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From: David Sterba <dsterba@suse.cz>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Christian Brauner <brauner@kernel.org>,
	Christoph Hellwig <hch@lst.de>,
	linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	linux-btrfs@vger.kernel.org,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2 7/9] btrfs_get_bdev_and_sb(): call set_blocksize() only for exclusive opens
Date: Fri, 10 May 2024 15:41:40 +0200	[thread overview]
Message-ID: <20240510134140.GT13977@twin.jikos.cz> (raw)
In-Reply-To: <20240503032329.2392931-7-viro@zeniv.linux.org.uk>

On Fri, May 03, 2024 at 04:23:27AM +0100, Al Viro wrote:
> btrfs_get_bdev_and_sb() has two callers - btrfs_open_one_device(),
> which asks for open to be exclusive and btrfs_get_dev_args_from_path(),
> which doesn't.  Currently it does set_blocksize() in all cases.
> 
> I'm rather dubious about the need to do set_blocksize() anywhere in btrfs,
> to be honest - there's some access to page cache of underlying block
> devices in there, but it's nowhere near the hot paths, AFAICT.
> 
> In any case, btrfs_get_dev_args_from_path() only needs to read
> the on-disk superblock and copy several fields out of it; all
> callers are only interested in devices that are already opened
> and brought into per-filesystem set, so setting the block size
> is redundant for those and actively harmful if we are given
> a pathname of unrelated device.
> 
> So we only need btrfs_get_bdev_and_sb() to call set_blocksize()
> when it's asked to open exclusive.
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Christian Brauner <brauner@kernel.org>
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Acked-by: David Sterba <dsterba@suse.com>

  reply	other threads:[~2024-05-10 13:41 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-27 21:09 [PATCHES][RFC] set_blocksize() rework Al Viro
2024-04-27 21:10 ` [PATCH 1/7] bcache_register(): don't bother with set_blocksize() Al Viro
2024-04-29  5:06   ` Christoph Hellwig
2024-04-29  8:37   ` Christian Brauner
2024-04-27 21:10 ` [PATCH 2/7] pktcdvd: sort set_blocksize() calls out Al Viro
2024-04-29  5:07   ` Christoph Hellwig
2024-04-29  8:38   ` Christian Brauner
2024-04-27 21:10 ` [PATCH 3/7] swapon(2)/swapoff(2): don't bother with block size Al Viro
2024-04-29  5:08   ` Christoph Hellwig
2024-04-29  8:38   ` Christian Brauner
2024-04-27 21:11 ` [PATCH 4/7] swapon(2): open swap with O_EXCL Al Viro
2024-04-27 21:40   ` Linus Torvalds
2024-04-27 23:46     ` Al Viro
2024-04-28  1:25       ` Al Viro
2024-04-28 18:19       ` Al Viro
2024-04-28 18:46         ` Linus Torvalds
2024-04-28 19:07           ` Al Viro
2024-04-29  5:10             ` Christoph Hellwig
2024-04-29  5:09   ` Christoph Hellwig
2024-04-29  8:39   ` Christian Brauner
2024-04-27 21:11 ` [PATCH 5/7] swsusp: don't bother with setting block size Al Viro
2024-04-29  5:10   ` Christoph Hellwig
2024-04-29  8:40   ` Christian Brauner
2024-04-27 21:12 ` [PATCH 6/7] btrfs_get_dev_args_from_path(): don't call set_blocksize() Al Viro
2024-04-29  5:11   ` Christoph Hellwig
2024-04-29  8:40   ` Christian Brauner
2024-04-29 15:11   ` David Sterba
2024-04-30  2:05     ` Al Viro
2024-04-27 21:13 ` [PATCH 7/7] set_blocksize(): switch to passing struct file *, fail if it's not opened exclusive Al Viro
2024-04-29  5:12   ` Christoph Hellwig
2024-04-29  8:42   ` Christian Brauner
2024-05-03  3:18 ` [PATCHES v2][RFC] set_blocksize() rework Al Viro
2024-05-03  3:23   ` [PATCH v2 1/9] bcache_register(): don't bother with set_blocksize() Al Viro
2024-05-03  3:23     ` [PATCH v2 2/9] pktcdvd: sort set_blocksize() calls out Al Viro
2024-05-03  3:23     ` [PATCH v2 3/9] swapon(2)/swapoff(2): don't bother with block size Al Viro
2024-05-03  3:23     ` [PATCH v2 4/9] swapon(2): open swap with O_EXCL Al Viro
2024-05-03  3:23     ` [PATCH v2 5/9] zram: don't bother with reopening - just use O_EXCL for open Al Viro
2024-05-03  3:23     ` [PATCH v2 6/9] swsusp: don't bother with setting block size Al Viro
2024-05-03  3:23     ` [PATCH v2 7/9] btrfs_get_bdev_and_sb(): call set_blocksize() only for exclusive opens Al Viro
2024-05-10 13:41       ` David Sterba [this message]
2024-05-03  3:23     ` [PATCH v2 8/9] set_blocksize(): switch to passing struct file * Al Viro
2024-05-03  3:23     ` [PATCH v2 9/9] make set_blocksize() fail unless block device is opened exclusive Al Viro
2024-05-03  4:17   ` [PATCH v2 1/9] bcache_register(): don't bother with set_blocksize() Al Viro
2024-05-03  4:17     ` [PATCH v2 2/9] pktcdvd: sort set_blocksize() calls out Al Viro
2024-05-03  4:17     ` [PATCH v2 3/9] swapon(2)/swapoff(2): don't bother with block size Al Viro
2024-05-03  4:17     ` [PATCH v2 4/9] swapon(2): open swap with O_EXCL Al Viro
2024-05-03  4:17     ` [PATCH v2 5/9] zram: don't bother with reopening - just use O_EXCL for open Al Viro
2024-05-03  4:17     ` [PATCH v2 6/9] swsusp: don't bother with setting block size Al Viro
2024-05-03  4:17     ` [PATCH v2 7/9] btrfs_get_bdev_and_sb(): call set_blocksize() only for exclusive opens Al Viro
2024-05-03  4:17     ` [PATCH v2 8/9] set_blocksize(): switch to passing struct file * Al Viro
2024-05-03  4:17     ` [PATCH v2 9/9] make set_blocksize() fail unless block device is opened exclusive Al Viro

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