From: Kent Overstreet <kent.overstreet@linux.dev>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-bcachefs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org,
Kent Overstreet <kent.overstreet@gmail.com>,
linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 04/20] block: Add some exports for bcachefs
Date: Tue, 1 Aug 2023 14:59:40 -0400 [thread overview]
Message-ID: <20230801185940.b4vsd62fjxwzv7ft@moria.home.lan> (raw)
In-Reply-To: <ZMEdqvzAUbQPs0io@infradead.org>
On Wed, Jul 26, 2023 at 06:20:42AM -0700, Christoph Hellwig wrote:
> On Mon, Jul 24, 2023 at 11:00:37PM -0400, Kent Overstreet wrote:
> > In short, iomap is heavily callback based, the bcachefs io paths are
> > not - we pass around data structures instead. I discussed this with
> > people when iomap was first being written, but iomap ended up being a
> > much more conservative approach, more in line with the old buffer heads
> > code where the generic code calls into the filesystem to obtain
> > mappings.
> >
> > I'm gradually convincing people of the merits of the bcachefs approach -
> > in particular reducing indirect function calls is getting more attention
> > these days.
>
> FYI, Matthew has had patches that convert iomap to be an iterator,
> and I've massage the first half of them and actuall got them in
> before. I'd much rather finish off that work (even if only for
> direct I/O initially) than adding another direct I/O code. But
> even with out that we should be able to easily pass more private
> data, in fact btrfs makes pretty heavy use of that.
That's wonderful, but getting iomap up to the level of what bcachefs
needs is still going to be a pretty big project and it's not going to be
my highest priority.
bcachefs also hangs more state off of the pagecache, in bcachefs's
equivvalent of iomap_page - we store reservations for dirty data there
and a few other things, which means the buffered IO paths don't have to
walk any other data structures.
I think that's another idea you guys will want to steal, but a higher
priority for me is getting a proper FUSE port done - and making bcachefs
more tightly weddded to VFS library code is not likely to make that
process any easier.
Once a proper fuse port is done and we know what that looks like will be
a better time for some consolidation.
next prev parent reply other threads:[~2023-08-01 19:00 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-12 21:10 [PATCH 00/20] bcachefs prereqs patch series Kent Overstreet
2023-07-12 21:10 ` [PATCH 01/20] sched: Add task_struct->faults_disabled_mapping Kent Overstreet
2023-07-12 21:10 ` [PATCH 02/20] fs: factor out d_mark_tmpfile() Kent Overstreet
2023-07-12 21:10 ` [PATCH 03/20] iov_iter: Handle compound highmem pages in copy_page_from_iter_atomic() Kent Overstreet
2023-07-12 21:10 ` [PATCH 04/20] block: Add some exports for bcachefs Kent Overstreet
2023-07-24 17:31 ` Christoph Hellwig
2023-07-25 3:00 ` Kent Overstreet
2023-07-26 13:20 ` Christoph Hellwig
2023-08-01 18:59 ` Kent Overstreet [this message]
2023-07-25 2:59 ` Matthew Wilcox
2023-07-12 21:11 ` [PATCH 05/20] block: Allow bio_iov_iter_get_pages() with bio->bi_bdev unset Kent Overstreet
2023-07-24 17:34 ` Christoph Hellwig
2023-07-25 2:43 ` Kent Overstreet
2023-07-26 13:23 ` Christoph Hellwig
2023-08-01 19:04 ` Kent Overstreet
2023-08-02 11:47 ` Christoph Hellwig
2023-08-02 16:44 ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 06/20] block: Bring back zero_fill_bio_iter Kent Overstreet
2023-07-24 17:35 ` Christoph Hellwig
2023-07-25 2:45 ` Kent Overstreet
2023-07-26 13:21 ` Christoph Hellwig
2023-08-01 19:05 ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 07/20] block: Don't block on s_umount from __invalidate_super() Kent Overstreet
2023-07-12 21:11 ` [PATCH 08/20] stacktrace: Export stack_trace_save_tsk Kent Overstreet
2023-07-12 21:11 ` [PATCH 09/20] lib/string_helpers: string_get_size() now returns characters wrote Kent Overstreet
2023-07-12 21:11 ` [PATCH 10/20] lib: Export errname Kent Overstreet
2023-07-13 7:10 ` Eric Biggers
2023-07-12 21:11 ` [PATCH 11/20] locking/osq: Export osq_(lock|unlock) Kent Overstreet
2023-08-02 20:16 ` Waiman Long
2023-08-02 20:44 ` Kent Overstreet
2023-08-02 21:09 ` Waiman Long
2023-08-02 21:42 ` Kent Overstreet
2023-10-10 8:09 ` [NAK] " Ingo Molnar
2023-10-18 21:04 ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 12/20] bcache: move closures to lib/ Kent Overstreet
2023-07-13 3:21 ` Randy Dunlap
2023-07-13 3:52 ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 13/20] MAINTAINERS: Add entry for closures Kent Overstreet
2023-07-12 21:11 ` [PATCH 14/20] closures: closure_wait_event() Kent Overstreet
2023-07-12 21:11 ` [PATCH 15/20] closures: closure_nr_remaining() Kent Overstreet
2023-07-12 21:11 ` [PATCH 16/20] closures: Add a missing include Kent Overstreet
2023-07-12 21:11 ` [PATCH 17/20] MAINTAINERS: Add entry for generic-radix-tree Kent Overstreet
2023-07-12 21:11 ` [PATCH 18/20] lib/generic-radix-tree.c: Don't overflow in peek() Kent Overstreet
2023-07-12 21:11 ` [PATCH 19/20] lib/generic-radix-tree.c: Add a missing include Kent Overstreet
2023-07-25 3:04 ` Matthew Wilcox
2023-07-25 3:36 ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 20/20] lib/generic-radix-tree.c: Add peek_prev() Kent Overstreet
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