From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: dsterba@suse.cz, Goldwyn Rodrigues <rgoldwyn@suse.de>,
linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 01/15] btrfs: create a mount option for dax
Date: Thu, 28 Mar 2019 10:57:36 -0700 [thread overview]
Message-ID: <20190328175736.GA1177@magnolia> (raw)
In-Reply-To: <20190328172825.GQ29086@twin.jikos.cz>
On Thu, Mar 28, 2019 at 06:28:25PM +0100, David Sterba wrote:
> On Tue, Mar 26, 2019 at 02:02:47PM -0500, Goldwyn Rodrigues wrote:
> > From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> >
> > This sets S_DAX in inode->i_flags, which can be used with
> > IS_DAX().
> >
> > The dax option is restricted to non multi-device mounts.
> > dax interacts with the device directly instead of using bio, so
> > all bio-hooks which we use for multi-device cannot be performed
> > here. While regular read/writes could be manipulated with
> > RAID0/1, mmap() is still an issue.
>
> I'm looking for other features that would not work with dax. Disabling
> multiple devices strikes out device add, device delete and device
> replace.
>
> To be verified:
>
> - balance - at least profile changes must be forbidden
>
> - defrag
>
> - compression - as it needs COW, it won't work on the nodatacow files,
> thus seems to be ok
>
> - resize/grow - this could work without changes, no block relocation is
> needed, only new structures created
>
> - resize/shrink - depends on balance, the block groups from the removed
> area need to be relocated
>
> - swapfiles - I'm sure somebody will try that; I haven't seen any
> IS_DAX checks in the swapfile activation code
I've never tried dax swapfiles, but so long as you can issue bios to the
underlying bdev they ought to work, right? Even if the swap code could
be streamlined by memcpy in the dax case.
(Granted I have no idea what sort of bio-hooks magic btrfs does, maybe
it really doesn't work there...)
--D
next prev parent reply other threads:[~2019-03-28 17:57 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190326190301.32365-1-rgoldwyn@suse.de>
2019-03-26 19:02 ` [PATCH 01/15] btrfs: create a mount option for dax Goldwyn Rodrigues
2019-03-26 19:10 ` Matthew Wilcox
2019-03-27 11:00 ` Goldwyn Rodrigues
2019-03-27 12:00 ` Matthew Wilcox
2019-03-27 12:26 ` Goldwyn Rodrigues
2019-03-27 23:31 ` Goldwyn Rodrigues
2019-03-27 17:38 ` Adam Borowski
2019-03-28 14:49 ` David Sterba
2019-03-28 17:28 ` David Sterba
2019-03-28 17:57 ` Darrick J. Wong [this message]
2019-04-01 20:43 ` Goldwyn Rodrigues
2019-03-26 19:02 ` [PATCH 02/15] btrfs: Carve out btrfs_get_extent_map_write() out of btrfs_get_blocks_write() Goldwyn Rodrigues
2019-03-26 19:02 ` [PATCH 03/15] btrfs: basic dax read Goldwyn Rodrigues
2019-03-26 19:02 ` [PATCH 04/15] dax: Introduce IOMAP_F_COW for copy-on-write Goldwyn Rodrigues
2019-03-27 17:54 ` Darrick J. Wong
2019-03-27 18:58 ` Goldwyn Rodrigues
2019-03-28 14:45 ` Darrick J. Wong
2019-04-01 4:38 ` Dave Chinner
2019-04-01 21:41 ` Goldwyn Rodrigues
2019-04-01 23:06 ` Dave Chinner
2019-04-03 1:56 ` Goldwyn Rodrigues
2019-04-03 3:20 ` Dave Chinner
2019-04-07 7:26 ` Christoph Hellwig
2019-03-26 19:02 ` [PATCH 05/15] btrfs: return whether extent is nocow or not Goldwyn Rodrigues
2019-03-31 18:42 ` Nikolay Borisov
2019-03-26 19:02 ` [PATCH 06/15] btrfs: Rename __endio_write_update_ordered() to btrfs_update_ordered_extent() Goldwyn Rodrigues
2019-03-26 19:02 ` [PATCH 07/15] btrfs: add dax write support Goldwyn Rodrigues
2019-03-28 14:53 ` Darrick J. Wong
2019-04-01 20:39 ` Goldwyn Rodrigues
2019-03-26 19:02 ` [PATCH 08/15] dax: add dax_iomap_cow to copy a mmap page before writing Goldwyn Rodrigues
2019-03-28 15:41 ` Darrick J. Wong
2019-03-26 19:02 ` [PATCH 09/15] btrfs: add dax mmap support Goldwyn Rodrigues
2019-03-28 15:45 ` Darrick J. Wong
2019-03-26 19:02 ` [PATCH 10/15] btrfs: Add dax specific address_space_operations Goldwyn Rodrigues
2019-03-26 19:02 ` [PATCH 11/15] fs: dedup file range to use a compare function Goldwyn Rodrigues
2019-03-28 17:04 ` Darrick J. Wong
2019-04-01 20:36 ` Goldwyn Rodrigues
2019-03-26 19:02 ` [PATCH 12/15] btrfs: trace functions for btrfs_iomap_begin/end Goldwyn Rodrigues
2019-03-26 19:02 ` [PATCH 13/15] btrfs: handle dax page zeroing Goldwyn Rodrigues
2019-03-26 19:03 ` [PATCH 14/15] btrfs: Disable dax-based defrag and send Goldwyn Rodrigues
2019-03-26 19:03 ` [PATCH 15/15] btrfs: Writeprotect mmap pages on snapshot Goldwyn Rodrigues
2019-03-28 15:48 ` Darrick J. Wong
2019-03-26 19:09 ` [PATCH v2 00/15] btrfs dax support Goldwyn Rodrigues
2019-03-27 20:14 ` Adam Borowski
2019-03-27 23:26 ` Goldwyn Rodrigues
2019-03-28 10:24 ` [PATCH] btrfs: allow MAP_SYNC mmap Adam Borowski
2019-03-28 10:42 ` Adam Borowski
2019-04-01 20:08 ` Goldwyn Rodrigues
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