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From: David Howells <dhowells@redhat.com>
To: Trond Myklebust <trondmy@hammerspace.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Steve French <sfrench@samba.org>,
	Dominique Martinet <asmadeus@codewreck.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Christoph Hellwig <hch@lst.de>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Christoph Hellwig <hch@lst.de>,
	linux-mm@kvack.org, linux-cachefs@redhat.com,
	linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org,
	linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
	v9fs-developer@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org, dhowells@redhat.com,
	Jeff Layton <jlayton@redhat.com>,
	David Wysochanski <dwysocha@redhat.com>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-cachefs@redhat.com, linux-afs@lists.infradead.org,
	linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org,
	ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 02/28] mm: Add an unlock function for PG_private_2/PG_fscache
Date: Wed, 10 Mar 2021 16:54:49 +0000	[thread overview]
Message-ID: <161539528910.286939.1252328699383291173.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <161539526152.286939.8589700175877370401.stgit@warthog.procyon.org.uk>

Add a function, unlock_page_private_2(), to unlock PG_private_2 analogous
to that of PG_lock.  Add a kerneldoc banner to that indicating the example
usage case.

A wrapper will need to be placed in the netfs header in the patch that adds
that.

[This implements a suggestion by Linus[1] to not mix the terminology of
 PG_private_2 and PG_fscache in the mm core function]

Changes:
- Remove extern from the declaration[2].

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
cc: Matthew Wilcox (Oracle) <willy@infradead.org>
cc: Alexander Viro <viro@zeniv.linux.org.uk>
cc: Christoph Hellwig <hch@lst.de>
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/1330473.1612974547@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/CAHk-=wjgA-74ddehziVk=XAEMTKswPu1Yw4uaro1R3ibs27ztw@mail.gmail.com/ [1]
Link: https://lore.kernel.org/r/20210216102659.GA27714@lst.de/ [2]
Link: https://lore.kernel.org/r/161340387944.1303470.7944159520278177652.stgit@warthog.procyon.org.uk/ # v3
---

 include/linux/pagemap.h |    1 +
 mm/filemap.c            |   20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 20225b067583..ac91b33f3873 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -591,6 +591,7 @@ extern int __lock_page_async(struct page *page, struct wait_page_queue *wait);
 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 				unsigned int flags);
 extern void unlock_page(struct page *page);
+void unlock_page_private_2(struct page *page);
 
 /*
  * Return true if the page was successfully locked
diff --git a/mm/filemap.c b/mm/filemap.c
index 43700480d897..925964b67583 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1432,6 +1432,26 @@ void unlock_page(struct page *page)
 }
 EXPORT_SYMBOL(unlock_page);
 
+/**
+ * unlock_page_private_2 - Unlock a page that's locked with PG_private_2
+ * @page: The page
+ *
+ * Unlocks a page that's locked with PG_private_2 and wakes up sleepers in
+ * wait_on_page_private_2().
+ *
+ * This is, for example, used when a netfs page is being written to a local
+ * disk cache, thereby allowing writes to the cache for the same page to be
+ * serialised.
+ */
+void unlock_page_private_2(struct page *page)
+{
+	page = compound_head(page);
+	VM_BUG_ON_PAGE(!PagePrivate2(page), page);
+	clear_bit_unlock(PG_private_2, &page->flags);
+	wake_up_page_bit(page, PG_private_2);
+}
+EXPORT_SYMBOL(unlock_page_private_2);
+
 /**
  * end_page_writeback - end writeback against a page
  * @page: the page



