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From: Christoph Hellwig <hch@infradead.org>
To: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: linux-btrfs@vger.kernel.org, Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 4/9] btrfs: Switch to iomap_dio_rw() for dio
Date: Fri, 27 Mar 2020 01:10:24 -0700	[thread overview]
Message-ID: <20200327081024.GA24827@infradead.org> (raw)
In-Reply-To: <20200326210254.17647-5-rgoldwyn@suse.de>

On Thu, Mar 26, 2020 at 04:02:49PM -0500, Goldwyn Rodrigues wrote:
> BTRFS direct I/O is now done under i_rwsem, shared in case of
> reads and exclusive in case of writes. This guards against simultaneous
> truncates.

Btw, you really want to add the optimization of only taking it shared
for all the easy write cases similar to what XFS has done for ages
and what ext4 picked up now.  Without that performance on someworkloads
is going to be horrible.  That could be a patch on top of this one,
though.

> +/*
> + * btrfs_direct_IO - perform direct I/O
> + * inode->i_rwsem must be locked before calling this function, shared or exclusive.
> + * @iocb - kernel iocb
> + * @iter - iter to/from data is copied

This adds a way too long line.  Also kerneldoc comments go below the
arguments.  Last but not least a lockdep_assert_held is much more useful
than comments trying to document locking patterns..

  reply	other threads:[~2020-03-27  8:10 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-26 21:02 [PATCH 0/9 v7] btrfs direct-io using iomap Goldwyn Rodrigues
2020-03-26 21:02 ` [PATCH 1/9] fs: Export generic_file_buffered_read() Goldwyn Rodrigues
2020-03-26 21:02 ` [PATCH 2/9] iomap: add a filesystem hook for direct I/O bio submission Goldwyn Rodrigues
2020-03-26 21:02 ` [PATCH 3/9] iomap: Remove lockdep_assert_held() Goldwyn Rodrigues
2020-03-26 21:02 ` [PATCH 4/9] btrfs: Switch to iomap_dio_rw() for dio Goldwyn Rodrigues
2020-03-27  8:10   ` Christoph Hellwig [this message]
2020-03-27 16:13     ` Goldwyn Rodrigues
2020-05-07  6:14       ` Christoph Hellwig
2020-05-07 11:37         ` David Sterba
2020-05-07 12:10           ` Christoph Hellwig
2020-05-07 13:44             ` Goldwyn Rodrigues
2020-05-08  3:14             ` Goldwyn Rodrigues
2020-05-09 13:59               ` Christoph Hellwig
2020-05-10  4:06                 ` Goldwyn Rodrigues
2020-05-12 14:58                   ` Christoph Hellwig
2020-05-12 17:19                     ` Goldwyn Rodrigues
2020-05-15 14:13                       ` Christoph Hellwig
2020-05-18 14:36                         ` Goldwyn Rodrigues
2020-05-19 20:11                         ` Goldwyn Rodrigues
2020-05-20  6:11                           ` Christoph Hellwig
2020-05-22 11:36                           ` David Sterba
2020-05-22 12:08                             ` Goldwyn Rodrigues
2020-03-26 21:02 ` [PATCH 5/9] btrfs: Use ->iomap_end() instead of btrfs_dio_data Goldwyn Rodrigues
2020-03-27  8:16   ` Christoph Hellwig
2020-03-27 16:11     ` Goldwyn Rodrigues
2020-03-26 21:02 ` [PATCH 6/9] fs: Remove dio_end_io() Goldwyn Rodrigues
2020-03-26 21:02 ` [PATCH 7/9] btrfs: remove BTRFS_INODE_READDIO_NEED_LOCK Goldwyn Rodrigues
2020-03-26 21:02 ` [PATCH 8/9] btrfs: btrfs: split btrfs_direct_IO Goldwyn Rodrigues
2020-03-26 21:02 ` [PATCH 9/9] btrfs: unlock extents in ->iomap_end() for DIO reads Goldwyn Rodrigues
2020-03-27 15:56 ` [PATCH 0/9 v7] btrfs direct-io using iomap David Sterba

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