sysvfs: fix NULL deref. when allocating new inode

A call to sysv_write_inode() in sysv_new_inode() to its new interface that
replaced wait flag with writeback structure.  This was broken by
a9185b41a4f84971b930c519f0c63bd450c4810d ("pass writeback_control to
->write_inode").

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@kernel.org>		[2.6.34.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/sysv/ialloc.c

@@ -25,6 +25,7 @@
 #include <linux/stat.h>
 #include <linux/string.h>
 #include <linux/buffer_head.h>
+#include <linux/writeback.h>
 #include "sysv.h"
 
 /* We don't trust the value of
@@ -139,6 +140,9 @@ struct inode * sysv_new_inode(const struct inode * dir, mode_t mode)
 	struct inode *inode;
 	sysv_ino_t ino;
 	unsigned count;
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_NONE
+	};
 
 	inode = new_inode(sb);
 	if (!inode)
@@ -168,7 +172,7 @@ struct inode * sysv_new_inode(const struct inode * dir, mode_t mode)
 	insert_inode_hash(inode);
 	mark_inode_dirty(inode);
 
-	sysv_write_inode(inode, 0);	/* ensure inode not allocated again */
+	sysv_write_inode(inode, &wbc);	/* ensure inode not allocated again */
 	mark_inode_dirty(inode);	/* cleared by sysv_write_inode() */
 	/* That's it. */
 	unlock_super(sb);