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[209.132.180.67]) by mx.google.com with ESMTP id m21si15763776pgv.453.2019.04.04.02.41.08; Thu, 04 Apr 2019 02:41:23 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731910AbfDDJkf (ORCPT + 99 others); Thu, 4 Apr 2019 05:40:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:45822 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728676AbfDDJkd (ORCPT ); Thu, 4 Apr 2019 05:40:33 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 4E461AC24; Thu, 4 Apr 2019 09:40:30 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 7D4DD1E11C8; Thu, 4 Apr 2019 11:40:29 +0200 (CEST) Date: Thu, 4 Apr 2019 11:40:29 +0200 From: Jan Kara To: Pankaj Gupta Cc: "Darrick J. Wong" , Dave Chinner , linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-acpi@vger.kernel.org, qemu-devel@nongnu.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, dan j williams , zwisler@kernel.org, vishal l verma , dave jiang , mst@redhat.com, jasowang@redhat.com, willy@infradead.org, rjw@rjwysocki.net, hch@infradead.org, lenb@kernel.org, jack@suse.cz, tytso@mit.edu, adilger kernel , lcapitulino@redhat.com, kwolf@redhat.com, imammedo@redhat.com, jmoyer@redhat.com, nilal@redhat.com, riel@surriel.com, stefanha@redhat.com, aarcange@redhat.com, david@redhat.com, cohuck@redhat.com, xiaoguangrong eric Subject: Re: [PATCH v4 5/5] xfs: disable map_sync for async flush Message-ID: <20190404094029.GD16131@quack2.suse.cz> References: <20190403104018.23947-1-pagupta@redhat.com> <20190403104018.23947-6-pagupta@redhat.com> <20190403220912.GB26298@dastard> <20190403223921.GM5147@magnolia> <1508883801.17367965.1554358418550.JavaMail.zimbra@redhat.com> <651986267.17402634.1554368950178.JavaMail.zimbra@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <651986267.17402634.1554368950178.JavaMail.zimbra@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 04-04-19 05:09:10, Pankaj Gupta wrote: > > > > On Thu, Apr 04, 2019 at 09:09:12AM +1100, Dave Chinner wrote: > > > > On Wed, Apr 03, 2019 at 04:10:18PM +0530, Pankaj Gupta wrote: > > > > > Virtio pmem provides asynchronous host page cache flush > > > > > mechanism. we don't support 'MAP_SYNC' with virtio pmem > > > > > and xfs. > > > > > > > > > > Signed-off-by: Pankaj Gupta > > > > > --- > > > > > fs/xfs/xfs_file.c | 8 ++++++++ > > > > > 1 file changed, 8 insertions(+) > > > > > > > > > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > > > > > index 1f2e2845eb76..dced2eb8c91a 100644 > > > > > --- a/fs/xfs/xfs_file.c > > > > > +++ b/fs/xfs/xfs_file.c > > > > > @@ -1203,6 +1203,14 @@ xfs_file_mmap( > > > > > if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC)) > > > > > return -EOPNOTSUPP; > > > > > > > > > > + /* We don't support synchronous mappings with DAX files if > > > > > + * dax_device is not synchronous. > > > > > + */ > > > > > + if (IS_DAX(file_inode(filp)) && !dax_synchronous( > > > > > + xfs_find_daxdev_for_inode(file_inode(filp))) && > > > > > + (vma->vm_flags & VM_SYNC)) > > > > > + return -EOPNOTSUPP; > > > > > + > > > > > file_accessed(filp); > > > > > vma->vm_ops = &xfs_file_vm_ops; > > > > > if (IS_DAX(file_inode(filp))) > > > > > > > > All this ad hoc IS_DAX conditional logic is getting pretty nasty. > > > > > > > > xfs_file_mmap( > > > > .... > > > > { > > > > struct inode *inode = file_inode(filp); > > > > > > > > if (vma->vm_flags & VM_SYNC) { > > > > if (!IS_DAX(inode)) > > > > return -EOPNOTSUPP; > > > > if (!dax_synchronous(xfs_find_daxdev_for_inode(inode)) > > > > return -EOPNOTSUPP; > > > > } > > > > > > > > file_accessed(filp); > > > > vma->vm_ops = &xfs_file_vm_ops; > > > > if (IS_DAX(inode)) > > > > vma->vm_flags |= VM_HUGEPAGE; > > > > return 0; > > > > } > > > > > > > > > > > > Even better, factor out all the "MAP_SYNC supported" checks into a > > > > helper so that the filesystem code just doesn't have to care about > > > > the details of checking for DAX+MAP_SYNC support.... > > > > > > Seconded, since ext4 has nearly the same flag validation logic. > > > > Only issue with this I see is we need the helper function only for supported > filesystems ext4 & xfs (right now). If I create the function in "fs.h" it > will be compiled for every filesystem, even for those don't need it. > > Sample patch below, does below patch is near to what you have in mind? So I would put the helper in include/linux/dax.h and have it like: bool daxdev_mapping_supported(struct vm_area_struct *vma, struct dax_device *dax_dev) { if (!(vma->vm_flags & VM_SYNC)) return true; if (!IS_DAX(file_inode(vma->vm_file))) return false; return dax_synchronous(dax_dev); } Honza > > ================= > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 1f2e2845eb76..614995170cac 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -1196,12 +1196,17 @@ xfs_file_mmap( > struct file *filp, > struct vm_area_struct *vma) > { > + struct dax_device *dax_dev = xfs_find_daxdev_for_inode(file_inode(filp)); > + > /* > - * We don't support synchronous mappings for non-DAX files. At least > - * until someone comes with a sensible use case. > + * We don't support synchronous mappings for non-DAX files and > + * for DAX files if underneath dax_device is not synchronous. > */ > - if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC)) > - return -EOPNOTSUPP; > + if (vma->vm_flags & VM_SYNC) { > + int err = is_synchronous(filp, dax_dev); > + if (err) > + return err; > + } > > file_accessed(filp); > vma->vm_ops = &xfs_file_vm_ops; > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 8b42df09b04c..add017de3dd7 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -2162,6 +2162,20 @@ static inline void file_accessed(struct file *file) > touch_atime(&file->f_path); > } > > +struct dax_device; > +extern bool dax_synchronous(struct dax_device *dax_dev); > +static inline int is_synchronous(struct file *filp, struct dax_device *dax_dev) > +{ > + struct inode *inode = file_inode(filp); > + > + if (!IS_DAX(inode)) > + return -EOPNOTSUPP; > + if (!dax_synchronous(dax_dev)) > + return -EOPNOTSUPP; > + > + return 0; > +} > + > int sync_inode(struct inode *inode, struct writeback_control *wbc); > int sync_inode_metadata(struct inode *inode, int wait); > > --------- > > Thanks, > Pankaj > > > -- Jan Kara SUSE Labs, CR