Messages in this thread | | | Date | Wed, 20 Apr 2016 04:25:42 +0100 | From | Al Viro <> | Subject | Re: [PATCH] devpts: Make each mount of devpts an independent filesystem. |
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On Tue, Apr 19, 2016 at 10:04:20PM -0500, Eric W. Biederman wrote: > +#ifdef CONFIG_UNIX98_PTYS > +int path_pts(struct path *path) > +{ > + /* Find "pts" in the same directory as the input path */ > + struct dentry *child, *parent; > + struct qstr this; > + int ret; > + > + ret = path_parent_directory(path); > + if (ret) > + return ret; > + > + parent = path->dentry; > + if (!d_can_lookup(parent)) > + return -ENOENT;
And how, pray tell, would a parent of anything fail to be a directory?
> + this.name = "pts"; > + this.len = 3; > + this.hash = full_name_hash(this.name, this.len); > + if (parent->d_flags & DCACHE_OP_HASH) { > + int err = parent->d_op->d_hash(parent, &this); > + if (err < 0) > + return err; > + } > + inode_lock(parent->d_inode);
What the hell for? What does that lock on parent change for the dcache lookup you are doing here?
> + child = d_lookup(parent, &this); > + inode_unlock(parent->d_inode); > + if (!child) > + return -ENOENT;
Take a look at d_hash_and_lookup(), BTW...
> + path->dentry = child; > + dput(parent); > + follow_mount(path); > + return 0; > +} > +#endif > + > int user_path_at_empty(int dfd, const char __user *name, unsigned flags, > struct path *path, int *empty) > { > diff --git a/include/linux/devpts_fs.h b/include/linux/devpts_fs.h > index e0ee0b3000b2..486f6282b0c6 100644 > --- a/include/linux/devpts_fs.h > +++ b/include/linux/devpts_fs.h > @@ -17,36 +17,21 @@ > > #ifdef CONFIG_UNIX98_PTYS > > -int devpts_new_index(struct inode *ptmx_inode); > -void devpts_kill_index(struct inode *ptmx_inode, int idx); > -void devpts_add_ref(struct inode *ptmx_inode); > -void devpts_del_ref(struct inode *ptmx_inode); > +struct pts_fs_info; > + > +struct pts_fs_info *devpts_acquire(struct file *filp); > +void devpts_release(struct pts_fs_info *fsi); > + > +int devpts_new_index(struct pts_fs_info *fsi); > +void devpts_kill_index(struct pts_fs_info *fsi, int idx); > /* mknod in devpts */ > -struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index, > +struct inode *devpts_pty_new(struct pts_fs_info *fsi, dev_t device, int index, > void *priv); > /* get private structure */ > void *devpts_get_priv(struct inode *pts_inode); > /* unlink */ > void devpts_pty_kill(struct inode *inode); > > -#else > - > -/* Dummy stubs in the no-pty case */ > -static inline int devpts_new_index(struct inode *ptmx_inode) { return -EINVAL; } > -static inline void devpts_kill_index(struct inode *ptmx_inode, int idx) { } > -static inline void devpts_add_ref(struct inode *ptmx_inode) { } > -static inline void devpts_del_ref(struct inode *ptmx_inode) { } > -static inline struct inode *devpts_pty_new(struct inode *ptmx_inode, > - dev_t device, int index, void *priv) > -{ > - return ERR_PTR(-EINVAL); > -} > -static inline void *devpts_get_priv(struct inode *pts_inode) > -{ > - return NULL; > -} > -static inline void devpts_pty_kill(struct inode *inode) { } > - > #endif > > > diff --git a/include/linux/namei.h b/include/linux/namei.h > index 77d01700daf7..f29abda31e6d 100644 > --- a/include/linux/namei.h > +++ b/include/linux/namei.h > @@ -45,6 +45,8 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; > #define LOOKUP_ROOT 0x2000 > #define LOOKUP_EMPTY 0x4000 > > +extern int path_pts(struct path *path); > + > extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty); > > static inline int user_path_at(int dfd, const char __user *name, unsigned flags, > -- > 2.8.1 >
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