Re: [PATCH 2/4] fs/sysv: Change the signature of dir_get_page()

From: Fabio M. De Francesco
Date: Wed Jan 04 2023 - 08:02:53 EST


On mercoledì 4 gennaio 2023 12:59:24 CET Dan Carpenter wrote:
> Hi Fabio,
>
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url:
> https://github.com/intel-lab-lkp/linux/commits/Fabio-M-De-Francesco/fs-sysv-U
> se-the-offset_in_page-helper/20221231-155850 base:
> git://git.infradead.org/users/hch/configfs.git for-next
> patch link:
> https://lore.kernel.org/r/20221231075717.10258-3-fmdefrancesco%40gmail.com
> patch subject: [PATCH 2/4] fs/sysv: Change the signature of dir_get_page()
> config: xtensa-randconfig-m031-20230101
> compiler: xtensa-linux-gcc (GCC) 12.1.0
>
> If you fix the issue, kindly add following tag where applicable
>
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Reported-by: Dan Carpenter <error27@xxxxxxxxx>
>
> smatch warnings:
> fs/sysv/dir.c:190 sysv_add_link() warn: passing zero to 'PTR_ERR'
>
> vim +/PTR_ERR +190 fs/sysv/dir.c
>
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 174 int
sysv_add_link(struct
> dentry *dentry, struct inode *inode) ^1da177e4c3f41 Linus Torvalds
> 2005-04-16 175 {
> 2b0143b5c986be David Howells 2015-03-17 176 struct inode *dir
=
> d_inode(dentry->d_parent); ^1da177e4c3f41 Linus Torvalds 2005-04-16
> 177 const char * name = dentry->d_name.name; ^1da177e4c3f41 Linus
Torvalds
> 2005-04-16 178 int namelen = dentry->d_name.len;
^1da177e4c3f41
> Linus Torvalds 2005-04-16 179 struct page *page = NULL;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 180 struct
sysv_dir_entry
> * de; ^1da177e4c3f41 Linus Torvalds 2005-04-16 181
unsigned long
> npages = dir_pages(dir); ^1da177e4c3f41 Linus Torvalds 2005-04-16
182
> unsigned long n; ^1da177e4c3f41 Linus Torvalds 2005-04-16
183
> char *kaddr;
> 26a6441aadde86 Nicholas Piggin 2007-10-16 184 loff_t pos;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 185 int err;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 186
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 187 /* We take care
of
> directory expansion in the same loop */ ^1da177e4c3f41 Linus Torvalds
> 2005-04-16 188 for (n = 0; n <= npages; n++) { 4b8a9c0afda16b Fabio M. De
> Francesco 2022-12-31 189 kaddr = dir_get_page(dir, n, &page);
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 @190 err =
PTR_ERR(page);
>
> This "err" assignment is a dead store (pointless/never used).

Hi Dan,

Thanks for catching it.
I'll wait for comments on this series one or two more days and then delete
that assignment.

Again thanks,

Fabio

> 4b8a9c0afda16b Fabio M. De Francesco 2022-12-31 191 if
(IS_ERR(kaddr))
> 4b8a9c0afda16b Fabio M. De Francesco 2022-12-31 192
return
> PTR_ERR(kaddr); ^1da177e4c3f41 Linus Torvalds 2005-04-16 193
de =
> (struct sysv_dir_entry *)kaddr; 09cbfeaf1a5a67 Kirill A. Shutemov
> 2016-04-01 194 kaddr += PAGE_SIZE - SYSV_DIRSIZE;
^1da177e4c3f41 Linus
> Torvalds 2005-04-16 195 while ((char *)de <= kaddr)
{
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 196
if (!de->inode)
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 197
goto got_it;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 198
err = -EEXIST;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 199
if
> (namecompare(namelen, SYSV_NAMELEN, name, de->name)) ^1da177e4c3f41 Linus
> Torvalds 2005-04-16 200 goto
out_page; ^1da177e4c3f41 Linus
> Torvalds 2005-04-16 201 de++;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 202 }
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 203
dir_put_page(page);
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 204 }
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 205 BUG();
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 206 return -EINVAL;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 207
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 208 got_it:
> 1023904333f9cb Fabio M. De Francesco 2022-12-31 209 pos =
page_offset(page)
> + offset_in_page(de); ^1da177e4c3f41 Linus Torvalds 2005-04-16 210
> lock_page(page); f4e420dc423148 Christoph Hellwig 2010-06-04
211 err
> = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE); ^1da177e4c3f41 Linus Torvalds
> 2005-04-16 212 if (err)
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 213 goto
out_unlock;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 214 memcpy (de->name,
name,
> namelen); ^1da177e4c3f41 Linus Torvalds 2005-04-16 215 memset
> (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2); ^1da177e4c3f41 Linus
> Torvalds 2005-04-16 216 de->inode =
> cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); 26a6441aadde86 Nicholas
> Piggin 2007-10-16 217 err = dir_commit_chunk(page, pos,
> SYSV_DIRSIZE); 02027d42c3f747 Deepa Dinamani 2016-09-14 218
> dir->i_mtime = dir->i_ctime = current_time(dir); ^1da177e4c3f41
Linus
> Torvalds 2005-04-16 219 mark_inode_dirty(dir); ^1da177e4c3f41
Linus
> Torvalds 2005-04-16 220 out_page:
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 221
dir_put_page(page);
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 222 return err;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 223 out_unlock:
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 224
unlock_page(page);
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 225 goto out_page;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 226 }
>
> --
> 0-DAY CI Kernel Test Service
> https://01.org/lkp