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From: Chuck Lever <chuck.lever@oracle.com>
To: Matthew Wilcox <willy@infradead.org>,
	David Howells <dhowells@redhat.com>,
	Dave Wysochanski <dwysocha@redhat.com>
Cc: Trond Myklebust <trondmy@hammerspace.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Steve French <sfrench@samba.org>,
	Dominique Martinet <asmadeus@codewreck.org>,
	Jeff Layton <jlayton@redhat.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	linux-cachefs <linux-cachefs@redhat.com>,
	"linux-afs@lists.infradead.org" <linux-afs@lists.infradead.org>,
	Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
	CIFS <linux-cifs@vger.kernel.org>,
	"ceph-devel@vger.kernel.org" <ceph-devel@vger.kernel.org>,
	"v9fs-developer@lists.sourceforge.net" 
	<v9fs-developer@lists.sourceforge.net>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache
Date: Tue, 26 Jan 2021 15:24:31 +0000
Message-ID: <D6C85B77-17CA-4BA6-9C2C-C63A8AF613AB@oracle.com> (raw)
In-Reply-To: <20210126013611.GI308988@casper.infradead.org>



> On Jan 25, 2021, at 8:36 PM, Matthew Wilcox <willy@infradead.org> wrote:
> 
> 
> For Subject: s/readpage/readpages/
> 
> On Mon, Jan 25, 2021 at 09:37:29PM +0000, David Howells wrote:
>> +int __nfs_readahead_from_fscache(struct nfs_readdesc *desc,
>> +				 struct readahead_control *rac)
> 
> I thought you wanted it called ractl instead of rac?  That's what I've
> been using in new code.
> 
>> -	dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
>> -		 nfs_i_fscache(inode), npages, inode);
>> +	dfprintk(FSCACHE, "NFS: nfs_readahead_from_fscache (0x%p/0x%p)\n",
>> +		 nfs_i_fscache(inode), inode);
> 
> We do have readahead_count() if this is useful information to be logging.

As a sidebar, the Linux NFS community is transitioning to tracepoints.
It would be helpful (but not completely necessary) to use tracepoints
in new code instead of printk.


>> +static inline int nfs_readahead_from_fscache(struct nfs_readdesc *desc,
>> +					     struct readahead_control *rac)
>> {
>> -	if (NFS_I(inode)->fscache)
>> -		return __nfs_readpages_from_fscache(ctx, inode, mapping, pages,
>> -						    nr_pages);
>> +	if (NFS_I(rac->mapping->host)->fscache)
>> +		return __nfs_readahead_from_fscache(desc, rac);
>> 	return -ENOBUFS;
>> }
> 
> Not entirely sure that it's worth having the two functions separated any more.
> 
>> 	/* attempt to read as many of the pages as possible from the cache
>> 	 * - this returns -ENOBUFS immediately if the cookie is negative
>> 	 */
>> -	ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
>> -					 pages, &nr_pages);
>> +	ret = nfs_readahead_from_fscache(&desc, rac);
>> 	if (ret == 0)
>> 		goto read_complete; /* all pages were read */
>> 
>> 	nfs_pageio_init_read(&desc.pgio, inode, false,
>> 			     &nfs_async_read_completion_ops);
>> 
>> -	ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
>> +	while ((page = readahead_page(rac))) {
>> +		ret = readpage_async_filler(&desc, page);
>> +		put_page(page);
>> +	}
> 
> I thought with the new API we didn't need to do this kind of thing
> any more?  ie no matter whether fscache is configured in or not, it'll
> submit the I/Os.

