Btrfs devel - May 2010 - [patch 5/11] btrfs: remove unneeded null check in btrfs_rename()

"old_inode" cannot be null here, because we dereference it
unconditionally throughout the function.

Signed-off-by: Dan Carpenter <error27@gmail.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index fa6ccc1..0bc29be 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6487,10 +6487,8 @@ static int btrfs_rename(struct inode *old_dir, struct
dentry *old_dentry,
 	 * make sure the inode gets flushed if it is replacing
 	 * something.
 	 */
-	if (new_inode && new_inode->i_size &&
-	    old_inode && S_ISREG(old_inode->i_mode)) {
+	if (new_inode && new_inode->i_size &&
S_ISREG(old_inode->i_mode))
 		btrfs_add_ordered_operation(trans, root, old_inode);
-	}
 
 	old_dir->i_ctime = old_dir->i_mtime = ctime;
 	new_dir->i_ctime = new_dir->i_mtime = ctime;
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On Sat, May 29, 2010 at 2:45 AM, Dan Carpenter <error27@gmail.com>
wrote:
> "old_inode" cannot be null here, because we dereference it
> unconditionally throughout the function.
>
> Signed-off-by: Dan Carpenter <error27@gmail.com>
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index fa6ccc1..0bc29be 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -6487,10 +6487,8 @@ static int btrfs_rename(struct inode *old_dir,
struct dentry *old_dentry,
>         * make sure the inode gets flushed if it is replacing
>         * something.
>         */
> -       if (new_inode && new_inode->i_size &&
> -           old_inode && S_ISREG(old_inode->i_mode)) {
> +       if (new_inode && new_inode->i_size &&
S_ISREG(old_inode->i_mode))
>                btrfs_add_ordered_operation(trans, root, old_inode);
> -       }
I think code like this is here because there are still a lot of
features that are being added to btrfs and it''s easier to have the
additional checks than continually adding and removing them as the
code changes.
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On Sat, May 29, 2010 at 11:01:56AM -0700, Mike Fedyk wrote:
> I think code like this is here because there are still a lot of
> features that are being added to btrfs and it''s easier to have the
> additional checks than continually adding and removing them as the
> code changes.
_What_ features?  Check for ->rename() argument not being negative is
done outside of btrfs.
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On Sat, May 29, 2010 at 11:01:56AM -0700, Mike Fedyk
wrote:
> On Sat, May 29, 2010 at 2:45 AM, Dan Carpenter <error27@gmail.com>
wrote:
> > "old_inode" cannot be null here, because we dereference it
> > unconditionally throughout the function.
> >
> > Signed-off-by: Dan Carpenter <error27@gmail.com>
> >
> > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> > index fa6ccc1..0bc29be 100644
> > --- a/fs/btrfs/inode.c
> > +++ b/fs/btrfs/inode.c
> > @@ -6487,10 +6487,8 @@ static int btrfs_rename(struct inode *old_dir,
struct dentry *old_dentry,
> >         * make sure the inode gets flushed if it is replacing
> >         * something.
> >         */
> > -       if (new_inode && new_inode->i_size &&
> > -           old_inode && S_ISREG(old_inode->i_mode)) {
> > +       if (new_inode && new_inode->i_size &&
S_ISREG(old_inode->i_mode))
> >                btrfs_add_ordered_operation(trans, root, old_inode);
> > -       }
> 
> I think code like this is here because there are still a lot of
> features that are being added to btrfs and it''s easier to have the
> additional checks than continually adding and removing them as the
> code changes.
Right right.  I understand about extra checks and api changes.  But in
this case that doesn''t aply.  There is no way this particular check
helps
now or in the future, and it just wastes time when someone is auditing
for inconsistent null checking.

regards,
dan carpenter
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