From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: "Darrick J. Wong" <djwong@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
Christian Brauner <christian@brauner.io>,
linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-xfs@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: allow building a kernel without buffer_heads v3
Date: Tue, 1 Aug 2023 19:21:55 +0200 [thread overview]
Message-ID: <20230801172201.1923299-1-hch@lst.de> (raw)
Hi all,
This series allows to build a kernel without buffer_heads, which I
think is useful to show where the dependencies are, and maybe also
for some very much limited environments, where people just needs
xfs and/or btrfs and some of the read-only block based file systems.
It first switches buffered writes (but not writeback) for block devices
to use iomap unconditionally, but still using buffer_heads, and then
adds a CONFIG_BUFFER_HEAD selected by all file systems that need it
(which is most block based file systems), makes the buffer_head support
in iomap optional, and adds an alternative implementation of the block
device address_operations using iomap. This latter implementation
will also be useful to support block size > PAGE_SIZE for block device
nodes as buffer_heads won't work very well for that.
Note that for now the md software raid drivers is also disabled as it has
some (rather questionable) buffer_head usage in the unconditionally built
bitmap code. I have a series pending to make the bitmap code conditional
and deprecated it, but it hasn't been merged yet.
This series is against Jens' for-6.6/block branch.
Changes since v2:
- fix handling of a negative return value from blkdev_direct_IO
- drop a WARN_ON that can happen when resizing block devices
- define away IOMAP_F_BUFFER_HEAD to keep the intrusions to the
iomap code minimal (even if that's not quite my preferred style)
Changes since v1:
- drop the already merged prep patches
- depend on FS_IOMAP not IOMAP
- pick a better new name for block_page_mkwrite_return
next reply other threads:[~2023-08-01 17:49 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-01 17:21 Christoph Hellwig [this message]
2023-08-01 17:21 ` [PATCH 1/6] fs: remove emergency_thaw_bdev Christoph Hellwig
2023-08-02 7:21 ` Christian Brauner
2023-08-02 15:13 ` Jens Axboe
2023-08-01 17:21 ` [PATCH 2/6] fs: rename and move block_page_mkwrite_return Christoph Hellwig
2023-08-02 7:22 ` Christian Brauner
2023-08-01 17:21 ` [PATCH 3/6] block: open code __generic_file_write_iter for blkdev writes Christoph Hellwig
2023-08-01 17:48 ` Hannes Reinecke
2023-08-01 18:11 ` Luis Chamberlain
2023-08-02 7:26 ` Christian Brauner
2023-08-02 10:06 ` Johannes Thumshirn
2023-08-29 2:06 ` Al Viro
2023-08-29 13:03 ` Christoph Hellwig
2023-08-01 17:21 ` [PATCH 4/6] block: stop setting ->direct_IO Christoph Hellwig
2023-08-29 2:13 ` Al Viro
2023-08-01 17:22 ` [PATCH 5/6] block: use iomap for writes to block devices Christoph Hellwig
2023-08-02 7:27 ` Christian Brauner
2023-08-02 11:50 ` Johannes Thumshirn
2024-04-26 10:37 ` Xu Yang
2024-05-08 1:45 ` Xu Yang
2023-08-01 17:22 ` [PATCH 6/6] fs: add CONFIG_BUFFER_HEAD Christoph Hellwig
2023-08-02 11:51 ` Johannes Thumshirn
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