From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: dsterba@suse.cz, linux-btrfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 01/15] btrfs: create a mount option for dax
Date: Mon, 1 Apr 2019 15:43:30 -0500 [thread overview]
Message-ID: <20190401204330.iaiyqvhaydkdjvrr@merlin> (raw)
In-Reply-To: <20190328172825.GQ29086@twin.jikos.cz>
On 18:28 28/03, 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.
I am glad you brought this up.
>
> To be verified:
>
> - balance - at least profile changes must be forbidden
>
> - defrag
Disabled for now with EOPNOTSUPP primarily because of (null) readpages()
in dax.
>
> - compression - as it needs COW, it won't work on the nodatacow files,
> thus seems to be ok
Compression would require some sort of processing before writes. However,
users are writing directly to disk. So no, this can't be supported either.
>
> - 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
--
Goldwyn
next prev parent reply other threads:[~2019-04-01 20:43 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
2019-04-01 20:43 ` Goldwyn Rodrigues [this message]
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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