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Date: Thu, 4 Apr 2019 02:12:30 -0400 (EDT)
From: Pankaj Gupta <pagupta@...hat.com>
To: Dave Chinner <david@...morbit.com>,
darrick wong <darrick.wong@...cle.com>
Cc: linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-acpi@...r.kernel.org,
qemu-devel@...gnu.org, linux-ext4@...r.kernel.org,
linux-xfs@...r.kernel.org,
dan j williams <dan.j.williams@...el.com>,
zwisler@...nel.org, vishal l verma <vishal.l.verma@...el.com>,
dave jiang <dave.jiang@...el.com>, mst@...hat.com,
jasowang@...hat.com, willy@...radead.org, rjw@...ysocki.net,
hch@...radead.org, lenb@...nel.org, jack@...e.cz, tytso@....edu,
adilger kernel <adilger.kernel@...ger.ca>,
darrick wong <darrick.wong@...cle.com>, lcapitulino@...hat.com,
kwolf@...hat.com, imammedo@...hat.com, jmoyer@...hat.com,
nilal@...hat.com, riel@...riel.com, stefanha@...hat.com,
aarcange@...hat.com, david@...hat.com, cohuck@...hat.com,
xiaoguangrong eric <xiaoguangrong.eric@...il.com>
Subject: Re: [PATCH v4 5/5] xfs: disable map_sync for async flush
Hi Dave,
> > 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 <pagupta@...hat.com>
> > ---
> > 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;
> }
Sure, this is better.
>
>
> 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....
o.k. Will add one common helper function for both ext4 & xfs filesystems.
Thanks for the suggestion.
Best regards,
Pankaj
>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@...morbit.com
>
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