diff -u -r --exclude='*.cmd' --exclude='*.o' --exclude='*.orig' --exclude='*.rej' linux-2.6.21-rc4-git7/fs/reiser4/inode.h linux-2.6.20.4/fs/reiser4/inode.h
--- linux-2.6.21-rc4-git7/fs/reiser4/inode.h	2007-03-23 14:40:53.445156464 +0300
+++ linux-2.6.20.4/fs/reiser4/inode.h	2007-04-06 04:02:40.000000000 +0400
@@ -136,6 +136,17 @@
 		cryptcompress_info_t cryptcompress_info;
 	} file_plugin_data;
 
+ 	/* this semaphore is used to serialize writes of any file plugin,
+	 * and should be invariant during file plugin conversion (which
+	 * is going in the context of ->write()).
+ 	 * inode->i_mutex can not be used for the serialization, because
+ 	 * write_unix_file uses get_user_pages which is to be used under
+ 	 * mm->mmap_sem and because it is required to take mm->mmap_sem before
+ 	 * inode->i_mutex, so inode->i_mutex would have to be up()-ed before
+ 	 * calling to get_user_pages which is unacceptable.
+	 */
+ 	struct mutex mutex_write;
+
 	/* this semaphore is to serialize readers and writers of @pset->file
 	 * when file plugin conversion is enabled
 	 */
diff -u -r --exclude='*.cmd' --exclude='*.o' --exclude='*.orig' --exclude='*.rej' linux-2.6.21-rc4-git7/fs/reiser4/plugin/file/file.c linux-2.6.20.4/fs/reiser4/plugin/file/file.c
--- linux-2.6.21-rc4-git7/fs/reiser4/plugin/file/file.c	2007-03-24 01:14:45.000000000 +0300
+++ linux-2.6.20.4/fs/reiser4/plugin/file/file.c	2007-04-06 04:02:40.000000000 +0400
@@ -1937,6 +1933,7 @@
 
 	uf_info = unix_file_inode_data(inode);
 
+	mutex_lock(&reiser4_inode_data(inode)->mutex_write);
 	get_exclusive_access(uf_info);
 
 	if (!IS_RDONLY(inode) && (vma->vm_flags & (VM_MAYWRITE | VM_SHARED))) {
@@ -1948,6 +1945,7 @@
 		result = find_file_state(inode, uf_info);
 		if (result != 0) {
 			drop_exclusive_access(uf_info);
+			mutex_unlock(&reiser4_inode_data(inode)->mutex_write);
 			reiser4_exit_context(ctx);
 			return result;
 		}
@@ -1963,6 +1961,7 @@
 			result = check_pages_unix_file(file, inode);
 			if (result) {
 				drop_exclusive_access(uf_info);
+				mutex_unlock(&reiser4_inode_data(inode)->mutex_write);
 				reiser4_exit_context(ctx);
 				return result;
 			}
@@ -1977,6 +1976,7 @@
 	result = reiser4_grab_space_force(needed, BA_CAN_COMMIT);
 	if (result) {
 		drop_exclusive_access(uf_info);
+		mutex_unlock(&reiser4_inode_data(inode)->mutex_write);
 		reiser4_exit_context(ctx);
 		return result;
 	}
@@ -1988,6 +1988,7 @@
 	}
 
 	drop_exclusive_access(uf_info);
+	mutex_unlock(&reiser4_inode_data(inode)->mutex_write);
 	reiser4_exit_context(ctx);
 	return result;
 }
@@ -2369,6 +2370,7 @@
 	if (in_reiser4 == 0) {
 		uf_info = unix_file_inode_data(inode);
 
+		mutex_lock(&reiser4_inode_data(inode)->mutex_write);
 		get_exclusive_access(uf_info);
 		if (atomic_read(&file->f_dentry->d_count) == 1 &&
 		    uf_info->container == UF_CONTAINER_EXTENTS &&
@@ -2384,6 +2386,7 @@
 			}
 		}
 		drop_exclusive_access(uf_info);
+		mutex_unlock(&reiser4_inode_data(inode)->mutex_write);
 	} else {
 		/*
 		   we are within reiser4 context already. How latter is
@@ -2678,9 +2681,11 @@
 			return PTR_ERR(ctx);
 
 		uf_info = unix_file_inode_data(dentry->d_inode);
+		mutex_lock(&reiser4_inode_data(dentry->d_inode)->mutex_write);
 		get_exclusive_access(uf_info);
 		result = setattr_truncate(dentry->d_inode, attr);
 		drop_exclusive_access(uf_info);
+		mutex_unlock(&reiser4_inode_data(dentry->d_inode)->mutex_write);
 		context_set_commit_async(ctx);
 		reiser4_exit_context(ctx);
 	} else
diff -u -r --exclude='*.cmd' --exclude='*.o' --exclude='*.orig' --exclude='*.rej' linux-2.6.21-rc4-git7/fs/reiser4/super_ops.c linux-2.6.20.4/fs/reiser4/super_ops.c
--- linux-2.6.21-rc4-git7/fs/reiser4/super_ops.c	2007-03-23 14:40:53.818099768 +0300
+++ linux-2.6.20.4/fs/reiser4/super_ops.c	2007-04-06 04:02:40.000000000 +0400
@@ -44,6 +44,7 @@
 		 * etc. that will be added to our private inode part.
 		 */
 		INIT_LIST_HEAD(get_readdir_list(&info->vfs_inode));
+		mutex_init(&info->p.mutex_write);
 		init_rwsem(&info->p.conv_sem);
 		/* init semaphore which is used during inode loading */
 		loading_init_once(&info->p);
--- original/fs/reiser4/plugin/file/cryptcompress.c	2007-04-06 08:00:28.000000000 +0400
+++ current/fs/reiser4/plugin/file/cryptcompress.c	2007-04-06 10:20:25.000000000 +0400
@@ -2783,7 +2783,7 @@
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 
- 	mutex_lock(&inode->i_mutex);
+ 	mutex_lock(&reiser4_inode_data(inode)->mutex_write);
 
 	result = generic_write_checks(file, &pos, &count, 0);
   	if (unlikely(result != 0))
@@ -2803,7 +2803,7 @@
   	/* update position in a file */
   	*off = pos + result;
  out:
-	mutex_unlock(&inode->i_mutex);
+	mutex_unlock(&reiser4_inode_data(inode)->mutex_write);
 
 	context_set_commit_async(ctx);
 	reiser4_exit_context(ctx);