[PATCH v4 02/28] mm: Add an unlock function for PG_private_2/PG_fscache
From: David Howells <dhowells@redhat.com>
Date: 2021-03-10 16:55:56
Also in:
ceph-devel, linux-cifs, linux-fsdevel, linux-nfs, lkml
Subsystem:
memory management, page cache, the rest · Maintainers:
Andrew Morton, Matthew Wilcox, Jan Kara, Linus Torvalds
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/ (local) # v1 Link: https://lore.kernel.org/r/CAHk-=wjgA-74ddehziVk=XAEMTKswPu1Yw4uaro1R3ibs27ztw@mail.gmail.com/ (local) [1] Link: https://lore.kernel.org/r/20210216102659.GA27714@lst.de/ (local) [2] Link: https://lore.kernel.org/r/161340387944.1303470.7944159520278177652.stgit@warthog.procyon.org.uk/ (local) # 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