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From: Matthew Wilcox <willy@infradead.org>
To: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org, v9fs-developer@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, linux-afs@lists.infradead.org,
	ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org,
	ecryptfs@vger.kernel.org, linux-um@lists.infradead.org,
	linux-mtd@lists.infradead.org,
	Richard Weinberger <richard@nod.at>
Subject: Re: [PATCH 01/13] mm: Add AOP_UPDATED_PAGE return value
Date: Thu, 17 Sep 2020 23:03:07 +0100	[thread overview]
Message-ID: <20200917220307.GX5449@casper.infradead.org> (raw)
In-Reply-To: <20200917151050.5363-2-willy@infradead.org>

On Thu, Sep 17, 2020 at 04:10:38PM +0100, Matthew Wilcox (Oracle) wrote:
> +++ b/mm/filemap.c
> @@ -2254,8 +2254,10 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
>  		 * PG_error will be set again if readpage fails.
>  		 */
>  		ClearPageError(page);
> -		/* Start the actual read. The read will unlock the page. */
> +		/* Start the actual read. The read may unlock the page. */
>  		error = mapping->a_ops->readpage(filp, page);
> +		if (error == AOP_UPDATED_PAGE)
> +			goto page_ok;
>  
>  		if (unlikely(error)) {
>  			if (error == AOP_TRUNCATED_PAGE) {

If anybody wants to actually test this, this hunk is wrong.

+++ b/mm/filemap.c
@@ -2256,8 +2256,11 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
                ClearPageError(page);
                /* Start the actual read. The read may unlock the page. */
                error = mapping->a_ops->readpage(filp, page);
-               if (error == AOP_UPDATED_PAGE)
+               if (error == AOP_UPDATED_PAGE) {
+                       unlock_page(page);
+                       error = 0;
                        goto page_ok;
+               }
 
                if (unlikely(error)) {
                        if (error == AOP_TRUNCATED_PAGE) {

> @@ -2619,7 +2621,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
>  	 */
>  	if (unlikely(!PageUptodate(page)))
>  		goto page_not_uptodate;
> -
> +page_ok:
>  	/*
>  	 * We've made it this far and we had to drop our mmap_lock, now is the
>  	 * time to return to the upper layer and have it re-find the vma and
> @@ -2654,6 +2656,8 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
>  	ClearPageError(page);
>  	fpin = maybe_unlock_mmap_for_io(vmf, fpin);
>  	error = mapping->a_ops->readpage(file, page);
> +	if (error == AOP_UPDATED_PAGE)
> +		goto page_ok;
>  	if (!error) {
>  		wait_on_page_locked(page);
>  		if (!PageUptodate(page))
> @@ -2867,6 +2871,10 @@ static struct page *do_read_cache_page(struct address_space *mapping,
>  			err = filler(data, page);
>  		else
>  			err = mapping->a_ops->readpage(data, page);
> +		if (err == AOP_UPDATED_PAGE) {
> +			unlock_page(page);
> +			goto out;
> +		}
>  
>  		if (err < 0) {
>  			put_page(page);
> -- 
> 2.28.0
> 

  reply	other threads:[~2020-09-17 22:03 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 [this message]
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
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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