On Thu, Aug 10, 2023 at 07:25:02PM +0800, Zhang Yi wrote:
> On 2023/8/10 18:31, Dan Carpenter wrote:
> > Hello Zhang Yi,
> >
> > The patch 6493792d3299: "ext4: convert symlink external data block
> > mapping to bdev" from Apr 24, 2022 (linux-next), leads to the
> > following Smatch static checker warning:
> >
> > fs/ext4/namei.c:3353 ext4_init_symlink_block()
> > error: potential NULL/IS_ERR bug 'bh'
> >
> > fs/ext4/namei.c
> > 3337 static int ext4_init_symlink_block(handle_t *handle, struct inode *inode,
> > 3338 struct fscrypt_str *disk_link)
> > 3339 {
> > 3340 struct buffer_head *bh;
> > 3341 char *kaddr;
> > 3342 int err = 0;
> > 3343
> > 3344 bh = ext4_bread(handle, inode, 0, EXT4_GET_BLOCKS_CREATE);
> > 3345 if (IS_ERR(bh))
> > 3346 return PTR_ERR(bh);
> >
> >>From reading the code, it looks like ext4_bread() can return both error
> > pointers and NULL. (Second return statement).
>
> Hello, Dan,
>
> After checking the code, we have passed in EXT4_GET_BLOCKS_CREATE to
> ext4_bread(), the return value must be an error code or a valid
> buffer_head, it's impossible to return NULL. So I think the warning
> is a false positive.
>
Yep. You're right. Thanks for taking a look at this.
Eventually, I will get around to tracking bits set across function
boundaries and that should silence this warning.
regards,
dan carpenter
