sysvfs: fix NULL deref. when allocating new inode

sysvfs: fix NULL deref. when allocating new inode

commit 46c23d7f520e315dde86881b38ba92ebdf34ced5 upstream.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>