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SubjectRe: [Patch 4/6] Bind Mount Extensions 0.06
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ty den 22.02.2005 Klokka 13:12 (+0100) skreiv Herbert Poetzl:

> diff -NurpP --minimal linux-2.6.11-rc4-bme0.06-bm0.01-at0.01-cc0.01/fs/namei.c linux-2.6.11-rc4-bme0.06-bm0.01-at0.01-cc0.01-co0.01/fs/namei.c
> --- linux-2.6.11-rc4-bme0.06-bm0.01-at0.01-cc0.01/fs/namei.c 2005-02-13 17:16:55 +0100
> +++ linux-2.6.11-rc4-bme0.06-bm0.01-at0.01-cc0.01-co0.01/fs/namei.c 2005-02-19 06:31:50 +0100
> @@ -1168,6 +1168,24 @@ static inline int may_create(struct inod
> return permission(dir,MAY_WRITE | MAY_EXEC, nd);
> }
>
> +static inline int mnt_may_create(struct vfsmount *mnt, struct inode *dir, struct dentry *child) {
> + if (child->d_inode)
> + return -EEXIST;
> + if (IS_DEADDIR(dir))
> + return -ENOENT;
> + if (MNT_IS_RDONLY(mnt))
> + return -EROFS;
> + return 0;
> +}
> +
> +static inline int mnt_may_unlink(struct vfsmount *mnt, struct inode *dir, struct dentry *child) {
> + if (!child->d_inode)
> + return -ENOENT;
> + if (MNT_IS_RDONLY(mnt))
> + return -EROFS;
> + return 0;
> +}

Most of these checks are redundant, since they are already being done
elsewhere in the code.
child->d_inode is, for instance checked in may_delete() and in
may_create.
IS_DEADDIR is also checked in may_create.

> /*
> * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security
> * reasons.
> @@ -1518,23 +1536,28 @@ do_link:
> struct dentry *lookup_create(struct nameidata *nd, int is_dir)
> {
> struct dentry *dentry;
> + int error;
>
> down(&nd->dentry->d_inode->i_sem);
> - dentry = ERR_PTR(-EEXIST);
> + error = -EEXIST;
> if (nd->last_type != LAST_NORM)
> - goto fail;
> + goto out;
> nd->flags &= ~LOOKUP_PARENT;
> dentry = lookup_hash(&nd->last, nd->dentry);
> if (IS_ERR(dentry))
> + goto ret;
> + error = mnt_may_create(nd->mnt, nd->dentry->d_inode, dentry);
> + if (error)
> goto fail;
> + error = -ENOENT;
> if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
> - goto enoent;
> + goto fail;
> +ret:
> return dentry;
> -enoent:
> - dput(dentry);
> - dentry = ERR_PTR(-ENOENT);
> fail:
> - return dentry;
> + dput(dentry);
> +out:
> + return ERR_PTR(error);
> }

What is the value of adding "error"? The current code is more efficient,
and just as readable.

Cheers,
Trond

--
Trond Myklebust <trond.myklebust@fys.uio.no>

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