Messages in this thread | | | From | (Eric W. Biederman) | Date | Tue, 19 Apr 2016 22:43:03 -0500 | Subject | Re: [PATCH] devpts: Make each mount of devpts an independent filesystem. |
| |
Al Viro <viro@ZenIV.linux.org.uk> writes:
> 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?
It is to make that function be visually distinct from path_parentat which does something rather different.
>> + 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?
Good point. That is overkill. As we know the dentry is a mount point and must be in the dcache, the customary lock for performing a lookup from the disk is not necessary.
>> + child = d_lookup(parent, &this); >> + inode_unlock(parent->d_inode); >> + if (!child) >> + return -ENOENT; > > Take a look at d_hash_and_lookup(), BTW...
Yes. That does look like a reasonable simplification.
Eric
| |