we need to check for it */
+
+	if(cifs_inode == NULL) {
+		cERROR(1,("Null inode passed to cifs_writeable_file"));
+		dump_stack();
+		return NULL;
+	}
 
 	read_lock(&GlobalSMBSeslock);
 	list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
···
 	if (cifs_sb->wsize < PAGE_CACHE_SIZE)
 		return generic_writepages(mapping, wbc);
 
-	/* BB FIXME we do not have code to sign across multiple buffers yet,
-	   so go to older writepage style write which we can sign if needed */
 	if((cifs_sb->tcon->ses) && (cifs_sb->tcon->ses->server))
 		if(cifs_sb->tcon->ses->server->secMode &
                           (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED))
-			return generic_writepages(mapping, wbc);
+			if(!experimEnabled)
+				return generic_writepages(mapping, wbc);
 
 	/*
 	 * BB: Is this meaningful for a non-block-device file system?

fs/cifs/ntlmssp.c

···
 	}
 
 
+	/* copy session key */
+
+	/* if Unicode, align strings to two byte boundary */
+
+	/* copy user name */ /* BB Do we need to special case null user name? */
+
+	/* copy domain name */
+
+	/* copy Linux version */
+
+	/* copy network operating system name */
+
+	/* update bcc and smb buffer length */
+
 /*	rc = SendReceive2(xid, ses, iov, num_iovecs, &resp_buf_type, 0); */
 	/* SMB request buf freed in SendReceive2 */
 

fs/cifs/readdir.c

···
 	first_entry_in_buffer = 
 		cifsFile->srch_inf.index_of_last_entry - 
 			cifsFile->srch_inf.entries_in_buffer;
+
+	/* if first entry in buf is zero then is first buffer
+	in search response data which means it is likely . and ..
+	will be in this buffer, although some servers do not return
+	. and .. for the root of a drive and for those we need
+	to start two entries earlier */
+
 /*	dump_cifs_file_struct(file, "In fce ");*/
 	if(((index_to_find < cifsFile->srch_inf.index_of_last_entry) && 
 	     is_dir_changed(file)) || 
···
 		char * end_of_smb = cifsFile->srch_inf.ntwrk_buf_start + 
 			smbCalcSize((struct smb_hdr *)
 				cifsFile->srch_inf.ntwrk_buf_start);
+
+		current_entry = cifsFile->srch_inf.srch_entries_start;
 		first_entry_in_buffer = cifsFile->srch_inf.index_of_last_entry
 					- cifsFile->srch_inf.entries_in_buffer;
 		pos_in_buf = index_to_find - first_entry_in_buffer;
 		cFYI(1,("found entry - pos_in_buf %d",pos_in_buf)); 
-		current_entry = cifsFile->srch_inf.srch_entries_start;
 		for(i=0;(i<(pos_in_buf)) && (current_entry != NULL);i++) {
 			/* go entry by entry figuring out which is first */
-			/* if( . or ..)
-				skip */
-			rc = cifs_entry_is_dot(current_entry,cifsFile);
-			if(rc == 1) /* is . or .. so skip */ {
-				cFYI(1,("Entry is .")); /* BB removeme BB */
-				/* continue; */
-			} else if (rc == 2 ) {
-				cFYI(1,("Entry is ..")); /* BB removeme BB */
-				/* continue; */
-			}
 			current_entry = nxt_dir_entry(current_entry,end_of_smb);
 		}
 		if((current_entry == NULL) && (i < pos_in_buf)) {
···
 
 	if(file->f_dentry == NULL)
 		return -ENOENT;
+
+	rc = cifs_entry_is_dot(pfindEntry,cifsF);
+	/* skip . and .. since we added them first */
+	if(rc != 0) 
+		return 0;
 
 	cifs_sb = CIFS_SB(file->f_dentry->d_sb);
 
···
 
 	switch ((int) file->f_pos) {
 	case 0:
-		/*if (filldir(direntry, ".", 1, file->f_pos,
+		if (filldir(direntry, ".", 1, file->f_pos,
 		     file->f_dentry->d_inode->i_ino, DT_DIR) < 0) {
-			cERROR(1, ("Filldir for current dir failed "));
+			cERROR(1, ("Filldir for current dir failed"));
 			rc = -ENOMEM;
 			break;
 		}
-		file->f_pos++; */
+		file->f_pos++;
 	case 1:
-		/* if (filldir(direntry, "..", 2, file->f_pos,
+		if (filldir(direntry, "..", 2, file->f_pos,
 		     file->f_dentry->d_parent->d_inode->i_ino, DT_DIR) < 0) {
 			cERROR(1, ("Filldir for parent dir failed "));
 			rc = -ENOMEM;
 			break;
 		}
-		file->f_pos++; */
-	case 2:
+		file->f_pos++;
+	default:
 		/* 1) If search is active, 
 			is in current search buffer? 
 			if it before then restart search
···
 				return rc;
 			}
 		}
-	default:
 		if(file->private_data == NULL) {
 			rc = -EINVAL;
 			FreeXid(xid);
···
 		} 
 		kfree(cifsFile->search_resume_name);
 		cifsFile->search_resume_name = NULL; */
-
-		/* BB account for . and .. in f_pos as special case */
 
 		rc = find_cifs_entry(xid,pTcon, file,
 				&current_entry,&num_to_fill);
···
 					  num_to_fill, i));
 				break;
 			}
-
+			/* if buggy server returns . and .. late do
+			we want to check for that here? */
 			rc = cifs_filldir(current_entry, file, 
 					filldir, direntry,tmp_buf);
 			file->f_pos++;