[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 <sfrench@us.ibm.com>

fs/cifs/CHANGES

@@ -1,7 +1,11 @@
 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

@@ -511,6 +511,14 @@ LinuxExtensionsEnabled	If set to one then the client will attempt to
 			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

@@ -3119,7 +3119,7 @@ CIFSFindFirst(const int xid, struct cifsTconInfo *tcon,
 				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

@@ -3447,7 +3447,10 @@ int cifs_setup_session(unsigned int xid, struct cifsSesInfo *pSesInfo,
 			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

@@ -904,8 +904,7 @@ static ssize_t cifs_write(struct file *file, const char *write_data,
 				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;
@@ -921,13 +920,13 @@ static ssize_t cifs_write(struct file *file, const char *write_data,
 						*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)
@@ -966,6 +965,16 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode)
 	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 (open_file->closePend)
@@ -1091,12 +1100,11 @@ static int cifs_writepages(struct address_space *mapping,
 	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

@@ -121,6 +121,20 @@ CIFS_SessSetup(unsigned int xid, struct cifsSesInfo *ses, const int type,
 	}
 
 
+	/* 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

@@ -590,6 +590,13 @@ static int find_cifs_entry(const int xid, struct cifsTconInfo *pTcon,
 	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)) || 
@@ -632,23 +639,14 @@ static int find_cifs_entry(const int xid, struct cifsTconInfo *pTcon,
 		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)) {
@@ -768,6 +766,11 @@ static int cifs_filldir(char *pfindEntry, struct file *file,
 	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);
 
 	qstring.name = scratch_buf;
@@ -896,22 +899,22 @@ int cifs_readdir(struct file *file, void *direntry, filldir_t filldir)
 
 	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
@@ -925,7 +928,6 @@ int cifs_readdir(struct file *file, void *direntry, filldir_t filldir)
 				return rc;
 			}
 		}
-	default:
 		if(file->private_data == NULL) {
 			rc = -EINVAL;
 			FreeXid(xid);
@@ -945,8 +947,6 @@ int cifs_readdir(struct file *file, void *direntry, filldir_t filldir)
 		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);
 		if(rc) {
@@ -975,7 +975,8 @@ int cifs_readdir(struct file *file, void *direntry, filldir_t filldir)
 					  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++;