update Documentation/filesystems/Locking

The rules for locking in many superblock operations has changed
significantly, so update the documentation for it.  Also correct some
older updates and ommissions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Documentation/filesystems/Locking

@@ -109,27 +109,28 @@ prototypes:
 
 locking rules:
 	All may block.
-			BKL	s_lock	s_umount
-alloc_inode:		no	no	no
-destroy_inode:		no
-dirty_inode:		no				(must not sleep)
-write_inode:		no
-drop_inode:		no				!!!inode_lock!!!
-delete_inode:		no
-put_super:		yes	yes	no
-write_super:		no	yes	read
-sync_fs:		no	no	read
-freeze_fs:		?
-unfreeze_fs:		?
-statfs:			no	no	no
-remount_fs:		yes	yes	maybe		(see below)
-clear_inode:		no
-umount_begin:		yes	no	no
-show_options:		no				(vfsmount->sem)
-quota_read:		no	no	no		(see below)
-quota_write:		no	no	no		(see below)
+	None have BKL
+			s_umount
+alloc_inode:
+destroy_inode:
+dirty_inode:				(must not sleep)
+write_inode:
+drop_inode:				!!!inode_lock!!!
+delete_inode:
+put_super:		write
+write_super:		read
+sync_fs:		read
+freeze_fs:		read
+unfreeze_fs:		read
+statfs:			no
+remount_fs:		maybe		(see below)
+clear_inode:
+umount_begin:		no
+show_options:		no		(namespace_sem)
+quota_read:		no		(see below)
+quota_write:		no		(see below)
 
-->remount_fs() will have the s_umount lock if it's already mounted.
+->remount_fs() will have the s_umount exclusive lock if it's already mounted.
 When called from get_sb_single, it does NOT have the s_umount lock.
 ->quota_read() and ->quota_write() functions are both guaranteed to
 be the only ones operating on the quota file by the quota code (via