From: Christoph Hellwig <hch@lst.de>
To: Andrew Morton <akpm@osdl.org>
Cc: viro@parcelfarce.linux.theplanet.co.uk, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] fs-private data in struct block_device
Date: Fri, 2 Jan 2004 00:22:12 +0100 [thread overview]
Message-ID: <20040101232212.GA5143@lst.de> (raw)
In-Reply-To: <20040101151017.3f7bc407.akpm@osdl.org>
On Thu, Jan 01, 2004 at 03:10:17PM -0800, Andrew Morton wrote:
> Christoph Hellwig <hch@lst.de> wrote:
> >
> > Al had some critism about a per-blockdev XFS datastructure a while ago
> > and so I tried to follow the suggestion in favour of using struct
> > block_device directly. Unfortunately XFS requires a little bit more
> > information than what's available in struct block_device, in particular
> > whether the blocksize (not sector size) for that devices is identical
> > to the page size, and we can't really get that from elsewhere due to
> > layering constraints.
>
> Why doesn't `if (bdev->bd_block_size == PAGE_SIZE)' work?
Because it's different from the XFS block size. In XFS terms it's
the sector size.
> Or sb->s_blocksize?
Would work, except that we don't get at per-superblock data in the
place we need that information - it's in pagebuf which is the IRIX
buffercache interface reimplemented ontop of the Linux pagecache,
and that has neither access to Linux VFS nor XFS-internal data
structures.
> Seems sane. You'll need to decide whether that field should be operated
> upon with atomic ops. If so, document it. If not, document its locking,
> please.
That's completly left to the filesystem. For XFS it would be set once
at mount time and then left constant.
next prev parent reply other threads:[~2004-01-01 23:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-01 16:42 [PATCH] fs-private data in struct block_device Christoph Hellwig
2004-01-01 23:10 ` Andrew Morton
2004-01-01 23:21 ` viro
2004-01-01 23:23 ` Christoph Hellwig
2004-01-01 23:28 ` viro
2004-01-01 23:32 ` Christoph Hellwig
2004-01-04 22:04 ` Randy.Dunlap
2004-01-01 23:22 ` Christoph Hellwig [this message]
2004-01-02 2:43 ` Jeff Garzik
2004-01-02 8:48 ` Christoph Hellwig
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