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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 02/33] mm: Add an unlock function for PG_private_2/PG_fscache From: David Howells To: Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet Cc: Linus Torvalds , Linus Torvalds , "Matthew Wilcox (Oracle)" , Alexander Viro , Christoph Hellwig , 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 , David Wysochanski , "Matthew Wilcox (Oracle)" , Alexander Viro , 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 Date: Mon, 15 Feb 2021 15:44:39 +0000 Message-ID: <161340387944.1303470.7944159520278177652.stgit@warthog.procyon.org.uk> In-Reply-To: <161340385320.1303470.2392622971006879777.stgit@warthog.procyon.org.uk> References: <161340385320.1303470.2392622971006879777.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 to not mix the terminology of PG_private_2 and PG_fscache in the mm core function] Suggested-by: Linus Torvalds Signed-off-by: David Howells cc: Linus Torvalds cc: Matthew Wilcox (Oracle) cc: Alexander Viro cc: Christoph Hellwig 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/linux-fsdevel/1330473.1612974547@warthog.procyon.org.uk/ Link: https://lore.kernel.org/linux-fsdevel/CAHk-=wjgA-74ddehziVk=XAEMTKswPu1Yw4uaro1R3ibs27ztw@mail.gmail.com/ Reviewed-by: Christoph Hellwig --- 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 d5570deff400..365a28ece763 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); +extern 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 5c9d564317a5..7d321152d579 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1466,6 +1466,26 @@ 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