From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 14/17] xfs: use bios directly to read and write the log recovery buffers
Date: Tue, 21 May 2019 09:32:33 +1000 [thread overview]
Message-ID: <20190520233233.GF29573@dread.disaster.area> (raw)
In-Reply-To: <20190520161347.3044-15-hch@lst.de>
On Mon, May 20, 2019 at 06:13:44PM +0200, Christoph Hellwig wrote:
> The xfs_buf structure is basically used as a glorified container for
> a vmalloc allocation in the log recovery code. Replace it with a
> real vmalloc implementation and just build bios directly as needed
> to read into or write from it to simplify things a bit.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
I like the way the series runs in general, and the end result is a
fair bit neater, but I'm struggling to work out how we translate
this to the userspace code that uses uncached/raw buffer IO.
i.e. I'm in the process of porting the xfs_buf.c code to userspace,
and was using the uncached buffer API to provide the bits the
log code and other raw IO users (xfs_db, repair prefetch) with this
functionality through the API this patchset removes.
I wrote the patches a couple of days ago to move all this uncached
IO and kernel memory and device specific stuff to a xfs_buftarg.[ch]
files. This leaves xfs_buf.c as purely cached buffer management
code, has no bio stuff in it, no memory allocation, no shrinkers,
LRUs, etc).
So while it's easy to drop the uncached buffer API from the kernel
side, it leaves me with the question of what API do we use in
userspace to provide this same functionality? I suspect that we
probably need to separate all this log-to-bio code out into a
separate file (e.g. xfs_log_io.[ch]) to leave a set of API stubs
that we can reimplement in userspace to pread/pwrite directly to
the log buftarg device fd as I've done already for the buffer
code...
Thoughts?
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2019-05-20 23:32 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-20 16:13 use bios directly in the log code Christoph Hellwig
2019-05-20 16:13 ` [PATCH 01/17] xfs: remove the no-op spinlock_destroy stub Christoph Hellwig
2019-05-20 16:13 ` [PATCH 02/17] xfs: remove the never used _XBF_COMPOUND flag Christoph Hellwig
2019-05-20 16:13 ` [PATCH 03/17] xfs: renumber XBF_WRITE_FAIL Christoph Hellwig
2019-05-20 16:13 ` [PATCH 04/17] xfs: reformat xlog_get_lowest_lsn Christoph Hellwig
2019-05-20 16:13 ` [PATCH 05/17] xfs: don't use REQ_PREFLUSH for split log writes Christoph Hellwig
2019-05-20 16:13 ` [PATCH 06/17] xfs: factor out log buffer writing Christoph Hellwig
2019-05-20 16:13 ` [PATCH 07/17] xfs: factor out splitting of an iclog from xlog_sync Christoph Hellwig
2019-05-20 16:13 ` [PATCH 08/17] xfs: split iclog size calculation out of xlog_sync Christoph Hellwig
2019-05-20 16:13 ` [PATCH 09/17] xfs: update both state counters together in xlog_sync Christoph Hellwig
2019-05-20 16:13 ` [PATCH 10/17] xfs: remove the syncing argument from xlog_verify_iclog Christoph Hellwig
2019-05-20 16:13 ` [PATCH 11/17] xfs: make use of the l_targ field in struct xlog Christoph Hellwig
2019-05-20 16:13 ` [PATCH 12/17] xfs: use bios directly to write log buffers Christoph Hellwig
2019-05-20 16:13 ` [PATCH 13/17] xfs: return an offset instead of a pointer from xlog_align Christoph Hellwig
2019-05-20 16:13 ` [PATCH 14/17] xfs: use bios directly to read and write the log recovery buffers Christoph Hellwig
2019-05-20 23:32 ` Dave Chinner [this message]
2019-05-21 5:09 ` Christoph Hellwig
2019-05-21 22:24 ` Dave Chinner
2019-05-22 5:12 ` Christoph Hellwig
2019-05-22 6:19 ` Dave Chinner
2019-05-22 17:31 ` Christoph Hellwig
2019-05-22 23:28 ` Dave Chinner
2019-05-23 6:22 ` Christoph Hellwig
2019-05-20 16:13 ` [PATCH 15/17] xfs: remove unused buffer cache APIs Christoph Hellwig
2019-05-20 16:13 ` [PATCH 16/17] xfs: properly type the b_log_item field in struct xfs_buf Christoph Hellwig
2019-05-20 16:13 ` [PATCH 17/17] xfs: remove the b_io_length " Christoph Hellwig
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