BKL: Remove BKL from ncpfs

Dozen of changes in ncpfs to provide some locking other than BKL.

In readdir cache unlock and mark complete first page as last operation,
so it can be used for synchronization, as code intended.

When updating dentry name on case insensitive filesystems do at least
some basic locking...

Hold i_mutex when updating inode fields.

Push some ncp_conn_is_valid down to ncp_request.  Connection can become
invalid at any moment, and fewer error code paths to test the better.

Use i_size_{read,write} to modify file size.

Set inode's backing_dev_info as ncpfs has its own special bdi.

In ioctl unbreak ioctls invoked on filesystem mounted 'ro' - tests are
for inode writeable or owner match, but were turned to filesystem
writeable and inode writeable or owner match.  Also collect all permission
checks in single place.

Add some locking, and remove comments saying that it would be cool to
add some locks to the code.

Constify some pointers.

Signed-off-by: Petr Vandrovec <petr@vandrovec.name>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/include/linux/ncp_fs_sb.h b/include/linux/ncp_fs_sb.h
index 8da05bc..d64b0e8 100644
--- a/include/linux/ncp_fs_sb.h
+++ b/include/linux/ncp_fs_sb.h
@@ -62,6 +62,7 @@
 	int ncp_reply_size;
 
 	int root_setuped;
+	struct mutex root_setup_lock;
 
 	/* info for packet signing */
 	int sign_wanted;	/* 1=Server needs signed packets */
@@ -81,13 +82,14 @@
 		size_t	len;
 		void*	data;
 	} priv;
+	struct rw_semaphore auth_rwsem;
 
 	/* nls info: codepage for volume and charset for I/O */
 	struct nls_table *nls_vol;
 	struct nls_table *nls_io;
 
 	/* maximum age in jiffies */
-	int dentry_ttl;
+	atomic_t dentry_ttl;
 
 	/* miscellaneous */
 	unsigned int flags;