--
Chuck Lever




  reply index

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
2021-01-25 21:31 ` [PATCH 01/32] iov_iter: Add ITER_XARRAY David Howells
2021-01-25 21:31 ` [PATCH 02/32] vm: Add wait/unlock functions for PG_fscache David Howells
2021-01-25 21:31 ` [PATCH 03/32] mm: Implement readahead_control pageset expansion David Howells
2021-01-25 21:31 ` [PATCH 04/32] vfs: Export rw_verify_area() for use by cachefiles David Howells
2021-01-25 21:31 ` [PATCH 05/32] netfs: Make a netfs helper module David Howells
2021-01-25 21:32 ` [PATCH 06/32] netfs: Provide readahead and readpage netfs helpers David Howells
2021-01-25 21:32 ` [PATCH 07/32] netfs: Add tracepoints David Howells
2021-01-25 21:32 ` [PATCH 08/32] netfs: Gather stats David Howells
2021-01-25 21:32 ` [PATCH 09/32] netfs: Add write_begin helper David Howells
2021-01-25 21:32 ` [PATCH 10/32] netfs: Define an interface to talk to a cache David Howells
2021-01-25 21:32 ` [PATCH 11/32] fscache, cachefiles: Add alternate API to use kiocb for read/write to cache David Howells
2021-01-25 21:33 ` [PATCH 12/32] afs: Disable use of the fscache I/O routines David Howells
2021-01-25 21:33 ` [PATCH 13/32] afs: Pass page into dirty region helpers to provide THP size David Howells
2021-01-25 21:33 ` [PATCH 14/32] afs: Print the operation debug_id when logging an unexpected data version David Howells
2021-01-25 21:33 ` [PATCH 15/32] afs: Move key to afs_read struct David Howells
2021-01-25 21:34 ` [PATCH 16/32] afs: Don't truncate iter during data fetch David Howells
2021-01-25 21:34 ` [PATCH 17/32] afs: Log remote unmarshalling errors David Howells
2021-01-25 21:34 ` [PATCH 18/32] afs: Set up the iov_iter before calling afs_extract_data() David Howells
2021-01-25 21:34 ` [PATCH 19/32] afs: Use ITER_XARRAY for writing David Howells
2021-01-25 21:34 ` [PATCH 20/32] afs: Wait on PG_fscache before modifying/releasing a page David Howells
2021-01-25 21:35 ` [PATCH 21/32] afs: Extract writeback extension into its own function David Howells
2021-01-25 21:35 ` [PATCH 22/32] afs: Prepare for use of THPs David Howells
2021-01-25 21:35 ` [PATCH 23/32] afs: Use the fs operation ops to handle FetchData completion David Howells
2021-01-25 21:35 ` [PATCH 24/32] afs: Use new fscache read helper API David Howells
2021-01-25 21:35 ` [PATCH 25/32] NFS: Clean up nfs_readpage() and nfs_readpages() David Howells
2021-01-26  3:59   ` Matthew Wilcox
2021-01-26 15:33     ` David Wysochanski
2021-01-25 21:36 ` [PATCH 26/32] NFS: In nfs_readpage() only increment NFSIOS_READPAGES when read succeeds David Howells
2021-01-25 21:36 ` [PATCH 27/32] NFS: Refactor nfs_readpage() and nfs_readpage_async() to use nfs_readdesc David Howells
2021-01-26  4:05   ` Matthew Wilcox
2021-01-26 15:24     ` David Wysochanski
2021-01-25 21:36 ` [PATCH 28/32] NFS: Call readpage_async_filler() from nfs_readpage_async() David Howells
2021-01-25 21:36 ` [PATCH 29/32] NFS: Add nfs_pageio_complete_read() and remove nfs_readpage_async() David Howells
2021-01-25 21:37 ` [PATCH 30/32] NFS: Allow internal use of read structs and functions David Howells
2021-01-25 21:37 ` [PATCH 31/32] NFS: Convert to the netfs API and nfs_readpage to use netfs_readpage David Howells
2021-01-25 21:37 ` [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache David Howells
2021-01-26  1:36   ` Matthew Wilcox
2021-01-26 15:24     ` Chuck Lever [this message]
2021-01-26 19:10       ` David Wysochanski
2021-01-26 18:25     ` David Wysochanski

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