On Thu, Jun 13, 2024 at 04:55:30PM +0300, Dan Carpenter wrote:
> Hello David Howells,
>
> Commit 74e797d79cf1 ("mm: Provide a means of invalidation without
> using launder_folio") from Mar 27, 2024 (linux-next), leads to the
> following Smatch static checker warning:
>
> mm/filemap.c:4229 filemap_invalidate_inode()
> error: we previously assumed 'mapping' could be null (see line 4200)
I think David has been overly cautious here. I don't think i_mapping
can ever be NULL. inode_init_always() sets i_mapping to be
&inode->i_data and I don't see anywhere that changes i_mapping to be
NULL.
> mm/filemap.c
> 4192 int filemap_invalidate_inode(struct inode *inode, bool flush,
> 4193 loff_t start, loff_t end)
> 4194 {
> 4195 struct address_space *mapping = inode->i_mapping;
> 4196 pgoff_t first = start >> PAGE_SHIFT;
> 4197 pgoff_t last = end >> PAGE_SHIFT;
> 4198 pgoff_t nr = end == LLONG_MAX ? ULONG_MAX : last - first + 1;
> 4199
> 4200 if (!mapping || !mapping->nrpages || end < start)
> ^^^^^^^^
> If mapping is NULL
