Messages in this thread | | | Date | Tue, 7 Mar 2017 18:49:09 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC] Add option to mount only a pids subset |
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I can't really review this... but in any case I think you should split this patch to separate the vfs and proc changes.
On 03/07, Alexey Gladkov wrote: > > @@ -962,6 +963,14 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void > mnt->mnt.mnt_sb = root->d_sb; > mnt->mnt_mountpoint = mnt->mnt.mnt_root; > mnt->mnt_parent = mnt; > + > + err = do_mount_sb(&mnt->mnt, flags, data); > + if(err) { > + mnt_free_id(mnt); > + free_vfsmnt(mnt); > + return ERR_PTR(err); > + }
This duplicates the error handling, we do the same if mount_fs() fails. Perhaps you should move these 2 lines into cleanup block and add goto's.
> +int proc_getattrfs(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) > +{ > + struct inode *inode = d_inode(dentry); > + struct pid *pid = proc_pid(dentry->d_inode); > + struct proc_options *opts = mnt->fs_data; > + > + if (opts && opts->pid_only && mnt->mnt_root != dentry && !pid) > + return -ENOENT;
Hmm. I don't quite understand why do we need this, and how this should work.
Yes, "/bin/ls /pidonly-proc/sys" or opendir(/pidonly-proc/sys) should fail, but only because they both do stat() ?
Afaics you still can do open("/pidonly-proc/sys") + getdents() and this should work ?
I still think proc_dir_operations.open() makes more sense. Yes, as you pointed out we also need to update proc_sys_dir_file_operations too and may be something else...
> + > + if (!inode->i_op->getattr) { > + generic_fillattr(inode, stat); > + return 0; > + } > + > + return inode->i_op->getattr(mnt, dentry, stat); > +}
Oh, it would be nice to not duplicate the code from the caller, imo.
Oleg.
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