From: Christoph Hellwig <hch@lst.de>
To: Omar Sandoval <osandov@osandov.com>
Cc: Christoph Hellwig <hch@lst.de>,
linux-btrfs@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 12/15] btrfs: get rid of one layer of bios in direct I/O
Date: Mon, 16 Mar 2020 11:49:26 +0100 [thread overview]
Message-ID: <20200316104926.GB14886@lst.de> (raw)
In-Reply-To: <20200311091940.GF252106@vader>
On Wed, Mar 11, 2020 at 02:19:40AM -0700, Omar Sandoval wrote:
> On Tue, Mar 10, 2020 at 05:38:35PM +0100, Christoph Hellwig wrote:
> > On Mon, Mar 09, 2020 at 02:32:38PM -0700, Omar Sandoval wrote:
> > > 1. The bio created by the generic direct I/O code (dio_bio).
> > > 2. A clone of dio_bio we create in btrfs_submit_direct() to represent
> > > the entire direct I/O range (orig_bio).
> > > 3. A partial clone of orig_bio limited to the size of a RAID stripe that
> > > we create in btrfs_submit_direct_hook().
> > > 4. Clones of each of those split bios for each RAID stripe that we
> > > create in btrfs_map_bio().
> >
> > Just curious: what is number 3 useful for?
>
> The next thing we do with bio 2 (which has a logical block address) is
> to map it to physical block addresses on each device (btrfs_map_bio()).
> That mapping is per-stripe, so we either have to avoid building bios
> that cross a stripe (which is what buffered I/O does)
And which seems inherently sensible..
> or we have to
> split up the bio (which is what direct I/O does). We probably want to
> move towards the first approach for direct I/O, as well, but reworking
> get_blocks would conflict with the iomap series, and it looks like that
> would be easier to do using iomap instead, anyways.
True.
next prev parent reply other threads:[~2020-03-16 10:49 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-09 21:32 [PATCH 00/15] btrfs: read repair/direct I/O improvements Omar Sandoval
2020-03-09 21:32 ` [PATCH 01/15] btrfs: fix error handling when submitting direct I/O bio Omar Sandoval
2020-03-11 17:54 ` Josef Bacik
2020-03-17 13:46 ` Nikolay Borisov
2020-03-09 21:32 ` [PATCH 02/15] btrfs: fix double __endio_write_update_ordered in direct I/O Omar Sandoval
2020-03-10 16:30 ` Christoph Hellwig
2020-03-11 9:03 ` Omar Sandoval
2020-03-17 14:04 ` Nikolay Borisov
2020-03-09 21:32 ` [PATCH 03/15] btrfs: look at full bi_io_vec for repair decision Omar Sandoval
2020-03-10 16:33 ` Christoph Hellwig
2020-03-11 9:07 ` Omar Sandoval
2020-03-16 10:48 ` Christoph Hellwig
2020-03-17 14:38 ` Nikolay Borisov
2020-03-09 21:32 ` [PATCH 04/15] btrfs: don't do repair validation for checksum errors Omar Sandoval
2020-03-11 17:55 ` Josef Bacik
2020-03-09 21:32 ` [PATCH 05/15] btrfs: clarify btrfs_lookup_bio_sums documentation Omar Sandoval
2020-03-11 17:56 ` Josef Bacik
2020-03-11 18:23 ` Omar Sandoval
2020-03-11 18:34 ` Josef Bacik
2020-03-17 14:38 ` Nikolay Borisov
2020-03-09 21:32 ` [PATCH 06/15] btrfs: rename __readpage_endio_check to check_data_csum Omar Sandoval
2020-03-10 14:46 ` Johannes Thumshirn
2020-03-11 17:57 ` Josef Bacik
2020-03-17 14:39 ` Nikolay Borisov
2020-03-09 21:32 ` [PATCH 07/15] btrfs: make btrfs_check_repairable() static Omar Sandoval
2020-03-10 14:53 ` Johannes Thumshirn
2020-03-11 17:58 ` Josef Bacik
2020-03-17 14:52 ` Nikolay Borisov
2020-03-09 21:32 ` [PATCH 08/15] btrfs: move btrfs_dio_private to inode.c Omar Sandoval
2020-03-10 14:56 ` Johannes Thumshirn
2020-03-11 8:48 ` Omar Sandoval
2020-03-17 14:53 ` Nikolay Borisov
2020-03-19 16:16 ` David Sterba
2020-03-09 21:32 ` [PATCH 09/15] btrfs: kill btrfs_dio_private->private Omar Sandoval
2020-03-11 17:59 ` Josef Bacik
2020-03-17 14:54 ` Nikolay Borisov
2020-03-09 21:32 ` [PATCH 10/15] btrfs: convert btrfs_dio_private->pending_bios to refcount_t Omar Sandoval
2020-03-11 18:00 ` Josef Bacik
2020-03-17 15:10 ` Nikolay Borisov
2020-03-09 21:32 ` [PATCH 11/15] btrfs: put direct I/O checksums in btrfs_dio_private instead of bio Omar Sandoval
2020-03-11 18:04 ` Josef Bacik
2020-03-17 16:37 ` Nikolay Borisov
2020-04-03 16:18 ` David Sterba
2020-03-09 21:32 ` [PATCH 12/15] btrfs: get rid of one layer of bios in direct I/O Omar Sandoval
2020-03-10 16:38 ` Christoph Hellwig
2020-03-11 9:19 ` Omar Sandoval
2020-03-16 10:49 ` Christoph Hellwig [this message]
2020-03-11 18:07 ` Josef Bacik
2020-03-17 16:48 ` Nikolay Borisov
2020-03-09 21:32 ` [PATCH 13/15] btrfs: simplify direct I/O read repair Omar Sandoval
2020-03-11 18:16 ` Josef Bacik
2020-04-03 16:40 ` David Sterba
2020-04-03 18:05 ` Omar Sandoval
2020-04-16 10:08 ` David Sterba
2020-03-09 21:32 ` [PATCH 14/15] btrfs: get rid of endio_repair_workers Omar Sandoval
2020-03-11 18:16 ` Josef Bacik
2020-03-09 21:32 ` [PATCH 15/15] btrfs: unify buffered and direct I/O read repair Omar Sandoval
2020-03-11 18:19 ` Josef Bacik
2020-03-19 8:53 ` Nikolay Borisov
2020-03-19 9:03 ` Christoph Hellwig
2020-03-20 21:28 ` Omar Sandoval
2020-03-10 16:39 ` [PATCH 00/15] btrfs: read repair/direct I/O improvements Christoph Hellwig
2020-03-11 9:22 ` Omar Sandoval
2020-03-18 16:33 ` Goldwyn Rodrigues
2020-03-19 14:08 ` David Sterba
2020-03-18 22:07 ` David Sterba
2020-03-20 21:29 ` Omar Sandoval
2020-03-20 14:10 ` Christoph Hellwig
2020-03-20 14:11 ` Christoph Hellwig
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