From: Al Viro <viro@zeniv.linux.org.uk>
To: linux-fsdevel@vger.kernel.org
Cc: Yu Kuai <yukuai1@huaweicloud.com>,
linux-block@vger.kernel.org,
Christian Brauner <brauner@kernel.org>,
Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>
Subject: [PATCHES][RFC] packing struct block_device flags
Date: Sun, 28 Apr 2024 06:12:32 +0100 [thread overview]
Message-ID: <20240428051232.GU2118490@ZenIV> (raw)
We have several bool members in struct block_device.
It would be nice to pack that stuff, preferably without
blowing the cacheline boundaries.
That had been suggested a while ago, and initial
implementation by Yu Kuai <yukuai1@huaweicloud.com> ran into
objections re atomicity, along with the obvious suggestion to
use unsigned long and test_bit/set_bit/clear_bit for access.
Unfortunately, that *does* blow the cacheline boundaries.
However, it's not hard to do that without bitops;
we have an 8-bit assign-once partition number nearby, and
folding it into a 32-bit member leaves us up to 24 bits for
flags. Using cmpxchg for setting/clearing flags is not
hard, and 32bit cmpxchg is supported everywhere.
Series below does that conversion. Please, review.
Individual patches in followups, the branch is in
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git #work.bd_flags
Shortlog:
Al Viro (8):
Use bdev_is_paritition() instead of open-coding it
wrapper for access to ->bd_partno
bdev: infrastructure for flags
bdev: move ->bd_read_only to ->__bd_flags
bdev: move ->bd_write_holder into ->__bd_flags
bdev: move ->bd_has_subit_bio to ->__bd_flags
bdev: move ->bd_ro_warned to ->__bd_flags
bdev: move ->bd_make_it_fail to ->__bd_flags
Diffstat:
block/bdev.c | 17 ++++++++---------
block/blk-core.c | 17 ++++++++++-------
block/blk-mq.c | 2 +-
block/early-lookup.c | 2 +-
block/genhd.c | 15 ++++++++++-----
block/ioctl.c | 5 ++++-
block/partitions/core.c | 12 ++++++------
include/linux/blk_types.h | 19 +++++++++++--------
include/linux/blkdev.h | 42 +++++++++++++++++++++++++++++++++++++++---
include/linux/part_stat.h | 2 +-
lib/vsprintf.c | 4 ++--
11 files changed, 93 insertions(+), 44 deletions(-)
next reply other threads:[~2024-04-28 5:12 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-28 5:12 Al Viro [this message]
2024-04-28 5:14 ` [PATCH 1/8] Use bdev_is_paritition() instead of open-coding it Al Viro
2024-04-29 5:19 ` Christoph Hellwig
2024-04-28 5:15 ` [PATCH 2/8] wrapper for access to ->bd_partno Al Viro
2024-04-28 5:16 ` [PATCH 3/8] bdev: infrastructure for flags Al Viro
2024-04-28 5:17 ` [PATCH 4/8] bdev: move ->bd_read_only to ->__bd_flags Al Viro
2024-04-28 5:18 ` [PATCH 5/8] bdev: move ->bd_write_holder into ->__bd_flags Al Viro
2024-04-28 5:19 ` [PATCH 6/8] bdev: move ->bd_has_subit_bio to ->__bd_flags Al Viro
2024-04-28 5:19 ` [PATCH 7/8] bdev: move ->bd_ro_warned " Al Viro
2024-04-28 5:21 ` [PATCH 8/8] bdev: move ->bd_make_it_fail " Al Viro
2024-04-29 5:23 ` [PATCHES][RFC] packing struct block_device flags Christoph Hellwig
2024-04-29 7:31 ` Al Viro
2024-04-29 17:02 ` Al Viro
2024-04-29 18:13 ` Al Viro
2024-04-29 18:30 ` Al Viro
2024-05-03 0:06 ` Al Viro
2024-05-03 0:07 ` [PATCH 1/8] Use bdev_is_paritition() instead of open-coding it Al Viro
2024-05-03 0:07 ` [PATCH 2/8] wrapper for access to ->bd_partno Al Viro
2024-05-03 0:08 ` [PATCH v2 3/8] bdev: infrastructure for flags Al Viro
2024-05-03 0:09 ` [PATCH v2 4/8] bdev: move ->bd_read_only to ->__bd_flags Al Viro
2024-05-03 0:09 ` [PATCH v2 5/8] bdev: move ->bd_write_holder into ->__bd_flags Al Viro
2024-05-03 0:10 ` [PATCH v2 6/8] bdev: move ->bd_has_subit_bio to ->__bd_flags Al Viro
2024-05-03 0:10 ` [PATCH v2 7/8] bdev: move ->bd_ro_warned " Al Viro
2024-05-03 0:11 ` [PATCH v2 8/8] bdev: move ->bd_make_it_fail " Al Viro
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