  parent reply	other threads:[~2021-03-10 16:55 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-10 16:54 [PATCH v4 00/28] Network fs helper library & fscache kiocb API David Howells
2021-03-10 16:54 ` [PATCH v4 01/28] iov_iter: Add ITER_XARRAY David Howells
2021-03-10 16:54 ` David Howells [this message]
2021-03-16 19:07   ` [PATCH v4 02/28] mm: Add an unlock function for PG_private_2/PG_fscache Matthew Wilcox
2021-03-17  0:43     ` Linus Torvalds
2021-03-17  0:43       ` Linus Torvalds
2021-03-17  2:12       ` Josef Bacik
2021-03-17  2:35         ` Linus Torvalds
2021-03-17  2:35           ` Linus Torvalds
2021-03-17  9:04         ` David Howells
2021-03-17 10:53         ` David Howells
2021-03-16 20:38   ` David Howells
2021-03-16 23:32     ` Matthew Wilcox
2021-03-21 10:53   ` Matthew Wilcox
2021-03-22 10:56   ` David Howells
2021-03-23 13:17   ` David Howells
2021-03-23 13:51     ` Matthew Wilcox
2021-03-23 14:16     ` David Howells
2021-03-23 22:06     ` David Howells
2021-03-23 22:06       ` David Howells
2021-03-10 16:55 ` [PATCH v4 03/28] mm: Implement readahead_control pageset expansion David Howells
2021-03-10 16:55 ` [PATCH v4 04/28] netfs: Make a netfs helper module David Howells
2021-03-10 16:55 ` [PATCH v4 05/28] netfs: Documentation for helper library David Howells
2021-03-10 16:55 ` [PATCH v4 06/28] netfs, mm: Move PG_fscache helper funcs to linux/netfs.h David Howells
2021-03-10 16:56 ` [PATCH v4 07/28] netfs, mm: Add unlock_page_fscache() and wait_on_page_fscache() David Howells
2021-03-10 16:56 ` [PATCH v4 08/28] netfs: Provide readahead and readpage netfs helpers David Howells
2021-03-21  1:42   ` Matthew Wilcox
2021-03-22 17:13   ` David Howells
2021-03-10 16:56 ` [PATCH v4 09/28] netfs: Add tracepoints David Howells
2021-03-10 16:56 ` [PATCH v4 10/28] netfs: Gather stats David Howells
2021-03-10 16:56 ` [PATCH v4 11/28] netfs: Add write_begin helper David Howells
2021-03-10 16:57 ` [PATCH v4 12/28] netfs: Define an interface to talk to a cache David Howells
2021-03-10 16:57 ` [PATCH v4 13/28] netfs: Hold a ref on a page when PG_private_2 is set David Howells
2021-03-10 16:57 ` [PATCH v4 14/28] fscache, cachefiles: Add alternate API to use kiocb for read/write to cache David Howells
2021-03-10 16:57 ` [PATCH v4 15/28] afs: Disable use of the fscache I/O routines David Howells
2021-03-10 16:58 ` [PATCH v4 16/28] afs: Pass page into dirty region helpers to provide THP size David Howells
2021-03-10 16:58 ` [PATCH v4 17/28] afs: Print the operation debug_id when logging an unexpected data version David Howells
2021-03-10 16:58 ` [PATCH v4 18/28] afs: Move key to afs_read struct David Howells
2021-03-10 16:58 ` [PATCH v4 19/28] afs: Don't truncate iter during data fetch David Howells
2021-03-10 16:58 ` [PATCH v4 20/28] afs: Log remote unmarshalling errors David Howells
2021-03-10 16:59 ` [PATCH v4 21/28] afs: Set up the iov_iter before calling afs_extract_data() David Howells
2021-03-10 16:59 ` [PATCH v4 22/28] afs: Use ITER_XARRAY for writing David Howells
2021-03-10 16:59 ` [PATCH v4 23/28] afs: Wait on PG_fscache before modifying/releasing a page David Howells
2021-03-10 16:59 ` [PATCH v4 24/28] afs: Extract writeback extension into its own function David Howells
2021-03-10 16:59 ` [PATCH v4 25/28] afs: Prepare for use of THPs David Howells
2021-03-10 17:00 ` [PATCH v4 26/28] afs: Use the fs operation ops to handle FetchData completion David Howells
2021-03-10 17:00 ` [PATCH v4 27/28] afs: Use new fscache read helper API David Howells
2021-03-10 17:00 ` [PATCH v4 28/28] afs: Use the fscache_write_begin() helper David Howells
2021-03-16 11:34 ` [PATCH v4 08/28] netfs: Provide readahead and readpage netfs helpers David Howells

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