linux-ext4 - Re: [PATCH v6 5/6] ext4: disable map

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Message-ID: <20190423142748.GE9910@quack2.suse.cz>
Date:   Tue, 23 Apr 2019 16:27:48 +0200
From:   Jan Kara <jack@...e.cz>
To:     Pankaj Gupta <pagupta@...hat.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@...el.com,
        zwisler@...nel.org, vishal.l.verma@...el.com, 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@...ger.ca,
        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, david@...morbit.com, cohuck@...hat.com,
        xiaoguangrong.eric@...il.com, pbonzini@...hat.com,
        yuval.shaia@...cle.com, kilobyte@...band.pl
Subject: Re: [PATCH v6 5/6] ext4: disable map_sync for async flush

On Tue 23-04-19 13:36:11, Pankaj Gupta wrote:
> Dont support 'MAP_SYNC' with non-DAX files and DAX files
> with asynchronous dax_device. Virtio pmem provides 
> asynchronous host page cache flush mechanism. We don't
> support 'MAP_SYNC' with virtio pmem and ext4.
> 
> Signed-off-by: Pankaj Gupta <pagupta@...hat.com>

The patch looks good to me. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza


> ---
>  fs/ext4/file.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 69d65d49837b..4b2ccaf1932e 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -360,15 +360,16 @@ static const struct vm_operations_struct ext4_file_vm_ops = {
>  static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
>  {
>  	struct inode *inode = file->f_mapping->host;
> +	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> +	struct dax_device *dax_dev = sbi->s_daxdev;
>  
> -	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
> +	if (unlikely(ext4_forced_shutdown(sbi)))
>  		return -EIO;
>  
> -	/*
> -	 * 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(file)) && (vma->vm_flags & VM_SYNC))
> +	if (!daxdev_mapping_supported(vma, dax_dev))
>  		return -EOPNOTSUPP;
>  
>  	file_accessed(file);
> -- 
> 2.20.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR