From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: [PATCH 24/32] vfs: syscall: Add fsopen() to prepare for superblock creation [ver #9] Date: Thu, 12 Jul 2018 18:20:24 +0100 Message-ID: <20180712172024.GZ30522@ZenIV.linux.org.uk> References: <153126248868.14533.9751473662727327569.stgit@warthog.procyon.org.uk> <153126264966.14533.3388004240803696769.stgit@warthog.procyon.org.uk> <20180712171505.GA23780@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20180712171505.GA23780@kroah.com> Sender: linux-kernel-owner@vger.kernel.org To: Greg KH Cc: David Howells , linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org List-Id: linux-api@vger.kernel.org On Thu, Jul 12, 2018 at 07:15:05PM +0200, Greg KH wrote: > On Tue, Jul 10, 2018 at 11:44:09PM +0100, David Howells wrote: > > Provide an fsopen() system call that starts the process of preparing to > > create a superblock that will then be mountable, using an fd as a context > > handle. fsopen() is given the name of the filesystem that will be used: > > > > int mfd = fsopen(const char *fsname, unsigned int flags); > > > > where flags can be 0 or FSOPEN_CLOEXEC. > > > > For example: > > > > sfd = fsopen("ext4", FSOPEN_CLOEXEC); > > write(sfd, "s /dev/sdb1"); // note I'm ignoring write's length arg > > write(sfd, "o noatime"); > > write(sfd, "o acl"); > > write(sfd, "o user_attr"); > > write(sfd, "o iversion"); > > write(sfd, "o "); > > write(sfd, "r /my/container"); // root inside the fs > > write(sfd, "x create"); // create the superblock > > Ugh, creating configfs again in a syscall form? I know people love > file descriptors, but can't you do this with a configfs entry instead if > you really want to do this type of thing from userspace in this type of > "style"? > > Why reinvent the wheel again? The damn thing REALLY, REALLY depends upon the fs type. How would you map it on configfs?