[PATCH] Revert UDF inode semaphore locking

For some reason I don't understand, the last UDF filesystem update makes
the UDF deadlock when I write a bunch of mp3 files to a CDRW using the
packet writing patch.  Both "cp" and pdflush get stuck in __down. 

Reverting the semaphore changes makes the problem go away.  Use the
kernel lock again, until whatever recursive offender gets fixed.

(The offensive recursion seems to be: write() takes the inode semaphore,
causes memory pressure, and then trying to write back the inode or dirty
data to disk tries to get the semaphore again and deadlocks.)

fs/udf/file.c

@@ -247,9 +247,9 @@ static int udf_release_file(struct inode * inode, struct file * filp)
 {
 	if (filp->f_mode & FMODE_WRITE)
 	{
-		down(&inode->i_sem);
+		lock_kernel();
 		udf_discard_prealloc(inode);
-		up(&inode->i_sem);
+		unlock_kernel();
 	}
 	return 0;
 }

fs/udf/inode.c

@@ -84,9 +84,9 @@ void udf_put_inode(struct inode * inode)
 {
 	if (!(inode->i_sb->s_flags & MS_RDONLY))
 	{
-		down(&inode->i_sem);
+		lock_kernel();
 		udf_discard_prealloc(inode);
-		up(&inode->i_sem);
+		unlock_kernel();
 	}
 }