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From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 16/13] iomap: Make readpage synchronous
Date: Sat, 19 Sep 2020 18:03:14 +0100	[thread overview]
Message-ID: <20200919170314.GO32101@casper.infradead.org> (raw)
In-Reply-To: <20200919064308.GA16257@infradead.org>

On Sat, Sep 19, 2020 at 07:43:08AM +0100, Christoph Hellwig wrote:
> On Sat, Sep 19, 2020 at 07:39:08AM +0100, Christoph Hellwig wrote:
> > I think just adding the completion and status to struct
> > iomap_readpage_ctx would be a lot easier to follow, at the cost
> > of bloating the structure a bit for the readahead case.  If we
> > are realy concerned about that, the completion could be directly
> > on the iomap_readpage stack and we'd pass a pointer.
> 
> Anbother option would be to chain the bios and use submit_bio_wait.
> That would take care of the completion and the status propagation
> withour extra fields and extra code in iomap.

But it wouldn't let us mark some blocks on the page as Uptodate, would it?
As I read the code, chaining two BIOs together will call the parent's
bi_end_io only once both the child and the parent BIOs have completed,
but at the point the parent's bi_end_io is called, the child bio has
already been put and we can't iterate over its bio_vec.

Maybe I misread the code; bio chaining does not seem to be well
documented.

  reply	other threads:[~2020-09-19 17:03 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-17 15:10 [PATCH 00/13] Allow readpage to return a locked page Matthew Wilcox (Oracle)
2020-09-17 15:10 ` [PATCH 01/13] mm: Add AOP_UPDATED_PAGE return value Matthew Wilcox (Oracle)
2020-09-17 22:03   ` Matthew Wilcox
2020-09-17 15:10 ` [PATCH 02/13] 9p: Tell the VFS that readpage was synchronous Matthew Wilcox (Oracle)
2020-09-18  5:59   ` [V9fs-developer] " Dominique Martinet
2020-09-18 11:19     ` Matthew Wilcox
2020-09-18 12:30   ` Dominique Martinet
2020-09-17 15:10 ` [PATCH 03/13] afs: " Matthew Wilcox (Oracle)
2020-09-17 15:10 ` [PATCH 04/13] ceph: " Matthew Wilcox (Oracle)
2020-09-17 16:49   ` Jeff Layton
2020-09-17 15:10 ` [PATCH 05/13] cifs: " Matthew Wilcox (Oracle)
2020-09-17 15:10 ` [PATCH 06/13] cramfs: " Matthew Wilcox (Oracle)
2020-09-17 15:10 ` [PATCH 07/13] ecryptfs: " Matthew Wilcox (Oracle)
2020-09-17 15:10 ` [PATCH 08/13] fuse: " Matthew Wilcox (Oracle)
2020-09-17 15:10 ` [PATCH 09/13] hostfs: " Matthew Wilcox (Oracle)
2020-09-17 15:10 ` [PATCH 10/13] jffs2: " Matthew Wilcox (Oracle)
2020-09-17 15:10 ` [PATCH 11/13] ubifs: " Matthew Wilcox (Oracle)
2020-09-17 20:46   ` Richard Weinberger
2020-09-17 15:10 ` [PATCH 12/13] udf: " Matthew Wilcox (Oracle)
2020-09-24  9:00   ` Jan Kara
2020-09-17 15:10 ` [PATCH 13/13] vboxsf: " Matthew Wilcox (Oracle)
2020-09-17 22:56 ` [PATCH 14/13] iomap: Inline iomap_iop_set_range_uptodate into its one caller Matthew Wilcox (Oracle)
2020-09-17 22:56   ` [PATCH 15/13] iomap: Inline iomap_read_finish " Matthew Wilcox (Oracle)
2020-09-19  6:31     ` Christoph Hellwig
2020-09-17 22:56   ` [PATCH 16/13] iomap: Make readpage synchronous Matthew Wilcox (Oracle)
2020-09-19  6:39     ` Christoph Hellwig
2020-09-19  6:43       ` Christoph Hellwig
2020-09-19 17:03         ` Matthew Wilcox [this message]
2020-09-19 17:10       ` Matthew Wilcox
2020-09-19  6:31   ` [PATCH 14/13] iomap: Inline iomap_iop_set_range_uptodate into its one caller Christoph Hellwig

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