From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <569DA62B.7070701@codeaurora.org> Date: Mon, 18 Jan 2016 18:57:47 -0800 From: Nikhilesh Reddy MIME-Version: 1.0 To: Linus Torvalds CC: Andy Lutomirski , Nikolaus Rath , fuse-devel , Al Viro , Greg KH , linux-fsdevel , Linux API , Jan Kara , Theodore Ts'o , sven.utcke@gmx.de, Miklos Szeredi , Richard Weinberger , Linux Kernel Mailing List , Antonio SJ Musumeci Subject: Re: [PATCH] fuse: Add support for fuse stacked I/O References: <565394BE.4040506@codeaurora.org> <5696E366.2080605@codeaurora.org> <20160114045716.GB8006@kroah.com> <5697EF97.9020800@codeaurora.org> <871t9i91e1.fsf@thinkpad.rath.org> <56994884.9060002@codeaurora.org> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: On 01/15/2016 01:53 PM, Linus Torvalds wrote: > On Fri, Jan 15, 2016 at 1:46 PM, Andy Lutomirski wrote: > >> If mmap sets vm_file to the underlying thing, wouldn't CRIU and >> anything else that uses map_files get confused? Or did you have >> something else in mind? > > Why would they care? > > Also, I don't think you actually need to change vm_file - we have this > whole notion of "inode->i_data" vs "inode->i_mapping". > > So I think you could set the "i_mapping" of the fuse inode to be the > i_mapping of the passed-through-to inode, and it should just work. > > And no, I didn't look into this very deeply, and maybe there is some > annoying detail that would make that not work well. But that's part of > the whole point of the i_mapping indirection: so that you can share > the page cache when you have two separate anchor points. I think coda > uses it for the local caching, and block devices use it to not have > mapping aliases between different inodex that all are the same block > device. > > Linus > Hi Thanks for your support. I am looking into adding the mmap by change the i_mmaping but seems to be getting stuck for some stress tests. Once i get that debugged and working i will definitely send out a new patch with that functionality. ( Sending it as a second patch will help make it easier to go through the legal redtape and procedures i am forced to follow). For now i am going to update the current patch and call it "passthrough" as you suggested and also update the commit message giving a clearer explanation of the motivation. Once i get it tested I can send it out for consideration and review Please do let me know if you have any questions or concerns on this and i will try my best to address them all. -- Thanks Nikhilesh Reddy Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.